Fosinopril Sodium

A to Z Drug Facts

 Action Competitively inhibits angiotensin I-converting enzyme, preventing conversion of angiotensin I to angiotensin II, a potent vasoconstrictor that also stimulates release of aldosterone. Results in decrease in blood pressure, reduced sodium reabsorption and potassium retention.

 Indications Hypertension; heart failure.

 Contraindications Hypersensitivity to ACE inhibitors.

 Route/Dosage

Hypertension

ADULTS: Initial dose: PO10 mg qd. Maintenance dose: 20 to 80 mg/day; if inadequate response, consider dividing into 2 doses.

Heart Failure

ADULTS: Initial dose: PO 10 mg qd. Increase over several weeks. Usual range is 20 to 40 mg/day. Do not exceed 40 mg/day.

 Interactions

Allopurinol: Increased risk of hypersensitivity reactions. Antacids: May decrease effects of fosinopril. Capsaicin: Cough may be exacerbated. Digoxin: May increase serum levels of digoxin. Indomethacin: Hypotensive effects may be reduced, especially in low-renin or volume-dependent hypertensive patients. Lithium: Increased lithium levels and symptoms of lithium toxicity may occur. Phenothiazines: May increase pharmacological effect of phenothiazines. Potassium preparations, potassium-sparing diuretics: May increase serum potassium levels.

 Lab Test Interferences Measurement of serum digoxin with DigiTab RIA kit may be falsely low. False elevation of liver enzymes, serum bilirubin, uric acid, or blood glucose may occur.

 Adverse Reactions

CV: Orthostatic hypotension. CNS: Headache; dizziness; fatigue. GI: Nausea; vomiting; diarrhea. HEMA: Hemoglobin decrease (transient); neutropenia; leukopenia; eosinophilia. META: Hyperkalemia; hyponatremia. RESP: Cough.

 Precautions

Pregnancy: Category D (second, third trimester); Category C (first trimester). Lactation: Excreted in breast milk. Children: Safety and efficacy not established. Angioedema: May occur. Use extreme caution in patients with hereditary angioedema. Hepatic impairment: May result in elevated plasma levels; monitor carefully; reduce doses. Hypotension/first-dose effect: Significant decreases in BP may occur after first dose, especially in severely salt- or volume-depleted patients or those with heart failure; monitor closely for at least 2 hr after initial dose and during first 2 wk of therapy. Minimize risk by discontinuing diuretics, decreasing dose, or increasing salt intake approximately 1 wk prior to initiating fosinopril. Neutropenia and agranulocytosis: Have occurred; risk appears greater in patients with renal dysfunction, heart failure, or immunosuppression; monitor WBC counts frequently. Proteinuria: May occur, especially in patients with prior renal disease or those receiving high doses; generally within 6 mo. Renal impairment: Reduce dose and give less frequently. In renal insufficiency, stable elevations in BUN and serum creatinine may occur because of inadequate renal perfusion; monitor renal function during first few weeks of therapy and adjust dosage.

 Administration/Storage

• May be administered with or without food.
• If patient is taking diuretic, it should be discontinued 2 to 3 days before initiation of fosinopril. If diuretic cannot be discontinued, reduced dose of fosinopril should be administered.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note renal impairment, angioedema, immunosuppression, nutritional status, history of smoking, and hypersensitivity to ACE inhibitors.
• Ensure that baseline serum electrolyte levels, BUN, serum creatinine levels, liver function tests, urine protein, and CBC have been obtained before beginning therapy, and monitor regularly during therapy.
• Obtain baseline BP and monitor at regular intervals. Compare with peak and trough blood levels at 2 to 6 hr after initial dose and then at 24 hr after. Observe for orthostatic changes.

 Patient/Family Education

• Instruct patient not to interrupt or stop medication or change dosage without consulting physician.
• Caution patient not to double up doses; if a dose is missed, it should be taken as soon as possible, unless close to time of next dose. Consult physician if more than one dose is missed.
• Inform patient not to use salt substitute or potassium supplement without consulting physician.
• Emphasize importance of follow-up visits and frequent assessment of BP while taking drug.
• Advise patient that he or she may feel tired for the first few days after starting medication. If tiredness increases and becomes a problem, notify physician.
• Explain that chronic cough may occur, especially in women. Instruct patient to avoid cough, cold, or allergy medications and to notify physician.
• Advise patient that dizziness or lightheadedness may occur after first doses. Instruct patient to avoid sudden changes in posture and hot baths or showers, and to call physician if symptoms become severe or if fainting occurs.
• Instruct patient to report the following symptoms to physician: Dizziness or fainting on arising, constant cough or any unusual symptoms or feelings; swelling of eyes, face, lips, tongue or throat; difficulty breathing, speaking (eg, hoarseness), or swallowing; signs of infection (eg, fever, sore throat).
• Advise patient to use caution while driving or performing other tasks requiring mental alertness.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts