- Email: [email protected]
The combined effect of cisplatin and furosemide on hearing function in guinea pigs
19
Hearing Research, 38 (1989) 19-26 Elsevier
HRR 01168
The combined
effect of cisplatin and furosemide in guinea pigs
on hearing function
Gbran Laurel1 1-2and Berit Engstrijm
1-3
’ Institute of Physiology II, Karolinska Institute, Stockholm, Sweden, and Departments of ’ Otorhinolaryngology, and ’ Audiology, Karolinska (Received
4 January
Hospital, Stockholm,
1988; accepted
11 October
Sweden 1988)
The effect of the combined administration of cisplatin and furosemide on the electrophysiological hearing thresholds and endocochlear DC potential (EP) was studied in guinea pigs. A lack of interaction was found in animals given repeated intraperitoneal injections of a low dose of cisplatin with a pharmacological dose of furosemide. An ototoxic interaction occurred when a moderately high dose of cisplatin was administered intravenously at a time when the strial function was most affected by a very high dose of furosemide. The interaction was seen both as a decreased EP and a pronounced shift of auditory thresholds. It is concluded that the stria vascularis plays a role in the ototoxic mechanism of cisplatin. Interaction;
Electrophysiological
hearing
thresholds;
Endocochlear
Introduction The antineoplastic drug cisplatin was first introduced into clinical trials in 1971. The platinum coordination complex has been shown to have an effect against a variety of solid human tumors. Cisplatin is nowadays used alone, or in combination with other antineoplastic drugs, in the treatment of an increasing number of patients. Like many other chemotherapeutic agents, cisplatin has severe side effects. Of these, nephrotoxicity was initially considered to be the most serious, but since the introduction of prehydration and mannitolor furosemide-induced diuresis, the incidence and severity of renal insufficiency have been reduced (Hayes et al., 1977; Cvitkovic et al., 1977; Ward et al., 1977; Pera et al., 1979; Ostrow et al., 1981). Inner ear toxicity is an other well-known side effect of cisplatin (Rossof et al., 1972; Lippman et al., 1973; Pie1 et al., 1974; Aguilar-Markulis et al.,
Correspondence to: Giiran Laurell, Institute of Physiology Karolinska Institute, S-104 01 Stockholm, Sweden. 0378-5955/89/$03.50
0 1989 Elsevier Science Publishers
II,
DC potential
1981; Brown et al., 1983; Laurel1 and Borg, 1988). With use of the high-dose regimen, ototoxicity can be the dose-limiting side effect. The side effects are the more important to consider since the antitumor effect is usually palliative and not curative. Morphologic alterations in the cochlea due to cisplatin administration have been documented in several animal and human studies (Fleischman et al., 1975; Estrem et al., 1981; Nakai et al., 1982; Wright and Schaeffer, 1982; Strauss et al., 1983; Tange and Vuzevski, 1984). The degenerative pattern seems to be similar to that produced by the aminoglycosides. The most obvious alteration is destruction of the outer hair cells (OHCs) of the organ of Corti. The first row of the OHCs is the most severely affected, and the most pronounced loss of OHCs occurs in the basal turn of the cochlea. However, the primary action of cisplatin responsible for the pathologic changes in the inner ear is not known. The loop diuretic furosemide is widely used in clinical practice, and is also given to patients undergoing chemotherapy. Its primary site of action has been found to be located at the ascending thick limb of the loop of Henle, where it inhibits
B.V. (Biomedical
Division)
20
the active transport of chloride ions and consequently of sodium ions (Burg et al., 1973). Ototoxicity is a rare side effect of furosemide (Schwartz et al., 1970), but it has been observed in several animal experimental studies. The stria vascularis is suggested as the primary target of the toxic action in the cochlea. The changes consist of marginal cell swelling, shrinkage of the intermediate cells and enlargement of intracellular spaces (Pike and Bosher, 1980; Forge and Brown, 1982). At a high dose, furosemide causes dramatic suppression of the endocochlear DC potential (EP). When furosemide is given i.v. in a high dose, the EP may even become negative; it reaches its lowest level after 2.3 min and thereafter starts to recover (Pike and Bosher, 1980). Reversible changes in the stria vascularis and EP have been observed both after an i.v. and after an i.p. injection of a very high dose (80 mg/kg) of furosemide (Forge and Brown, 1982). Disturbances of the OHCs have also been found after administration of furosemide in a high dose, with reversible cytoplasmatic swelling (Ayiyoshi, 1981) and collapse of the stereocilia on the third row of the OHC (Forge and Brown, 1982). The purpose of the present study was to investigate the effect of cisplatin on the auditory thresholds and EP, particularly when administered in combination with the loop diuretic furosemide. The study was divided into two parts, in both the guinea pig was used as an experimental model. In the first part, under simulated clinical conditions a pharmacological dose of furosemide (Formanek and Kenner, 1966) was administered by a multiple-dose schedule in combination with a low dose of cisplatin in order to study the possible interaction between the two drugs. In the second part, the ototoxic effect of a single, moderately high dose of cisplatin was investigated after the positive EP had been abolished by a high dose of furosernide. Materials and Methods Fourty pigmented guinea pigs (180-420 g) were used for the experiments. On initial examination no sign of external ear or middle ear infection was seen. Before treatment the auditory brainstem response (ABR) thresholds were within the normal
range in all animals. The animals were divided into two groups for part one of the study, IA and IB, and into three groups for part two, IIA, IIB and IIC. Drug administration Multiple
low-dose i.p. injections
Group IA (nine guinea pigs). This group was used to determine the ototoxic effect of a low-dose schedule of cisplatin alone. Each animal was given 1 mg/kg body weight cisplatin i.p. once a day, five days a week, up to a total dose of 25 mg/kg. The ABR thresholds were measured 21-25 days after the last injection. Group IB (nine guinea pigs). In this group the ototoxic effect of a low-dose schedule of a combination of cisplatin and furosemide was investigated. Each animal was given 1 mg/kg cisplatin and 15 mg/kg furosemide i.p. once a day, five days a week, up to a total dose of 25 mg/kg cisplatin and 375 mg/kg furosemide. The two drugs were injected simultaneously. The ABR thresholds were measured 21-31 days after the last injection. Single high-dose i.u. injections Group ZIA (three guinea pigs). The ototoxic effect of a single high dose of furosemide was studied in this group. Each animal was given 80 mg/kg furosemide iv. The ABR thresholds were measured after three days, and EP one day later. Group IIB (four guinea pigs). In this group the ototoxic effect of a single moderately high dose of cisplatin was determined. Each animal was first given normal saline i.v. (in the same volume as the 80 mg/kg dose of furosemide) and after 2.3 min an i.v. dose of 5 mg/kg cisplatin. The ABR thresholds were measured after three days, and EP the same day or two days later. Group IIC (12 guinea pigs). This group was used to investigate the ototoxic effect of a single moderately high dose of cisplatin after abolition of the positive EP by a high dose of furosemide. Each
21
animal was given 80 mg/kg furosemide i.v., and after 2.3 min 5 mg/kg cisplatin i.v. The ABR thresholds were measured after three days, and EP on the same day or one day later. Electrophysiological
recordings
The electrophysiological hearing thresholds were determined by brainstem audiometry using full cycle sine wave pulses filtered with a l/3 octave band pass filter (Briiel and Kjaer, type 1617) centered at the frequency of the sine wave. The animals were anesthetized with i.p. injection of droperidol- 6 mg/kg body weight followed by sodium pentobarbitol, 25 mg/kg body weight. The electrical signals were picked up by subcutaneous needle electrodes between the vertex and the ipsilateral retroauricular region. The responses were amplified lo4 times, band pass filtered between 50 and 4700 Hz, and fed into a Datalab 4000 signal averager. The ABR was based on the average of 2000 epochs (Borg and Engstriim, 1983). The ABR thresholds were determined at 1.6, 3.15, 6.3, 12.5, and 20 kHz. The thresholds of the ears of 11 healthy guinea pigs served as a normal material and were used as reference for calculation of the hearing loss (Laurel1 and Borg, 1986). EP was measured from the basal turn of the cochlea. The bulla was exposed through a dorsolateral approach. A glass micropipette filled with 0.5 M KC1 was lowered by a micromanipulator into the Scala media via the round window and basilar membrane. The micropipette was electrically connected to a DC amplifier (Keithly 602 Electrometer) by an Ag-AgCl electrode. Another Ag-AgCl electrode was placed on the neck muscle as the indifferent electrode. The EPs of six healthy guinea pig ears were evaluated and were found to be in the normal range 80-90 mV (mean 87 mV S.D. k4 mV) with this equipment.
injection to allow the drug effect to stabilize. The ABR thresholds were determined 21-31 days post-treatment. The ABR threshold sensitivity varied considerably in both groups. Audiograms from the most resistant and the most susceptible animal in group IA, which received cisplatin only, are presented in Fig. 1, and those in group IB, which received cisplatin plus furosemide, are shown in Fig. 2. The audiograms correspond to an ordinary clinical audiogram, showing loss of ABR thresholds in relation to ABR thresholds of a control group. A rise in threshold is indicated downwards in the audiogram. The variation of the ABR threshold shifts after the i.p. injections ranged from no changes to severe high-frequency hearing loss. The mean values of the audiograms for the two groups are compared in Fig. 3. The changes were greater for the high frequencies. It is seen that there was no difference in the ABR threshold sensitivity between the animals exposed to intraperitoneal injections of cisplatin and those given the combination of cisplatin and furosemide (P > 0.05, t-test). There was even a somewhat smaller loss for the combined treatment. In conclusion, the first part of the study showed that the ototoxic effect of a low dose of cisplatin was not increased
I
1
I
I
I
I
0
z0 0 ; 20 ”
2
4
5 40
w
I: Results
60
Ototoxicity
of the multiple low-dose i.p. injections
Groups IA and IB The animals receiving the multiple low-dose regimen of cisplatin or cisplatin plus furosemide i.p., rested for at least three weeks after the last
_ o=right X=left
I
ear ear
1
I
I
I
I
I
0.6
1.6
3.15
6.3
12.5
20
Frequency
(ki-iz)
Fig. 1. Loss of ABR thresholds in the most resistant () and the most susceptible (- - -) guinea pig after administration of a cumulative dose of 25 mg/kg cisplatin.
22
by simultaneous administration logical dose of furosemide. Ototoxicity
of a pharmaco-
after a single high-dose iv. injection
Group ZZA None of the three guinea pigs, which received a single furosemide dose of 80 mg/kg i.v., showed any change in the ABR thresholds three days after the injection or in EP recorded one day later (80-90 mv). Group ZZB In the four animals that were given an i.v. injection of normal saline plus cisplatin 5 mg/kg body weight, the ABR thresholds of one ear were determined three days after the injection. A normal threshold sensitivity was found in all four animals. In two of the animals, EP was recorded three days after the injection, and in one animal, five days after the injection, and in all three cases it was found to be in the normal range (SO-85 mV). Group ZZC Twelve animals cisplatin 5 mg/kg I
’
I
were given body weight I
i.v. injection of 2.3 min after an I
1
I
1
0
“Ob 0.8
1.6
3.15
6.3
12.5
20
Frequency IkHz)
Fig. 2. Loss of ABR thresholds in the most resistant ( -) and the most susceptible (- - -) guinea pig after administration of a cumulative dose of 25 mg/kg cisplatin and 375 mg/kg furosemide.
I
I
0.8
I
1.6
I
315
I
6.3
I
I
12.5
20
1
Frequency (kHz)
Fig. 3. A comparison of the mean loss of ABR thresholds for the two groups IA and IB receiving multiple i.p. injections.
iv. injection of furosemide in a dose of 80 mg/kg, which is known to abolish the positive component of the endocochlear potential (Pike and Bosher, 1980). Three days after the treatment, the ABR thresholds were determined in one ear of each of the 12 animals. All of the animals had large shift of the auditory thresholds. This dramatic ototoxic effect contrasted with the findings that neither 80 mg/kg furosemide (group HA), nor 5 mg/kg cisplatin (group IIB), injected alone, produced any shift of the auditory thresholds three days after an i.v. injection. The severe shift of ABR thresholds was most obvious for the higher frequencies 6.3, 12.5 and 20 kHz. For these frequencies, none of the 12 animals showed any ABR threshold shift for less than 60 dB, and it was mostly not possible to determine any ABR threshold at all. The hearing loss for the lower frequencies of 1.6 and 3.15 kHz was also pronounced in all 12 animals, with no ABR threshold shift for less than 47 dB. EP was recorded in nine of these animals three or four days after the drug injection. The magnitude of the EP ranged from +45 to +65 mV (mean value 55 mV and S.D. L-S). In order to evaluate the possibility of recovery, the ABR thresholds and EP were recorded in the other ear 14-19 days
23
I
I
I
I
I
I
60 mg/kg furosemide and 5 mglkg cisplatin iv.
X,EP 65 mV \,Left ear \,
20 days after \
injection
1
I
I
I
I
I
0.8
1.6
3.15
6.3
12.5
20
Frequency
1kHz 1
Fig. 4. Changes in ABR thresholds and EP of one guinea pig three and 20 days after administration of 80 mg/kg furosemide and 5 mg/kg cisplatin i.v. _1 = ABR threshold not reached.
later, but in only four guinea pigs. The other eight guinea pigs died or showed a middle ear infection. There was a tendency to slight recovery of the ABR threshold shifts and EP (mean 65 mV, S.D. +O). Fig. 4 shows the typical slight improvement in the ABR thresholds and EP of one guinea pig over a period of 17 days. Discussion
Dose-dependent ototoxic interaction In the first part of this study the use of furosemide, in a dose high enough to induce diuresis during treatment with a low dose of cisplatin, was found not to have any ototoxic interaction effect in guinea pigs. In contrast, the results of the second part of the experiment indicated a risk of potentiation of the ototoxic effect of cisplatin in guinea pigs when this chemotherapeutic drug is administered i.v. in combination with an extremely high dose of the loop diuretic furosemide. This observation is in accordance with earlier results of Brummett (1981).
