Cimetidine

Duodenal or benign gastric ulceration: a single daily dose of 800 mg at bedtime is recommended. Other effective regimens: 200 mg three times a day with meals plus 400 mg at bedtime (1.0 g/day) and, if inadequate, 400 mg four times a day (1.6 g/day) with meals and at bedtime. Treat initially for at least four weeks (six weeks in benign gastric ulcer); ulcers not healed by then usually heal after a further course. For longer-term treatment the dose may be reduced to 400 mg at bedtime, or 400 mg in the morning and at bedtime. Relapse prevention in benign peptic ulcer disease: usually 400 mg at bedtime (400 mg morning and bedtime has also been used). Oesophageal reflux disease: 400 mg four times a day with meals and at bedtime for four to eight weeks to heal oesophagitis and relieve symptoms. Very high gastric acid secretion (e.g. Zollinger-Ellison syndrome): may need 400 mg four times a day, or occasionally more. Prophylaxis of haemorrhage from stress ulceration in seriously ill patients: 200-400 mg every four to six hours. Risk of acid aspiration syndrome: 400 mg orally 90-120 minutes before induction of general anaesthesia, or at the start of labour in obstetric practice; while the risk persists a dose of up to 400 mg may be repeated at four-hourly intervals, up to the usual daily maximum of 2.4 g, with the usual precautions to avoid acid aspiration. Short bowel syndrome (e.g. after substantial resection for Crohn's disease): the usual dosage range according to individual response. To reduce degradation of pancreatic enzyme supplements: 800-1600 mg a day in four divided doses, one to one and a half hours before meals. Elderly: normal adult dosage unless renal function is markedly impaired. Malignancy should be excluded by endoscopy and biopsy before treating gastric ulceration, since cimetidine can relieve symptoms and help superficial healing of gastric cancer.

SPC §4.2 states: experience in children is less than that in adults. Children more than one year old: 25-30 mg/kg body weight per day in divided doses may be administered. Infants under one year old: use is not yet fully evaluated; 20 mg/kg body weight per day in divided doses has been used. A single dosePerKg value has deliberately not been asserted because the source states a range and the under-1-year figure is described as 'has been used' rather than recommended. Verify against a children's formulary before prescribing.