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Effect of suloctidil on platelet function in patients with shortened platelet. Survival time
THROMBOSIS RESEARCH 35; 397-406, 1984 0049-3848/84 $3.00 + .OO Printed in the USA. Copyright (c) 1984 Pergamon Press Ltd. All rights reserved.
EFFECT OF SULOCTIDIL ON PLATELET FUNCTION IN PATIENTS WITH SHORTENED PLATELET.SURVIVAL TIME
A.G.G. Turpie: M. Gent, A.C. deBoer: M. Giroux, D. Kinch, R. Butt: J. Gunstensen, E. Saerens and E. Genton" Departments of Medicine*, Clinical Epidemiology & Biostatistics, and Surgery , McMaster University, Hamilton, Ontario, Canada and Continental Pharma, Brussells, Belgium
(Received 26.1.1984; Accepted in revised form 8.5.1984 by Editor M. Frojmovic) ABSTRACT The effect of suloctidil (600 mg/day) on platelet survival time (PST) and plasma and urine betathromboglobulin (BTC) was studied in a double-blind, placebo-controlled six-week crossover trial in 13 patients with shortened PST (
INTRODUCTION There is evidence that platelets play a major role in the development of thrombosis, especially in the arterial circulation and on the surface of implanted prostheses (1). A number of tests have been developed to measure platelet function, which is altered when platelets are st&muf&ed, for example, by interaction with prosthetic surfaces. Two widely used tests are
Key words: suloctidil, platelet survival time betathromboglobulin, randomized crossover trial 397
398
SULOCTIDIL AND PLATELET FUNCTION
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platelet survival time (PST) and the measurement of the platelet specific proteins such as betathromboglobulin (BTG) which is released into plasma and excreted in the urine when platelets are activated. Several studies have demonstrated that patients with reduced PST are at increased risk of thromboembolism (2-4). A number of platelet suppressing drugs have been shown to increase platelet survival among patients with shortened PST, and there is evidence that such drugs, either alone or in combination with anticoagulants, reduce the frequency of thromboembolic events (5-9). Suloctidil is a new synthetic compound which has been demonstrated in animals and man to alter platelet function (10). It has vasoactive properties and blocks the aggregating effects of adenosine diphosphate, epinephrine and collagen for up to six hours after a single dose, without prolonging the bleeding time. The mode of action of suloctidil is not established precisely but it is known to be different from that of aspirin and sulfinpyrazone which block prostaglandin synthesis, and from dipyridamole which inhibits the breakdown of cyclic AMP (11). To assess its potential as an antithrombotic agent, the effect of suloctidil (200 mg., three times per day) on PST and BTG concentration in plasma and urine was assessed in a randomized, double-blind crossover trial in patients who had reduced platelet survival. These were selected from a screened population of patients with mitral valve replacement, a high proportion of whom are expected to have shortened PST (12). METHODS atelet Survival Time: Platelet survival time was performed with autologous chromium-labelled platelets using the method recommended by the International Committee for Standardization in Haematology (i3). Platelet-rich plasma was prepared from 350 ml of blood drawn into acid citrate dextrose by differential centrifugation and the red cells retransfused. A platelet pellet was produced by centrifugation and gysuspended in 5 ml of platelet-poor plasma and incubated with 250 MCi of chromium for 30 minutes. The labelled platelets were washed, separated, resuspended in platelet-poor plasma and reinjected into the patients. The degree of red cell contamination was measured and a correction factor applied in the estimation of platelet survival. Mean in vivo platelet recovery was 69.9% f 14 (sd). There was no significant correlation between in vivo platelet recovery and the mean PST (r= -0.13). The PST was calculated from the radioactivity in duplicate blood samples collected daily over seven days, based on the least square regression technique using three mathematical functions: linear, exponential and gamma. In an earlier study it was demonstrated that the survival time, calculated from the linear or exponential functions, correlated closely (t-=0.84) but estimates from the gamma function correlated poorly with the linear or exponential estimates (r=O.3) (14). However, for completeness, results from For the purposes of this study a PST ,110 all three models are presented. hours using the exponential model was considered normal and (110 hours was considered to be significantly shortened. This limit was pre-determined and was based on previous experience with normals in our own laboratory (15). Betathromboglobulin: Plasma BTG concentration was measured using a radioimmunoassay as previously described (16). Blood was collected through a 19 gauge needle into a plastic syringe and 2.7 ml was immediately transferred