Individual variability The wide individual variability of the ABR threshold sensitivity seen in the two multiple lowdose regimen groups may indicate individual susceptibility to drug-induced hearing loss. But this finding may also be explained, for example, by differences in the degree of absorption after i.p. administration. The less pronounced variability in the i.v. group receiving the combination of cisplatin and furosemide would seem to support the latter concept. The differences in the variability of the ABR threshold shifts between the i.p. groups (groups IA and IB) and the combined i.v. group (group IIC) were found to be statistically significant at the 0.005 level. The results of comparisons of i.p. injected animals therefore have to be interpreted cautiously. It seems still unlikely that a furosemide dose of 15 mg/kg body weight injected i.p. will be high enough to cause toxic changes in the cochlea. However, increases in the Na and K concentrations in cerebrospinal fluid and perilymph have even been observed after an iv. injection of furosemide in this dose 15 mg/kg, in guinea pigs (Kanoh and Makimoto, 1984) indicating that the dose used i.p. has significant physiological effects in this species. Interaction effects In the second part of the present investigations, much higher doses of cisplatin and furosemide were used, with more dramatic physiological effects. The pronounced hearing loss three days after the combined i.v. injection, and the less decreased EP, could constitute some evidence of increased uptake of cisplatin by the inner ear structures. Especially the OHCs have been suggested to be directly affected by furosemide (Forge and Brown, 1982; Ayiyoshi, 1981), with consequent change in membrane permeability. Involvement of the biochemical mechanisms of the stria vascularis induced by furosemide, could perhaps result in an increase in passive leakage of cisplatin from the vessels of the stria vascularis into the endolymph, i.e. impairment of the blood-cochlear barrier. An increased influx of cisplatin may also reach the vulnerable OHCs through the perilymphatic-cortilymphatic system. This simple model reflects only the initial step of the interac-
24
tion. The complexity of the ototoxic interaction between furosemide and cisplatin, cannot be discussed on the basis of only the present results. The decrease in EP also indicates some permanent disturbance of the functional capacity of the stria vascularis, although it seems unlikely that any prolonged presence of furosemide will contribute to this change in EP. A reversible decline of EP after furosemide administration has otherwise been shown to be related to the perilymph concentration of this drug (Green et al., 1981; Rybak et al., 1984). It is more reasonable that the toxic interaction between furosemide and cisplatin is responsible for strial impairment, with alteration of the DC potential in the Scala media. The pathological processes in the stria vascularis could influence the ionic composition of the endolymph, which may affect the cochlear sensitivity. The acute effect of i.v. high-dose furosemide is merely an endolymphatic potassium decrease (Syka and Melichar, 1981). A dependence of the cochlear function upon the magnitude of EP may therefore result in decreased ABR threshold sensitivity when EP is permanently depressed; that is the pronounced hearing loss following the combined intravenous administration of furosemide and cisplatin does not only reflect destruction of the organ of Corti. Furthermore, a linear decrease in EP and in the cochlear microphonic (Syka and Melichar, 1981), and a proportional decrease in EP and in the spontaneous activity in the auditory nerve fibers, have previously been demonstrated after a single i.v. injection of high-dose furosemide (Sewell, 1984). Furosemide is known not only to depress EP reversibly, but also to cause reversible morphologic changes in the stria vascularis (Pike and Bosher, 1980; Forge and Brown, 1982). Although cisplatin is especially toxic to the OHCs, damage to the stria vascularis has also been observed (Tange and Vuzevski, 1984) but this is not generally reported. A decrease in EP to approximately zero mV has been found to occur three to four days after i.v. injection of a single high dose of cisplatin (12.5 mg/kg body weight) (Komune et al., 1981; Laurel1 and Engstrijm, 1988). This finding indicates that not only furosemide, but also cisplatin has a direct toxic effect on the stria vascularis.
Biodistrihution The entry kinetics of cisplatin to the organ of Corti is not known. Likewise, it is not established at which site cisplatin has its primary effect. However, two- to three-fold increase in the platinum concentration in the stria vascularis in comparison with the organ of Corti, has been found 2 h after administration of radioactive platinum (Schweitzer et al., 1984). The degree of damage to the sensory structures in the inner ear may be assumed to be dependent upon the concentrations of cisplatin and furosemide in the plasma during administration of multiple moderate doses intraperitoneally, and after a single high dose intravenously. For gentamicin, a dose-dependent relationship has been found between the drug concentrations in plasma and perilymph. There is no evidence for an accumulation of gentamicin in the inner ear (Tran Ba Huy et al., 1986). The pharmacokinetics of cisplatin is more complex, however, than that of the aminoglycosides. Cisplatin binds extensively to albumin and other blood proteins, and the active free cytotoxic component is not easily detected. A second slow phase of elimination has been demonstrated, indicating that the drug is accumulated in the tissues for a long period of time (Patton et al., 1978; Gormley et al., 1979). The cytotoxic mechanisms of cisplatin and the aminoglycosides in the cochlea seem unlikely to be the same. Clinical application Injection of a single high dose of cisplatin has been associated with development of clinical hearing loss (Chapman, 1982; Vermorken et al., 1983; Laurel1 and Borg, 1988). Furosemide is also a potentially ototoxic agent, but no reports on an interaction between cisplatin and furosemide based on clinical studies are known to us. Patients with renal insufficiency, or severe congestive heart failure, are not routinely exposed to cisplatin, or are given a reduced dose. The dose of furosemide administered in clinical practice to induce diuresis is generally low and does not seem to contribute to inner ear damage. The lack of interaction in guinea pigs given a repeated low dose of cisplatin
25
with a pharmacological dose of furosemide, is therefore not surprising. On the other hand, there is obviously a risk of ototoxic interaction in patients undergoing cisplatin treatment in combination with a high i.v. dose of furosemide. Unless the therapeutic effect is necessary, high-dose loop diuretic treatment should be avoided during cisplatin therapy. Conclusion Use of a pharmacological dose of furosemide to induce diuresis during treatment with a repeated low dose of cisplatin does not result in an ototoxic interaction between the two drugs, I.v. administration of a high dose of furosemide potentiates the ototoxic effect of cisplatin when the latter is given at a time when the strial function is most affected by the furosemide. This indicates that the stria vascularis plays a role in the ototoxic mechanism of cisplatin. Acknowledgements This study was supported by grants from Stiftelsen Tysta Skolan, Torsten and Ragnar Soderbergs Stiftelser. Bristol-Myers and Hoechst have kindly supplied us with cisplatin and furosemide, respectively. References Aguilar-Markulis, N.V., Beckley, S., Priore, R. and Mettlin, C. (1981) Auditory toxicity effects of long-term cis-dichlorodiammineplatinum II therapy in genitourinary cancer patients. J. Surg. Oncol. 16, 111-123. Ayiyoshi, M. (1981) Effect of loop-diuretics on hair cells of the cochlea in guinea pigs. Histological and histochemical study. Stand. Audio]. Suppl. 14, 185-197. Borg, E. and Engstrom, B. (1983) Hearing thresholds in the rabbit. A behavioural and electrophysiological study. Acta Otolaryngol. (Stockh.) 95, 19-26. Brown, RI., Nuss, R.C., Pattersson, R. and Irey, J. (1983) Audiometric monitoring of cis-platinum ototoxicity. Gynecol. Oncol. 16, 254-262. Brummett, R.E. (1981) Ototoxicity resulting from the combined administration of potent diuretics and other agents. Stand. Audiol. Suppl. 14, 215-224. Burg, M., Stoner, L., Cardinal, J. and Green, N. (1973) Furosemide effect on isolated perfused tubules. Am. J. Physiol. 225, 119-124. Chapman, P. (1982) Rapid onset hearing loss after Cisplatinum therapy. J. Laryngol. Otol. 97, 159-162.
