Consensus statement: octreotide dose titration in secretory diarrhea. Diarrhea Management Consensus Development Panel

Vasoactive intestinal peptide secreting tumour: An overview

Vasoactive intestinal peptide (VIP) secreting tumour (VIPoma) is a rare functional neuroendocrine tumour that typically arises from pancreatic islet cells. These present as sporadic, solitary pancreatic neoplasias with an estimated incidence of one in ten million individuals per year. Only around 5% of VIPomas are associated with multiple endocrine neoplasia type I syndrome. Excessive VIP secretion produces a clinical syndrome characterized by refractory watery diarrhoea, hypokalemia and metabolic acidosis. These coupled with elevated plasma levels of VIP are diagnostic. The majority of VIPomas are malignant and have already metastasized at the time of diagnosis (60%). Metastases occur most frequently in the liver, or regional lymph nodes, lungs, kidneys and bones. Some reports of skin metastases have been documented. Complete surgical resection continues to be the only potentially curative treatment. However, when the neoplasia cannot be excised completely, surgical debulking may provide palliative benefit. Other palliative options have included recently the peptide receptor radionuclide therapy which has shown to be effective and well-tolerated. This article will review all aspects of pancreatic VIPomas highlighting aspects such as clinical presentation, diagnosis and management.

Evolution of Neuroendocrine Tumor Therapy

To better understand developments in treatment of neuroendocrine tumors of the gastroenteropancreatic system, and the pivotal roles of native somatostatin and its long-acting analogues play in normal peptide regulation and neuropeptide excess associated with neuroendocrine tumors (NETs), this article delineates and defines distinct eras in the history and discovery of gastrointestinal endocrinology. We highlight the collaboration between academia and industry in basic science and the clinical research that advanced Lu-177-DOTATATE to approval as standard of care therapy for low-grade NETs. Examples of new radioisotopes and therapy compounds currently in development for diagnosis and therapy for high-grade NETs are also discussed.

Functional, Diagnostic and Therapeutic Aspects of Gastrointestinal Hormones

Gastrointestinal (GI) hormones are essential to many physiologic functions in our body. They have many GI and extra-GI functions. Some of the functions of these hormones, which have GI and extra-GI sources, are still unknown. Specific GI hormones can affect the brain to control food intake, while others can proliferate normal and neoplastic tissue when their receptors are expressed in certain neoplasms. GI hormones also have many diagnostic and therapeutic roles. Physiologic and pathophysiologic aspects as well as the diagnostic and therapeutic values of GI hormones are elaborated in this review.

Diagnostic and Management Challenges in Vasoactive Intestinal Peptide Secreting Tumors: A Series of 15 Patients

OBJECTIVES

Vasoactive intestinal peptide-secreting tumors (VIPomas) are rare functioning neuroendocrine tumors often characterized by a difficult-to-control secretory syndrome and high potential to develop metastases. We hereby present the characteristics of 15 cases of VIPomas and provide a recent literature review.

METHODS

This was a retrospective data analysis of 15 patients with VIPoma from 3 different centers and literature research through PubMed database during the last 10 years.

RESULTS

Fifteen patients with VIPomas (9 with hepatic metastases at diagnosis) with watery diarrhea and raised VIP levels were studied. Ten patients (67%) had grade 2 tumors, 6 of 15 had localized disease and underwent potentially curative surgery, whereas the remaining 9 received multiple systemic therapies; 3 patients died during follow-up. The median overall survival was 71 months (range, 41-154 months). Patients who were treated with curative surgery (n = 7) had longer median overall survival compared with patients who were treated with other therapeutic modalities (44 vs 33 months).

CONCLUSIONS

The management of VIPomas is challenging requiring the application of multiple treatment modalities. Patients who underwent surgical treatment with curative intent appear to have higher survival rate. Central registration and larger prospective studies are required to evaluate the effect of currently employed therapies in these patients.