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399
into pre-cooled tubes containing 0.3 ml of an anticoagulant mixture consisting of 0.1 ml ethylene diamine tetra-acetate (0.219 M); 0.1 ml theophylline (30 mM); and 0.1 ml prostaglandin E, (10 uM); to prevent in vitro release. Platelet-poor plasma was prepared by centrifugation at 2000 g for 60 minutes at 4’C within one hour of collection and stored at -7O’C until assayed. The assay was sufficiently sensitive to be able to detect 3 ng/ml. Urine BTG concentration was measured using a radioimmunoassay as Early morning specimens of urine were spun at 2000 previously described (17). g for IO minutes within one hour of collection and the supernatant stored at The sensitivity of this assay was 0.04 ng/ml, the -7O’C for batch analysis. intra-assay variation was 9.7% and the inter-assay variation was 11.4%. Specimens showing macroscopic haematuria were discarded because it has been shown to elevate urine BTG concentration significantly (17). Paired t-tests were used to analyze differences in outcomes Data Analysis: between the two treatment groups in the crossover study. All tests were one-tailed. Platelet survival time and plasma and urine BTG were measured in a Patients: screened population of 49 patients with mitral valve replacement, who met specified criteria: they had received mitral valve replacement after 1975 but more than three months prior to the study; had no cardiac, renal or hepatic decompensation of severe degree; were not being treated with drugs known to alter platelet reactivity (oral anticoagulants were permitted); had no history Thirty-five of these patients had of thromboembolism; and were not pregnant. tissue heterografts and 14 had mechanical protheses. The mean age of all 49 patients was 55.8 years _c 1.39 s.e.; and 16 were males. Seventeen patients had reduced PST (
RESULTS The PST and the plasma and urine population of 49 patients with mitral
BTG concentrations valve replacement
in the screened are summarized in
400
Table 1. patients
SULOCTIDILAND PLATELET FUNCTION
Reduced (35%).
PST (
hours,
exponential)
occurred
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in
17 of the
49
TABLE 1 --Platelet m-ents
Survival
Time (Hours) and Betathromboglobulin (ng/ml) after _--Mitral Valve Replacement (Mean f s.e.) ----.
PLATELET SURVIVAL TIME (hrs)
Linear
220.2
-+ 2.93
Exponential
122.7
_c 2.99
Gamma
165.9
+ 5.91
BETATHROMBOGLOBULIN (ng/ml)
Plasma Urine
45.5 0.433
-+ 4.13 -+ 0.0607
reduced PST (
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SULOCTIDIL AND PLATELET FUNCTION
TABLE 2 Effect of Suloctidil on Platelet Survival Time (Hours) --- and Plasma and Urine Betathromboglobulin (ng/ml) (Mean it s.e.1 ----
Placebo (P)
Suloctidil (S)
Difference (S - P)
P-Value
PLATELET SURVIVAL TIME (hrs) Linear
195.5
210.0
14.5
-+4.74
4.48
6.57
94.5
110.6
16.1
26.96
4.90
28.26
0.02
Exponential
0.04
Gamma
161.1
157.2
- 3.9
212.80
+14.81
0.40 +8.22 -
BETATHROMBOGLOBULIN (ng/ml) Plasma
65.8
42.8
-+9.26
5.27
- 23.0 0.02
Urine
0.411
0.393
-+0.1289
+0.1058
-+9.04 - 0.018 0.46 20.1663
and exponential models to calculate PST, there were statistically significant increases with suloctidil compared to placebo (p=O.O2 and p=o.O4 respectively); with the gamma model, the difference was not significant (p=O.40). There was a statistically significant reduction in plasma BTC concentration at the end of the suloctidil phase compared with the placebo phase (p=O.O2), but the observed reduction in the urine BTG was not statistically significant (p=O.46). There were no significant differences in routine haematological tests between the placebo or treatment phases of the study (Table 3).
SULOCTIDILAND PLATELET FUNCTION
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TABLE 3 Effect
of Suloctidil With Shortened
Haemoglobin (gm)
Suloctidil (S)
13.54
13.51
-+0.183
-+0.210
40.42
39.85
-+0 .689
-+0.446
7.46
7.31
20.652
+o. 618
Difference (S - P)
P-Value
- 0.03 -+0.219 - 0.57 0.24
WBC (x109L)
PT (set)
Placebo (P)
Parameters in 13 Patients Time (Mean k s.e.1
0.45
Haematocrit (X1
Platslet (x10 L)
on Haematological Platelet Survival
to.761 - 0.15 0.30
Count
-+0.273
225.6
209.2
-16.5
-+14.01
-+12.55
-+10.68
16.1
15.8
- 0.3
21.93
-+1.66
0.08
-+1.19
0.42
Thirteen patients with normal PST (2110 hours, exponential) were imilarly randomized to either suloctidil or placebo treatments, of whom nine In two patients blood samples were unable to be ompleted the study. was withdrawn to have prostatic surgery and a fourth btained ; one patient atient withdrew due to gastrointestinal side-effects; all four patients were n placebo at the time of withdrawal. The mean age was 56.7 years 2 2.78 s.e. There were no significant differences between nd four patients were male. he two treatment phases in mean PST or in plasma or urine BTG (Table 4); or n the haematological tests (Table 5).
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SULOCTIDIL AND PLATELET FUNCTION
403
TABLE 4 Effect of Suloctidilon PlateletSurvivalTime (Hours)and Plasma and Urine Betathromboglobulin (ng/ml)in ---Nine PatientsWith-Normal PlateletSurvivalTime (Mean_ 2 s.e.1 Placebo (P)
Suloctidil Difference P-Value (S) (S - P)
PLATELETSURVIVALTIME (hrs) Linear
- 4.8
221.8
217.0
2 4.48
+ 4.54
123.6
122.2
-+ 4.07
_+ 4.21
165.2
152.0
-13.2
+11.53 -
of: 9.84
215.78
0.21 Exponential
25.69 - 1.3 0.40
Gamma
25.36 0.21
BETATHROMBOGLOBULIN (ng/ml) Plasma
48.6
60.4
11.9
29.32
28.93
514.13
0.21
Urine
0.403
0.803
0.400
50.1054
kO.4059
20.3350
0.14
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SULOCTIDILAND PLATELET FUNCTION
404
TABLE 5 Effect of Suloctidil on Haematological Parameters ----I--~---_ -~._- in Nine Patients With Normal Platelet Survival --Time (Mean & s.e.1 --_ Placebo (P) Haemoglobin (gm) Haematocrit (X)
PT (set)
14.21
14.10
+ 0.592
f. 0.599
41.54
41.72 f
2 1.565
WBC (x109/L) Platelet Coun (x10 6 /L)
Suloctidil (S)
6.32
-
Difference (S - P) - 0.11
-+ 0.352
0.38
1.342
+ 0.590
6.17
- 0.16
+ 0.471
+ 0.535
214.8
212.1
- 2.7
19.8 -+ 1.88
-
+18.35 19.8
-+ 2.17
0.38
0.18
-+ 0.432
+16.25
P-Value
-
+15.55
0.39
0.43
0.0 -+ 0.88
0.50
The effect of suloctidil on vital signs and on side-effects was assessed by combining results for all 22 randomized patients (i.e. 13 with shortened PST and nine with normal PST). No significant differences were observed in vital signs (pulse rate and blood pressure) between the suloctidil and placebo phases. Although a statistically significant increase in the frequency of non-specific side-effects was reported in the suloctidil phase (p=O.O4) these were generally mild and of no clinical significance (e.g. nausea, indigestion 1. DISCUSSION_ This study was carried out to determine the effect of suloctidil, a new antiplatelet drug, on platelet function in a group of patients who had shortened platelet survival. The rationale for the study was that shortened platelet survival time has been shown to be associated with an increased risk of thromboembolism and several antiplatelet drugs have been shown to correct reduced platelet survival time and reduce the risk of subsequent thromboembolism (2,3,8,18). The population of patients screened in this study were those with mitral valve replacement, a group in whom a relatively large proportion are expected to have significantly reduced platelet survival time (12). The results of this study demonstrate that suloctidil, in a dose of 200 mg three times a day,
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405
SULOCTIOIL AND PLATELET FUNCTION
significantly increases platelet survival time among a group of patients with reduced survival times. In previously reported studies of antiplatelet drugs comparing platelet survival time before and after a particular treatment intervention, the apparent improvement in PST may have been, in part, simply The use of the crossover design in this study regression towards the mean. in outcomes while eliminates this potential bias and the observed differences respectively, can reasonably be attributed to a on suloctidil and placebo, real effect of suloctidil. The effect of suloctidil on plasma BTC concentration was also measured. BTG concentration has been demonstrated to vary appreciably both within and which makes demonstration of a among patients with thromboembolic disease, Again, the double-blind true drug effect in lowering BTG more difficult. crossover design of this study eliminates the variation among patients from the assessment of benefit of treatment, and thus maximizes the chance of In this study suloctidil demonstrating a true effect of treatment. significantly reduced the level of plasma BTG but had no demonstrable effect less than 1% of BTG is cleared in the on urine BTG concentration. However, urine which would make demonstration of the drug effect difficult (15). This study supports the results of Col-de Beys et al. (19) who demonstrated, in 23 patients with cardiac valve replacement, that reduced platelet survival time was significantly increased after six weeks treatment with suloctidil. This demonstration that suloctidil improves platelet survival time among patients in whom it is initially shortened, supports an evaluation of its potential benefit in reducing the frequency of thromboembolic events in high risk patients.
REFERENCES --
1. MUSTARD, J.F. Function of blood platelets and their Trans Am Clin Climat ASSOC, 87, 104, 1976. ___~_
role
in thrombosis.
2. HARKER, L.A., SLICHTER, S.J. Studies of platelet and fibrinogen kinetics in patients with prosthetic heart valves. N Engl J Med, 283, 1302-1305, 1970. 3. WEILY, H.S., STEELE, P.P., DAVIES, H., PAPPAS, G., GENTON, E. Platelet survival in patients with substitute heart valves. N Engl J_&l_, 23, 534-537, 1974. 4. STEELE, P., WEILY, H., DAVIES, H ., PAPPAS, G., GENTON, E. Platelet survival time following aortic valve replacement. Circulation, 51, 358-362, 1975. 5. CHESEBRO, J.H., FUSTER, V. Thromboembolism in heart valve replacement. In: Thrombosis. H.C. Kwaan, E.J.W. Bowie, (Eds.) Philadelphia: W.B. Saunders, 1982, pp. 146-153. 6. SULLIVAN, J.M., HARKEN, D.E., GORLIN, R. Pharmacologic control of thromboembolic complications of cardiac valve replacement. N Engl J Med, 284, 1391, 1971.
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7. DALE, J., MYHRE, E., ROOTWELT, K. Effects of dipyridamole and acetylsalicylic acid on platelet functions in patients with aortic ball-valve prostheses. Am Heart J, -89, 613-618, 1975. 8. STEELE, P., RAINWATER, J. Favorable effect on sulfinpyrazone on thromboembolism in patients with rheumatic heart disease. Circulation, 62, 462-468, 1980. 9. TAGUCHI, K., MATSUMURA, H., WASHIZU, T., HIRAO, M., KATO, K., KATO, E., MOCHIZUKI, T., TAKAMURA, K., MASHIMO, I., MORIFUJI, K., NAKAGAKI, M., SUMA, T. Effect of athrombogenic therapy, especially high dose therapy of dipyridamole, after prosthetic valve replacement. J Cardiovasc --SUB, 16, 8-15, 1975. 10. DEGAETANO, G., MIRAGLIOTTA, G., RONCUCCU, R., LANSEN, J., LAMBELIN, G. Suloctidil: a novel inhibitor of platelet aggregation in human beings. Thromb Res, 4, 361-371, 1976. 11.
GUREWICH, V., LIPINSKI, B.: Evaluation of antithrombotic properties of suloctidil in comparison with aspirin and dipyridamole. Thromb Res, -- 2, 101-108, 1976.
12. TURPIE, A.G.G., DEBOER, A.C., GENTON, E. Platelet consumption in cardiovascular disease. Seminars in Thrombosis $, 161, - and Hemostas, 1982.
13. INTERNATIONAL COMMITTEE FOR STANDARDIZATION IN HEMATOLOGY. Recommended methods for radioisotope platelet survival studies. Blood, 50, 1137, 1977. 14. TURPIE, A.G.G., GENTON, E., HAN, P., DEBOER, A.C., GENT, M. Evaluation of gamma function calculation of platelet survival time (abstr) Circulation, 62, (suppl III), 111-277, 1980. 15. DEBOER, A.C., HAN, P., TURPIE, A.G.G., BUTT, R., GENT, M., GENTON, E. Platelet tests and antiplatelet,drugs in coronary artery disease. Circulation, 2, 500-504, 1983. 16. HAN, P., BUTT, R.W., TURPIE, A.G.G., WALKER, W.H.C., GENTON, E. B-thromboglobulin radioimmunoassay: A laboratory characterization and evaluation. J Immunoassay, l_, 211, 1980. 17. DEBOER, A.C., HAN, P., TURPIE, A.G.G., BUTT, R., ZIELINSKY, A., GENTON, E. Plasma and urine BTG concentration in patients with deep vein thrombosis. Blood, 3, 693-698, 1981. 18. STEEL&, P.P., WEILY, H.S., DAVIES, H., GENTON, E.
patients with rheumatic heart disease.
Platelet survival in N Engl J Med 290, 537-539, 1974.
19. COL-DE BEYS,CHR., FERRANT, A., MORIAU, M.
Effects of suloctidil on platelet survival time following cardiac valve replacement. Thrombos Haemostas, (Stuttgart)2, 550-553, 1981.
