Methyldopa

Many patients experience sedation for two or three days when therapy is started or when the dose is increased, so when increasing the dosage it may be desirable to increase the evening dose first. Withdrawal of methyldopa is followed by return of hypertension, usually within 48 hours. Renal impairment: methyldopa is largely excreted by the kidney and patients with impaired renal function may respond to smaller doses. Patients already on other antihypertensives: terminate the other agents gradually if required; limit methyldopa to an initial dose of not more than 500 mg daily, increased as required at intervals of not less than two days, and adjust the dose of the other agents to effect a smooth transition. When 500 mg of methyldopa is added to 50 mg of hydrochlorothiazide, the two agents may be given together once daily. Elderly: initial dose should be kept as low as possible, not exceeding 250 mg daily; an appropriate starting dose would be 125 mg twice daily, increasing slowly as required, not exceeding a maximum daily dosage of 2 g. Syncope in older patients may relate to increased sensitivity and advanced arteriosclerotic vascular disease and may be avoided by lower doses. Liver function tests and a total and differential white blood cell count are advisable before therapy and at intervals during the first six to twelve weeks of therapy, or whenever an unexplained fever occurs; withdraw therapy if fever, abnormal liver function or jaundice occurs.

SPC section 4.2 states the initial paediatric dosage is based on 10 mg/kg body weight daily in 2-4 oral doses; the daily dose is then increased or decreased until an adequate response is obtained. Verify against a children's formulary before prescribing.