Practical Guide to Intestinal Rehabilitation for Postresection Intestinal Failure: A Case Study

After massive small-intestinal resection or combined small-intestinal and colonic resection, diarrhea with resulting dehydration, electrolyte abnormalities, and malnutrition occur. Many patients become dependent on IV fluids and nutrition. An adaptation process manifested clinically by decreased diarrhea and improved nutrient absorption according to decreased parenteral nutrition and fluid requirements has been noted to occur over time. In some patients, adaptation is inadequate and may require special techniques to enhance and augment this process. This is a case of a 52-year-old woman who experienced increased stoma output 1 week after major intestinal resection, resulting in dehydration. She required IV fluids in order to maintain hydration. After the initiation of an intestinal rehabilitation program, which included modified diet, soluble fiber, oral rehydration solution (ORS), and medications, IV fluids were successfully weaned off in 3 months. She continues not to receive IV fluids and continues to follow the intestinal rehabilitation plan.

Emergency therapy for liver metastases from advanced VIPoma: surgery or transarterial chemoembolization?

VIPoma is a rare neuroendocrine tumor (NET) with a high potential to develop hepatic metastases and poor prognosis. The primitive tumor is nonsymptomatic and usually localized within the pancreas. Liver metastasis drives the prognosis and induces profuse watery diarrhea or renal failure. We herein present severe renal failure or diarrhea in two patients hospitalized in intensive care justifying emergency treatment of liver metastasis. The two patients experienced severe diarrhea due to a hypersecretion of vasoactive intestinal peptide (VIP) from liver metastasis released into the blood circulation. Therapeutic management was discussed and liver transarterial chemoembolization (TACE) was performed with chemotherapy-loaded embospheres, which cause necrosis of tumor lesions. TACE controlled the hormonal syndrome and made patients eligible for curative surgery. Tumor necrosis occurred and VIP levels collapsed. Surgery was performed in one of the two cases after TACE and the patient was considered in remission. Both patients were still alive after 3 years of follow up. Thus, TACE is feasible and appears to be an effective emergency treatment in patients with a VIP-hormonal syndrome due to liver metastases. Despite the biological disorder due to the hormonal secretion, an aggressive approach is warranted in VIP liver metastasis.

The role of octreotide in symptom management in oncology and palliative care

Objective. To provide an overview of the role of octreotide for managing symptoms in oncology and palliative care.

Data Sources. A search of MEDLINE and IDIS databases from 1985 to 1999 and CANCERLIT from 1993 to 1999 was conducted using the terms octreotide, cancer and palliative care. The reference lists from selected articles were also reviewed. Clinical trial databases on the Internet were searched. Oncology and palliative care textbooks were also used to obtain additional references.

Data Extraction. The retrieved literature was reviewed to discuss the pharmacology, pharmacokinetics, adverse effects, indications and principally, the clinical use of octreotide for controlling a number of symptoms encountered in the oncology and palliative care population.

Data Synthesis. The unique inhibitory activity of octreotide lends itself to many possible indications, including diarrhoea from a number of causes, bowel obstruction, nausea and vomiting, bleeding, death rattle, gastrointestinal fistulae, pain and hypercalcaemia. However, convincing pieces of evidence from large prospective clinical trials are required to realise its full potential in oncology and palliative care. Completed studies and clinical experience suggest that octreotide has a role in the treatment of a number of difficult-to-manage conditions, particularly bowel obstruction and diarrhoea due to disease or treatment-related causes. Proposed benefits of octreotide must be weighed against the possible adverse effects and cost effectiveness of treatment.

Medical Management of Pancreatic Neuroendocrine Tumors: Current and Future Therapy

When diagnosed at an early stage, resection of pancreatic neuroendocrine tumors (NETs) is often curative. Unfortunately, curative surgery is rarely an option for patients with metastatic disease. Multiple options are available for the management of patients with advanced pancreatic NETs, including surgery, liver-directed therapy, and systemic therapies. Because of the heterogeneity of disease biology and presentation, a multidisciplinary approach to management is critical. Treatment with somatostatin analogs, sunitinib, everolimus, and alkylating agents provide effective systemic therapeutic options for patients. Future studies to evaluate the optimal timing, sequence, and combination of therapies, as well as to identify predictors of response, are warranted.