EFFECT OF SULOCTIDIL ON PLATELET FUNCTION IN PATIENTS WITH SHORTENED PLATELET.SURVIVAL TIME
A.G.G. Turpie: M. Gent, A.C. deBoer: M. Giroux, D. Kinch, R. Butt: J. Gunstensen, E. Saerens and E. Genton" Departments of Medicine*, Clinical Epidemiology & Biostatistics, and Surgery , McMaster University, Hamilton, Ontario, Canada and Continental Pharma, Brussells, Belgium
(Received 26.1.1984; Accepted in revised form 8.5.1984 by Editor M. Frojmovic) ABSTRACT The effect of suloctidil (600 mg/day) on platelet survival time (PST) and plasma and urine betathromboglobulin (BTC) was studied in a double-blind, placebo-controlled six-week crossover trial in 13 patients with shortened PST (
INTRODUCTION There is evidence that platelets play a major role in the development of thrombosis, especially in the arterial circulation and on the surface of implanted prostheses (1). A number of tests have been developed to measure platelet function, which is altered when platelets are st&muf&ed, for example, by interaction with prosthetic surfaces. Two widely used tests are
Key words: suloctidil, platelet survival time betathromboglobulin, randomized crossover trial 397
398
SULOCTIDIL AND PLATELET FUNCTION
vo1.35, No.4
platelet survival time (PST) and the measurement of the platelet specific proteins such as betathromboglobulin (BTG) which is released into plasma and excreted in the urine when platelets are activated. Several studies have demonstrated that patients with reduced PST are at increased risk of thromboembolism (2-4). A number of platelet suppressing drugs have been shown to increase platelet survival among patients with shortened PST, and there is evidence that such drugs, either alone or in combination with anticoagulants, reduce the frequency of thromboembolic events (5-9). Suloctidil is a new synthetic compound which has been demonstrated in animals and man to alter platelet function (10). It has vasoactive properties and blocks the aggregating effects of adenosine diphosphate, epinephrine and collagen for up to six hours after a single dose, without prolonging the bleeding time. The mode of action of suloctidil is not established precisely but it is known to be different from that of aspirin and sulfinpyrazone which block prostaglandin synthesis, and from dipyridamole which inhibits the breakdown of cyclic AMP (11). To assess its potential as an antithrombotic agent, the effect of suloctidil (200 mg., three times per day) on PST and BTG concentration in plasma and urine was assessed in a randomized, double-blind crossover trial in patients who had reduced platelet survival. These were selected from a screened population of patients with mitral valve replacement, a high proportion of whom are expected to have shortened PST (12). METHODS atelet Survival Time: Platelet survival time was performed with autologous chromium-labelled platelets using the method recommended by the International Committee for Standardization in Haematology (i3). Platelet-rich plasma was prepared from 350 ml of blood drawn into acid citrate dextrose by differential centrifugation and the red cells retransfused. A platelet pellet was produced by centrifugation and gysuspended in 5 ml of platelet-poor plasma and incubated with 250 MCi of chromium for 30 minutes. The labelled platelets were washed, separated, resuspended in platelet-poor plasma and reinjected into the patients. The degree of red cell contamination was measured and a correction factor applied in the estimation of platelet survival. Mean in vivo platelet recovery was 69.9% f 14 (sd). There was no significant correlation between in vivo platelet recovery and the mean PST (r= -0.13). The PST was calculated from the radioactivity in duplicate blood samples collected daily over seven days, based on the least square regression technique using three mathematical functions: linear, exponential and gamma. In an earlier study it was demonstrated that the survival time, calculated from the linear or exponential functions, correlated closely (t-=0.84) but estimates from the gamma function correlated poorly with the linear or exponential estimates (r=O.3) (14). However, for completeness, results from For the purposes of this study a PST ,110 all three models are presented. hours using the exponential model was considered normal and (110 hours was considered to be significantly shortened. This limit was pre-determined and was based on previous experience with normals in our own laboratory (15). Betathromboglobulin: Plasma BTG concentration was measured using a radioimmunoassay as previously described (16). Blood was collected through a 19 gauge needle into a plastic syringe and 2.7 ml was immediately transferred
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399
