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Effect of somatostatin analogue (SMS 201-995, sandostatin) on pancreatic secretion in humans
Effect of Somatostatin Analogue (SMS 201-995, Sandostatin) on Pancreatic Secretion in Humans
WERNER CREUTZFELDT, M.D. BERNHARD LEMBCKE, M.D. ULRICH R. FCLSCH, M.D. SEBASTIAN SCHLESER GBitingen,
Federal
Republic
of Germany
IRMTRAUT KOOP, M.D. Marburg,
Federal
Republic
of Germany
From the Division of Gastroenterology and Endocrinology, Department of Medicine, University of Gettingen, Gottingen, Federal Republic of Germany, and the Division of Gastroenterology, Department of Medicine, University of Marburg, Marburg, Federal Republic of Germany. Requests for reprints should be addressed to Dr. Werner Creutzfeldt, Medizinische Universitatsklinik, Robert-KochStrasse 40, D-3400 Gettingen, Federal Republic of Germany. Sandostatin (octreotide) is a registered trademark of Sandoz Pharmaceuticals Corporation, East Hanover, New Jersey. Sandostatin is also known as SMS 201-995, SMS, and somatostatin analogue.
The effect of the long-acting somatostatin analogue SMS 201-995 on exocrine pancreatic function and hormone release was investigated in a double-blind, placebo-controlled study in healthy subjects. SMS 201-995 was administered subcutaneously at a dose of 25 pg twice daily, and all tests were performed 30 minutes after the morning injection. Pancreatic enzyme secretion, gall bladder contraction, and cholecystokinin response after a Lundh meal were completely inhibited by SW, while pancreatic enzyme secretion elicited by intravenous injection of secretin and pancreozymin was suppressed by 80 percent. The inhibitory effect of SMS on endogenous cholecystokinin release was fully operative on the sixth day of injection treatment, whereas the inhibitory effect on exogenous cholecystokinin injection significantly decreased after SMS administration for seven days, indicating desensitization of the end organ by somatostatin. The release of pancreatic polypeptide by a solid test meal is abolished by administration of 25 pg of SMS, the release of gastric inhibitory polypeptide is nearly completely suppressed, the response of insulin and C-peptide are significantly lowered, and the gastrin response is only slightly reduced. Somatostatin inhibits the release of numerous peptide hormones and has many effects on gastrointestinal function (for a review, see [l]). The inhibitory effect on pentagastrin-stimulated gastric secretion [2], secretinstimulated pancreatic secretion [3], and cholecystokinin (CCK)-induced gall bladder contraction [3] suggests a direct inhibitory effect of somatostatin on the gastrointestinal target organs. As early as 1975, it was noted that such findings need to be considered in discussions about the possible therapeutic use of somatostatin in different endocrine diseases [3]. The short half-life of cyclic somatostatin-14 did not allow such therapeutic trials in endocrine diseases. However, such treatment has become possible with the development of long-acting somatostatin analogues. During the last two years, we have had the opportunity to study the effect of such an analogue (the octapeptide SMS 201-995) [4] on symptoms and tumor growth in patients with malignant endocrine gastrointestinal tumors [5,6]. One important clinical finding was severe steatorrhea in the majority of patients with carcinoid syndrome who were receiving the analogue for symptomatic control. After several months of treatment with the analogue, a secretin-pancreozymin pancreatic function test was performed in two of these patients one hour after subcutaneous injection of 50-/*g of SMS 201-995. Surprisingly, bicarbonate and enzyme secretion in these patients were completely normal, suggesting a non-pancreatic origin of the steatorrhea [6]. The discrepancy between the significant inhibition of
May
29, 1987
The
American
Journal
of Medicine
Volume
92 (suppl
56)
49
SYMPOSIUM
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Test meal
ENDOCRINE
TUMORS-CREUTZFELDT
ET AL
twice daily. This dose of somatostatin was chosen as being clinically relevant since it has been suggested for future longterm treatment of patients. The injections of SMS 201-995 or saline were given for periods of seven days each, with a minimum of one week between treatment periods. Subcutaneous
_
injections were administered t in the morning-30
0’ 1
4
12 IngImll
Oh 00i
0
50
30
90
120
150
leOImin1
Figure 7. Effect of SMS 201-995 on the responses of blood glucose, serum insulin, C-pepride, and pancreatic polypepride to a standard mixed meal ingested by volunteers on the fourth day of twice-daily injection of 25 pg of SMS or saline (n = 10). Values are mean t SEM; asterisks indicate significant (p cO.05) differences.
