Intravenous and subcutaneous administration of a long-acting somatostatin analogue: effects on glucose metabolism and splanchnic haemodynamics in healthy subjects

Characterization and Optimal Management of High-risk Pancreatic Anastomoses During Pancreatoduodenectomy

OBJECTIVE

The aim of this study was to identify the optimal fistula mitigation strategy following pancreaticoduodenectomy.

BACKGROUND

The utility of technical strategies to prevent clinically relevant postoperative pancreatic fistula (CR-POPF) following pancreatoduodenectomy (PD) may vary by the circumstances of the anastomosis. The Fistula Risk Score (FRS) identifies a distinct high-risk cohort (FRS 7 to 10) that demonstrates substantially worse clinical outcomes. The value of various fistula mitigation strategies in these particular high-stakes cases has not been previously explored.

METHODS

This multinational study included 5323 PDs performed by 62 surgeons at 17 institutions. Mitigation strategies, including both technique related (ie, pancreatogastrostomy reconstruction; dunking; tissue patches) and the use of adjuvant strategies (ie, intraperitoneal drains; anastomotic stents; prophylactic octreotide; tissue sealants), were evaluated using multivariable regression analysis and propensity score matching.

RESULTS

A total of 522 (9.8%) PDs met high-risk FRS criteria, with an observed CR-POPF rate of 29.1%. Pancreatogastrostomy, prophylactic octreotide, and omission of externalized stents were each associated with an increased rate of CR-POPF (all P < 0.001). In a multivariable model accounting for patient, surgeon, and institutional characteristics, the use of external stents [odds ratio (OR) 0.45, 95% confidence interval (95% CI) 0.25-0.81] and the omission of prophylactic octreotide (OR 0.49, 95% CI 0.30-0.78) were independently associated with decreased CR-POPF occurrence. In the propensity score matched cohort, an "optimal" mitigation strategy (ie, externalized stent and no prophylactic octreotide) was associated with a reduced rate of CR-POPF (13.2% vs 33.5%, P < 0.001).

CONCLUSIONS

The scenarios identified by the high-risk FRS zone represent challenging anastomoses associated with markedly elevated rates of fistula. Externalized stents and omission of prophylactic octreotide, in the setting of intraperitoneal drainage and pancreaticojejunostomy reconstruction, provides optimal outcomes.

Gastrointestinal Angiodysplasia: Diagnosis and Management

Gastrointestinal angiodysplasia (GIAD) are red flat arborized lesions that are found throughout the entire gastrointestinal tract. GIAD can vary in size and have a range of presentation from occult to life-threatening bleeding. The typical presentation is intermittent bleeding in the setting of iron deficiency anemia. Endoscopy is the primary means of diagnosis and endoscopic therapy is noted to be initially effective. However, rebleeding can be as high as 40% to 50% in patients with small bowel GIAD. This review describes the pathophysiology for the development of GIAD and the current roles of endoscopic, medical, and surgical therapy in its treatment.

Prophylactic octreotide for pancreatoduodenectomy: more harm than good?

BACKGROUND

Most accrued evidence regarding prophylactic octreotide for a pancreatoduodenectomy (PD) predates the advent of the International Study Group of Pancreatic Fistula (ISGPF) classification system for a post-operative pancreatic fistula (POPF), and its efficacy in the setting of high POPF risk is unknown. The Fistula Risk Score (FRS) predicts the risk and impact of a clinically relevant (CR)-POPF and can be useful in assessing the impact of octreotide in scenarios of risk.

METHODS

From 2001-2013, 1018 PDs were performed at four institutions, with octreotide administered at the surgeon's discretion. The FRS was used to analyse the occurrence and burden of POPF across various risk scenarios.

RESULTS

Overall, 391 patients (38.4%) received octreotide. A CR-POPF occurred more often when octreotide was used (21.0% versus 7.0%; P < 0.001), especially when there was advanced FRS risk. Octreotide administration also correlated with an increased hospital stay (mean: 13 versus 11 days; P < 0.001). Regression analysis, controlling for FRS risk, demonstrated that octreotide increases the risk for CR-POPF development.

CONCLUSION

This multi-institutional study, using ISGPF criteria, evaluates POPF development across the entire risk spectrum. Octreotide appears to confer no benefit in preventing a CR-POPF, and may even potentiate CR-POPF development in the presence of risk factors. This analysis suggests octreotide should not be utilized as a POPF mitigation strategy.