The pharmacologic treatment of short bowel syndrome: new tricks and novel agents

Short bowel syndrome (SBS) is a manifestation of massive resection of the intestines resulting in severe fluid, electrolyte, and vitamin/mineral deficiencies. Diet and parenteral nutrition play a large role in the management of SBS; however, pharmacologic options are becoming more readily available. These pharmacologic agents focus on reducing secretions and stimulating intestinal adaptation. The choice of medication is highly dependent on the patient's symptoms, remaining anatomy, and risk versus benefit profile for each agent. This article focuses on common and novel pharmacologic medications used in SBS, including expert advice on their indications and use.

Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems

OBJECTIVES

The World Health Organization convened a panel of experts to rank the evidence for medical countermeasures for management of acute radiation syndrome (ARS) in a hypothetical scenario involving the hospitalization of 100 to 200 victims. The goal of this panel was to achieve consensus on optimal management of ARS affecting nonhematopoietic organ systems based upon evidence in the published literature.

METHODS

English-language articles were identified in MEDLINE and PubMed. Reference lists of retrieved articles were distributed to conferees in advance of and updated during the meeting. Published case series and case reports of ARS, publications of randomized controlled trials of relevant interventions used to treat nonirradiated individuals, reports of studies in irradiated animals, and prior recommendations of subject matter experts were selected. Studies were extracted using the Grading of Recommendations Assessment Development and Evaluation system. In cases in which data were limited or incomplete, a narrative review of the observations was made.

RESULTS

No randomized controlled trials of medical countermeasures have been completed for individuals with ARS. Reports of countermeasures were often incompletely described, making it necessary to rely on data generated in nonirradiated humans and in experimental animals. A strong recommendation is made for the administration of a serotonin-receptor antagonist prophylactically when the suspected exposure is >2 Gy and topical steroids, antibiotics, and antihistamines for radiation burns, ulcers, or blisters; excision and grafting of radiation ulcers or necrosis with intractable pain; provision of supportive care to individuals with neurovascular syndrome; and administration of electrolyte replacement therapy and sedatives to individuals with significant burns, hypovolemia, and/or shock. A strong recommendation is made against the use of systemic steroids in the absence of a specific indication. A weak recommendation is made for the use of fluoroquinolones, bowel decontamination, loperamide, and enteral nutrition, and for selective oropharyngeal/digestive decontamination, blood glucose maintenance, and stress ulcer prophylaxis in critically ill patients.

CONCLUSIONS

High-quality studies of therapeutic interventions in humans exposed to nontherapeutic radiation are not available, and because of ethical concerns regarding the conduct of controlled studies in humans, such studies are unlikely to emerge in the near future.

Octreotide acetate is efficacious and safe in children for treating diarrhea due to chemotherapy but not acute graft versus host disease

BACKGROUND

The Common Toxicity Criteria of the National Cancer Institute evaluates diarrhea as an adverse event of chemotherapy administration. Acute graft versus host disease (aGVHD) causes diarrhea in allogeneic hematopoietic stem cell transplant patients. Guidelines for treating grade 3 and 4 chemotherapy induced diarrhea (CID) include octreotide acetate, a somatostatin analogue. These recommendations are based on adult octreotide trials. Data on octreotide use for treatment of CID in pediatric oncology patients are limited. This study evaluated the efficacy and safety of octreotide in the treatment of CID or aGVHD induced diarrhea in pediatric patients.

METHODS

This is a retrospective review of 34 patients of average age 6 years who received octreotide between 1994 and 2008 for treatment of CID or aGVHD induced diarrhea.

RESULTS

Thirty-eight courses of intravenous octreotide were administered. A complete response was achieved during 25/27 (92%) CID and 5/11 (45%) aGVHD induced diarrhea courses. A partial response was achieved during 4/38 courses, all in the aGVHD induced diarrhea group. No response was observed for 3 of the aGVHD induced diarrhea courses and 1 for the CID course. Octreotide was initiated at 2 mcg/kg/day and increased to a maximum of 9 mcg/kg/day. The mean total duration of treatment was 9 days. Common adverse effects observed were hyperglycemia, hyberbilirubinemia, nausea/vomiting, and abdominal cramping.