pancreatic secretion observed in short-term experiments [1,7] and the lack of this inhibitory effect during long-term treatment could be interpreted as an escape phenomenon, i.e., desensitization to somatostatin. This observation and the recent suggestion to use somatostatin analogues in the long-term treatment of patients with acromegaly and type I diabetes prompted us to investigate the effect of SMS 201-995 on pancreatic function and hormone release in healthy subjects. The study was designed as a placebo-controlled, double-blind, crossover investigation. SUBJECTS
AND METHODS
Ten healthy male volunteers (aged 23 to 36 years; weight 59 to 82 kg, all within +lO percent of ideal body weight) were studied. After an explanation of the protocol and the test procedures, all subjects gave consent to participate. The protocol had been approved by the Ethical Committee of the Georg-August University School of Medicine, Gottingen, Federal Republic of Germany. In a randomized fashion, each subject received either a subcutaneous injection of 25 pg of SMS 201-995, kindly provided by Sandoz AG, Easel/Switzerland, or placebo (saline)
50
May
29, 1997
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of Medicine
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minutes
before breakfast (or the respective test)-and in the evening. The following investigations were performed to evaluate pancreatic function and hormone response during the two treatment periods: Day 4: Following ingestion of a standard meal consisting of 40 percent fat, 35 percent carbohydrates, and 25 percent protein (= 550 kcal) 30 minutes after subcutaneous injection of 25 pg of SMS 201-995 or placebo, blood glucose, insulin, C-peptide, gastric inhibitory polypeptide (GIP), gastrin, and pancreatic polypeptide concentrations were determined at 30-minute intervals for three hours. Day 6: A double-lumen radiolucent tube was placed into the duodenum and a Lundh test was performed 30 minutes after subcutaneous injection of SMS 201-995 or placebo. Duodenal contents were aspirated before ingestion and at 15-minute intervals after ingestion (for 120 minutes) of a liquid test meal (composition: 45 percent fat, 40 percent carbohydrates, and 15 percent protein = 380 kcal) [a]. Estimates of concentrations of lipase, trypsin, and bilirubin were obtained for each aspirate. Blood samples were obtained at 15minute intervals from 30 minutes before until two hours after ingestion of the Lundh meal and, in addition, at 5minute intervals in the first 15 minutes after the meal for estimation of the CCK concentration. Day 7: A Lagerlof tube was placed into the duodenum and a pancreatic function test (secretin-pancreozymin test) was performed [9]. Gastric secretions were aspirated continu-
ously and discarded, and duodenal secretions were collected at 15-minute intervals. After 30 minutes of basal secretion, secretin (1 U/kg body weight) and, 30 minutes later, CCKpancreozymin (1 U/kg body weight) were given intravenously. Both hormones were obtained from the Gill Research Laboratory, Karolinska Institute, Stockholm, Sweden. Duodenal aspirations were analyzed for volume and concentration of bicarbonate, amylase, trypsin, lipase, and bilirubin. Four to eight weeks later, a second secretin-pancreozymin test was performed in six of the volunteers 30 minutes after a single subcutaneous injection of 25 pg of SMS 201-995. Analytic Methods. In the duodenal aspirate, bicarbonate was measured by the micro-van Slyke method, amylase by reduction of 3.5-dinitro-salicylic acid, trypsin by the BAPNA technique using benzoylarginine-p-nitroanilide as substrate, lipase by a titrimetric method using olive oil emulsion, and bilirubin according to the method of Jendrassik and Grof. Blood glucose levels were measured by a glucose oxidase method. Pancreatic and gastrointestinal hormones were measured in plasma by radioimmunologic methods developed or validated in our laboratory (gastrin [lo], GIP [ll], pancreatic polypeptide [12], insulin [13], and C-peptide [Novo-Kit]). CCK was estimated in EDTA plasma with aprotinin, extracted with 98 percent ethanol using antibody G 160, provided by Dr. Schafmayer, and CCK8 as standard and ‘251-Bolton-Hunter-labeled CCK-8 as tracer [14]. The sensitivity of the CCK assay was 1 pmol/liter. Calculations. In the secretin-pancreozymin test, the output
92 (suppl
5B)
SYMPOSIUM
ON GASTROINTESTINAL
ENDOCRINE
TUMORS-CREUTZFELDT
ET AL
Test meal
[pglmll
1200
E zSEM MO)
GASTRIN
80= 60LO= 20Figure 2. Effect of SMS 207-995 on the responses of G/P and gastrin to a standard mixed meal. Same conditions as in Figure 7.
0’
I 0
1 30
of bicarbonate and enzymes was calculated as the product of concentration and duodenal volume aspirated for the 15minute periods. All results were expressed as mean It SEM and the results of the test and placebo periods were compared using the Student t test.
. 90
120
150 180 [min.] ,
trin response was only moderately diminished (significant only at 30 and 90 minutes). Lundh Test. The increases in lipase, trypsin, and bilirubin concentrations in the duodenal aspirate after the Lundh meal were nearly completely suppressed by pretreatment with 25 ,ug of SMS; the concentrations were even lower than the basal concentrations measured in the duodenal aspirate. The concentration of bilirubin, in particular, dropped to zero in the majority of aspirates (Figure 3). During the placebo period, plasma CCK levels increased from 1 pmoliliter (the lower limit of detection) to 7 pmoliliter as early as 10 minutes after ingestion of the Lundh meal and stayed elevated over the whole 120minute observation period. In contrast, the plasma CCK response was nearly completely abolished during the SMS period (Figure 4). Secretin-Pancreozymin Test. The increase of volume and bicarbonate concentration in the duodenal aspirate after intravenous injection of secretin and pancreozymin was not affected by the previous injection of SMS, no matter whether the secretin-pancreozymin test was per-
RESULTS Test Meal.
