Monopril (Fosinopril Sodium)

Fosinopril is an ACE inhibitor used to treat conditions related to the renin‑angiotensin system.

• Hypertension: reduces systolic and diastolic blood pressure, helping patients reach target levels.
• Heart failure: improves cardiac output and reduces symptoms such as dyspnea and edema.
• Diabetic nephropathy: slows progression of kidney damage by lowering intraglomerular pressure.

• Fosinopril is converted in vivo to its active form, which binds to and inhibits angiotensin‑converting enzyme (ACE). This blocks the conversion of angiotensin I to the potent vasoconstrictor angiotensin II, leading to vasodilation, reduced aldosterone secretion, decreased sodium and water retention, and ultimately lower blood pressure and reduced cardiac workload.

Adverse reactions may occur with any ACE inhibitor and should be monitored.

Common Side Effects

• Cough: persistent dry cough in some patients.
• Dizziness: especially after the first dose or dose increase.
• Headache: mild to moderate intensity.
• Fatigue: general feeling of tiredness.
• Nausea: occasional upset stomach.
• Taste disturbance: altered sense of taste.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips, tongue or throat, potentially airway‑obstructing.
• Severe hypotension: marked drop in blood pressure causing faintness.
• Neutropenia: significant reduction in white blood cells.
• Hepatic dysfunction: abnormal liver enzyme elevations.
• Renal impairment: worsening kidney function, especially in volume‑depleted patients.

Before initiating therapy, clinicians should consider several safety aspects.

• Blood pressure monitoring: ensure adequate control and avoid excessive hypotension.
• Renal function assessment: check serum creatinine and eGFR periodically.
• Serum potassium: monitor for hyperkalaemia, particularly when combined with potassium‑sparing agents.
• History of angioedema: avoid use in patients with prior ACE‑inhibitor‑related angioedema.
• Pregnancy and lactation: use only if clearly needed after risk‑benefit evaluation.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Fosinopril may interact with other medicines, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Aliskiren: combined renin‑angiotensin blockade can increase risk of renal dysfunction, hyperkalaemia and hypotension.
• Potassium‑sparing diuretics (e.g., spironolactone): may cause dangerous elevations in serum potassium.
• Lithium: ACE inhibition can raise lithium levels, leading to toxicity.

Moderate Interactions (Monitor Closely)

• Thiazide diuretics: may enhance antihypertensive effect and increase risk of electrolyte disturbances.
• NSAIDs: can attenuate the antihypertensive effect and worsen renal function.
• Cyclosporine: may increase serum fosinopril concentrations and affect kidney function.