REN and Hypertension: Patients with a history of hypertension are treated with medications such as hydralazine, labetalol, and nicardipine. However, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, direct renin inhibitors, and sodium nitroprusside are not advised. The initial dose is 20 mg of hydralazine, followed by 0.3 to 1.0 mg/kg of labetalol, for a total dose of 300 mg.