Cvitkovic, E., Spaulding, J., Bethune, V., Martin, J. and Whitmore, W.F. (1977) Improvement of cis-dichlorodiammineplatinum (NSC 119875): Therapeutic index in an animal model. Cancer 39, 1357-1361. Estrem, S.A., Babin, R.W., Ryu, J.H. and Moore, K.C. (1981) Cis-diamminedichloroplatinum (II). Ototoxicity in the guinea pig. Otolaryngol. Head Neck Surg., 89, 638-645. Fleischman, R.W., Stadnicki, S.W., Ethier, M.F. and Schaeppi, U. (1975) Ototoxicity of cis-dichlorodiammine platinum (II) in the guinea pig. Toxicol. Appl. Pharmacol. 33, 320-332. Forge, A. and Brown, A.M. (1982) Ultrastructural and electrophysiological studies of acute ototoxic effects of furosemide. Br. J. Audiol. 16, 109-116. Formanek, K. and Kenner, T. (1966) Special features of the action of a new diuretic. Br. J. Pharmacol. 26, 21-33. Gormley, P.E., Bull, J.M., LeRoy, A.F. and Cysyk, R. (1979) Kinetics of cis-dichlorodiammineplatinum. Clin. Pharmacol. Ther. 25, 351-357. Green, T.P., Rybak, L.P., Mirkin, B.L., Juhn, S.K. and Morizono, T. (1981) Pharmacologic determinants of ototoxicity of furosemide in the chinchilla. J. Pharmacol. Exp. Ther. 216, 537-542. Hayes, D.M., Cvitkovic, E., Golbey, R.B., Scheiner, E., Helson, L. and Krakoff, I.H. (1977) High dose cis-platinum diammine dichloride. Amelioration of renal toxicity by mannitol diuresis. Cancer 39, 1372-1381. Kanoh, N. and Makimoto, K. (1984) The effect of furosemide on sodium and potassium concentrations in guinea pig perilymph. Arch. Otorhinolaryngol. 240, 21-26. Komune, S., Asakuma, S. and Snow, J.B. (1981) Pathophysiology of the ototoxicity of cis-diammine-dichloroplatinum. Otolaryngol Head Neck Surg. 89, 275-282. Laurel], G. and Borg, E. (1986) Cis-platin ototoxicity in previously noise-exposed guinea pigs. Acta Otolaryngol. (Stockh) 101, 66-74. Laurell, G. and Borg, E. (1988) Ototoxicity of cisplatin in gynecologic cancer patients. Stand. Audiol. (in press). Laurel], G. and Engstriim, B. (1989) The ototoxic effect of cisplatin on guinea pigs in relation to dosage. Hear. Res. 38, 27-34. Lippman, A.J., Helson, C., Helson, L. and Krakoff, I.H. (1973) Clinical trials of Cis-diamminedichloroplatinum (NSC119875). Cancer Chemother. Rep. 57, 191-200. Nakai, Y., Konishi, K., Chang, K.C., Ohashi, K., Morisaki, N., Minowe, Y. and Morimoto, A. (1982) Ototoxicity of the anticancer drug cis-platin. Acta Otolaryngol. (Stockh) 93, 227-232. Ostrow, S., Egurin, M.J., Hahn, D., Markus, S., Aisner, J., Chang, P., LeRoy, A., Bachur, N.R. and Wiernik, P.H. (1981) High-dose cisplatin therapy using mannitol versus furosemide diuresis: Comparative pharmacokinetics and toxicity. Cancer Treat. Rep. 65, 73-78. Patton, T.F., Himmelstein, K.J., Belt, R. Bannister, S.J., Stemson, L.A. and Repta, A.J. (1978) Plasma levels and urinary excretion of filterable platinum species following bolus injection and iv infusion of cis-dichlorodiammineplatinum (II) in man. Cancer Treat. Rep. 62, 1359-1362.
26 Pera, M.F., Zook, B.C. and Harder, H.C. (1979) Effects of mannitol or furosemide diuresis on the nephrotoxicity and physiological disposition of cis-dichlorodiammineplatinum (II) in rats. Cancer Res. 39, 1269-1278. Piel, I.J., Meyer, D., Perlia, C.P. and Wolfe, V.I. (1974) Effects of cis-diamminedichloroplatinum (NSC-119875) on hearing function in man. Cancer Chemother. Rep. 58, 871-875. Pike, D.A. and Bosher, SK. (1980) The time course of the strial changes produced by intravenous furosemide. Hear. Res. 3, 79-89. Rossof, A.H., Slayton, R.E. and Perlia, C.P. (1972) Preliminary clinical experience with cis-diamminedichloroplatinum (II) (NSC 119875, CACP). Cancer 30, 1451-1456. Rybak, L.P.. Green, T.P., Juhn, SK. and Morizono, T. (1984) Probenecid reduces cochlear effects and perilymph penetration of furosemide in chinchilla. J. Pharmacol. Exp. Ther. 230, 706-709. Schwartz, G.H., David, D.S., Riggio, R.R., Stenzel, K.H. and Rubin, A.L. (1970) Ototoxicity induced by furosemide. N. Engl. J. Med. 282, 1413-1414. Schweitzer, V.G., Rarey, K.E., Dolon, D.F.. Abrans, G., Litterst, C.J. and Scheridan, C. (1984) Ototoxicity of cisplatin vs platinum analogs CDDCA (JM-8) and CHIP (JM-9). Presented at the AAO-AR0 Research Forum, Las Vegas, Nevada 15 Sept. 1984.
Sewell, W.F. (1984) The relation between the endocochlear potential and spontaneous activity in auditory nerve fibers of the cat. J Physiol 347. 685-696. Strauss, M., Towfighi, J., Lipton, A., Brown, B., Lord, S. and Harvey, H. (1983) Cis-platinum ototoxicity: Clinical experience and temporal bone histopathology. Laryngoscope 93. 1554-1559. Syka, J. and Melichar, I. (1981) Comparison of the effects of furosemide and ethacrynic acid upon cochlear function in the guinea pig. Stand. Audiol. Suppl. 14, 63-69. Tange, R.A. and Vuzevski. V.D. (1984) Changes in the stria vascularis of the guinea pig due to cis-platinum. Arch. Otorhinolaryngol. 239, 41-47. Tran Ba Huy, P., Bernard, P. and Schacht, J. (1986) Kinetics of gentamicin uptake and release in the rat..J. Clin. Invest. 77, 1492-1500. Ward, J.M., Grabin, M.E.. LeRoy, A.F. and Young, D.M. (1977) Modification of the renal toxicity of cis-dichlorodiammineplatinum (II) with furosemide in male F344 rats. Cancer Treat. Rep. 61, 3755378. Wright, C.G. and Schaeffer. SD. (1982) Inner ear histopathology in patients treated with cis-platinum. Laryngoscope 92, 1408-1413.