Following subcutaneous injection of SMS 201-995, the rise in serum glucose concentration was significantly greater (between 60 and 150 minutes) after the meal, whereas the insulin and C-peptide response was significantly smaller (30 to 60 minutes) when compared with the results of placebo administration. Starting at 120 minutes, C-peptide levels were significantly higher during the SMS period, indicating delayed secretion of insulin. In contrast to the insulin and C-peptide responses, which were only delayed and a little diminished after administration of SMS, the response of pancreatic polypeptide was completely abolished at all time points (Figure 1). SMS 201-995 suppressed release of both gastrin and GIP (Figure 2). While the GIP response was nearly completely suppressed (significant at all time points), the gas-
May 29, 1987
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formed after SMS treatment for seven days or without such pretreatment (data not shown). In contrast, the increase in enzymes and bilirubin in the duodenal aspirate was significantly smaller if SMS was applied 30 minutes before the injection of secretin and pancreozymin than in the placebo period. This inhibitory effect of SMS on hormone-stimulated enzyme secretion and gall bladder contraction (as reflected by increased bilirubin output) was significantly greater if SMS was given without pretreatment, compared with pretreatment for seven days with 25 pg of SMS 201-995 twice daily. Enzyme secretion was suppressed by SMS administration to about 20 percent of the placebo values without pretreatment (this is in the range of the maximal effect achieved in a recent doseresponse study with intravenous injection of SMS [7]), but to only 35 to 50 percent if SMS was given after treatment for seven days (Figure 5). The bilirubin increase was reduced to 55 percent after a single SMS dose but did not differ from placebo at Day 7 of SMS treatment. Side Effects. During the SMS 201-995 treatment period, most of the subjects experienced a feeling of abdominal fullness, loss of appetite, and several episodes of abdominal cramps. These complaints decreased towards the end of the treatment week. The subcutaneous injection of SMS was regarded as painful by most subjects.
ii f SEM in=91
U/ml 1 Lundh meal
ET AL
mu/ml
1X0 1000
600 400 ;
COMMENTS
Figure 3. Concentrations of lipase, trypsin, and bilirubin in duodenal aspirates after a standard Lundh test meal ingested by volunteers on the sixth day of twice-daily injection of 25 pg of SMS or saline (n = 9). Values are mean + SEM; asterisks indicate significant (p <0.05) differences.
I pmulll 1 0-
Lundh meal
6-
i? *_SEM In=81
I-
Control 2
*
$ SMS 201-995
-
O:g)
0306090
[min.]
120
igure 4. Serum CCK response to the Lundh meal (same conditions as Figure 3). Values are mean + SEM (n = 8); asterisks indicate significant (p ~0.05) differences.
52
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This placebo-controlled, double-blind, crossover study has demonstrated that after subcutaneous injection of healthy subjects with the long-acting somatostatin analogue SMS 201-995 at the low dose of 25 pg twice daily the following occur: (1) the response of pancreatic and gastrointestinal hormones to a test meal is partially or completely suppressed; (2) pancreatic enzyme secretion, gallbladder contraction, and the plasma CCK response to the Lundh meal is abolished; and (3) the pancreatic enzyme secretion and gallbladder contraction induced by intravenously administered secretin and pancreozymin are significantly less suppressed after seven days of treatment with SMS than after a single injection of the analogue. The first observation indicates that different peptide hormone-producing endocrine cells in the pancreas and the gastrointestinal tract have a differential sensitivity to SMS 201-995. This may be of interest if this analogue is used therapeutically. At a dose of 25 pg, SMS completely abolished the response of pancreatic polypeptide and CCK, nearly abolished the release of GIP, and significantly lowered plasma insulin and C-peptide concentrations, while hardly affecting gastrin secretion. It is likely that such differences will only be found when low doses of SMS 201-995 are used. The simultaneous suppression by SMS of CCK plasma levels, pancreatic enzyme secretion, and gall bladder contraction in response to the Lundh meal is compatible
82 (suppl
58)
SYMPOSIUM
ON GASTROINTESTINAL
AMYLAY
Figure 5. Enzyme and bilirubin output after secretin and pancreozymin injection at control conditions (saline), after a single dose (25 cog subcutaneously) of SMS 201-995, and at Day 7 of twice-daily injections of SMS 201-995 (25 pg subcutaneously). Results are mean t SEM; the respective number of volunteers studied is given below each bar. Significance limits are given both for the differences between placebo and the single SMS injection, and for single SMS injection in comparison to the one-week adminishation of SMS 201-995. Dotted lines refer to the lower limit of normal of enzyme output during secretin-pancreozymin test (mean - 2 SD).
