Desensitization to the effects of intravenous octreotide in cirrhotic patients with portal hypertension

TIPS: an update

During the last 15 years the transjugular intrahepatic portosystemic shunt (TIPS) procedure has become a safe and effective treatment of portal hypertension. Its major obstacle, the high rate of shunt insufficiency, is going to be solved by the availability of covered stents showing a patency rate of up to 90%. The treatment of acute oesophageal and gastric variceal bleeding is an unsolved problem because variceal bleeding remains the major cause of death in patients with cirrhosis. TIPS has become the rescue treatment of choice because it combines high efficacy with low invasiveness. In this context, the timing of the rescue TIPS is of major importance for achieving definitive haemostasis before multi-organ failure develops. In the prevention of re-bleeding, TIPS is accepted as a second-line treatment, required in about 10-20% of patients. TIPS may be indicated when more than two significant re-bleedings occurred within a time frame of 12 months in spite of adequate first-line measures i.e. drugs or ligation. Refractory ascites is the third main indication for TIPS. Five randomized studies comparing TIPS with paracentesis show good response and comparable survival. Interpretations of authors and comments of reviewers are, however, controversial and do not permit a definitive recommendation.

Effect of propranolol and depot lanreotide SR on postprandial and circadian portal haemodynamics in cirrhosis

BACKGROUND

Long-acting somatostatin analogues have been suggested as an alternative to propranolol for the prevention of variceal rebleeding.

AIM

To compare the effectiveness of lanreotide SR, a new depot formulation injected once-weekly, and propranolol in reducing circadian portal blood flow (PVF) and meal-stimulated hepatic venous pressure gradient (HVPG) in patients with liver cirrhosis.

METHODS

Patients were randomized to receive either lanreotide SR intramuscularly (30 mg once weekly, n=12) or propranolol (n=12) orally. Hemodynamic measurements were performed on day 0 and on day 21 after a 3-week period of drug administration, while patients received three standard oral liquid test meals. On each study day 27 PVF measurements were performed over 24 h and eight measurements of HVPG during the first postprandial period.

RESULTS

Propranolol was more effective than lanreotide SR in reducing baseline HVPG (-21.9 vs. -13.6%, P=0.04) and meal-stimulated HVPG (-16.6 vs. -3.8%, P=0.04). Propranolol reduced circadian PVF significantly by 9.3% (P=0.03) but not lanreotide SR.

CONCLUSIONS

Long-term treatment with propranolol reduced baseline and postprandial HVPG and circadian PVF, while lanreotide SR did not. The results of our study do not encourage clinical testing of lanreotide SR 30 mg for the prevention of variceal haemorrhage.

Pharmacological rationale for the use of somatostatin and analogues in portal hypertension

Somatostatin and its analogue octreotide have been used for two decades to treat oesophageal variceal haemorrhage. The drug was introduced because of its capacity to decrease portal venous pressure without major side effects. In clinical trials assessing the efficacy of somatostatin and long-acting analogues in arresting variceal haemorrhage, conflicting results have been obtained. Furthermore, in haemodynamic studies evaluating the effects of somatostatin and analogues in patients with cirrhosis, divergent effects were observed. The main reason for these differences is probably related to different affinities of the drugs for different somatostatin receptor subtypes. The effects of somatostatin and analogues are mediated via five different G-protein coupled receptors (somatostatin receptor subtypes 1-5), which regulate the activity of ion channels (Ca2+, K+, Na+ and Cl-) and enzymes (adenyl cyclase, phospholipase C, phospholipase A2, phosphoinositide 3-kinase and guanylate cyclase) responsible for the synthesis or degradation of intracellular second messengers including cyclic AMP, inositol 1,4,5-trisphosphate, diacylglycerol and cyclic GMP. Despite universal use of somatostatin, the cellular and biochemical mechanisms of its effects in portal hypertension are relatively poorly studied and remain incompletely understood. In this review, we summarize relevant signal transduction of somatostatin and analogues, the haemodynamic effects of the drugs and the possible mechanisms by which these effects are mediated.