CONCLUSION

In pediatric patients, octreotide exhibits 92% efficacy in treating CID and 45% efficacy in aGVHD induced diarrhea. Further studies to better characterize the starting dose and dose escalation algorithm for treating CID in children are required.

A prospective trial on the effect of body mass index and sex on plasma octreotide levels in patients undergoing long-term octreotide LAR therapy

OBJECTIVES

Octreotide long acting repeatable (LAR) is commonly used to control the symptoms of patients with functional neuroendocrine tumors. Unfortunately, most patients escape control over time and require higher LAR doses or more frequent rescue therapy to remain asymptomatic. Previous work has shown that body weight and monthly LAR dose will significantly affect circulating plasma octreotide levels in patients undergoing therapy.

METHODS

To determine if other parameters change circulating plasma octreotide levels, we prospectively studied 82 patients undergoing long-term LAR therapy.

RESULTS

Multivariate analysis demonstrated that the plasma octreotide levels decrease by approximately 3.4% for each unit of body mass index (BMI) increase (P = 0.03), adjusting for sex and monthly LAR dose. Plasma octreotide levels for females were approximately 47.6% higher than those for males (P = 0.045), adjusting for BMI and monthly LAR dose. Initial and subsequent octreotide LAR doses should take into consideration sex and BMI. Males are estimated to require 14.1-mg (SD, 7.25) higher monthly LAR doses than females with the same BMI.

CONCLUSIONS

We have shown that plasma octreotide levels are affected by not only monthly LAR dose but also BMI and sex. We hope these observations will make choosing initial and subsequent octreotide LAR doses easier for physicians.

NANETS consensus guideline for the diagnosis and management of neuroendocrine tumors: well-differentiated neuroendocrine tumors of the thorax (includes lung and thymus)

Neuroendocrine tumors (NETs) of the thorax, including bronchial and thymic neuroendocrine NETs, are often referred to as NETs of the foregut. The incidence and prevalence of NETs are increasing in the United States as demonstrated in the Surveillance, Epidemiology, and End Results from 1973 to 2004 (J Clin Oncol. 2008;26[18]:3063-3072). Although the majority of bronchial and thymic NETs are sporadic, approximately 5% to 10% can be associated with hereditary syndrome, multiple endocrine neoplasms type 1 (Nat Rev Cancer. 2005;5[5]:367-375). Diagnosis is made by tissue pathology, allowing for characterization and classification of the NET. Radiologic evaluation is performed to determine the extent of disease involvement. Clinical symptoms from hormonal overproduction or from paraneoplastic processes are medically managed to improve patients' quality of life. Locoregional disease can be curative with surgery; however, distant or metastatic disease is rarely curable. Therapeutic options for metastatic/advanced NETs of the thorax are mainly to palliate symptoms. Final treatment recommendations for patients with either bronchial or thymic NETs should be individualized, weighing the risks and benefits of therapy.

Octreotide: Dumping Syndrome

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a quarterly publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. A summary of the most relevant data is provided, including background, study design, patient population, dosage information, therapy duration, results, safety, and therapeutic considerations. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to hospital pharmacy@drugfacts.com .

Clinical value of monitoring plasma octreotide levels during chronic octreotide long-acting repeatable therapy in carcinoid patients

OBJECTIVE

Octreotide is used to treat patients with neuroendocrine tumors. Previous reports show that octreotide long-acting repeatable (LAR) dose and patient body weight affect nadir plasma octreotide levels (approximately 1250, 2500, 5000, and 11,000 pg/mL for LAR doses of 10, 20, 30 and 60 mg/mo). However, plasma octreotide levels have decreased over time in patients receiving these doses of LAR.

METHODS

From November 2004 until July 2007, trough plasma octreotide levels were determined in 86 patients on long-term octreotide LAR therapy at doses of 30, 60, and 120 mg/mo. Changes in plasma drug levels were analyzed over time using random effects models.

RESULTS

Current plasma octreotide levels for octreotide LAR doses of 30, 60, and 120 mg/mo are approximately 2200, 5200, and 6500 pg/mL, respectively, representing a decrease of approximately 50% to 70% compared with previously reported plasma octreotide levels. The decreases in octreotide levels over time with the 30- and 60-mg/mo LAR doses are highly statistically significant (P = 0.0067, 0.0149, respectively).