h&l
ENDOCRINE
TR(PSIN
TUMORS-CREUTZFELDT
BLIRUBIN
LEASE
wllnout pmtrtinmnt h4 In4
In4
with the contention that the effect of the Lundh meal on pancreas and gallbladder is mediated by CCK. This function may be especially sensitive to SMS because the CCK (and pancreatic polypeptide) response is more easily suppressed than are those of the other pancreatic or gastrointestinal hormones. Since this suppression is still complete on the sixth day of our investigation, desensitization of the CCK-secreting cells by SMS 201-995 does not appear to occur. This is different from the decreasing sensitivity of pancreatic enzyme secretion and gall bladder contraction to SMS inhibition after intravenous injection of secretin and pancreozymin as demonstrated in Figure 5. The latter finding indicates an escape, i.e., desensitization of the end organ by SMS 201-995. This is in agreement with the finding of the normal secretin-pancreozymin test results observed in patients receiving long-term treatment with SMS [6]. Such desensitization to somatostatin has been described for the parietal cells, i.e., gastric secretion in rats [15] and recently also in humans [I 61. According to our current findings, this desensitization is only operative at the level of the target organ and not at the level of the hormone-producing cells. However, further studies are needed to confirm this suggestion, which may be of practi-
ET AL
protmtfmnt ln4 h&l
J
cal importance if long-term treatment with SMS 201-995 is considered. This study cannot resolve the question of whether the observed suppression of CCK response and CCK-mediated pancreatic secretion and gallbladder contraction will become of clinical significance during long-term treatment with SMS 201-995 even at such a low dose as 25 pg twice daily. Marked steatorrhea (average stool fat, 55 g per day) was observed after much higher doses (50 to 100 pg three times a day given for three of four days) in patients with diarrhea and initially mild steatorrhea (10 to 20 g per day) due to metastatic carcinoid syndrome [5,6]. In these studies, supplementation with pancreatin in high doses did not reduce the SMS-induced steatorrhea. This indicates that other effects of somatostatin and its analogue, such as direct inhibition of absorption at the mucosal level, may be responsible for fat malabsorption. Native somatostatin has been shown to inhibit the absorption of glucose, amino acids [17,18], and triglycerides [19], and also to inhibit CCK-mediated gallbladder contraction [3,20], which, if it is permanent, may, along with a reduced bile flow [21], facilitate the formation of gall stones.
REFERENCES 1. 2.
3.
Arnold R, Lank&h PL: Somatostatin and the gastrointestinal tract. Clin Gastroenterol 1980; 9: 733-753. Arnold R, Creutzfeldt W: Hemmung der pentagastrininduzierten SBuresekretion des Magens beim Menschen durch Somatostatin. Dtsch Med Wochenschr 1975; 100: 1014-1018. Creutzfeldt W, Lankisch PG, Fiilsch UR: Hemmung der sekretin- und cholecystokinin-pankreozymininduzierten Saft-und Enzymsekretion des Pankreas und der Gallenblasenkontraktion beim Menschen durch Somatostatin. Dtsch Med
May
29,1997
4.
5.
6.
The
Wochenschr 1975; 100: 1135-l 138. Bauer W, Briner U, Doepfner W, et al: SMS 201-995: a very potent and selective octapeptide analogue of somatostatin with prolonged action. Life Sci 1982; 31: 1133-l 140. Richter G, Stiickmann F, Lembcke B, Conlon JM, Creutzfeldt W: Short-term administration of the somatostatin analogue SMS 201-995 in patients with carcinoid tumours. Stand J Gastroenterol [Suppl] 1988; 119: 193-198. Stiickmann F, Richter G, Lembcke B, Conlon JM, Creutzfeldt W:
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7.
8.
9.
10.
11.
12.
13.
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Long-term treatment of patients with endocrine gastrointestinal tumors with the somatostatin analogue SMS 201-995. Stand J Gastroenterol [Suppl] 1986; 119: 230-237. Kdhler E, Beglinger Ch, Dettwiler S, Whitehouse I, Gyr K: Effect of a new somatostatin analogue on pancreatic function in healthy volunteers. Pancreas 1986; 1: 154-l 59. Lundh G: Pancreatic exocrine function in neoplastic and inflammatory disease; a simple and reliable new test. Gastroenterology 1962; 42: 275-280. Creutzfeldt W: Funktionsdiagnostik bei Erkrankungen des exokrinen Pankreas. Verh Dtsch Ges Inn Med 1964; 70: 781801. Mayer G, Arnold R, Feurle G, et al: Influence of feeding and sham feeding upon serum gastrin and gastric acid secretion in control subjects and duodenal ulcer patients. Stand J Gastroenterol 1974; 9: 703-7iO. Ebert R, lllmer K, Creutzfeldt W: Release of gastric inhibitory polypeptide (GIP) by intraduodenal acidification in rats and humans and abolishment of the incretin effect of acid by GIPantiserum in rats. Gastroenterology 1979; 76: 515-523. Cichy W, Lankisch PG, Arnold A, Creufzfeldt W: Evaluation of serum pancreatic polypeptide estimations following hormonal stimulation for the diagnosis of exocrine pancreatic insufficiency. Digestion 1984; 30: 218-223. Melani F, Ditschuneit H, Bartelt HM, Friedrich H, Pfeiffer EF: Uber die radioimmunologische Bestimmung von Insulin im
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ET AL
14.
15.
16.
17.
18.
19.
20.
21.