Hearing Research, 38 (1989) 19-26 Elsevier
HRR 01168
The combined
effect of cisplatin and furosemide in guinea pigs
on hearing function
Gbran Laurel1 1-2and Berit Engstrijm
1-3
’ Institute of Physiology II, Karolinska Institute, Stockholm, Sweden, and Departments of ’ Otorhinolaryngology, and ’ Audiology, Karolinska (Received
4 January
Hospital, Stockholm,
1988; accepted
11 October
Sweden 1988)
The effect of the combined administration of cisplatin and furosemide on the electrophysiological hearing thresholds and endocochlear DC potential (EP) was studied in guinea pigs. A lack of interaction was found in animals given repeated intraperitoneal injections of a low dose of cisplatin with a pharmacological dose of furosemide. An ototoxic interaction occurred when a moderately high dose of cisplatin was administered intravenously at a time when the strial function was most affected by a very high dose of furosemide. The interaction was seen both as a decreased EP and a pronounced shift of auditory thresholds. It is concluded that the stria vascularis plays a role in the ototoxic mechanism of cisplatin. Interaction;
Electrophysiological
hearing
thresholds;
Endocochlear
Introduction The antineoplastic drug cisplatin was first introduced into clinical trials in 1971. The platinum coordination complex has been shown to have an effect against a variety of solid human tumors. Cisplatin is nowadays used alone, or in combination with other antineoplastic drugs, in the treatment of an increasing number of patients. Like many other chemotherapeutic agents, cisplatin has severe side effects. Of these, nephrotoxicity was initially considered to be the most serious, but since the introduction of prehydration and mannitolor furosemide-induced diuresis, the incidence and severity of renal insufficiency have been reduced (Hayes et al., 1977; Cvitkovic et al., 1977; Ward et al., 1977; Pera et al., 1979; Ostrow et al., 1981). Inner ear toxicity is an other well-known side effect of cisplatin (Rossof et al., 1972; Lippman et al., 1973; Pie1 et al., 1974; Aguilar-Markulis et al.,
Correspondence to: Giiran Laurell, Institute of Physiology Karolinska Institute, S-104 01 Stockholm, Sweden. 0378-5955/89/$03.50
0 1989 Elsevier Science Publishers
II,
DC potential
1981; Brown et al., 1983; Laurel1 and Borg, 1988). With use of the high-dose regimen, ototoxicity can be the dose-limiting side effect. The side effects are the more important to consider since the antitumor effect is usually palliative and not curative. Morphologic alterations in the cochlea due to cisplatin administration have been documented in several animal and human studies (Fleischman et al., 1975; Estrem et al., 1981; Nakai et al., 1982; Wright and Schaeffer, 1982; Strauss et al., 1983; Tange and Vuzevski, 1984). The degenerative pattern seems to be similar to that produced by the aminoglycosides. The most obvious alteration is destruction of the outer hair cells (OHCs) of the organ of Corti. The first row of the OHCs is the most severely affected, and the most pronounced loss of OHCs occurs in the basal turn of the cochlea. However, the primary action of cisplatin responsible for the pathologic changes in the inner ear is not known. The loop diuretic furosemide is widely used in clinical practice, and is also given to patients undergoing chemotherapy. Its primary site of action has been found to be located at the ascending thick limb of the loop of Henle, where it inhibits
B.V. (Biomedical
Division)
20
the active transport of chloride ions and consequently of sodium ions (Burg et al., 1973). Ototoxicity is a rare side effect of furosemide (Schwartz et al., 1970), but it has been observed in several animal experimental studies. The stria vascularis is suggested as the primary target of the toxic action in the cochlea. The changes consist of marginal cell swelling, shrinkage of the intermediate cells and enlargement of intracellular spaces (Pike and Bosher, 1980; Forge and Brown, 1982). At a high dose, furosemide causes dramatic suppression of the endocochlear DC potential (EP). When furosemide is given i.v. in a high dose, the EP may even become negative; it reaches its lowest level after 2.3 min and thereafter starts to recover (Pike and Bosher, 1980). Reversible changes in the stria vascularis and EP have been observed both after an i.v. and after an i.p. injection of a very high dose (80 mg/kg) of furosemide (Forge and Brown, 1982). Disturbances of the OHCs have also been found after administration of furosemide in a high dose, with reversible cytoplasmatic swelling (Ayiyoshi, 1981) and collapse of the stereocilia on the third row of the OHC (Forge and Brown, 1982). The purpose of the present study was to investigate the effect of cisplatin on the auditory thresholds and EP, particularly when administered in combination with the loop diuretic furosemide. The study was divided into two parts, in both the guinea pig was used as an experimental model. In the first part, under simulated clinical conditions a pharmacological dose of furosemide (Formanek and Kenner, 1966) was administered by a multiple-dose schedule in combination with a low dose of cisplatin in order to study the possible interaction between the two drugs. In the second part, the ototoxic effect of a single, moderately high dose of cisplatin was investigated after the positive EP had been abolished by a high dose of furosernide. Materials and Methods Fourty pigmented guinea pigs (180-420 g) were used for the experiments. On initial examination no sign of external ear or middle ear infection was seen. Before treatment the auditory brainstem response (ABR) thresholds were within the normal
range in all animals. The animals were divided into two groups for part one of the study, IA and IB, and into three groups for part two, IIA, IIB and IIC. Drug administration Multiple
low-dose i.p. injections
Group IA (nine guinea pigs). This group was used to determine the ototoxic effect of a low-dose schedule of cisplatin alone. Each animal was given 1 mg/kg body weight cisplatin i.p. once a day, five days a week, up to a total dose of 25 mg/kg. The ABR thresholds were measured 21-25 days after the last injection. Group IB (nine guinea pigs). In this group the ototoxic effect of a low-dose schedule of a combination of cisplatin and furosemide was investigated. Each animal was given 1 mg/kg cisplatin and 15 mg/kg furosemide i.p. once a day, five days a week, up to a total dose of 25 mg/kg cisplatin and 375 mg/kg furosemide. The two drugs were injected simultaneously. The ABR thresholds were measured 21-31 days after the last injection. Single high-dose i.u. injections Group ZIA (three guinea pigs). The ototoxic effect of a single high dose of furosemide was studied in this group. Each animal was given 80 mg/kg furosemide iv. The ABR thresholds were measured after three days, and EP one day later. Group IIB (four guinea pigs). In this group the ototoxic effect of a single moderately high dose of cisplatin was determined. Each animal was first given normal saline i.v. (in the same volume as the 80 mg/kg dose of furosemide) and after 2.3 min an i.v. dose of 5 mg/kg cisplatin. The ABR thresholds were measured after three days, and EP the same day or two days later. Group IIC (12 guinea pigs). This group was used to investigate the ototoxic effect of a single moderately high dose of cisplatin after abolition of the positive EP by a high dose of furosemide. Each
21
animal was given 80 mg/kg furosemide i.v., and after 2.3 min 5 mg/kg cisplatin i.v. The ABR thresholds were measured after three days, and EP on the same day or one day later. Electrophysiological
recordings
The electrophysiological hearing thresholds were determined by brainstem audiometry using full cycle sine wave pulses filtered with a l/3 octave band pass filter (Briiel and Kjaer, type 1617) centered at the frequency of the sine wave. The animals were anesthetized with i.p. injection of droperidol- 6 mg/kg body weight followed by sodium pentobarbitol, 25 mg/kg body weight. The electrical signals were picked up by subcutaneous needle electrodes between the vertex and the ipsilateral retroauricular region. The responses were amplified lo4 times, band pass filtered between 50 and 4700 Hz, and fed into a Datalab 4000 signal averager. The ABR was based on the average of 2000 epochs (Borg and Engstriim, 1983). The ABR thresholds were determined at 1.6, 3.15, 6.3, 12.5, and 20 kHz. The thresholds of the ears of 11 healthy guinea pigs served as a normal material and were used as reference for calculation of the hearing loss (Laurel1 and Borg, 1986). EP was measured from the basal turn of the cochlea. The bulla was exposed through a dorsolateral approach. A glass micropipette filled with 0.5 M KC1 was lowered by a micromanipulator into the Scala media via the round window and basilar membrane. The micropipette was electrically connected to a DC amplifier (Keithly 602 Electrometer) by an Ag-AgCl electrode. Another Ag-AgCl electrode was placed on the neck muscle as the indifferent electrode. The EPs of six healthy guinea pig ears were evaluated and were found to be in the normal range 80-90 mV (mean 87 mV S.D. k4 mV) with this equipment.