CONCLUSIONS

Current plasma octreotide values are significantly lower than previously reported for 30-, 60-, and 120-mg/mo LAR doses. Serial plasma octreotide value measurements should be used to determine if increasing symptoms or tumor growth are associated with suboptimal octreotide levels.

Effect of long-term treatment with octreotide on rectal sensitivity in patients with non-constipated irritable bowel syndrome

BACKGROUND

Acute administration of octreotide reduces visceral perception and therefore has been suggested as potential treatment for irritable bowel syndrome. Whether prolonged treatment with octreotide also reduces visceral sensitivity and improves gastrointestinal symptoms remains, however, unknown.

AIM

To investigate the effect of a slow release preparation of octreotide on rectal sensitivity and symptoms in irritable bowel syndrome patients.

METHODS

Forty-six non-constipated irritable bowel syndrome patients (52% female, 19-63 years) participated. Before and after 8 weeks of treatment with octreotide (Sandostatin LAR 20 mg i.m.) or placebo, patients underwent a barostat study to assess the rectal sensitivity. During a 2-week run-in period and treatment, abdominal pain, defecation frequency, consistency and symptom relief were scored weekly.

RESULTS

Octreotide, but not placebo, significantly increased the threshold for first sensation. Thresholds for urge to defecate and discomfort/pain and rectal compliance were not altered by either treatment. Octreotide improved stool consistency compared with placebo (loose stools after eight weeks: octreotide: 52%, placebo: 81%, P < 0.05). In contrast, abdominal pain and defecation frequency were not affected.

CONCLUSIONS

Although the threshold of first rectal sensation increased and stool consistency improved, long-term treatment with octreotide, at least at the current dose used, has no visceral analgesic effect and fails to improve irritable bowel syndrome symptoms.

Diagnosis and treatment of VIPoma in a female patient

We report a case of VIPoma in an 83-year-old female patient, who presented with frequent and excessive diarrhoea, muscle weakness, and severe hypokalaemia. Abdominal computed tomography (CT) revealed a 4x6 cm mass in the body of the pancreas. Laboratory analysis showed elevated levels of both vasoactive intestinal polypeptide (VIP; 153 pmol/l) and pancreatic polypeptide (161 pmol/l). In view of the patient's age, physical condition, and tumour size, surgical resection was not performed. The patient was treated with a long-acting octreotide, after which her symptoms diminished. After 24 months of follow-up, the patient remained in good physical condition without any further serious gastrointestinal symptoms. The VIPoma syndrome is caused by a neuroendocrine tumour, usually located in the pancreas, which secretes VIP, causing severe diarrhoea, dehydration and hypokalaemia. Treatment options include resection of the tumour, chemotherapy or the reduction of symptoms with somatostatin analogues. We provide an overview of the incidence, pathophysiology, diagnosis, treatment strategies, and prognosis of this rare syndrome.

Effect of octreotide LAR dose and weight on octreotide blood levels in patients with neuroendocrine tumors

OBJECTIVES

Octreotide long acting repeatable (LAR) is widely used for the control of symptoms of functional neuroendocrine tumors. At doses of 30 mg/mo, up to 40% of patients require subcutaneous octreotide "rescue" and up to 40% of patients are given more than 30 mg of LAR/mo. Octreotide acetate binds to the sst2 receptor with an affinity (Kd) of approximately 1 x 10(-9) mol/L (approximately equal to 1000 pg/mL), but higher (approximately equal to 10,000 pg/mL) concentrations of octreotide are required to completely saturate this receptor. Octreotide blood level measurement may be useful to guide LAR therapy in symptomatic patients or in patients who have tumor growth on traditional LAR doses. We hypothesize that LAR doses of 60 mg/mo will produce blood levels of 10,000 pg/mL or greater. At identical monthly LAR doses, patients with higher weights will require more medication to achieve similar plasma octreotide levels than individuals with lower body weights.

METHODS

Trough plasma, serum, urine, and saliva octreotide levels were obtained from 52 patients with carcinoid syndrome receiving 20 (n = 8), 30 (n = 19), or 60 mg LAR/mo (n = 10). Octreotide levels were determined by radioimmunoassay.