into pre-cooled tubes containing 0.3 ml of an anticoagulant mixture consisting of 0.1 ml ethylene diamine tetra-acetate (0.219 M); 0.1 ml theophylline (30 mM); and 0.1 ml prostaglandin E, (10 uM); to prevent in vitro release. Platelet-poor plasma was prepared by centrifugation at 2000 g for 60 minutes at 4’C within one hour of collection and stored at -7O’C until assayed. The assay was sufficiently sensitive to be able to detect 3 ng/ml. Urine BTG concentration was measured using a radioimmunoassay as Early morning specimens of urine were spun at 2000 previously described (17). g for IO minutes within one hour of collection and the supernatant stored at The sensitivity of this assay was 0.04 ng/ml, the -7O’C for batch analysis. intra-assay variation was 9.7% and the inter-assay variation was 11.4%. Specimens showing macroscopic haematuria were discarded because it has been shown to elevate urine BTG concentration significantly (17). Paired t-tests were used to analyze differences in outcomes Data Analysis: between the two treatment groups in the crossover study. All tests were one-tailed. Platelet survival time and plasma and urine BTG were measured in a Patients: screened population of 49 patients with mitral valve replacement, who met specified criteria: they had received mitral valve replacement after 1975 but more than three months prior to the study; had no cardiac, renal or hepatic decompensation of severe degree; were not being treated with drugs known to alter platelet reactivity (oral anticoagulants were permitted); had no history Thirty-five of these patients had of thromboembolism; and were not pregnant. tissue heterografts and 14 had mechanical protheses. The mean age of all 49 patients was 55.8 years _c 1.39 s.e.; and 16 were males. Seventeen patients had reduced PST (
RESULTS The PST and the plasma and urine population of 49 patients with mitral
BTG concentrations valve replacement
in the screened are summarized in
400
Table 1. patients
SULOCTIDILAND PLATELET FUNCTION
Reduced (35%).
PST (
hours,
exponential)
occurred
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in
17 of the
49
TABLE 1 --Platelet m-ents
Survival
Time (Hours) and Betathromboglobulin (ng/ml) after _--Mitral Valve Replacement (Mean f s.e.) ----.
PLATELET SURVIVAL TIME (hrs)
Linear
220.2
-+ 2.93
Exponential
122.7
_c 2.99
Gamma
165.9
+ 5.91
BETATHROMBOGLOBULIN (ng/ml)
Plasma Urine
45.5 0.433
-+ 4.13 -+ 0.0607
reduced PST (
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SULOCTIDIL AND PLATELET FUNCTION
TABLE 2 Effect of Suloctidil on Platelet Survival Time (Hours) --- and Plasma and Urine Betathromboglobulin (ng/ml) (Mean it s.e.1 ----
Placebo (P)
Suloctidil (S)
Difference (S - P)
P-Value
PLATELET SURVIVAL TIME (hrs) Linear
195.5
210.0
14.5
-+4.74
4.48
6.57
94.5
110.6
16.1
26.96
4.90
28.26
0.02
Exponential
0.04
Gamma
161.1
157.2
- 3.9
212.80
+14.81
0.40 +8.22 -
BETATHROMBOGLOBULIN (ng/ml) Plasma
65.8
42.8
-+9.26
5.27
- 23.0 0.02
Urine
0.411
0.393
-+0.1289
+0.1058
-+9.04 - 0.018 0.46 20.1663
and exponential models to calculate PST, there were statistically significant increases with suloctidil compared to placebo (p=O.O2 and p=o.O4 respectively); with the gamma model, the difference was not significant (p=O.40). There was a statistically significant reduction in plasma BTC concentration at the end of the suloctidil phase compared with the placebo phase (p=O.O2), but the observed reduction in the urine BTG was not statistically significant (p=O.46). There were no significant differences in routine haematological tests between the placebo or treatment phases of the study (Table 3).
SULOCTIDILAND PLATELET FUNCTION
vo1.35, No.4
TABLE 3 Effect
of Suloctidil With Shortened
Haemoglobin (gm)
Suloctidil (S)
13.54
13.51
-+0.183
-+0.210
40.42
39.85
-+0 .689
-+0.446
7.46
7.31
20.652
+o. 618
Difference (S - P)
P-Value
- 0.03 -+0.219 - 0.57 0.24
WBC (x109L)
PT (set)
Placebo (P)
Parameters in 13 Patients Time (Mean k s.e.1
0.45
Haematocrit (X1
Platslet (x10 L)
on Haematological Platelet Survival
to.761 - 0.15 0.30
Count
-+0.273
225.6
209.2
-16.5
-+14.01
-+12.55
-+10.68
16.1
15.8
- 0.3
21.93
-+1.66
0.08
-+1.19
0.42
Thirteen patients with normal PST (2110 hours, exponential) were imilarly randomized to either suloctidil or placebo treatments, of whom nine In two patients blood samples were unable to be ompleted the study. was withdrawn to have prostatic surgery and a fourth btained ; one patient atient withdrew due to gastrointestinal side-effects; all four patients were n placebo at the time of withdrawal. The mean age was 56.7 years 2 2.78 s.e. There were no significant differences between nd four patients were male. he two treatment phases in mean PST or in plasma or urine BTG (Table 4); or n the haematological tests (Table 5).