injection to allow the drug effect to stabilize. The ABR thresholds were determined 21-31 days post-treatment. The ABR threshold sensitivity varied considerably in both groups. Audiograms from the most resistant and the most susceptible animal in group IA, which received cisplatin only, are presented in Fig. 1, and those in group IB, which received cisplatin plus furosemide, are shown in Fig. 2. The audiograms correspond to an ordinary clinical audiogram, showing loss of ABR thresholds in relation to ABR thresholds of a control group. A rise in threshold is indicated downwards in the audiogram. The variation of the ABR threshold shifts after the i.p. injections ranged from no changes to severe high-frequency hearing loss. The mean values of the audiograms for the two groups are compared in Fig. 3. The changes were greater for the high frequencies. It is seen that there was no difference in the ABR threshold sensitivity between the animals exposed to intraperitoneal injections of cisplatin and those given the combination of cisplatin and furosemide (P > 0.05, t-test). There was even a somewhat smaller loss for the combined treatment. In conclusion, the first part of the study showed that the ototoxic effect of a low dose of cisplatin was not increased
I
1
I
I
I
I
0
z0 0 ; 20 ”
2
4
5 40
w
I: Results
60
Ototoxicity
of the multiple low-dose i.p. injections
Groups IA and IB The animals receiving the multiple low-dose regimen of cisplatin or cisplatin plus furosemide i.p., rested for at least three weeks after the last
_ o=right X=left
I
ear ear
1
I
I
I
I
I
0.6
1.6
3.15
6.3
12.5
20
Frequency
(ki-iz)
Fig. 1. Loss of ABR thresholds in the most resistant () and the most susceptible (- - -) guinea pig after administration of a cumulative dose of 25 mg/kg cisplatin.
22
by simultaneous administration logical dose of furosemide. Ototoxicity
of a pharmaco-
after a single high-dose iv. injection
Group ZZA None of the three guinea pigs, which received a single furosemide dose of 80 mg/kg i.v., showed any change in the ABR thresholds three days after the injection or in EP recorded one day later (80-90 mv). Group ZZB In the four animals that were given an i.v. injection of normal saline plus cisplatin 5 mg/kg body weight, the ABR thresholds of one ear were determined three days after the injection. A normal threshold sensitivity was found in all four animals. In two of the animals, EP was recorded three days after the injection, and in one animal, five days after the injection, and in all three cases it was found to be in the normal range (SO-85 mV). Group ZZC Twelve animals cisplatin 5 mg/kg I
’
I
were given body weight I
i.v. injection of 2.3 min after an I
1
I
1
0
“Ob 0.8
1.6
3.15
6.3
12.5
20
Frequency IkHz)
Fig. 2. Loss of ABR thresholds in the most resistant ( -) and the most susceptible (- - -) guinea pig after administration of a cumulative dose of 25 mg/kg cisplatin and 375 mg/kg furosemide.
I
I
0.8
I
1.6
I
315
I
6.3
I
I
12.5
20
1
Frequency (kHz)
Fig. 3. A comparison of the mean loss of ABR thresholds for the two groups IA and IB receiving multiple i.p. injections.
iv. injection of furosemide in a dose of 80 mg/kg, which is known to abolish the positive component of the endocochlear potential (Pike and Bosher, 1980). Three days after the treatment, the ABR thresholds were determined in one ear of each of the 12 animals. All of the animals had large shift of the auditory thresholds. This dramatic ototoxic effect contrasted with the findings that neither 80 mg/kg furosemide (group HA), nor 5 mg/kg cisplatin (group IIB), injected alone, produced any shift of the auditory thresholds three days after an i.v. injection. The severe shift of ABR thresholds was most obvious for the higher frequencies 6.3, 12.5 and 20 kHz. For these frequencies, none of the 12 animals showed any ABR threshold shift for less than 60 dB, and it was mostly not possible to determine any ABR threshold at all. The hearing loss for the lower frequencies of 1.6 and 3.15 kHz was also pronounced in all 12 animals, with no ABR threshold shift for less than 47 dB. EP was recorded in nine of these animals three or four days after the drug injection. The magnitude of the EP ranged from +45 to +65 mV (mean value 55 mV and S.D. L-S). In order to evaluate the possibility of recovery, the ABR thresholds and EP were recorded in the other ear 14-19 days
23
I
I
I
I
I
I
60 mg/kg furosemide and 5 mglkg cisplatin iv.
X,EP 65 mV \,Left ear \,
20 days after \
injection
1
I
I
I
I
I
0.8
1.6
3.15
6.3
12.5
20
Frequency
1kHz 1
Fig. 4. Changes in ABR thresholds and EP of one guinea pig three and 20 days after administration of 80 mg/kg furosemide and 5 mg/kg cisplatin i.v. _1 = ABR threshold not reached.
later, but in only four guinea pigs. The other eight guinea pigs died or showed a middle ear infection. There was a tendency to slight recovery of the ABR threshold shifts and EP (mean 65 mV, S.D. +O). Fig. 4 shows the typical slight improvement in the ABR thresholds and EP of one guinea pig over a period of 17 days. Discussion
Dose-dependent ototoxic interaction In the first part of this study the use of furosemide, in a dose high enough to induce diuresis during treatment with a low dose of cisplatin, was found not to have any ototoxic interaction effect in guinea pigs. In contrast, the results of the second part of the experiment indicated a risk of potentiation of the ototoxic effect of cisplatin in guinea pigs when this chemotherapeutic drug is administered i.v. in combination with an extremely high dose of the loop diuretic furosemide. This observation is in accordance with earlier results of Brummett (1981).