Role of acute elevation of portal venous pressure by exogenous glucagon on gastric mucosal injury in rats with portal hypertension

Time-course studies revealed the increased susceptibility of the gastric mucosa to noxious injury in portal hypertension correlates with the level of elevated portal venous pressure and hyperglucagonemia. Whether acute elevation of portal venous pressure by exogenous glucagon aggravates such injury is not known. We tested the hypothesis that glucagon in a dose sufficient to acutely elevate portal venous pressure aggravates noxious injury of the gastric mucosa in rats with portal hypertension. Infusion of a portal hypotensive dose of somatostatin should reverse these changes. In anesthetized rats with portal vein ligation, glucagon, somatostatin or the combination was administered intravenously in a randomized, coded fashion. Acidified ethanol-induced gastric mucosal injury was determined. Portal venous pressure and gastric mucosal perfusion and oxygenation (reflectance spectrophotometry) were monitored to confirm the effects of the respective intravenous treatments. Exogenous glucagon exacerbated acidified ethanol-induced gastric mucosal injury. The exacerbation was attenuated by somatostatin. These changes paralleled the portal hypertensive and hypotensive effects of glucagon and somatostatin, respectively. Our data suggest that a unique mechanism is triggered with the onset of portal hypertension. In an antagonistic manner, glucagon and somatostatin modulate this novel mechanism that controls portal venous pressure and susceptibility of the gastric mucosa to noxious injury.

Octreotide in hepatorenal syndrome: a randomized, double-blind, placebo-controlled, crossover study

The hepatorenal syndrome (HRS) is related to vasoconstriction of the renal cortex induced by systemic hypovolemia that follows splanchnic vasodilatation as the primary event in the cascade of hemodynamic changes associated with portal hypertension. We evaluated the effects of octreotide, a splanchnic vasoconstrictor, on HRS in cirrhotic patients. We compared the effects of octreotide infusion (50 microg/h) to placebo using a randomized, double-blind, cross-over design over 2, 4-day periods. Nineteen patients were included, and 14 patients could complete the 2 phases of the study (group 1: placebo first; n = 8 and group 2: octreotide first; n = 6) The end point of the study was to evaluate improvement in renal function as defined by a 20% decrease in serum creatinine value after a 4-day treatment as compared with baseline. In all the patients, a normal central venous pressure was maintained by daily intravenous administration of 2 units of albumin. The 2 groups were similar with regard to demographic data and liver and kidney function parameters at baseline. Improvement in renal function was observed in 2 patients after the placebo and 1 patient after octreotide infusion in group 1 and in 2 patients after octreotide infusion and 1 patient after placebo in group 2 (P = not significant). In addition, treatment with octreotide infusion did not result in significant changes in creatinine clearance, daily urinary sodium, plasma renin activity, plasma aldosterone and glucagon levels, or renal and mesenteric artery resistance indices as measured by Doppler ultrasonography. In conclusion, the present study demonstrates that, under our experimental conditions, octreotide infusion combined with albumin is not effective for the treatment of HRS in cirrhotic patients.

When endoscopic therapy or pharmacotherapy fails to control variceal bleeding: what should be done? Immediate control of bleeding by TIPS?

BACKGROUND

Acute variceal bleeding is the major cause of death in patients with chronic liver disease. This justifies the search for a more effective therapy to achieve rapid and definitive hemostasis in every patient. At present, the recommended standard treatment for acute variceal bleeding consists of immediate drug treatment with terlipressin or octreotide together with early endoscopic band ligation or sclerotherapy. In the case of ectopic varices terlipressin and cyanoacrylate embolization (if varices can be reached by endoscope) are in use.

FOCUS

The treatment is considered to have failed when bleeding continues or significant bleeding recurs within 48 h. This indicates the need for emergency transjugular intrahepatic portosystemic shunting (TIPS) which has been regarded as rescue treatment of choice when standard treatment fails. Although randomized studies against supportive treatment are lacking, the high efficacy and relatively low mortality after TIPS implantation are convincing. It is reasonable that smaller shunts should be preferred (probably 8 mm in diameter) since most patients have an increased risk of liver failure. To increase the effect of the shunt with respect to acute hemostasis it should be combined with transjugular embolization of the varices.

