Fosinopril and Hydrochlorothiazide

Fosinopril sodium and hydrochlorothiazide tablets are indicated for the treatment of hypertension. These fixed dose combinations are not indicated for initial therapy. In using fosinopril sodium and hydrochlorothiazide, consideration should be given to the fact that another angiotensin-converting enzyme inhibitor, captopril, has caused agranulocytosis, particularly in patients with renal impairment or collagen-vascular disease. Available data are insufficient to show that fosinopril does not have a similar risk. ACE inhibitors (for which adequate data are available) cause a higher rate of angioedema in black than in non-black patients.

Fosinopril and fosinoprilat inhibit angiotensin-converting enzyme (ACE) in human subjects and in animals. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor substance, angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex. Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and to decreased aldosterone secretion. The latter decrease may result in a small increase of serum potassium. Hypertensive patients treated with fosinopril alone for an average of 8 weeks had elevations of serum potassium of approximately 0.1 mEq/L.

Fosinopril is an effective treatment of hypertension in once-daily doses of 10 to 80 mg, while hydrochlorothiazide is effective in doses of 12.5 to 50 mg per day. In clinical trials of fosinopril/hydrochlorothiazide combination therapy using fosinopril doses of 2.5 to 40 mg and hydrochlorothiazide doses at 5 to 37.5 mg, the antihypertensive effects increased with increasing dose of either component. The hazards 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.

Fosinopril sodium and hydrochlorothiazide tablets are contraindicated in patients who are anuric. Fosinopril sodium and hydrochlorothiazide is also contraindicated in patients who are hypersensitive to fosinopril, to any other ACE inhibitor, to hydrochlorothiazide, or other sulfonamide-derived drugs, or any other ingredient or component in the formulation. Hypersensitivity reactions are more likely to occur in patients with a history of allergy or bronchial asthma.

Boxed warning (fetal toxicity): When pregnancy is detected, discontinue fosinopril and hydrochlorothiazide as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. See WARNINGS: Fetal Toxicity Anaphylactoid and Possibly Related Reactions Presumably because angiotensin-converting enzyme inhibitors affect the metabolism of eicosanoids and polypeptides, including endogenous bradykinin, patients receiving ACE inhibitors (including fosinopril sodium and hydrochlorothiazide) may be subject to a variety of adverse reactions, some of them serious. Head and Neck Angioedema Angioedema of the face, extremities, lips, tongue, glottis, and larynx has been reported in patients treated with angiotensin-converting enzyme inhibitors. Angioedema associated with laryngeal edema can be fatal.

Fosinopril sodium and hydrochlorothiazide tablets have been evaluated for safety in over 660 patients with hypertension, approximately 137 of these patients were treated for more than one year. The observed adverse events were generally mild, transient, and similar to those seen with fosinopril and hydrochlorothiazide taken separately. There was no relationship between the incidence of side effects and age. In placebo-controlled clinical trials of fosinopril sodium and hydrochlorothiazide, the usual duration of therapy was two months. Adverse clinical or laboratory events led to discontinuation of therapy by 4.3% of 368 placebo-treated patients and by 3.5% of 660 fosinopril sodium and hydrochlorothiazide-treated patients.

Potassium supplements and potassium-sparing diuretics As noted above (“Derangements of Serum Electrolytes”), the net effect of fosinopril sodium and hydrochlorothiazide may be to elevate a patient’s serum potassium, to reduce it, or to leave it unchanged. Potassium-sparing diuretics (spironolactone, amiloride, triamterene, and others) or potassium supplements can increase the risk of hyperkalemia. If concomitant use of such agents is indicated, they should be given with caution, and the patient’s serum potassium should be monitored frequently. Lithium Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors during therapy with lithium.

Store at 20° to 25°C (68° to 77°F), excursions permitted to 15° to 30°C (59° to 86°F). Protect from moisture by keeping bottle tightly closed.