Management of gastrointestinal angiodysplastic lesions (GIADs): a systematic review and meta-analysis

OBJECTIVES

Gastrointestinal angiodysplastic lesions (GIADs) are defined as pathologically dilated communications between veins and capillaries. The objective of this systematic review and meta-analysis was to determine the efficacy of available treatment modalities for GIADs.

METHODS

We identified eligible studies by searching through PubMed, SCOPUS, and Cochrane central register of controlled trials. We searched for clinical trials examining the efficacy of endoscopic, pharmacologic, or surgical therapy for GIADs. Data were pooled using a random-effects model, and the effect of response to medical or surgical therapy was reported as odds ratios with 95% confidence intervals (CIs). Data and quality indicators were extracted by two authors from 22 studies, including 831 individuals with GIADs. The analysis included 623 patients treated with endoscopic therapy, 63 with hormonal therapy, 72 patients with octreotide, and 73 status post aortic valve replacement surgery.

RESULTS

Hormonal therapy, based on two case-control studies, was not effective for bleeding cessation (odds ratio: 1.0, 95% CI: 0.5-1.96). On the basis of 14 studies including patients with gastric, colonic, and small-bowel GIADs, endoscopic therapy was effective as initial therapy, but the pooled recurrence bleeding rate was 36% (95% CI: 28-44%) over a mean (±s.d.) of 22±13 months. The event rate for re-bleeding increased to 45% (95% CI: 37-52%) when studies including only small-bowel GIADs were included (N=341). In four studies assessing the efficacy of somatostatin analogs, the pooled odds ratio was 14.5 (95% CI: 5.9-36) for bleeding cessation. In two studies assessing the role of aortic valve replacement (AVR) in 73 patients with Heyde's syndrome, the event rate for re-bleeding was 0.19 (95% CI: 0.11-0.30) over a mean follow-up period of 4 years postoperatively.

CONCLUSIONS

Over one-third of patients with GIADs experienced re-bleeding after endoscopic therapy. Somatostatin analogs and AVR for Heyde's syndrome appeared to be effective therapy for GIADs.

Refractive properties of the healthy human eye during acute hyperglycemia

Purpose

To measure the refractive properties of the healthy human eye during acute hyperglycemia by means of Scheimpflug imaging and Hartmann-Shack aberrometry.

Methods

Acute hyperglycemia was induced in five healthy subjects (two males, three females, mean age ±SD 24.8 years ± 4.6) by means of an oral glucose tolerance test (OGTT) after subcutaneous somatostatin injection. Before and every 30 minutes after the OGTT, measurements with Scheimpflug imaging and Hartmann-Shack aberrometry were performed. The main outcome measures were the thickness and shape of the lens, and the ocular refractive error and higher order aberrations. The equivalent refractive index of the lens was calculated from these parameters. Measurements at baseline and during hyperglycemia were analyzed by means of Wilcoxon signed rank sum tests.

Results

During hyperglycemia (mean blood glucose level at baseline: 4.0 mmol/l; mean maximal blood glucose level: 18.4 mmol/l) no changes could be found in the refractive properties within the group. In one subject, a hyperopic shift (0.4 D) was observed, together with a more convex shape of the anterior lens surface and a decrease in the equivalent refractive index of the lens.

Conclusions

This study shows that hyperglycemia generally does not cause changes in the refractive properties of the healthy eye. Nevertheless, in one subject a hyperopic shift accompanied by a change in shape and refractive index of the lens was measured. This finding could provide an explanation for the mechanism underlying the refractive changes that are often observed during hyperglycemia.

Long-term efficacy of octreotide in the prevention of recurrent bleeding from gastrointestinal angiodysplasia

OBJECTIVES

Preliminary studies suggested that octreotide may be therapeutic in bleeding angiodysplasia. Our aim was to investigate the efficacy of long-term octreotide therapy in the prevention of rebleeding from gastrointestinal angiodysplasia.

METHODS

A cohort of 32 patients diagnosed with bleeding from angiodysplasia was treated with octreotide 50 mu 12 h subcutaneously for a 1-2 yr period. This cohort was compared with an external control group (38 patients who had received placebo [1 tablet/day] in a concurrent randomized clinical trial for the same period.

