Fosinopril

What it is used for

Fosinopril sodium tablets are indicated for the treatment of hypertension. It may be used alone or in combination with thiazide diuretics.

Fosinopril sodium tablets are indicated in the management of heart failure as adjunctive therapy when added to conventional therapy including diuretics with or without digitalis (see DOSAGE AND ADMINISTRATION ).

In using fosinopril sodium, 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 sodium does not have a similar risk (see WARNINGS ).

In considering use of fosinopril sodium, it should be noted that in controlled trials ACE inhibitors have an effect on blood pressure that is less in black patients than in non-blacks. In addition, ACE inhibitors (for which adequate data are available) cause a higher rate of angioedema in black than in non-black patients (see WARNINGS: Head and Neck Angioedema and Intestinal Angioedema ).

How to take it

Hypertension

Adults

The recommended initial dose of fosinopril sodium tablets is 10 mg once a day, both as monotherapy and when the drug is added to a diuretic. Dosage should then be adjusted according to blood pressure response at peak (2 to 6 hours) and trough (about 24 hours after dosing) blood levels. The usual dosage range needed to maintain a response at trough is 20 mg to 40 mg but some patients appear to have a further response to 80 mg. In some patients treated with once daily dosing, the antihypertensive effect may diminish toward the end of the dosing interval. If trough response is inadequate, dividing the daily dose should be considered. If blood pressure is not adequately controlled with fosinopril sodium alone, a diuretic may be added.

Concomitant administration of fosinopril sodium with potassium supplements, potassium salt substitutes, or potassium-sparing diuretics can lead to increases of serum potassium (see PRECAUTIONS ).

In patients who are currently being treated with a diuretic, symptomatic hypotension occasionally can occur following the initial dose of fosinopril sodium tablets. To reduce the likelihood of hypotension, the diuretic should, if possible, be discontinued two to three days prior to beginning therapy with fosinopril sodium tablets (see WARNINGS ). Then, if blood pressure is not controlled with fosinopril sodium tablets alone diuretic therapy should be resumed. If diuretic therapy cannot be discontinued, an initial dose of 10 mg of fosinopril sodium tablets should be used with careful medical supervision for several hours and until blood pressure has stabilized. (See WARNINGS and PRECAUTIONS: Information for Patients and Drug Interactions ).

Since concomitant administration of fosinopril sodium tablets with potassium supplements, or potassium containing salt substitutes or potassium-sparing diuretics may lead to increases in serum potassium, they should be used with caution (see PRECAUTIONS ).

Pediatrics

In children, doses of fosinopril sodium tablets between 0.1 and 0.6 mg/kg have been studied and shown to reduce blood pressure to a similar extent (see CLINICAL PHARMACOLOGY Pharmacodynamics and Clinical Effects ). Based on this, the recommended dose of fosinopril sodium tablets USP in children weighing more than 50 kg is 5 to 10 mg once per day as monotherapy. An appropriate dosage strength is not available for children weighing less than 50 kg.

Heart Failure

Digitalis is not required for fosinopril sodium tablets to manifest improvements in exercise tolerance and symptoms. Most placebo-controlled clinical trial experience has been with both digitalis and diuretics present as background therapy.

The usual starting dose of fosinopril sodium tablets should be 10 mg once daily. Following the initial dose of fosinopril sodium tablets, the patient should be observed under medical supervision for at least two hours for the presence of hypotension or orthostasis and, if present, until blood pressure stabilizes. An initial dose of 5 mg is preferred in heart failure patients with moderate to severe renal failure or those who have been vigorously diuresed.

Dosage should be increased, over a several week period, to a dose that is maximal and tolerated but not exceeding 40 mg once daily. The usual effective dosage range is 20 mg to 40 mg once daily.

The appearance of hypotension, orthostasis, or azotemia early in dose titration should not preclude further careful dose titration. Consideration should be given to reducing the dose of concomitant diuretic.

For Hypertensive or Heart Failure Patients With Renal Impairment: In patients with impaired renal function, the total body clearance of fosinoprilat is approximately 50% slower than in patients with normal renal function. Since hepatobiliary elimination partially compensates for diminished renal elimination, the total body clearance of fosinoprilat does not differ appreciably with any degree of renal insufficiency (creatinine clearances <80 mL/min/1.73m 2 ), including end-stage renal failure (creatinine clearance <10 mL/min/1.73m 2 ) This relative constancy of body clearance of active fosinoprilat, resulting from the dual route of elimination, permits use of the usual dose in patients with any degree of renal impairment. (See WARNINGS: Anaphylactoid reactions during membrane exposure and PRECAUTIONS: Hemodialysis.)