Blut. Klin Wochenschr 1965; 43: 1000-1006. Mundlos S, Adler G, Schaar M, Koop I, Arnold R: Exocrine pancreatic function in oleic acid-induced pancreatic insufficiency in rats. Pancreas 1986; 1: 29-36. Ekelund M, Ekman R, Hakanson R, Sundler F: Continuous infusion of somatostatin evokes escape of gastric acid inhibition in the rat. Gastroenterology 1984; 86: 861-865. Londong W, Angerer M, Kutz K, Londong V: Diminishing sensitivity of human parietal cell function to SMS 201-995 treatment (abstr). Gut 1986; 27: A613. Krejs GJ, Browne R, Raskin P: Effect of intravenous somatostatin on jejunal absorption of glucose, amino acids, water, and electrolytes. Gastroenterology 1980; 78: 26-31. Johansson C, Wisen 0, Efendic S, et al: Effects of somatostatin on gastrointestinal propagation and absorption of oral glucose in man. Digestion 1981; 22: 126-137. Hengl G, Prager J, Pointner H: The influence of somatostatin on the absorption of triglycerides in partially gastrectomized subjects. Acta Hepato-Gastroenterol 1979, 26: 392-395. Johansson C, Kollberg B, Efendic S, Uvnas-Wallensten K: Effects of graded doses of somatostatin on gallbladder emptying and pancreatic enzyme output after oral glucose in man. Digestion 1981; 22: 24-31, Hanks JB, Kortz WJ, Andersen DK, Scott Jones R: Somatostatin suppression of canine fasting bile secretion. Gastroenterology 1983; 84: 130-137.
92 (suppl
5B)
WERNER CREUTZFELDT, M.D. BERNHARD LEMBCKE, M.D. ULRICH R. FCLSCH, M.D. SEBASTIAN SCHLESER GBitingen,
Federal
Republic
of Germany
IRMTRAUT KOOP, M.D. Marburg,
Federal
Republic
of Germany
From the Division of Gastroenterology and Endocrinology, Department of Medicine, University of Gettingen, Gottingen, Federal Republic of Germany, and the Division of Gastroenterology, Department of Medicine, University of Marburg, Marburg, Federal Republic of Germany. Requests for reprints should be addressed to Dr. Werner Creutzfeldt, Medizinische Universitatsklinik, Robert-KochStrasse 40, D-3400 Gettingen, Federal Republic of Germany. Sandostatin (octreotide) is a registered trademark of Sandoz Pharmaceuticals Corporation, East Hanover, New Jersey. Sandostatin is also known as SMS 201-995, SMS, and somatostatin analogue.
The effect of the long-acting somatostatin analogue SMS 201-995 on exocrine pancreatic function and hormone release was investigated in a double-blind, placebo-controlled study in healthy subjects. SMS 201-995 was administered subcutaneously at a dose of 25 pg twice daily, and all tests were performed 30 minutes after the morning injection. Pancreatic enzyme secretion, gall bladder contraction, and cholecystokinin response after a Lundh meal were completely inhibited by SW, while pancreatic enzyme secretion elicited by intravenous injection of secretin and pancreozymin was suppressed by 80 percent. The inhibitory effect of SMS on endogenous cholecystokinin release was fully operative on the sixth day of injection treatment, whereas the inhibitory effect on exogenous cholecystokinin injection significantly decreased after SMS administration for seven days, indicating desensitization of the end organ by somatostatin. The release of pancreatic polypeptide by a solid test meal is abolished by administration of 25 pg of SMS, the release of gastric inhibitory polypeptide is nearly completely suppressed, the response of insulin and C-peptide are significantly lowered, and the gastrin response is only slightly reduced. Somatostatin inhibits the release of numerous peptide hormones and has many effects on gastrointestinal function (for a review, see [l]). The inhibitory effect on pentagastrin-stimulated gastric secretion [2], secretinstimulated pancreatic secretion [3], and cholecystokinin (CCK)-induced gall bladder contraction [3] suggests a direct inhibitory effect of somatostatin on the gastrointestinal target organs. As early as 1975, it was noted that such findings need to be considered in discussions about the possible therapeutic use of somatostatin in different endocrine diseases [3]. The short half-life of cyclic somatostatin-14 did not allow such therapeutic trials in endocrine diseases. However, such treatment has become possible with the development of long-acting somatostatin analogues. During the last two years, we have had the opportunity to study the effect of such an analogue (the octapeptide SMS 201-995) [4] on symptoms and tumor growth in patients with malignant endocrine gastrointestinal tumors [5,6]. One important clinical finding was severe steatorrhea in the majority of patients with carcinoid syndrome who were receiving the analogue for symptomatic control. After several months of treatment with the analogue, a secretin-pancreozymin pancreatic function test was performed in two of these patients one hour after subcutaneous injection of 50-/*g of SMS 201-995. Surprisingly, bicarbonate and enzyme secretion in these patients were completely normal, suggesting a non-pancreatic origin of the steatorrhea [6]. The discrepancy between the significant inhibition of
May
29, 1987
The
American
Journal
of Medicine
Volume
92 (suppl
56)
49
SYMPOSIUM
ON GASTROINTESTINAL
Test meal
ENDOCRINE
TUMORS-CREUTZFELDT
ET AL
twice daily. This dose of somatostatin was chosen as being clinically relevant since it has been suggested for future longterm treatment of patients. The injections of SMS 201-995 or saline were given for periods of seven days each, with a minimum of one week between treatment periods. Subcutaneous
_
injections were administered t in the morning-30
0’ 1
4
12 IngImll
Oh 00i
0
50
30
90
120
150
leOImin1
Figure 7. Effect of SMS 201-995 on the responses of blood glucose, serum insulin, C-pepride, and pancreatic polypepride to a standard mixed meal ingested by volunteers on the fourth day of twice-daily injection of 25 pg of SMS or saline (n = 10). Values are mean t SEM; asterisks indicate significant (p cO.05) differences.