RESULTS

Two patients of the octreotide group were lost to follow-up. Treatment failure occurred in seven of 30 (23%) patients in the octreotide group and in 17 of 35 (48%) in the placebo group (three dropouts before first visit) (P= 0.043). The actuarial probability of remaining free of rebleeding at 1 and 2 yr of follow-up was 77% and 68%, respectively, for the octreotide group and 55% and 36%, respectively, for the placebo group (log rank P= 0.030). Multivariate proportional hazards-regression analysis showed that octreotide therapy and previous bleeding episodes were positive and negative predictors of efficacy, respectively. No significant differences between the groups were observed according to number of bleeding episodes (0.4 +/- 0.7 vs 0.9 +/- 1.5, P= 0.070) and transfusion requirements (1.1 +/- 2.6 vs 0.7 +/- 1.5 units); however, iron requirements were lower in the octreotide than in the placebo group (22 +/- 62 vs 166 +/- 267 units; P < 0.001). Likewise, major adverse events (1 vs 1) and mortality (0 vs 1) were similar between groups.

CONCLUSIONS

This study suggests that octreotide treatment may be beneficial in preventing rebleeding from gastrointestinal angiodysplasia.

The effect of insulin and glucagon on splanchnic oxygen consumption

The purpose of these experiments was to measure the influence of insulin and glucagon on the splanchnic oxygen consumption. Two experiments were performed.

METHODS

In one experiment, the influence of hyperinsulinaemia was investigated in six healthy subjects, who were studied during a euglycaemic hyperinsulinaemic clamp. In another experiment, the influence of glucagon was investigated in seven healthy subjects, who were studied twice during a pancreatic islet clamp with either supplementation of insulin and glucagon, or of insulin alone. In both situations the measurements were performed during euglycaemia. Splanchnic oxygen consumption and net substrate balances were studied by the arterio-hepatic venous catheterisation technique and measurement of splanchnic blood flow in all experiments.

RESULTS

During the euglycaemic hyperinsulinaemic clamp, the splanchnic blood flow increased significantly and the splanchnic oxygen consumption decreased by about 20%, while the net splanchnic glucose output reversed to a net uptake. In the pancreatic islet clamp experiments there was a significant difference between the net splanchnic glucose outputs whether glucagon and insulin or only insulin was supplemented. In spite of this, the splanchnic oxygen consumption decreased by about 20% in both situations, i.e. independent of glucagon supplementation. In both experiments there was a pronounced inhibition of lipolysis, which led to decreased fatty acids availability to the liver. This resulted in a concomitant decrease in hepatic ketone body formation. This decrease could account for about 30% of the decrease in splanchnic oxygen consumption.

CONCLUSION

The reduction in splanchnic oxygen consumption can be explained by decreased ketogenesis, decreased protein synthesis and changes in splanchnic fuel selection, while changes in the rate of gluconeogenesis does not seem to play a significant role.

Combination of continuous subcutaneous infusion of insulin and octreotide in Type 1 diabetic patients

The effect of 7 day continuous subcutaneous infusion of octreotide (200 microg day(-1)) was evaluated in seven insulin-pump treated Type 1 diabetic patients (age 43+/-1.5 year; BMI 25.1+/-0.7 kg m(-2); HbA(1c) 7.4+/-0.3%). A 24-h metabolic and hormonal profile, and a euglycaemic hyperinsulinaemic clamp (0.25, 0.5, 1.0 mg kg(-1) min(-1)), with [3H]glucose infusion and indirect calorimetry, were performed before and after a 7-day octreotide infusion. Mean 24-h plasma glucose was similar before and after octreotide (9.7+/-0.8 vs. 9.1+/-1.0 mmol l(-1)) but insulin requirement dropped by 45% (49+/-4 vs. 27+/-2 U day(-1); P<0.01). Both 24-h plasma hGH and glucagon were suppressed by octreotide (1.85+/-0.35 vs. 0.52+/-0.04 microg l(-1), and 117+/-23 vs. 102+/-14 ng l(-1), respectively). Glucose utilisation increased after octreotide (insulin 0.5 mU kg(-1) min(-1) clamp 3.09+/-0.23 vs. 4.19+/-0.19 mg kg(-1) min(-1); 1 mU kg(-1) min(-1) clamp 5.64+/-0.61 vs. 7.93+/-0.57 mg kg(-1) min(-1); both P<0.05) and endogenous glucose production was similarly suppressed. Glucose oxidation was not affected by octreotide, while the improvement in glucose storage (insulin 1.0 mU kg(-1) min(-1) clamp 3.89+/-0.60 vs. 5.64+/-0.67 mg kg(-1) min(-1), P<0.05) entirely accounted for the increase in glucose disposal. Endogenous glucose production was more effectively suppressed at the two lower insulin infusion rates (P>0.05). Energy expenditure declined after octreotide. Continuous subcutaneous octreotide infusion suppresses counterregulatory hormones, increases insulin-mediated glucose metabolism by enhancing glucose storage, and reduces energy expenditure. These results support a role for counterregulatory hormones in the genesis of insulin resistance and the catabolic state of Type 1 diabetes.