RESULTS

The mean +/- SD plasma octreotide levels for patients receiving 20, 30, or 60 mg LAR/mo were 2518 +/- 1020, 5241 +/- 3004, and 10,925 +/- 5330 pg/mL, respectively. Patient weight (kilograms) was inversely related to plasma octreotide levels. There was a significant correlation between plasma octreotide levels and octreotide levels measured in urine, saliva, and serum.

CONCLUSIONS

Frequent measurement of octreotide levels may be useful to guide octreotide therapy in patients with poorly controlled symptoms or those patients experiencing tumor growth.

Recommended guidelines for the treatment of cancer treatment-induced diarrhea

PURPOSE

To update and expand on previously published clinical practice guidelines for the treatment of cancer treatment-induced diarrhea.

METHODS

An expert multidisciplinary panel was convened to review the recent literature and discuss recommendations for updating the practice guidelines previously published by this group in the Journal of Clinical Oncology in 1998. MEDLINE searches were performed and the relevant literature published since 1998 was reviewed by all panel members. The treatment recommendations and algorithm were revised by panel consensus.

RESULTS

A recent review of early toxic deaths occurring in two National Cancer Institute-sponsored cooperative group trials of irinotecan plus high-dose fluorouracil and leucovorin for advanced colorectal cancer has led to the recognition of a life-threatening gastrointestinal syndrome and highlighted the need for vigilant monitoring and aggressive therapy for this serious complication. Loperamide remains the standard therapy for uncomplicated cases. However, the revised guidelines reflect the need for recognition of the early warning signs of complicated cases of diarrhea and the need for early and aggressive management, including the addition of antibiotics. Management of radiation-induced diarrhea is similar but may not require hospitalization, and chronic low- to intermediate-grade symptoms can be managed with continued loperamide.

CONCLUSION

With vigilant monitoring and aggressive therapy for cancer treatment-induced diarrhea, particularly in patients with early warning signs of severe complications, morbidity and mortality may be reduced.

Symptom control

Symptom control has become increasingly recognized as an important goal in patient care. In this article, advances in symptom assessment, and various definitions of symptom improvement are reviewed. Theoretical concepts underlying symptom control and clinically significant change are presented, as well as the role of symptom control as an endpoint in clinical trials. Symptom control is then surveyed in two broad categories for selected symptoms. The first area is therapy related symptoms, secondary to chemotherapy, radiation, hormonal therapy, and surgery. Symptoms reviewed include chemotherapy related mucositis, emesis, fatigue; hot flashes; and radiation related dermatitis, xerostomia, and mucositis. The second area is palliative oncologic approaches to disease-related symptoms. Results in palliative chemotherapy, palliative radiation therapy, cancer pain, and lack of appetite are summarized. Areas requiring further research are noted. Findings are presented in both a clinical and research context to help guide the reader with interpreting symptom control studies.

Somatostatin analog therapy in treatment of gastrointestinal disorders and tumors

Long-acting octapeptide somatostatin analogs can effectively control symptoms resulting from excessive hormone release in patients with endocrine tumors of the gastrointestinal tract, provided that these tumors and metastases show a high expression of the somatostatin receptor subtype 2. The presence of this receptor subtype on these tumors can be demonstrated by in vitro studies, but also in vivo using 111In-pentetreotide scintigraphy. In a few studies, significant antiproliferative effects of these drugs on these tumors have also been demonstrated. The effectiveness of octapeptide somatostatin analogs in the management of chemotherapy- related and AIDS-related diarrhea and in reducing postoperative complications of pancreatic surgery have also been demonstrated. These drugs have been used to decrease the output of enterocutaneous pancreatic fistulas and are prophylactically used to prevent the development of these fistulas. Octapeptide somatostatin analog therapy is widely accepted for the initial management of acute variceal bleeding in cirrhotic patients. These drugs are currently also being evaluated for the treatment of advanced hepatocellular carcinoma and malignant intestinal obstruction. Radiotherapy with octapeptide somatostatin analogs coupled to radionuclides such as indium-111, yttrium-90, and lutetium- 177 is currently being studied in phase I-III trials.