Individual variability The wide individual variability of the ABR threshold sensitivity seen in the two multiple lowdose regimen groups may indicate individual susceptibility to drug-induced hearing loss. But this finding may also be explained, for example, by differences in the degree of absorption after i.p. administration. The less pronounced variability in the i.v. group receiving the combination of cisplatin and furosemide would seem to support the latter concept. The differences in the variability of the ABR threshold shifts between the i.p. groups (groups IA and IB) and the combined i.v. group (group IIC) were found to be statistically significant at the 0.005 level. The results of comparisons of i.p. injected animals therefore have to be interpreted cautiously. It seems still unlikely that a furosemide dose of 15 mg/kg body weight injected i.p. will be high enough to cause toxic changes in the cochlea. However, increases in the Na and K concentrations in cerebrospinal fluid and perilymph have even been observed after an iv. injection of furosemide in this dose 15 mg/kg, in guinea pigs (Kanoh and Makimoto, 1984) indicating that the dose used i.p. has significant physiological effects in this species. Interaction effects In the second part of the present investigations, much higher doses of cisplatin and furosemide were used, with more dramatic physiological effects. The pronounced hearing loss three days after the combined i.v. injection, and the less decreased EP, could constitute some evidence of increased uptake of cisplatin by the inner ear structures. Especially the OHCs have been suggested to be directly affected by furosemide (Forge and Brown, 1982; Ayiyoshi, 1981), with consequent change in membrane permeability. Involvement of the biochemical mechanisms of the stria vascularis induced by furosemide, could perhaps result in an increase in passive leakage of cisplatin from the vessels of the stria vascularis into the endolymph, i.e. impairment of the blood-cochlear barrier. An increased influx of cisplatin may also reach the vulnerable OHCs through the perilymphatic-cortilymphatic system. This simple model reflects only the initial step of the interac-
24
tion. The complexity of the ototoxic interaction between furosemide and cisplatin, cannot be discussed on the basis of only the present results. The decrease in EP also indicates some permanent disturbance of the functional capacity of the stria vascularis, although it seems unlikely that any prolonged presence of furosemide will contribute to this change in EP. A reversible decline of EP after furosemide administration has otherwise been shown to be related to the perilymph concentration of this drug (Green et al., 1981; Rybak et al., 1984). It is more reasonable that the toxic interaction between furosemide and cisplatin is responsible for strial impairment, with alteration of the DC potential in the Scala media. The pathological processes in the stria vascularis could influence the ionic composition of the endolymph, which may affect the cochlear sensitivity. The acute effect of i.v. high-dose furosemide is merely an endolymphatic potassium decrease (Syka and Melichar, 1981). A dependence of the cochlear function upon the magnitude of EP may therefore result in decreased ABR threshold sensitivity when EP is permanently depressed; that is the pronounced hearing loss following the combined intravenous administration of furosemide and cisplatin does not only reflect destruction of the organ of Corti. Furthermore, a linear decrease in EP and in the cochlear microphonic (Syka and Melichar, 1981), and a proportional decrease in EP and in the spontaneous activity in the auditory nerve fibers, have previously been demonstrated after a single i.v. injection of high-dose furosemide (Sewell, 1984). Furosemide is known not only to depress EP reversibly, but also to cause reversible morphologic changes in the stria vascularis (Pike and Bosher, 1980; Forge and Brown, 1982). Although cisplatin is especially toxic to the OHCs, damage to the stria vascularis has also been observed (Tange and Vuzevski, 1984) but this is not generally reported. A decrease in EP to approximately zero mV has been found to occur three to four days after i.v. injection of a single high dose of cisplatin (12.5 mg/kg body weight) (Komune et al., 1981; Laurel1 and Engstrijm, 1988). This finding indicates that not only furosemide, but also cisplatin has a direct toxic effect on the stria vascularis.
Biodistrihution The entry kinetics of cisplatin to the organ of Corti is not known. Likewise, it is not established at which site cisplatin has its primary effect. However, two- to three-fold increase in the platinum concentration in the stria vascularis in comparison with the organ of Corti, has been found 2 h after administration of radioactive platinum (Schweitzer et al., 1984). The degree of damage to the sensory structures in the inner ear may be assumed to be dependent upon the concentrations of cisplatin and furosemide in the plasma during administration of multiple moderate doses intraperitoneally, and after a single high dose intravenously. For gentamicin, a dose-dependent relationship has been found between the drug concentrations in plasma and perilymph. There is no evidence for an accumulation of gentamicin in the inner ear (Tran Ba Huy et al., 1986). The pharmacokinetics of cisplatin is more complex, however, than that of the aminoglycosides. Cisplatin binds extensively to albumin and other blood proteins, and the active free cytotoxic component is not easily detected. A second slow phase of elimination has been demonstrated, indicating that the drug is accumulated in the tissues for a long period of time (Patton et al., 1978; Gormley et al., 1979). The cytotoxic mechanisms of cisplatin and the aminoglycosides in the cochlea seem unlikely to be the same. Clinical application Injection of a single high dose of cisplatin has been associated with development of clinical hearing loss (Chapman, 1982; Vermorken et al., 1983; Laurel1 and Borg, 1988). Furosemide is also a potentially ototoxic agent, but no reports on an interaction between cisplatin and furosemide based on clinical studies are known to us. Patients with renal insufficiency, or severe congestive heart failure, are not routinely exposed to cisplatin, or are given a reduced dose. The dose of furosemide administered in clinical practice to induce diuresis is generally low and does not seem to contribute to inner ear damage. The lack of interaction in guinea pigs given a repeated low dose of cisplatin
25
with a pharmacological dose of furosemide, is therefore not surprising. On the other hand, there is obviously a risk of ototoxic interaction in patients undergoing cisplatin treatment in combination with a high i.v. dose of furosemide. Unless the therapeutic effect is necessary, high-dose loop diuretic treatment should be avoided during cisplatin therapy. Conclusion Use of a pharmacological dose of furosemide to induce diuresis during treatment with a repeated low dose of cisplatin does not result in an ototoxic interaction between the two drugs, I.v. administration of a high dose of furosemide potentiates the ototoxic effect of cisplatin when the latter is given at a time when the strial function is most affected by the furosemide. This indicates that the stria vascularis plays a role in the ototoxic mechanism of cisplatin. Acknowledgements This study was supported by grants from Stiftelsen Tysta Skolan, Torsten and Ragnar Soderbergs Stiftelser. Bristol-Myers and Hoechst have kindly supplied us with cisplatin and furosemide, respectively. References Aguilar-Markulis, N.V., Beckley, S., Priore, R. and Mettlin, C. (1981) Auditory toxicity effects of long-term cis-dichlorodiammineplatinum II therapy in genitourinary cancer patients. J. Surg. Oncol. 16, 111-123. Ayiyoshi, M. (1981) Effect of loop-diuretics on hair cells of the cochlea in guinea pigs. Histological and histochemical study. Stand. Audio]. Suppl. 14, 185-197. Borg, E. and Engstrom, B. (1983) Hearing thresholds in the rabbit. A behavioural and electrophysiological study. Acta Otolaryngol. (Stockh.) 95, 19-26. Brown, RI., Nuss, R.C., Pattersson, R. and Irey, J. (1983) Audiometric monitoring of cis-platinum ototoxicity. Gynecol. Oncol. 16, 254-262. Brummett, R.E. (1981) Ototoxicity resulting from the combined administration of potent diuretics and other agents. Stand. Audiol. Suppl. 14, 215-224. Burg, M., Stoner, L., Cardinal, J. and Green, N. (1973) Furosemide effect on isolated perfused tubules. Am. J. Physiol. 225, 119-124. Chapman, P. (1982) Rapid onset hearing loss after Cisplatinum therapy. J. Laryngol. Otol. 97, 159-162.