Sorbitol as a marker for drug-induced decreases of variable duration in liver blood flow in healthy volunteers

OBJECTIVE

Sorbitol has been suggested as a suitable marker to assess liver blood flow (LBF), after it was shown to adequately reflect prolonged changes in LBF but changes of a shorter duration have not been investigated. We therefore used sorbitol to evaluate drug-induced decreases in LBF of variable duration with i.v. infusions of somatostatin and its synthetic analogue octreotide.

METHODS

In a double-blind, placebo controlled, randomised study, six healthy males received sorbitol for 170 min. At sorbitol steady state, which was at 45 min after the start of the infusion (t=0), somatostatin or octreotide was infused for 30 min. Sampling for sorbitol assay and echo-Doppler hepatic portal vein flow measurements were done regularly and treatments were compared using ANOVA.

RESULTS

The sorbitol AUC over the 30-min intervention period was 15% (95% C.I.: +4, +22%) and 13% (+5, +24%) higher compared to placebo after somatostatin and octreotide respectively. The decline of sorbitol levels after termination of the intervention was faster for somatostatin compared to octreotide, demonstrated by the difference in the AUC (0-2 h) with placebo which was 8% (-3, +19%) lower after somatostatin, and 15% (+5, +26%) after octreotide. Portal venous blood flow decreased during the 30-min interventions; after somatostatin 27% (-14, -40%) and after octreotide 29% (-17, -42%). Portal flow was lower than placebo during the entire experiment after octreotide 30% (-10, -50%), but not after somatostatin 13% (-33, +7%). Changes in sorbitol levels and portal venous blood flow occurred simultaneously and were well correlated for each individual, making it likely that the interventions did not interfere with metabolism.

CONCLUSION

Sorbitol can be used to adequately assess decreases in LBF of variable duration in healthy volunteers.

Effects of somatostatin (SMS) on pancreatic microcirculation

The effect of bolus infusion of increasing somatostatin (SMS) concentrations (1, 10, 100, 200 micrograms/100 g body wt) on pancreatic microcirculation and pancreatic tissue PO2 were investigated by using in vivo epifluorescence microscopy and a polarographic PO2 measurement technique. Additionally, the microperfusion of the pancreas, liver, spleen, stomach, and duodenum was measured by a laser Doppler device. Bolus infusion of SMS caused a significant, transient, and dose-dependent decrease in pancreatic capillary RBC velocities (to 50% of baseline) and acinar capillary overall perfusion (to 20% of baseline), which was not caused by a macrocirculatory depression. This pronounced decrease in microperfusion was not paralleled by a decline in tissue PO2. Laser Doppler measurements revealed that pancreatic and gastric microperfusion were reduced only at maximal SMS concentrations, considering that microperfusion of the liver, spleen, and duodenum was not altered. Therefore, we found further evidence that circulatory adjustment might occur during SMS inhibited secretory activity of the exocrine pancreas.

Effects of octreotide on cardiovascular hormones and haemodynamics in conscious dogs