CONCLUSION

Only strict adherence to the definition of failure of standard treatment and a generous indication to the TIPS implantation before multiorgan failure occurs may decrease the high mortality of acute variceal bleeding.

Portal Hypertensive gastropathy

Portal hypertensive gastropathy (PHG), a term used to describe the endoscopic appearance of gastric mucosa with a characteristic mosaic-like pattern with or without red spots, is a common finding in patients with portal hypertension. Current classification systems that describe the severity of PHG have many limitations, but it appears that simple grading systems have better inter- and intraobserver agreement. The wide variation in the reported prevalence of PHG is probably related to selection bias, absence of uniform criteria and classification, and more importantly, the differences in inter- and intraobserver variation. Pathogenesis of PHG is not clearly defined, but there is a very close relationship between portal hypertension and development of PHG. GAVE is a separate entity from PHG, but patients with severe PHG may have a GAVE-like appearance in the gastric antrum. Acute bleeding from PHG, seen usually in the presence of severe PHG, is often mild and self-limiting. Currently, the only treatment that could be recommended for prophylaxis of bleeding from PHG is nonselective B-blockers.

Management of Gastrointestinal Bleeding in Children

Gastrointestinal bleeding in infants and children is a potentially life-threatening problem that is encountered by virtually all practicing pediatric gastroenterologists. Youngsters with a normal hematocrit, hemodynamic stability, and a history consistent with an acute, self-limited illness most frequently need only close observation; others require more in-depth assessment and intervention. Meticulous attention to the patient's cardiopulmonary status and knowledge of appropriate pediatric resuscitation schemes form the cornerstones on which more specific therapeutic interventions are based. Many treatment techniques and approaches have been extrapolated for pediatric use from adult studies; the regimen implemented for a child should be individualized and based on factors such as patient size, underlying condition, and operator expertise. Although the physician treating pediatric gastrointestinal hemorrhage requires more than a modicum of patience and determination, this must be tempered with a ready willingness to seek consultation from surgical colleagues to ensure optimal outcomes. Knowledge of acid-suppressive and vasoactive medications is essential, as is familiarity with at least one injection technique and one thermocoagulation technique for hemostasis. Endoscopic sclerotherapy and variceal band ligation are equally efficacious in achieving control of acute variceal bleeding, but band ligation is emerging as the technique best suited for prophylaxis. Beta blockade appears to have a smaller and less well-defined role in pediatric variceal prophylaxis compared with that in adults, but random controlled trials are necessary to confirm this impression.

Somatostatin analogues in the treatment of endocrine tumors of the gastrointestinal tract

Somatostatin and its long-acting analogues have been introduced for the treatment of endocrine tumours of the gastrointestinal tract as they have been shown to effectively control symptoms resulting from excessive hormone release in patients with carcinoid, Verner-Morrison and glucagonoma syndromes. This beneficial effect is due to the presence of somatostatin receptors in high densities on the majority of endocrine tumours. The symptomatic effect is less pronounced in insulinomas, since 30 - 50% of these tumours lack or express only a few somatostatin receptors. With respect to symptomatic control, somatostatin receptor subtypes 2 and 5 are the most important and the currently available long-acting analogues octreotide and lanreotide bind preferentially to these receptor subtypes. Long-term studies have shown that somatostatin analogues are safe and that the most important adverse advent is the development of gallstones. The antiproliferative potency of somatostatin and its analogues in vitro and in experimental tumour models prompted a number of studies in patients with metastatic endocrine tumours that are generally unresponsive to conventional chemotherapeutic protocols. Stabilisation of tumour growth lasting for months to a few years was the most favourable result, occurring in 30 - 70% of patients. However, definite proof of antiproliferative potency in man is still pending since placebo-controlled studies are not available. Radioligand therapy based on 111Indium, 90Yttrium and 177Lutetium coupled to somatostatin analogues via bifunctional chelators is currently under investigation with promising data concerning long-lasting control of symptoms and tumour growth from Phase I trials.