Effect of octreotide on fluid absorption and secretion by the normal human jejunum and ileum in vivo

BACKGROUND

We hypothesized that part of the non-specific antidiarrhoeal effect of octreotide is mediated by a proabsorptive or antisecretory effect on small intestinal active electrolyte transport.

METHODS

To measure the effect of octreotide on net absorption, the jejunum and ileum of normal human subjects were perfused with a balanced electrolyte solution; to measure the effect of octreotide on normal active chloride secretion, the jejunum was perfused with a bicarbonate-free solution.

RESULTS

During perfusion of a balanced electrolyte solution, octreotide increased basal net fluid absorption in the jejunum and ileum by about 40 mL/h per 30 cm. In the jejunum, octreotide markedly inhibited basal and sham feeding-stimulated active chloride secretion and inhibited water secretion by 28 and 51 mL/h per 30 cm, respectively.

CONCLUSIONS

Octreotide causes an increase in the net epithelial cell absorption rate of a balanced electrolyte solution in the normal jejunum and ileum. In the jejunum, this proabsorptive effect is mediated mainly by the reduction of normal active electrolyte secretion, rather than by stimulation of normal active electrolyte absorption. These results support the hypothesis that part of the antidiarrhoeal action of octreotide is due to its effects on active electrolyte transport mechanisms by normal epithelial cells of the small intestine.

Review article: the complexity of drug development for irritable bowel syndrome

Drug development for functional gastrointestinal disorders is complex. These conditions involve central and peripheral physiological changes, together with psychological factors. Methodological problems have included a poor appreciation of the physiological and psychological correlates of patients' symptoms, a lack of animal models of proven relevance, and safety issues. Government, patient pressure groups and the Internet can also influence a drug's success. Most recent interest has focused on the serotonin (5-HT) modifying drugs. Cisapride has been withdrawn in some countries because of concerns related to QT prolongation and cardiac arrhythmias. The 5-HT3 antagonists, developed to modify visceral sensation, have caused constipation; alosetron, also withdrawn, caused ischaemic colitis. The 5-HT4 agonists induce peristalsis; tegaserod and prucalopride, both delayed in their development due to issues of safety and efficacy, benefit patients with 'constipation-predominant' irritable bowel syndrome or idiopathic constipation. 5-HT1 agonists improve impaired gastric accommodation and symptoms in patients with functional dyspepsia. Antidepressants also affect serotonin metabolism. Previous examples of success in this area involved drugs targeted at peripheral receptors mediating motor function or secretion. Modification of sensory function is a much more challenging objective. The experience with serotonin modifying drugs has been mixed, and some important lessons are there to be learnt.

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.

Carcinoid and pancreatic endocrine tumors: recent advances in molecular pathogenesis, localization, and treatment

Neuroendocrine tumors include carcinoids and pancreatic endocrine tumors, which share a number of common features in their pathology, ability to cause clinical symptoms due to ectopic hormone and bioamine release, localization methods, and treatment. Although generally slow growing, a proportion demonstrate aggressive tumor growth. Therefore, in many cases treatment must be directed against both the tumor and the hormone-excess state. There have been significant recent advances into their molecular pathogenesis, natural history, and prognostic factors; clinical presentation defined by larger series analysis; localization methods; and the development of new treatments directed against the tumor and to control the hormone-excess state (including depot somatostatin analogues, interferon combinations, embolization, chemoembolization, radiotherapy with novel somatostatin analogues, and liver transplantation). Recent advances in each of these areas are briefly discussed.

Palliative care and AIDS: 2 – Gastrointestinal symptoms

With the use of more intensive antiretroviral therapies (highly-active antiretroviral therapy, HAART) particularly in first world countries, reductions in the mortality and morbidity of HIV infection are being seen. However, though the prevalence of symptoms may change, symptom control does continue to be a problem for many people with HIV, particularly as their disease progresses. This is the second of 2 CME articles about palliative care and HIV infection. The first gave a background to palliative care, and covered symptom control of pain1. This article gives suggestions for the treatment of common gastrointestinal symptoms in HIV infection; nausea and vomiting, cachexia and anorexia and chronic diarrhoea.