pancreatic secretion observed in short-term experiments [1,7] and the lack of this inhibitory effect during long-term treatment could be interpreted as an escape phenomenon, i.e., desensitization to somatostatin. This observation and the recent suggestion to use somatostatin analogues in the long-term treatment of patients with acromegaly and type I diabetes prompted us to investigate the effect of SMS 201-995 on pancreatic function and hormone release in healthy subjects. The study was designed as a placebo-controlled, double-blind, crossover investigation. SUBJECTS
AND METHODS
Ten healthy male volunteers (aged 23 to 36 years; weight 59 to 82 kg, all within +lO percent of ideal body weight) were studied. After an explanation of the protocol and the test procedures, all subjects gave consent to participate. The protocol had been approved by the Ethical Committee of the Georg-August University School of Medicine, Gottingen, Federal Republic of Germany. In a randomized fashion, each subject received either a subcutaneous injection of 25 pg of SMS 201-995, kindly provided by Sandoz AG, Easel/Switzerland, or placebo (saline)
50
May
29, 1997
The
American
Journal
of Medicine
Volume
minutes
before breakfast (or the respective test)-and in the evening. The following investigations were performed to evaluate pancreatic function and hormone response during the two treatment periods: Day 4: Following ingestion of a standard meal consisting of 40 percent fat, 35 percent carbohydrates, and 25 percent protein (= 550 kcal) 30 minutes after subcutaneous injection of 25 pg of SMS 201-995 or placebo, blood glucose, insulin, C-peptide, gastric inhibitory polypeptide (GIP), gastrin, and pancreatic polypeptide concentrations were determined at 30-minute intervals for three hours. Day 6: A double-lumen radiolucent tube was placed into the duodenum and a Lundh test was performed 30 minutes after subcutaneous injection of SMS 201-995 or placebo. Duodenal contents were aspirated before ingestion and at 15-minute intervals after ingestion (for 120 minutes) of a liquid test meal (composition: 45 percent fat, 40 percent carbohydrates, and 15 percent protein = 380 kcal) [a]. Estimates of concentrations of lipase, trypsin, and bilirubin were obtained for each aspirate. Blood samples were obtained at 15minute intervals from 30 minutes before until two hours after ingestion of the Lundh meal and, in addition, at 5minute intervals in the first 15 minutes after the meal for estimation of the CCK concentration. Day 7: A Lagerlof tube was placed into the duodenum and a pancreatic function test (secretin-pancreozymin test) was performed [9]. Gastric secretions were aspirated continu-
ously and discarded, and duodenal secretions were collected at 15-minute intervals. After 30 minutes of basal secretion, secretin (1 U/kg body weight) and, 30 minutes later, CCKpancreozymin (1 U/kg body weight) were given intravenously. Both hormones were obtained from the Gill Research Laboratory, Karolinska Institute, Stockholm, Sweden. Duodenal aspirations were analyzed for volume and concentration of bicarbonate, amylase, trypsin, lipase, and bilirubin. Four to eight weeks later, a second secretin-pancreozymin test was performed in six of the volunteers 30 minutes after a single subcutaneous injection of 25 pg of SMS 201-995. Analytic Methods. In the duodenal aspirate, bicarbonate was measured by the micro-van Slyke method, amylase by reduction of 3.5-dinitro-salicylic acid, trypsin by the BAPNA technique using benzoylarginine-p-nitroanilide as substrate, lipase by a titrimetric method using olive oil emulsion, and bilirubin according to the method of Jendrassik and Grof. Blood glucose levels were measured by a glucose oxidase method. Pancreatic and gastrointestinal hormones were measured in plasma by radioimmunologic methods developed or validated in our laboratory (gastrin [lo], GIP [ll], pancreatic polypeptide [12], insulin [13], and C-peptide [Novo-Kit]). CCK was estimated in EDTA plasma with aprotinin, extracted with 98 percent ethanol using antibody G 160, provided by Dr. Schafmayer, and CCK8 as standard and ‘251-Bolton-Hunter-labeled CCK-8 as tracer [14]. The sensitivity of the CCK assay was 1 pmol/liter. Calculations. In the secretin-pancreozymin test, the output
92 (suppl
5B)
SYMPOSIUM
ON GASTROINTESTINAL
ENDOCRINE
TUMORS-CREUTZFELDT
ET AL
Test meal
[pglmll
1200
E zSEM MO)
GASTRIN
80= 60LO= 20Figure 2. Effect of SMS 207-995 on the responses of G/P and gastrin to a standard mixed meal. Same conditions as in Figure 7.
0’
I 0
1 30
of bicarbonate and enzymes was calculated as the product of concentration and duodenal volume aspirated for the 15minute periods. All results were expressed as mean It SEM and the results of the test and placebo periods were compared using the Student t test.