Side effects, and when to stop

Fosinopril sodium has been evaluated for safety in more than 2100 individuals in hypertension and heart failure trials, including approximately 530 patients treated for a year or more. Generally adverse events were mild and transient, and their frequency was not prominently related to dose within the recommended daily dosage range.

Who should not take it

Fosinopril sodium tablets are contraindicated in patients who are hypersensitive to this product or to any other angiotensin converting enzyme inhibitor (e.g., a patient who has experienced angioedema with any other ACE inhibitor therapy).

Do not co-administer fosinopril sodium tablets with aliskiren in patients with diabetes.

Other medicines and interactions

With diuretics: Patients on diuretics, especially those with intravascular volume depletion, may occasionally experience an excessive reduction of blood pressure after initiation of therapy with fosinopril sodium. The possibility of hypotensive effects with fosinopril sodium can be minimized by either discontinuing the diuretic or increasing salt intake prior to initiation of treatment with fosinopril sodium. If this is not possible, the starting dose should be reduced and the patient should be observed closely for several hours following an initial dose and until blood pressure has stabilized. (see DOSAGE AND ADMINISTRATION ).

With potassium supplements and potassium-sparing diuretics: Fosinopril sodium can attenuate potassium loss caused by thiazide diuretics. Potassium-sparing diuretics (spironolactone, amiloride, triamterene, and others) or potassium supplements can increase the risk of hyperkalemia. Therefore, if concomitant use of such agents is indicated, they should be given with caution, and the patient's serum potassium should be monitored frequently.

With lithium: Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors during therapy with lithium. These drugs should be co administered with caution, and frequent monitoring of serum lithium levels is recommended. If a diuretic is also used, the risk of lithium toxicity may be increased.

With antacids: In a clinical pharmacology study, coadministration of an antacid (aluminum hydroxide, magnesium hydroxide, and simethicone) with fosinopril reduced serum levels and urinary excretion of fosinoprilat as compared with fosinopril administrated alone, suggesting that antacids may impair absorption of fosinopril. Therefore, if concomitant administration of these agents is indicated, dosing should be separated by 2 hours.

Gold: Nitritoid reactions (symptoms include facial flushing, nausea, vomiting, and hypotension) have been reported rarely in patients on therapy with injectable gold (sodium aurothiomalate) and concomitant ACE inhibitor therapy including fosinopril sodium.

Non-steroidal anti-inflammatory agents including selective cyclooxygenase-2 inhibitors (COX-2 inhibitors): In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, co-administration of NSAIDs, including selective COX-2 inhibitors, with ACE inhibitors, including fosinopril, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving quinapril and NSAID therapy.

The antihypertensive effect of ACE inhibitors, including fosinopril may be attenuated by NSAIDs.

Agents that inhibit mTOR: Patients taking concomitant mTOR inhibitor (e.g. temsirolimus) therapy may be at increased risk for angioedema.

Dual Blockade of the Renin-Angiotensin System (RAS): Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Closely monitor blood pressure, renal function and electrolytes in patients on fosinopril and other agents that affect the RAS.

Do not co-administer aliskiren with fosinopril in patients with diabetes. Avoid use of aliskiren with fosinopril in patients with renal impairment (GFR <60 ml/min).

Other: Neither fosinopril sodium nor its metabolites have been found to interact with food. In separate single or multiple dose pharmacokinetic interaction studies with chlorthalidone, nifedipine, propranolol, hydrochlorothiazide, cimetidine, metoclopramide, propantheline, digoxin, and warfarin, the bioavailability of fosinoprilat was not altered by coadministration of fosinopril with any one of these drugs. In a study with concomitant administration of aspirin and fosinopril sodium, the bioavailability of unbound fosinoprilat was not altered.

In a pharmacokinetic interaction study with warfarin, bioavailability parameters, the degree of protein binding, and the anticoagulant effect (measured by prothrombin time) of warfarin were not significantly changed.