[Gastrointestinal complications of diabetes mellitus]

BACKGROUND

Diabetes mellitus leads to a broad spectrum of symptoms and manifestations in the field of gastroenterology.

BASIS

This article reviews the pathophysiology, differential diagnoses and secondary diseases of the gastrointestinal tract in diabetic patients.

CLINICAL APPEARANCE

Motility disorders, infectious complications, secondary diseases of the stomach, liver, pancreas, gall bladder, small and large bowel are considered and discussed. Diagnostic and therapeutic approaches for the management of diabetic enteropathy are presented.

CONCLUSION

The new strategies in diagnosis and therapy for a successful prevention or treatment of gastrointestinal complications due to diabetes mellitus need good cooperation of clinical specialties.

Octreotide acetate long-acting formulation versus open-label subcutaneous octreotide acetate in malignant carcinoid syndrome

PURPOSE

Subcutaneous (SC) octreotide acetate effectively relieves the diarrhea and flushing associated with carcinoid syndrome but requires long-term multiple injections daily. A microencapsulated long-acting formulation (LAR) of octreotide acetate has been developed for once-monthly intramuscular dosing.

PATIENTS AND METHODS

A randomized trial compared double-blinded octreotide LAR at 10, 20, and 30 mg every 4 weeks with open-label SC octreotide every 8 hours for the treatment of carcinoid syndrome. Seventy-nine patients controlled with treatment of SC octreotide 0.3 to 0.9 mg/d whose symptoms returned during a washout period and who returned for at least the week 20 evaluation constituted the efficacy-assessable population.

RESULTS

Complete or partial treatment success was comparable in each of the four arms of the study (SC, 58.3%; 10 mg, 66.7%; 20 mg, 71.4%; 30 mg, 61.9%; P> or =.72 for all pairwise comparisons). Control of stool frequency was similar in all treatment groups. Flushing episodes were best controlled in the 20-mg LAR and SC groups; the 10-mg LAR treatment was least effective in the control of flushing. Treatment was well tolerated by patients in all four groups.

CONCLUSION

Once octreotide steady-state concentrations are achieved, octreotide LAR controls the symptoms of carcinoid syndrome at least as well as SC octreotide. A starting dose of 20 mg of octreotide LAR is recommended. Supplemental SC octreotide is needed for approximately 2 weeks after initiation of octreotide LAR treatment. Occasional rescue SC injections may be required for possibly 2 to 3 months until steady-state octreotide levels from the LAR formulation are achieved.

Carcinoid Tumors of the Gut

BACKGROUND: Carcinoid tumors are the most frequently encountered endocrine tumors of the gastrointestinal tract. They are most often found in the appendix, although they can arise in any location of the gut. Carcinoid tumors may secrete a variety of bioactive substances, which can cause the complex of symptoms associated with the carcinoid syndrome. METHODS: The authors reviewed the pathology, clinical presentation, and management of carcinoid tumors with an emphasis on the surgical management. RESULTS: The primary treatment for a carcinoid tumor located anywhere in the gut is surgical. Those who have widely metastatic disease or who are anatomically unresectable may undergo cytoreductive surgical debulking and/or hepatic arterial embolization followed by palliation of symptoms with octreotide, the long-acting somatostatin analog. CONCLUSIONS: The prognosis for patients with carcinoid tumors that are fully resected is excellent. Those with hepatic metastases and the carcinoid syndrome have a less favorable prognosis.

Vasoactive intestinal polypeptide-secreting tumours: biology and therapy

VIP-secreting tumours are rare, but they produce a dramatic clinical picture, the most prominent feature being profuse, watery diarrhoea and hypokalaemia. VIPomas are malignant and require sophisticated diagnostic and localization techniques in order to identify their presence. Delays in diagnosis are the rule rather than the exception. Improvements in the diagnosis of VIPomas appear to result in an increase in resectability rates. A definitive diagnosis is aided by the determination of plasma VIP concentrations through the use of sensitive radioimmunoassays. With heightened awareness of this syndrome, increasing numbers of patients can be identified and more effective treatments developed for the refractory and recurrent tumours.