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SULOCTIDIL AND PLATELET FUNCTION
403
TABLE 4 Effect of Suloctidilon PlateletSurvivalTime (Hours)and Plasma and Urine Betathromboglobulin (ng/ml)in ---Nine PatientsWith-Normal PlateletSurvivalTime (Mean_ 2 s.e.1 Placebo (P)
Suloctidil Difference P-Value (S) (S - P)
PLATELETSURVIVALTIME (hrs) Linear
- 4.8
221.8
217.0
2 4.48
+ 4.54
123.6
122.2
-+ 4.07
_+ 4.21
165.2
152.0
-13.2
+11.53 -
of: 9.84
215.78
0.21 Exponential
25.69 - 1.3 0.40
Gamma
25.36 0.21
BETATHROMBOGLOBULIN (ng/ml) Plasma
48.6
60.4
11.9
29.32
28.93
514.13
0.21
Urine
0.403
0.803
0.400
50.1054
kO.4059
20.3350
0.14
Vo1.35, No.4
SULOCTIDILAND PLATELET FUNCTION
404
TABLE 5 Effect of Suloctidil on Haematological Parameters ----I--~---_ -~._- in Nine Patients With Normal Platelet Survival --Time (Mean & s.e.1 --_ Placebo (P) Haemoglobin (gm) Haematocrit (X)
PT (set)
14.21
14.10
+ 0.592
f. 0.599
41.54
41.72 f
2 1.565
WBC (x109/L) Platelet Coun (x10 6 /L)
Suloctidil (S)
6.32
-
Difference (S - P) - 0.11
-+ 0.352
0.38
1.342
+ 0.590
6.17
- 0.16
+ 0.471
+ 0.535
214.8
212.1
- 2.7
19.8 -+ 1.88
-
+18.35 19.8
-+ 2.17
0.38
0.18
-+ 0.432
+16.25
P-Value
-
+15.55
0.39
0.43
0.0 -+ 0.88
0.50
The effect of suloctidil on vital signs and on side-effects was assessed by combining results for all 22 randomized patients (i.e. 13 with shortened PST and nine with normal PST). No significant differences were observed in vital signs (pulse rate and blood pressure) between the suloctidil and placebo phases. Although a statistically significant increase in the frequency of non-specific side-effects was reported in the suloctidil phase (p=O.O4) these were generally mild and of no clinical significance (e.g. nausea, indigestion 1. DISCUSSION_ This study was carried out to determine the effect of suloctidil, a new antiplatelet drug, on platelet function in a group of patients who had shortened platelet survival. The rationale for the study was that shortened platelet survival time has been shown to be associated with an increased risk of thromboembolism and several antiplatelet drugs have been shown to correct reduced platelet survival time and reduce the risk of subsequent thromboembolism (2,3,8,18). The population of patients screened in this study were those with mitral valve replacement, a group in whom a relatively large proportion are expected to have significantly reduced platelet survival time (12). The results of this study demonstrate that suloctidil, in a dose of 200 mg three times a day,
Vo1.35, No.4
405
SULOCTIOIL AND PLATELET FUNCTION
significantly increases platelet survival time among a group of patients with reduced survival times. In previously reported studies of antiplatelet drugs comparing platelet survival time before and after a particular treatment intervention, the apparent improvement in PST may have been, in part, simply The use of the crossover design in this study regression towards the mean. in outcomes while eliminates this potential bias and the observed differences respectively, can reasonably be attributed to a on suloctidil and placebo, real effect of suloctidil. The effect of suloctidil on plasma BTC concentration was also measured. BTG concentration has been demonstrated to vary appreciably both within and which makes demonstration of a among patients with thromboembolic disease, Again, the double-blind true drug effect in lowering BTG more difficult. crossover design of this study eliminates the variation among patients from the assessment of benefit of treatment, and thus maximizes the chance of In this study suloctidil demonstrating a true effect of treatment. significantly reduced the level of plasma BTG but had no demonstrable effect less than 1% of BTG is cleared in the on urine BTG concentration. However, urine which would make demonstration of the drug effect difficult (15). This study supports the results of Col-de Beys et al. (19) who demonstrated, in 23 patients with cardiac valve replacement, that reduced platelet survival time was significantly increased after six weeks treatment with suloctidil. This demonstration that suloctidil improves platelet survival time among patients in whom it is initially shortened, supports an evaluation of its potential benefit in reducing the frequency of thromboembolic events in high risk patients.