Octreotide inhibits the secretion of several hormones and exerts vasopressor effects. To clarify the mechanism of atrial natriuretic factor (ANF) secretion and to assess the cardiovascular effects of octreotide in relation to changes in vasoactive peptide secretion, four groups of conscious dogs were studied: group I (n = 11) received saline infusion after placebo, group II (n = 10), the same infusion after octreotide, group III (n = 10), placebo only and group IV (n = 10) octreotide injection only. Saline (10% body wt) was infused over 40 min after subcutaneous injection of placebo or octreotide (1 microgram/kg). Saline produced a rise (p < 0.001) of plasma ANF from 32.4 +/- 4.1 to 59.0 +/- 8.5 pM after placebo and from 35.6 +/- 5.5 to 77.0 +/- 12.6 pM after octreotide. This rise, not significantly different between groups I and II paralleled a 4-5-fold increase (p < 0.005) of right and left atrial pressures. With a higher dose of octreotide (4 micrograms/kg) injected in 4 dogs, plasma ANF increased by 27.5 +/- 5 pM. During hypervolemia, plasma endothelin-1 remained unchanged but plasma angiotensin II and epinephrine decreased (p < 0.05) approximately by 80% without being affected by octreotide. Octreotide did not influence the basal secretion of ANF, endothelin-1, angiotensin II and catecholamines. However, in basal conditions, octreotide injection resulted in a 9% increase (p < 0.005) of left ventricular systolic pressure, unobserved after placebo. Plasma glucose decreased (p < 0.005) in groups receiving octreotide. Thus, octreotide does not impair the stretch-mediated release of ANF which implies a release mechanism independent from somatostatin receptors and consequent changes in intracellular c-AMP. Octreotide has also a pressor effect, unrelated to changes in vasoactive peptide production.

Clinical efficacy of octreotide in the treatment of metastatic neuroendocrine tumors. A study by the Italian Trials in Medical Oncology Group

BACKGROUND

The unsatisfactory control of neuroendocrine tumor growth with chemotherapy and/or interferon (IFN-2a) stimulated us to investigate the role of the somatostatin analogue octreotide (SMS 201.995), which is reported to be highly effective in controlling carcinoid syndrome symptoms. Octreotide has been used in a wide range of doses, and it was postulated that higher doses might lead to an objective response.

METHODS

The aim of the present multicenter Phase II study was to determine the safety and efficacy of SMS 201.995 in controlling carcinoids and other neuroendocrine tumors. Fifty-eight patients were treated subcutaneously with 2 sequential doses of the drug (Sandostatina, Sandoz, Inc., S.b.A. Pharmaceuticals, Basel, Switzerland). The first 23 patients received 500 micrograms 3 times a day and the remaining 35 patients received 1000 micrograms 3 times a day. The treatment was continued until the tumor progressed.

RESULTS

All of the patients were adequately treated and evaluated. The predominant histotype was carcinoid, although there were instances of medullary thyroid carcinoma, pancreatic islet cell tumors, and Merkel cell carcinoma. Carcinoid syndrome was documented in 16 patients and abnormal urinary 5-hydroxyindoloacetic acid excretion in 15. The median treatment duration was 5 months (range, 2-31 months). The responses were evaluated in three categories: tumor regression for tumor growth control, symptom response, and biochemical response. There was an effect on tumor growth in two patients with carcinoids. Symptomatic control was achieved in 73% of patients and a biochemical response in 77% of patients. In twenty-seven patients, the disease stabilized for at least 6 months (range, 6-32+). The median survival time for all patients was 22 months (range, 1-32+).

CONCLUSIONS

In terms of tumor regression, octreotide is disappointing (partial response: 3%); symptomatic response and biochemical control are satisfactory. These data confirm that somatostatin analogues are comparable to interferons in the treatment of carcinoid syndrome, although other efforts are necessary to control tumor regression.

Assessment of functional liver mass and plasma flow in acromegaly before and after long-term treatment with octreotide

Functional liver mass and functional liver plasma flow (FLPF) were assessed in 11 patients with clinical features of acromegaly by determining galactose elimination capacity (GEC) and extrarenal clearance of sorbitol, before and 5 to 7 months after treatment with the long-acting somatostatin analog, octreotide (150 to 600 micrograms/d in three subcutaneous injections). Growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels, as well as liver size by ultrasound, were also recorded. Baseline GEC was increased in every patient but one, for a mean of 0.78 +/- 0.10 g/min (normal, 0.53 +/- 0.07; P < .01). At reevaluation after 5 to 7 months of octreotide treatment, a significant reduction of GEC was observed (0.62 +/- 0.08 g/min, P < .001). Changes of GEC paralleled those of GH (38.6 +/- 34.4 v 11.7 +/- 15.2 micrograms/L, P < .01) and IGF-I (5.0 +/- 1.7 v 2.7 +/- 2.2 U/ml, P < .001). Significant correlations were found between GEC and GH (r = .50, P < .05) and between GEC and IGF-I (r = .55, P < .01). FLPF, assessed by extrarenal clearance of sorbitol, was within the normal limit in all cases (0.98 +/- 0.19 v 0.97 +/- 0.12 L/min, NS) and remained normal after 5 to 7 months of octreotide treatment (0.99 +/- 0.11 L/min). Hepatic structure determined with ultrasonic scanning and conventional liver-function tests were basally normal in all patients, with a slight increase of liver volume in three cases. No change of biochemical and/or morphological features occurred during follow-up evaluation. The results support the hypothesis that GH and especially IGF-I enhance liver metabolic capacity; conversely, functional liver perfusion is largely independent of their actions. Our data also suggest that octreotide is unable to produce well-structured changes of liver circulation when administered long-term.

