The angiotensin-converting enzyme inhibitors have been found to be safe and efficacious in the treatment of essential hypertension. Fosinopril is the first angiotensin-converting enzyme inhibitor from a new class of agents containing phosphorus. This drug is known to be metabolized to almost and equal extent by the hepatic and renal pathways.

This study was performed to investigate the efficacy and safety of oral fosinopril, a new class of phosporus-containing angiotensin converting enzyme inhibitor, on essential hypertension. A single daily dose of 10mg to 20mg fosinopril was administered in 21 hypertensive patients with diastolic blood pressure in the range of 95mmHg-115mmHg while off all other anti-hypertensive agents for 10 weeks. Blood pressure and heart rate were measured every 4 weeks. The complete blood count, blood chemistry by SMA-12, serum electrolytes and urinalysis were performed at 12th week of therapy.

1) Baseline systolic and diastolic blood pressures after 2 weeks of placebo at sitting position were 158.8±15.7 and 99.4±6.3mmHg respectively. There was a statistcally significant reduction of blood pressure after 4 week treatment of fosinopril which was maintained up to 12 weeks of follow-up(158.8±15.7-99.4±6.3mmHg vs 139.3±18.2/86.6±10.3mmHg, p<0.05).

2) The proportion of responders defined by diastolic blood pressures less than 90mmHg or decline more than 10mmHg at 4, 8 and 12 weeks after treatment with fosinopril were 90.5, 95.2, and 95.2% respectively.

3) THere were no significant changes in blood chemistry, serum electrolytes, hematologic findings and heart rate over the treatment period.

4) Three patients experienced severe non-productive cough that required to discontinue the medication.

In patients with mild to moderate hypertension, once-daily fosinopril(10mg and 20mg) provided significant anti-hypertensive effects without serious side effects. The 10mg dose was effective in majority of patients and may be considered as a starting dose.