Cisapride

Publisher Website
Google Scholar
Abstract
Cisapride, a substituted piperidinyl benzamide chemically related to metoclopramide, is an orally administered prokinetic agent which facilitates or restores motility throughout the length of the gastrointestinal tract. Its novel mechanism of action is thought to involve enhancement of acetylcholine release in the myenteric plexus of the gut. Because of its specificity cisapride is devoid of central depressant or antidopaminergic effects; side effects such as diarrhoea or loose stools, which occur infrequently, are related to its primary pharmacological action. Evidence exists from comparisons with placebo in initial trials to establish the efficacy of cisapride in improving healing rates and symptoms in patients with reflux oesophagitis, in alleviating symptoms in patients with non-ulcer dyspepsia, and in accelerating gastric emptying in gastroparesis. There are less conclusive data regarding the efficacy of cisapride in relieving symptoms in patients with gastroparesis, although preliminary results support a role for cisapride in certain groups such as diabetics. Limited data suggest that patients with chronic constipation due to underlying motility disorders may benefit from cisapride. Unfortunately, there is a paucity of trials comparing the efficacy of cisapride with other therapeutic agents. Thus, the relative position of cisapride in therapy cannot be defined at present. Should future results support preliminary evidence of comparable efficacy to metoclopramide, domperidone and ranitidine (in oesophagitis), cisapride with its favourable tolerability profile should claim a prominent position in the therapy of patients with a variety of gastrointestinal motility disorders. Cisapride enhances gastrointestinal motility along the length of the gastrointestinal tract. In general, when administered in single or repeated doses, cisapride increases lower oesophageal sphincter pressure and oesophageal motility by about 20 to 50% in healthy volunteers and patients with gastrointestinal motility disorders, although oral use has given somewhat less consistent results than intravenous use. The magnitude of the increase is directly related to the degree of deficiency at baseline. Oesophageal pH is also elevated to >4 for prolonged periods during both the day and the night with cisapride administration. The magnitude of these effects of cisapride are at least comparable to those seen with metoclopramide. Gastric emptying is accelerated by cisapride administration to a significantly greater extent than by placebo, and to a similar extent as occurs with metoclopramide in healthy subjects. In general, single dose or short term administration of cisapride shortens gastric transit time of solids, often to within normal limits, in patients with gastroparesis of idiopathic, diabetic or postsurgical origin. The volume threshold required for antral stimulation is decreased by cisapride. Several authors have found that cisapride stimulates interdigestive gastric motility in a fashion similar to the natural progression of the interdigestive migrating motor complex. Comparisons with placebo have shown that transit time through the small and large bowel is significantly reduced after ingestion of cisapride. Plasma concentrations of human pancreatic polypeptide and cholecystokinin have increased after single but not after repeated doses of cisapride. Concentrations of gastrin, insulin, glucose and prolactin do not appear to be altered by the drug. The lack of effect on prolactin concentrations reflects the lack of antidopaminergic activity of cisapride. Cisapride appears to have no inherent activity in the central nervous system and thus caused no impairment of psychomotor function in the one study which investigated such a possibility. However, the depressant effects of drugs such as diazepam may be enhanced due to increased absorption rate of the benzodiazepine when cisapride is given concomitantly. The mechanisms by which cisapride stimulates gastrointestinal motor activity are not clear. It seems likely that the drug acts principally by indirect mechanisms to facilitate acetylcholine release through a process mediated by postganglionic nerve endings in the myenteric plexus of the gut. There is some evidence that cisapride acts both as an antagonist and an agonist of serotonin (5-hydroxytryptamine), but the contribution, if any, of these effects to the drug’s mechanism of clinical activity is unknown. Maximal plasma concentrations are attained within 1 to 2 hours after single oral doses of cisapride 5 to 20mg, as shown in healthy subjects and patients. Absolute bioavailability of oral cisapride is about 40 to 50%, indicating first-pass metabolism in the liver or gut. The presence of food enhances absorption of cisapride. Studies in rats showed that cisapride was found in highest concentrations in the liver, and in the stomach and small intestinal walls; concentrations of cisapride in brain tissue were 2 to 3 times less than in plasma. In man the volume of distribution is 2.4 L/kg, and cisapride is 98% bound to plasma proteins in vitro. A study in puerperal women has demonstrated that cisapride is excreted in breast milk in small amounts which represent about 0.1% of the cisapride dose given to the mother. Cisapride is extensively metabolised via oxidative-N-dealkylation to yield the major metabolite, norcisapride, and by aromatic hydroxylation. The contribution of the metabolites to the overall pharmacological activity of cisapride is reported to be negligible. In one study using radiolabelled cisapride, the parent drug accounted for 1 to 3% of the urinary and 5% of the faecal radioactivity. The elimination half-life of cisapride is about 10 hours in healthy subjects, and this value may be lengthened in patients with hepatic disease and in some elderly subjects. Available evidence suggests that in the presence of renal insufficiency, the elimination of cisapride is not significantly altered. Cisapride is more effective than placebo in patients with reflux oesophagitis. In initial published studies in which cisapride was administered in a dosage of 10mg 4 times daily for 6 to 16 weeks endoscopically confirmed cure rates were 63 to 73%, compared with rates of 12 to 13% with placebo. Good or excellent results in terms of symptomatic improvement (relief from heartburn, regurgitation, postprandial discomfort) were achieved in 67 to 91% of cisapride recipients, compared with 13 to 51% in placebo groups. Cisapride therapy also enabled reductions in antacid use. Preliminary evidence suggests that infants and children with gastro-oesophageal reflux disease unresponsive to non-drug therapy may benefit from cisapride treatment. Symptoms of non-ulcer dyspepsia (belching, bloatedness, abdominal distension, early satiety) are similarly alleviated by cisapride. In clinical trials, 63 to 86% of patients treated with cisapride had ‘good’ to ‘excellent’ response, almost twice the number of placebo recipients with similar improvement (27 to 55%). Many patients responded to a dosage regimen of 5mg administered 3 times daily for 3 to 6 weeks, although some required an increase to 10mg 3 times daily, which was also the dosage utilised in the largest study. Gastric emptying is consistently accelerated in patients with gastroparesis of various origins treated with cisapride, but this is not always associated with an improvement in symptoms greater than that which occurs with placebo. Evidence from long term studies tends to support a role for cisapride in alleviating gastrointestinal discomfort in diabetic patients with gastroparesis, particularly when the drug is given in a dosage of 10mg 4 times daily. Similarly, preliminary results indicate a possible place for cisapride in the therapy of some patients with chronic constipation. At present there are insufficient data to define clearly the efficacy of cisapride relative to that of other available gastrokinetic drugs. However, the few comparative trials conducted to date have demonstrated that cisapride was similar in efficacy to metoclopramide in relieving symptoms, and to ranitidine and cimetidine in healing oesophageal erosions, in patients with oesophagitis. Moreover, there was some evidence that adding cisapride to cimetidine therapy improved healing rates in patients with severe oesophagitis. Lastly, patients with non-ulcer dyspepsia responded equally as well to cisapride as to usual doses of metoclopramide or domperidone. Cisapride is well tolerated. Side effects most often reported — transient abdominal cramping, borborygmi and diarrhoea or loose stools — are an extension of its pharmacological profile and have necessitated treatment withdrawal only rarely. Notably, there is an absence of central nervous system effects, such as somnolence or fatigue, during cisapride therapy.