Methyldopa (Chronic Hypertension in Pregnancy)

SPC §4.2 (Methyldopa 125 mg Tablets). INDICATION CAVEAT: this UK SPC gives methyldopa posology for hypertension generally and does not contain a separate regimen for chronic hypertension in pregnancy; §4.6 states methyldopa has been used under close medical supervision for the treatment of hypertension during pregnancy with no clinical evidence of foetal abnormality or effect on the neonate. Many patients experience sedation for two or three days when therapy is started or the dose is increased — when increasing the dosage it may therefore be desirable to increase the evening dose first. Withdrawal of methyldopa is followed by return of hypertension, usually within 48 hours, generally without an overshoot of blood pressure. WITH OTHER ANTIHYPERTENSIVES: methyldopa may be initiated in most patients already on other antihypertensives by terminating those agents gradually if required; following previous antihypertensive therapy, methyldopa should be limited to an initial dose of not more than 500 mg daily, increased as required at intervals of not less than two days; the dose of the other agents may need adjustment for a smooth transition. When 500 mg of methyldopa is added to 50 mg of hydrochlorothiazide, the two agents may be given together once daily. OLDER PEOPLE: keep the initial dose as low as possible, not exceeding 250 mg daily — an appropriate starting dose would be 125 mg twice daily, increasing slowly as required but not exceeding a maximum of 2 g daily; 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, or whenever an unexplained fever occurs. US LABELLING (cross-check only): usual starting dosage 250 mg two to three times a day in the first 48 hours; usual maintenance 500 mg to 2 g daily in two to four doses; maximum recommended daily dosage 3 g; initial dosage limited to 500 mg daily in divided doses when given with antihypertensives other than thiazides. Interactions listed below are from the US label — UK SPC §4.5 was not captured in this bundle.

SPC §4.2 paediatric population: 'Initial 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. The maximum dosage is 65 mg/kg or 3.0 g daily, whichever is less.' The US label states the same figures. This is a general paediatric hypertension dose from the label, not an obstetric dose — verify against a children's formulary before prescribing.