. 90
120
150 180 [min.] ,
trin response was only moderately diminished (significant only at 30 and 90 minutes). Lundh Test. The increases in lipase, trypsin, and bilirubin concentrations in the duodenal aspirate after the Lundh meal were nearly completely suppressed by pretreatment with 25 ,ug of SMS; the concentrations were even lower than the basal concentrations measured in the duodenal aspirate. The concentration of bilirubin, in particular, dropped to zero in the majority of aspirates (Figure 3). During the placebo period, plasma CCK levels increased from 1 pmoliliter (the lower limit of detection) to 7 pmoliliter as early as 10 minutes after ingestion of the Lundh meal and stayed elevated over the whole 120minute observation period. In contrast, the plasma CCK response was nearly completely abolished during the SMS period (Figure 4). Secretin-Pancreozymin Test. The increase of volume and bicarbonate concentration in the duodenal aspirate after intravenous injection of secretin and pancreozymin was not affected by the previous injection of SMS, no matter whether the secretin-pancreozymin test was per-
RESULTS Test Meal.
Following subcutaneous injection of SMS 201-995, the rise in serum glucose concentration was significantly greater (between 60 and 150 minutes) after the meal, whereas the insulin and C-peptide response was significantly smaller (30 to 60 minutes) when compared with the results of placebo administration. Starting at 120 minutes, C-peptide levels were significantly higher during the SMS period, indicating delayed secretion of insulin. In contrast to the insulin and C-peptide responses, which were only delayed and a little diminished after administration of SMS, the response of pancreatic polypeptide was completely abolished at all time points (Figure 1). SMS 201-995 suppressed release of both gastrin and GIP (Figure 2). While the GIP response was nearly completely suppressed (significant at all time points), the gas-
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formed after SMS treatment for seven days or without such pretreatment (data not shown). In contrast, the increase in enzymes and bilirubin in the duodenal aspirate was significantly smaller if SMS was applied 30 minutes before the injection of secretin and pancreozymin than in the placebo period. This inhibitory effect of SMS on hormone-stimulated enzyme secretion and gall bladder contraction (as reflected by increased bilirubin output) was significantly greater if SMS was given without pretreatment, compared with pretreatment for seven days with 25 pg of SMS 201-995 twice daily. Enzyme secretion was suppressed by SMS administration to about 20 percent of the placebo values without pretreatment (this is in the range of the maximal effect achieved in a recent doseresponse study with intravenous injection of SMS [7]), but to only 35 to 50 percent if SMS was given after treatment for seven days (Figure 5). The bilirubin increase was reduced to 55 percent after a single SMS dose but did not differ from placebo at Day 7 of SMS treatment. Side Effects. During the SMS 201-995 treatment period, most of the subjects experienced a feeling of abdominal fullness, loss of appetite, and several episodes of abdominal cramps. These complaints decreased towards the end of the treatment week. The subcutaneous injection of SMS was regarded as painful by most subjects.
ii f SEM in=91
U/ml 1 Lundh meal
ET AL
mu/ml
1X0 1000
600 400 ;
COMMENTS
Figure 3. Concentrations of lipase, trypsin, and bilirubin in duodenal aspirates after a standard Lundh test meal ingested by volunteers on the sixth day of twice-daily injection of 25 pg of SMS or saline (n = 9). Values are mean + SEM; asterisks indicate significant (p <0.05) differences.
I pmulll 1 0-
Lundh meal
6-
i? *_SEM In=81
I-
Control 2
*
$ SMS 201-995
-
O:g)
0306090
[min.]
120
igure 4. Serum CCK response to the Lundh meal (same conditions as Figure 3). Values are mean + SEM (n = 8); asterisks indicate significant (p ~0.05) differences.
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This placebo-controlled, double-blind, crossover study has demonstrated that after subcutaneous injection of healthy subjects with the long-acting somatostatin analogue SMS 201-995 at the low dose of 25 pg twice daily the following occur: (1) the response of pancreatic and gastrointestinal hormones to a test meal is partially or completely suppressed; (2) pancreatic enzyme secretion, gallbladder contraction, and the plasma CCK response to the Lundh meal is abolished; and (3) the pancreatic enzyme secretion and gallbladder contraction induced by intravenously administered secretin and pancreozymin are significantly less suppressed after seven days of treatment with SMS than after a single injection of the analogue. The first observation indicates that different peptide hormone-producing endocrine cells in the pancreas and the gastrointestinal tract have a differential sensitivity to SMS 201-995. This may be of interest if this analogue is used therapeutically. At a dose of 25 pg, SMS completely abolished the response of pancreatic polypeptide and CCK, nearly abolished the release of GIP, and significantly lowered plasma insulin and C-peptide concentrations, while hardly affecting gastrin secretion. It is likely that such differences will only be found when low doses of SMS 201-995 are used. The simultaneous suppression by SMS of CCK plasma levels, pancreatic enzyme secretion, and gall bladder contraction in response to the Lundh meal is compatible
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Figure 5. Enzyme and bilirubin output after secretin and pancreozymin injection at control conditions (saline), after a single dose (25 cog subcutaneously) of SMS 201-995, and at Day 7 of twice-daily injections of SMS 201-995 (25 pg subcutaneously). Results are mean t SEM; the respective number of volunteers studied is given below each bar. Significance limits are given both for the differences between placebo and the single SMS injection, and for single SMS injection in comparison to the one-week adminishation of SMS 201-995. Dotted lines refer to the lower limit of normal of enzyme output during secretin-pancreozymin test (mean - 2 SD).