Portal hypertension

Portal hypertension is the main complication of cirrhosis and is responsible for its most common complications: variceal hemorrhage, ascites, and portosystemic encephalopathy. Portal hypertension is the result of increased intrahepatic resistance and increased portal venous inflow. Vasodilatation (splanchnic and systemic) and the hyperdynamic circulation are hemodynamic abnormalities typical of cirrhosis and portal hypertension. Gastroesophageal varices result almost solely from portal hypertension, although the hyperdynamic circulation contributes to variceal growth and hemorrhage. Ascites results from sinusoidal hypertension and sodium retention, which is in turn secondary to vasodilatation and activation of neurohumoral systems. Hepatic hydrothorax results from the passage of ascites across the diaphragm and into the pleural space. The hepatorenal syndrome represents the result of extreme vasodilatation with an extreme decrease in effective blood volume that leads to maximal activation of vasoconstrictive systems, renal vasoconstriction, and renal failure. Spontaneous bacterial peritonitis is a potentially lethal infection of ascites that occurs in the absence of a local source of infection. Portosystemic encephalopathy is a consequence of both portal hypertension (shunting of blood through portosystemic collaterals) and hepatic insufficiency resulting in the accumulation of neurotoxins in the brain.

Effects of long-term propranolol and octreotide on postprandial hemodynamics in cirrhosis: a randomized, controlled trial

BACKGROUND & AIMS

Postprandial increases in portal pressure may influence esophageal variceal rupture. The effects of chronic propranolol and octreotide (100 and 200 microg subcutaneously in a single dose) on postprandial hemodynamics were evaluated.

METHODS

FIRST STUDY: 36 cirrhotic patients were studied at baseline and 30 and 60 minutes after a standard meal and then treated with propranolol (139 +/- 9 mg/d during 39 +/- 2 days). SECOND STUDY: After baseline measurements, patients were randomized into 3 groups: (1) placebo, (2) octreotide (100 microg), or (3) octreotide (200 microg) (n = 12 for each group). Thirty minutes postinjection a new baseline was established and measurements were repeated 30 and 60 minutes after the meal.

RESULTS

First study: Baseline portal pressure was 18.1 +/- 1.2 mm Hg, 30 and 60 minutes after the meal it was 21.5 +/- 0.8 mm Hg and 20.5 +/- 0.8 mm Hg, respectively (both P < 0.01 vs. baseline). Cardiac index (CI) was 4.5 +/- 0.2, 4.8 +/- 0.2, and 4.9 +/- 0.2 L x min(-1) x m(-2), respectively (both P < 0.05 vs. baseline). Peripheral vascular resistance was 1012 +/- 56, 902 +/- 51 (P = NS), and 884 +/- 49 dynes x sec x cm(-5) (P< 0.05 vs. baseline), respectively. Second study: Propranolol and placebo did not blunt postprandial increase in portal pressure. Octreotide (100 microg) partially ameliorated postprandial increase in portal pressure. Octreotide (200 microg) significantly enhanced the portal hypotensive effect of propranolol and blunted the postprandial increase in portal pressure.

CONCLUSIONS

Octreotide blunts postprandial increase in portal pressure not prevented by long-term propranolol administration.

Management of variceal bleeding

Variceal hemorrhage complicates cirrhosis in as many as 50% of patients and results in considerable morbidity and mortality. This review covers all areas of importance in the prevention and treatment of this area, highlighting recent developments. Primary prophylaxis prevents first bleed, and pharmacotherapy with beta-blockade is the most widely accepted option. In an acute variceal hemorrhage, initial resuscitation and multiple organ support are paramount and are recommended along with antibiotic prophylaxis and specific medical therapies that may be given empirically before emergency endoscopy to reduce bleeding. Endoscopic techniques usually arrest bleeding, but when they fail, salvage therapy in the form of balloon tamponade, then transjugular intrahepatic portosystemic shunts or surgery, may be appropriate. Secondary prophylaxis to prevent rebleeding is often instituted in the ICU and is vital to prevent recurrence of this life-threatening complication.

