CIMETIDINE

4 g. 4).

Adults:

The usual dosage is 400 mg twice a day, with breakfast and at bedtime. Alternatively for patients with duodenal or benign gastric ulceration, a single daily dose of 800 mg at bedtime is recommended. 6 g/day), also with meals and at bedtime.

Treatment should be given initially for at least four weeks (six week in benign gastric ulcer, eight weeks in ulcer associated with continued non-steroidal anti-inflammatory agents) even if symptomatic relief has been achieved sooner.

Most ulcers will have healed by that stage, but those which have not will usually do so after a further course of treatment. Treatment may be continued for longer periods in those patients who may benefit from reduction of gastric secretion and the dosage may be reduced in those who have responded to treatment, for example to 400 mg at bedtime or 400 mg in the morning and at bedtime.

In patients with benign peptic ulcer disease who have responded to the initial course, relapse may be prevented by continued treatment, usually with 400 mg at bedtime; 400mg in the morning and at bedtime has also been used. In oesophageal reflux disease, 400 mg four times a day, with meals and at bedtime, for four to eight weeks is recommended to heal oesophagitis and relieve associated symptoms.

g. Zollinger Ellison syndrome) it may be necessary to increase the dose to 400 mg four times a day or in occasional cases further. Antacids can be made available to all patients until symptoms disappear. In the prophylaxis of haemorrhage from stress ulceration in seriously ill patients, doses of 200 to 400 mg can be given every four to six hours.

In patients thought to be at risk of acid aspiration syndrome, an oral dose of 400 mg can be given 90 to 120 minutes before induction of general anaesthesia or, in obstetric practice, at the start of labour. 4 g. The usual precautions to avoid acid aspiration should be taken.

g. following substantial resection for Crohn’s disease, the usual dosage range (see above) can be used according to individual response. To reduce degradation of pancreatic enzyme supplements, 800 to 1600 mg a day may be given, according to response, in four divided doses, one to one and a half hours before meals.

Adverse experiences with cimetidine are listed below by system organ class and frequency. Frequencies are defined as: very common (>1/10), common (>1/100, <1/10), uncommon (>1/1000, <1/100), rare (>1/10000, <1/1000), very rare (<1/10000).

Blood and lymphatic system disorders Uncommon:

Leukopenia Rare: Thrombocytopenia, aplastic anaemia Very rare: Pancytopenia, agranulocytosis Immune system disorders Very rare: Anaphylaxis. Anaphylaxis is usually cleared on withdrawal of the drug.

Psychiatric disorders Uncommon:

Depression, confusional states, hallucinations. Confusional states, reversible within a few days of withdrawing cimetidine, have been reported, usually in elderly or ill patients.

Nervous system disorders Common:

Headache, dizziness Cardiac disorders Uncommon: Tachycardia Rare: Sinus bradycardia Very rare: Heart block Gastrointestinal disorders Common: Diarrhoea Very rare: Pancreatitis. Pancreatitis cleared on withdrawal of the drug.

Hepatobiliary disorders Uncommon:

Hepatitis Rare: Increased serum transaminase levels. Hepatitis and increased serum transaminase levels cleared on withdrawal of the drug.

Skin and subcutaneous tissue disorders Common:

Skin rashes Very rare: Reversible alopecia and hypersensitivity vasculitis. Hypersensitivity vasculitis usually cleared on withdrawal of the drug.

Musculoskeletal and connective tissue disorders Common:

Myalgia Very rare: Arthralgia Renal and urinary disorders Uncommon: Increases in plasma creatinine Rare: Interstitial nephritis. Interstitial nephritis cleared on withdrawal of the drug. Small increases in plasma creatinine have been reported, unassociated with changes in glomerular filtration rate.

Dosage should be reduced in patients with impaired renal function according to creatinine clearance.

The following doses are suggested:

Creatinine clearance of: 0 to 15 ml per minute, 200 mg twice a day; 15 to 30 ml per minute 200 mg three times a day; 30 to 50 ml per minute, 200 mg four times a day; over 50 ml per minute, normal dosage. Cimetidine is removed by haemodialysis, but not to any significant extent by peritoneal dialysis.

Clinical trials of over six years ‘continuous treatment and more than 15 years’ widespread use have not revealed unexpected adverse reactions related to long-term therapy. The safety of prolonged use is not fully established and care should be taken to observe periodically patients given prolonged treatment.

Care should be taken that patients with a history of peptic ulcer, particularly the elderly, being treated with cimetidine and a non-steroidal anti-inflammatory agent are observed regularly. Before initiating therapy with this preparation for any gastric ulceration, malignancy should be excluded by endoscopy and biopsy, if possible, because Cimetidine treatment can mask symptoms and allow transient healing of gastric cancer.

The potential delay in diagnosis should particularly be borne in mind in patients of middle age and over, with new or recently changed dyspeptic symptoms. Due to possible interaction with coumarins, close monitoring of prothrombin time is recommended when cimetidine is concurrently used.

5). Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine

1.