h&l
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BLIRUBIN
LEASE
wllnout pmtrtinmnt h4 In4
In4
with the contention that the effect of the Lundh meal on pancreas and gallbladder is mediated by CCK. This function may be especially sensitive to SMS because the CCK (and pancreatic polypeptide) response is more easily suppressed than are those of the other pancreatic or gastrointestinal hormones. Since this suppression is still complete on the sixth day of our investigation, desensitization of the CCK-secreting cells by SMS 201-995 does not appear to occur. This is different from the decreasing sensitivity of pancreatic enzyme secretion and gall bladder contraction to SMS inhibition after intravenous injection of secretin and pancreozymin as demonstrated in Figure 5. The latter finding indicates an escape, i.e., desensitization of the end organ by SMS 201-995. This is in agreement with the finding of the normal secretin-pancreozymin test results observed in patients receiving long-term treatment with SMS [6]. Such desensitization to somatostatin has been described for the parietal cells, i.e., gastric secretion in rats [15] and recently also in humans [I 61. According to our current findings, this desensitization is only operative at the level of the target organ and not at the level of the hormone-producing cells. However, further studies are needed to confirm this suggestion, which may be of practi-
ET AL
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cal importance if long-term treatment with SMS 201-995 is considered. This study cannot resolve the question of whether the observed suppression of CCK response and CCK-mediated pancreatic secretion and gallbladder contraction will become of clinical significance during long-term treatment with SMS 201-995 even at such a low dose as 25 pg twice daily. Marked steatorrhea (average stool fat, 55 g per day) was observed after much higher doses (50 to 100 pg three times a day given for three of four days) in patients with diarrhea and initially mild steatorrhea (10 to 20 g per day) due to metastatic carcinoid syndrome [5,6]. In these studies, supplementation with pancreatin in high doses did not reduce the SMS-induced steatorrhea. This indicates that other effects of somatostatin and its analogue, such as direct inhibition of absorption at the mucosal level, may be responsible for fat malabsorption. Native somatostatin has been shown to inhibit the absorption of glucose, amino acids [17,18], and triglycerides [19], and also to inhibit CCK-mediated gallbladder contraction [3,20], which, if it is permanent, may, along with a reduced bile flow [21], facilitate the formation of gall stones.
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Arnold R, Lank&h PL: Somatostatin and the gastrointestinal tract. Clin Gastroenterol 1980; 9: 733-753. Arnold R, Creutzfeldt W: Hemmung der pentagastrininduzierten SBuresekretion des Magens beim Menschen durch Somatostatin. Dtsch Med Wochenschr 1975; 100: 1014-1018. Creutzfeldt W, Lankisch PG, Fiilsch UR: Hemmung der sekretin- und cholecystokinin-pankreozymininduzierten Saft-und Enzymsekretion des Pankreas und der Gallenblasenkontraktion beim Menschen durch Somatostatin. Dtsch Med
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Wochenschr 1975; 100: 1135-l 138. Bauer W, Briner U, Doepfner W, et al: SMS 201-995: a very potent and selective octapeptide analogue of somatostatin with prolonged action. Life Sci 1982; 31: 1133-l 140. Richter G, Stiickmann F, Lembcke B, Conlon JM, Creutzfeldt W: Short-term administration of the somatostatin analogue SMS 201-995 in patients with carcinoid tumours. Stand J Gastroenterol [Suppl] 1988; 119: 193-198. Stiickmann F, Richter G, Lembcke B, Conlon JM, Creutzfeldt W:
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Blut. Klin Wochenschr 1965; 43: 1000-1006. Mundlos S, Adler G, Schaar M, Koop I, Arnold R: Exocrine pancreatic function in oleic acid-induced pancreatic insufficiency in rats. Pancreas 1986; 1: 29-36. Ekelund M, Ekman R, Hakanson R, Sundler F: Continuous infusion of somatostatin evokes escape of gastric acid inhibition in the rat. Gastroenterology 1984; 86: 861-865. Londong W, Angerer M, Kutz K, Londong V: Diminishing sensitivity of human parietal cell function to SMS 201-995 treatment (abstr). Gut 1986; 27: A613. Krejs GJ, Browne R, Raskin P: Effect of intravenous somatostatin on jejunal absorption of glucose, amino acids, water, and electrolytes. Gastroenterology 1980; 78: 26-31. Johansson C, Wisen 0, Efendic S, et al: Effects of somatostatin on gastrointestinal propagation and absorption of oral glucose in man. Digestion 1981; 22: 126-137. Hengl G, Prager J, Pointner H: The influence of somatostatin on the absorption of triglycerides in partially gastrectomized subjects. Acta Hepato-Gastroenterol 1979, 26: 392-395. Johansson C, Kollberg B, Efendic S, Uvnas-Wallensten K: Effects of graded doses of somatostatin on gallbladder emptying and pancreatic enzyme output after oral glucose in man. Digestion 1981; 22: 24-31, Hanks JB, Kortz WJ, Andersen DK, Scott Jones R: Somatostatin suppression of canine fasting bile secretion. Gastroenterology 1983; 84: 130-137.
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