REFERENCES --
1. MUSTARD, J.F. Function of blood platelets and their Trans Am Clin Climat ASSOC, 87, 104, 1976. ___~_
role
in thrombosis.
2. HARKER, L.A., SLICHTER, S.J. Studies of platelet and fibrinogen kinetics in patients with prosthetic heart valves. N Engl J Med, 283, 1302-1305, 1970. 3. WEILY, H.S., STEELE, P.P., DAVIES, H., PAPPAS, G., GENTON, E. Platelet survival in patients with substitute heart valves. N Engl J_&l_, 23, 534-537, 1974. 4. STEELE, P., WEILY, H., DAVIES, H ., PAPPAS, G., GENTON, E. Platelet survival time following aortic valve replacement. Circulation, 51, 358-362, 1975. 5. CHESEBRO, J.H., FUSTER, V. Thromboembolism in heart valve replacement. In: Thrombosis. H.C. Kwaan, E.J.W. Bowie, (Eds.) Philadelphia: W.B. Saunders, 1982, pp. 146-153. 6. SULLIVAN, J.M., HARKEN, D.E., GORLIN, R. Pharmacologic control of thromboembolic complications of cardiac valve replacement. N Engl J Med, 284, 1391, 1971.
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Vo1.35, No.4
7. DALE, J., MYHRE, E., ROOTWELT, K. Effects of dipyridamole and acetylsalicylic acid on platelet functions in patients with aortic ball-valve prostheses. Am Heart J, -89, 613-618, 1975. 8. STEELE, P., RAINWATER, J. Favorable effect on sulfinpyrazone on thromboembolism in patients with rheumatic heart disease. Circulation, 62, 462-468, 1980. 9. TAGUCHI, K., MATSUMURA, H., WASHIZU, T., HIRAO, M., KATO, K., KATO, E., MOCHIZUKI, T., TAKAMURA, K., MASHIMO, I., MORIFUJI, K., NAKAGAKI, M., SUMA, T. Effect of athrombogenic therapy, especially high dose therapy of dipyridamole, after prosthetic valve replacement. J Cardiovasc --SUB, 16, 8-15, 1975. 10. DEGAETANO, G., MIRAGLIOTTA, G., RONCUCCU, R., LANSEN, J., LAMBELIN, G. Suloctidil: a novel inhibitor of platelet aggregation in human beings. Thromb Res, 4, 361-371, 1976. 11.
GUREWICH, V., LIPINSKI, B.: Evaluation of antithrombotic properties of suloctidil in comparison with aspirin and dipyridamole. Thromb Res, -- 2, 101-108, 1976.
12. TURPIE, A.G.G., DEBOER, A.C., GENTON, E. Platelet consumption in cardiovascular disease. Seminars in Thrombosis $, 161, - and Hemostas, 1982.
13. INTERNATIONAL COMMITTEE FOR STANDARDIZATION IN HEMATOLOGY. Recommended methods for radioisotope platelet survival studies. Blood, 50, 1137, 1977. 14. TURPIE, A.G.G., GENTON, E., HAN, P., DEBOER, A.C., GENT, M. Evaluation of gamma function calculation of platelet survival time (abstr) Circulation, 62, (suppl III), 111-277, 1980. 15. DEBOER, A.C., HAN, P., TURPIE, A.G.G., BUTT, R., GENT, M., GENTON, E. Platelet tests and antiplatelet,drugs in coronary artery disease. Circulation, 2, 500-504, 1983. 16. HAN, P., BUTT, R.W., TURPIE, A.G.G., WALKER, W.H.C., GENTON, E. B-thromboglobulin radioimmunoassay: A laboratory characterization and evaluation. J Immunoassay, l_, 211, 1980. 17. DEBOER, A.C., HAN, P., TURPIE, A.G.G., BUTT, R., ZIELINSKY, A., GENTON, E. Plasma and urine BTG concentration in patients with deep vein thrombosis. Blood, 3, 693-698, 1981. 18. STEEL&, P.P., WEILY, H.S., DAVIES, H., GENTON, E.
patients with rheumatic heart disease.
Platelet survival in N Engl J Med 290, 537-539, 1974.
19. COL-DE BEYS,CHR., FERRANT, A., MORIAU, M.
Effects of suloctidil on platelet survival time following cardiac valve replacement. Thrombos Haemostas, (Stuttgart)2, 550-553, 1981.