Adult: PO HTN Initial: 100 mg bid, may increase gradually according to patients response to 200-400 mg bid. Max: 2.4 g/day in 2-4 divided doses. IV Emergency treatment of HTN 20 mg injected slowly for at least 2 min; followed by 40-80 mg dose every 10 min. Max: 200 mg. Patient should remain supine during and 3 hr after the procedure. HTN in pregnancy Start infusion at a rate of 20 mg/hr, then doubled every 30 min until a satisfactory response is achieved or a dose of 160 mg/hr is reached. HTN after MI Initiate infusion at a rate of 15 mg/hr, then increase gradually until a favourable response is obtained or a dose of 120 mg/hr is reached. Hypotensive anaesthesia Initial: 10-20 mg, increase at 5-10 mg increments if satisfactory hypotension is not achieved after 5 min. Administer higher initial doses if halothane anaesth is not used.