Endoscopic treatment versus endoscopic plus pharmacologic treatment for acute variceal bleeding: a meta-analysis

Endoscopic therapy, involving either injection sclerosis or band ligation, is considered the intervention of first choice for acute variceal bleeding (AVB). Pharmacologic agents have also been shown to be highly effective in the control of the bleeding episode. The purpose of this meta-analysis was to assess whether vasoactive drugs may improve the efficacy of endoscopic therapy (injection sclerosis or band ligation) in the control of AVB and thus increase survival rates. Computer databases and scientific meeting abstracts from 1994 to 2001 were used to search for randomized trials that compared the combined use of endoscopic and drug therapy with endoscopic therapy alone in the control of AVB. Eight trials involving 939 patients fulfilled the selection criteria and the following evaluated by standard meta-analysis methods: initial hemostasis, 5-day hemostasis, 5-day mortality, and adverse events. Combined treatment improved initial control of bleeding (relative risk [RR], 1.12; 95% confidence interval (CI), 1.02-1.23), and 5-day hemostasis (RR, 1.28; 95% CI, 1.18-1.39), with numbers of patients needed to treat (NNT) of 8 and 5, respectively. The difference in favor of combined treatment remained significant when trials that used drugs other than octreotide or that included a low proportion of alcoholic patients (<40%) or high-risk cirrhotic patients (<35%) were excluded. Mortality was not significantly decreased by combined therapy (RR, 0.73; 95% CI, 0.45-1.18). Severe adverse events were similar in both groups. In conclusion, in patients with AVB, pharmacologic agents improve the efficacy of endoscopic therapy to achieve initial control of bleeding and 5-day hemostasis, yet fail to affect mortality.

Systematic review: the use of somatostatin or octreotide in refractory diarrhoea

BACKGROUND

Somatostatin and octreotide have multiple effects which make them ideal for treating diarrhoea of different aetiologies. Their use in a variety of conditions with refractory diarrhoea, however, is based on a limited number of studies.

AIM

We undertook a systematic review of the available English literature to maximize an evidence-based approach to the treatment of refractory diarrhoea. We tested the hypothesis that efficacy is independent of aetiology.

METHODS AND RESULTS

A Medline and individual article search from 1965 to 2000 was undertaken on the use of somatostatin and octreotide in diarrhoea. All reports containing at least five subjects were included. The percentage response in case series and randomized controlled trials was compared, and a meta-analysis of randomized controlled trials where patient level data were provided was carried out. There were 30 publications found (18 case series, 12 randomized controlled trials). The response percentage was 73% overall in case series and 64% in randomized controlled trials (not significant). A meta-analysis of nine randomized controlled trials revealed significant heterogeneity despite an overall relative risk of 0.5 (95% confidence interval, 0.27-0.91). Subgroup analysis of the largest aetiological groups showed that acquired immunodeficiency syndrome studies were homogeneous, but somatostatin and octreotide were less effective. Post-chemotherapy studies remained heterogeneous and somatostatin and octreotide were highly effective.

CONCLUSIONS

While this review strengthens the consensus guidelines on the use of somatostatin and octreotide for refractory diarrhoea, evidence-based support requires additional studies.

Somatostatin suppresses endothelin-1-induced rat hepatic stellate cell contraction via somatostatin receptor subtype 1

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) are considered therapeutic targets to decrease portal hypertension. To elucidate some of the hemodynamic effects of somatostatin (SST) on portal pressure, the presence and function of SST receptors (SSTRs) on HSCs were investigated.

METHODS

SSTR messenger RNA expression, and SSTR presence was investigated using reverse-transcription polymerase chain reaction, real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemistry. The function of SSTRs was studied by examining the effects of SST and specific SSTR agonists on endothelin-1(ET-1)-induced HSC contraction.

