Fosinopril is an effective treatment of hypertension in once-daily doses of 10-80 mg, while hydrochlorothiazide is effective in doses of 12.5-50 mg per day. In clinical trials of fosinopril/hydrochlorothiazide combination therapy using fosinopril doses of 2.5-40 mg and hydrochlorothiazide doses at 5-37.5 mg, the antihypertensive effects increased with increasing dose of either component.
The hazards (see WARNINGS) of fosinopril are generally rare and apparently independent of dose; those of hydrochlorothiazide are a mixture of dose-dependent phenomena (primarily hypokalemia) and dose-independent phenomena (e.g., pancreatitis), the former much more common than the latter. Therapy with any combination of fosinopril and hydrochlorothiazide will be associated with both sets of dose-independent hazards. To minimize doseindependent hazards, it is usually appropriate to begin combination therapy only after a patient has failed to achieve the desired effect with monotherapy.
Dose Titration by Clinical Effect
A patient whose blood pressure is not adequately controlled with fosinopril or hydrochlorothiazide monotherapy may be switched to combination therapy with Fosinopril Sodium and Hydrochlorothiazide. Dosage must be guided by clinical response; controlled clinical trials showed that the addition of 12.5 mg of hydrochlorothiazide to 10-20 mg of fosinopril will typically be associated with additional reduction in seated diastolic blood pressure at 24 hours after dosing. On average, the effect of the combination of 10 mg of fosinopril with 12.5 mg of hydrochlorothiazide was similar to the effect seen with monotherapy using either 40 mg of fosinopril or 37.5 mg of hydrochlorothiazide.
Use in Renal Impairment
In patients with severe renal impairment (creatinine clearance is < 30 mL/min/1.73m2, serum creatine roughly ≥ 3 mg/dL or 265 μmol/L), loop diuretics are preferred to thiazides, so Fosinopril Sodium and Hydrochlorothiazide is not recommended. In patients with lesser degrees of renal impairment. Fosinopril Sodium and Hydrochlorothiazide may be used with no change in dosage.