Cvitkovic, E., Spaulding, J., Bethune, V., Martin, J. and Whitmore, W.F. (1977) Improvement of cis-dichlorodiammineplatinum (NSC 119875): Therapeutic index in an animal model. Cancer 39, 1357-1361. Estrem, S.A., Babin, R.W., Ryu, J.H. and Moore, K.C. (1981) Cis-diamminedichloroplatinum (II). Ototoxicity in the guinea pig. Otolaryngol. Head Neck Surg., 89, 638-645. Fleischman, R.W., Stadnicki, S.W., Ethier, M.F. and Schaeppi, U. (1975) Ototoxicity of cis-dichlorodiammine platinum (II) in the guinea pig. Toxicol. Appl. Pharmacol. 33, 320-332. Forge, A. and Brown, A.M. (1982) Ultrastructural and electrophysiological studies of acute ototoxic effects of furosemide. Br. J. Audiol. 16, 109-116. Formanek, K. and Kenner, T. (1966) Special features of the action of a new diuretic. Br. J. Pharmacol. 26, 21-33. Gormley, P.E., Bull, J.M., LeRoy, A.F. and Cysyk, R. (1979) Kinetics of cis-dichlorodiammineplatinum. Clin. Pharmacol. Ther. 25, 351-357. Green, T.P., Rybak, L.P., Mirkin, B.L., Juhn, S.K. and Morizono, T. (1981) Pharmacologic determinants of ototoxicity of furosemide in the chinchilla. J. Pharmacol. Exp. Ther. 216, 537-542. Hayes, D.M., Cvitkovic, E., Golbey, R.B., Scheiner, E., Helson, L. and Krakoff, I.H. (1977) High dose cis-platinum diammine dichloride. Amelioration of renal toxicity by mannitol diuresis. Cancer 39, 1372-1381. Kanoh, N. and Makimoto, K. (1984) The effect of furosemide on sodium and potassium concentrations in guinea pig perilymph. Arch. Otorhinolaryngol. 240, 21-26. Komune, S., Asakuma, S. and Snow, J.B. (1981) Pathophysiology of the ototoxicity of cis-diammine-dichloroplatinum. Otolaryngol Head Neck Surg. 89, 275-282. Laurel], G. and Borg, E. (1986) Cis-platin ototoxicity in previously noise-exposed guinea pigs. Acta Otolaryngol. (Stockh) 101, 66-74. Laurell, G. and Borg, E. (1988) Ototoxicity of cisplatin in gynecologic cancer patients. Stand. Audiol. (in press). Laurel], G. and Engstriim, B. (1989) The ototoxic effect of cisplatin on guinea pigs in relation to dosage. Hear. Res. 38, 27-34. Lippman, A.J., Helson, C., Helson, L. and Krakoff, I.H. (1973) Clinical trials of Cis-diamminedichloroplatinum (NSC119875). Cancer Chemother. Rep. 57, 191-200. Nakai, Y., Konishi, K., Chang, K.C., Ohashi, K., Morisaki, N., Minowe, Y. and Morimoto, A. (1982) Ototoxicity of the anticancer drug cis-platin. Acta Otolaryngol. (Stockh) 93, 227-232. Ostrow, S., Egurin, M.J., Hahn, D., Markus, S., Aisner, J., Chang, P., LeRoy, A., Bachur, N.R. and Wiernik, P.H. (1981) High-dose cisplatin therapy using mannitol versus furosemide diuresis: Comparative pharmacokinetics and toxicity. Cancer Treat. Rep. 65, 73-78. Patton, T.F., Himmelstein, K.J., Belt, R. Bannister, S.J., Stemson, L.A. and Repta, A.J. (1978) Plasma levels and urinary excretion of filterable platinum species following bolus injection and iv infusion of cis-dichlorodiammineplatinum (II) in man. Cancer Treat. Rep. 62, 1359-1362.
26 Pera, M.F., Zook, B.C. and Harder, H.C. (1979) Effects of mannitol or furosemide diuresis on the nephrotoxicity and physiological disposition of cis-dichlorodiammineplatinum (II) in rats. Cancer Res. 39, 1269-1278. Piel, I.J., Meyer, D., Perlia, C.P. and Wolfe, V.I. (1974) Effects of cis-diamminedichloroplatinum (NSC-119875) on hearing function in man. Cancer Chemother. Rep. 58, 871-875. Pike, D.A. and Bosher, SK. (1980) The time course of the strial changes produced by intravenous furosemide. Hear. Res. 3, 79-89. Rossof, A.H., Slayton, R.E. and Perlia, C.P. (1972) Preliminary clinical experience with cis-diamminedichloroplatinum (II) (NSC 119875, CACP). Cancer 30, 1451-1456. Rybak, L.P.. Green, T.P., Juhn, SK. and Morizono, T. (1984) Probenecid reduces cochlear effects and perilymph penetration of furosemide in chinchilla. J. Pharmacol. Exp. Ther. 230, 706-709. Schwartz, G.H., David, D.S., Riggio, R.R., Stenzel, K.H. and Rubin, A.L. (1970) Ototoxicity induced by furosemide. N. Engl. J. Med. 282, 1413-1414. Schweitzer, V.G., Rarey, K.E., Dolon, D.F.. Abrans, G., Litterst, C.J. and Scheridan, C. (1984) Ototoxicity of cisplatin vs platinum analogs CDDCA (JM-8) and CHIP (JM-9). Presented at the AAO-AR0 Research Forum, Las Vegas, Nevada 15 Sept. 1984.
Sewell, W.F. (1984) The relation between the endocochlear potential and spontaneous activity in auditory nerve fibers of the cat. J Physiol 347. 685-696. Strauss, M., Towfighi, J., Lipton, A., Brown, B., Lord, S. and Harvey, H. (1983) Cis-platinum ototoxicity: Clinical experience and temporal bone histopathology. Laryngoscope 93. 1554-1559. Syka, J. and Melichar, I. (1981) Comparison of the effects of furosemide and ethacrynic acid upon cochlear function in the guinea pig. Stand. Audiol. Suppl. 14, 63-69. Tange, R.A. and Vuzevski. V.D. (1984) Changes in the stria vascularis of the guinea pig due to cis-platinum. Arch. Otorhinolaryngol. 239, 41-47. Tran Ba Huy, P., Bernard, P. and Schacht, J. (1986) Kinetics of gentamicin uptake and release in the rat..J. Clin. Invest. 77, 1492-1500. Ward, J.M., Grabin, M.E.. LeRoy, A.F. and Young, D.M. (1977) Modification of the renal toxicity of cis-dichlorodiammineplatinum (II) with furosemide in male F344 rats. Cancer Treat. Rep. 61, 3755378. Wright, C.G. and Schaeffer. SD. (1982) Inner ear histopathology in patients treated with cis-platinum. Laryngoscope 92, 1408-1413.