RESULTS

Specific amplicons for SSTR subtypes 1, 2, and 3 were demonstrated in rat liver and in activated HSCs. The presence of SSTR subtypes 1, 2, and 3 was confirmed by Western blotting. With immunohistochemistry, a strong staining of HSCs was obtained for SSTR subtypes 1, 2, and 3 in CCl4-treated rats, but not in normal rat liver. Incubation of HSCs on collagen gels with buffer, 10(-8) mol/L SST, and 2 x 10(-8) mol/L ET-1 resulted in collagen surface area decreases of 5.5% +/- 3.3%, 6.8% +/- 4.4%, and 49.8% +/- 8.3%, respectively. Relative contraction of gels preincubated with 10(-8) mol/L SST followed by 2 x 10(-8) mol/L ET-1 or vice versa as compared with maximal contraction (100%) with 2 x 10(-8) mol/L ET-1 were 72.6% +/- 17.9% and 76.2% +/- 12.6%, respectively (P < 0.05). SSTR agonist 1, but not SSTR agonist 2 or 3, was able to counteract the contractile effect of ET-1. CONCLUSIONA: Activated rat HSCs bear SSTR subtypes 1, 2, and 3. SST causes significant partial inhibition of ET-1-induced contraction of activated HSCs, mainly by stimulation of SSTR subtype 1.

Octreotide for severe acute bleeding from portal hypertensive colopathy: a case report

A 56-year-old man developed severe lower gastrointestinal bleeding. He was classified as Child-Pugh grade C. Colonoscopy revealed multiple angiodysplasia-like lesions and mucosal friability throughout the entire colon (portal hypertensive colopathy, PHC). Haemostasis was immediately achieved with octreotide treatment, although melaena recurred after discontinuation of the infusion. Propranolol treatment before discontinuation of octreotide infusin prevented the recurrence of bleeding from PHC. Octreotide is a safe and effective treatment for severe acute bleeding from PHC, especially if the patient is not a candidate for transjugular intrahepatic portosystemic shunt (TIPS) or treatment with a beta-blocker due to the severity of liver disease or haemodynamic instability. However, a sufficient reduction of portal pressure by propranolol or other medical treatment may be needed in order to discontinue octreotide infusion without the recurrence of bleeding.

Management of portal hypertension after variceal hemorrhage

Each variceal bleed is associated with 20% to 30% risk of dying. Management of portal hypertension after a bleed consists of (1) control of bleeding and (2) prevention of rebleeding. Effective control of bleeding can be achieved either pharmacologically by administering somatostatin or octreotide or endoscopically via sclerotherapy or variceal band ligation. In practice, both pharmacologic and endoscopic therapy are used concomitantly. Rebleeding can be prevented by endoscopic obliteration of varices. In this setting, variceal ligation is the preferred endoscopic modality. B-blockade is as effective as endoscopic therapy and, in combination, the two modalities may be additive.

Effects of different octreotide dosages on splanchnic hemodynamics and glucagon in patients with TIPS

OBJECTIVE

The aim of this study was to evaluate the hemodynamic effects of octreotide in patients treated with transjugular intrahepatic portosystemic stent shunt in relation to plasma levels of octreotide and glucagon and the correlation between portal pressure and noninvasive Doppler parameters.

METHODS

In 15 fasting patients, we i.v. administered isotonic sodium chloride followed by octreotide 25 microg/h and 100 microg/h, each over 1 h. We measured portal pressure (PP) directly and portal vein blood flow velocity by Doppler ultrasound simultaneously and calculated portal vascular resistance (PVR) and portal venous flow (PVF). Blood samples were taken for glucagon and octreotide (mean +/- SE).

RESULTS

Octreotide reduced PP (120': -7.7+/-2.2%, p < 0.01 vs baseline; 180': - 11.4+/-2.1%, p < 0.01 vs baseline) and PVF (120': -21.7+/-31.7%, p < 0.01 vs baseline; 180': -11.6+/-18.1%, p < 0.05 vs baseline). Glucagon decreased with the increase in octreotide levels and showed a correlation with the decrease in PP and with PVF. In patients with a high PVR, we found a close inverse correlation between PP and portal vein blood flow velocity (r = -0.83, p = 0.03) as well as Cl (r = 0.81, p = 0.05), whereas poor correlation was found in patients with low PVR.

CONCLUSIONS

Octreotide caused a dose-related, moderate but sustained reduction in PP in patients with transjugular intrahepatic portosystemic stent shunt. PVR seems to be an important parameter that influences the efficacy of octreotide and the relation between PP and noninvasive Doppler parameters.