Effects of octreotide on healing of intestinal anastomosis following small bowel obstruction in rats

PURPOSE

Octreotide is an analog of somatostatin, with the same biologic effects but a longer half-life than somatostatin. The purpose of this experimental study was to search the effects of octreotide on the healing of bowel anastomosis and to observe the anatomic and physiologic changes in the obstructed bowel.

METHODS

Two groups of ten male Wistar albino rats (average weight, 250 grams) were used in this study. One group was the octreotide group, and the other was the control group. In both groups, the basal diameters of jejunum were measured before ligation of the bowel 20 cm from the duodenum. Octreotide was administered subcutaneously (7 micrograms/kg/day, in two equal doses) in the first group, and the same volume of saline was used in the control group. Diameters of the obstructed segments were measured, and sodium and potassium levels, obtained from the luminal fluid of the obstructed bowel, were recorded 48 hours following the first operation. Dilated segments were resected, and end-to-end intestinal anastomoses were performed. In rats sacrificed on the fourth and seventh days following the second operation, bursting pressures of the anastomotic and hydroxyproline levels in tissue samples taken from the anastomosis were measured.

RESULTS

The diameter of the obstructed bowel increased significantly in the control group (P < 0.05). Sodium and potassium losses were significantly less in the octreotide group (P < 0.001 for sodium; P < 0.01 for potassium). In histopathologic examination, ischemic changes were more evident in the control group (P < 0.05). Anastomotic bursting pressure differences were not significant on the fourth postoperative day (P > 0.05), but differences were significant on the seventh postoperative day (P < 0.05). Anastomotic tissue hydroxproline synthesis on the fourth and seventh postoperative days of the octreotide and control groups did not show significant difference (P > 0.05).

CONCLUSION

In this experimental model, it appears that octreotide attenuates the ischemic changes and electrolyte losses in the obstructed bowel.

The role of octreotide in palliative care

Octreotide, an analogue of somatostatin with a more favorable pharmacokinetic profile, is a new drug that may offer some advantages in the palliative care setting. It has been used with favorable results in the management of some gastrointestinal disorders, such as gastrointestinal hemorrhage, diarrhea, short-bowel syndrome, fistula, and intestinal occlusion in the palliative care setting. These favorable results occurred without important side effects, underlining the potential role of this drug. The cost-benefit ratio of this expensive drug must be considered, however.

Ventilation-perfusion relationships and central haemodynamics in patients with cirrhosis. Effects of a somatostatin analogue

The ventilation-perfusion relationships of the lung (VA/Q) and central haemodynamics were studied in seven patients with cirrhosis before and 30 min after a bolus injection of a somatostatin analogue, octreotide (Sandostatin, 50 micrograms i.v.), to elucidate the role of this substance in the hepatopulmonary syndrome. In the basal state all patients had normal spirometry but reduced diffusing capacity. Three patients had various degrees of hypoxaemia (6.9-8.3 kPa) and three had clubbing of the fingers. In the basal state VA/Q distributions, determined by inert gas elimination technique, showed an intrapulmonary shunt of 7.9 +/- 2.2% of cardiac output (range 1.5 to 17.1) and perfusion of lung regions with "low VA/Q" of 4.4 +/- 2.2% of cardiac output (range 0 to 15.4). After octreotide, the amount of shunting increased (10.9 +/- 4.4% of cardiac output; non-significant), while "low VAQ" was unchanged (3.7 +/- 1.3% of cardiac output). Arterial oxygen tension decreased from 10.2 +/- 1.1 to 9.7 +/- 1.1 kPa (non-significant). The mean pulmonary arterial pressure increased from 14.5 +/- 1.9 to 16.3 +/- 1.8 mmHg (p < 0.01). No alterations were seen in heart rate, stroke volume, cardiac output, central pressures or vascular resistances. The results of the present study do not support the hypothesis that octreotide improves hypoxaemia and ventilation-perfusion relationships in patients with hepatopulmonary syndrome.

Effects of the long-acting somatostatin analogue octreotide on abomasal function and plasma level of insulin and glucagon in sheep

The effects of the long-acting somatostatin analogue octreotide were studied in sheep. Octreotide was given subcutaneously at a dose of 0.75 microgram/kg bodyweight and, as a control, 0.9% saline solution was injected in a change-over design. Octreotide inhibited abomasal acid secretion and retarded the turnover time of digesta through the abomasum. The plasma levels of insulin and glucagon decreased due to the octreotide injection, while the plasma glucose level was not affected. The effects of octreotide lasted for 3-4h. There were no significant effects of the saline injection. The effects of octreotide showed similarities with results from previous studies on monogastric species.

Pharmacodynamic effects of Sandostatin in the gastrointestinal tract

Somatostatin (SST) is widely distributed throughout the human gastrointestinal system. There, it is found in neurons and fibers of both the submucosal and myenteric plexus and the pancreas, and also in the D cells of the stomach, gut, and pancreatic islets. Whereas in the intestinal nervous system, duodenum, and pancreas, somatostatin-14 (SST-14) appears to be the predominant molecular form, the endocrine-type D cells of the intestine primarily contain somatostatin-28 (SST-28). SST peptides may act very differently at different sites, as hormones, paracrine substances, or neurotransmitters. Because of this complexity of action, very little is known about the physiological effects of SST in the gastrointestinal tract. In contrast, the pharmacological actions of natural synthetic SST have been thoroughly studied and have given rise to many therapeutic applications. Octreotide, an analogue with a longer half-life and higher potency, has greatly facilitated the clinical application of SST. This review deals with the pharmacological effects of octreotide on different gastrointestinal functions. The SST analogue exerts a long-lasting inhibitory action on gastric acid, pancreatic enzyme, bicarbonate secretion, and on bile flow. It also inhibits stimulated intestinal secretion, ie, the release of neuropeptides from the gut and pancreas. It can also prolong orocecum transit time and prevent gallbladder contraction. It inhibits absorption of nutrients and exerts inhibitory effects on splanchnic hemodynamics. It is because of these actions that SST has attracted so much attention in the treatment of different gastrointestinal disorders.

Impact of octreotide, a long-acting somatostatin analogue, on glucose tolerance and insulin sensitivity in acromegaly

OBJECTIVE

We aimed to investigate the impact of a long-acting somatostatin analogue, octreotide, on glucose tolerance and on insulin sensitivity in acromegaly.

DESIGN

We performed a non-randomized controlled trial.

PATIENTS

Seven patients with active acromegaly were assessed before and during octreotide therapy given in a dose of 500 micrograms three times daily subcutaneously.

MEASUREMENTS

The effects of octreotide on carbohydrate metabolism were assessed by performing a glucose tolerance test and a euglycaemic hyperinsulinaemic clamp. These latter tests were undertaken 8 hours after the last dose, allowing GH and glucagon to return to pretreatment levels during the study.

RESULTS

Octreotide significantly reduced (P less than 0.05) mean +/- SEM 12-h GH (from 42 +/- 13 to 10 +/- 3 mIU/I) and IGF-I (from 4.2 +/- 0.5 to 2.1 +/- 0.5 U/ml) concentrations. Glucose tolerance was normalized in four of five patients with impaired glucose tolerance without a significant change in mean insulin concentrations. The improvement in fasting and mean blood glucose during glucose tolerance testing was dependent on the pretherapy blood glucose concentrations (r = -0.95, P = 0.002). The glucose infusion rate during the hyperinsulinaemic (5 U/h) clamp was significantly increased (P less than 0.05, 15.3 +/- 1.8 vs 24.2 +/- 5.4 mumol/kg min) following octreotide treatment. Insulin infusion during the glucose clamp completely suppressed hepatic glucose production during but not before octreotide treatment (7.9 +/- 2.4 vs 0.7 +/- 2.2 mumol/kg min, P = 0.02). Insulin-mediated stimulation of peripheral glucose uptake was unaffected by treatment. Mean GH and glucagon levels during both clamp studies were not significantly different.

CONCLUSIONS

Octreotide improves whole body insulin sensitivity by an increased ability of insulin to suppress hepatic glucose production without affecting the substantial impairment of peripheral insulin action. Octreotide has beneficial effects on carbohydrate metabolism in acromegalic patients with glucose intolerance.