Indications
Enalapril is indicated in-

    All grades of essential hypertension and renovascular hypertension either alone or in combination with other antihypertensive agents especially thiazide diuretics.
    Prevention of symptomatic heart failure.
    Treatment of congestive heart failure (adjunct), usually in combination with diuretics and digitalis.
    Prevention of coronary ischaemic events in patients with left ventricular dysfunction.

Enalapril is also used either alone or as an adjunct in the treatment of angina, diabetic nephropathy and Raynaud’s disease.
Therapeutic Class
Angiotensin-converting enzyme (ACE) inhibitors
Pharmacology
Enalapril, after hydrolysis to enalaprilate, inhibits Angiotensin Converting Enzyme (ACE). ACE is a peptidyl dipeptidase that catalyses the conversion of angiotensin I to the vasoconstrictor substance angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex. The beneficial effects of enalapril in hypertension and heart failure appear to result primarily from suppression of the renin-angiotensin aldosterone system
Dosage & Administration
Hypertension: Initially 5 mg once daily if used alone or 2.5 mg daily if used in addition to diuretic, in elderly patients or in patients with renal impairment. Usual maintenance dose is 10-20 mg once daily. However, in severe hypertension it may be increased to a maximum of 40 mg once daily.

Heart failure (adjunct) and asymptomatic left ventricular dysfunction: Initially 2.5 mg under close medical supervision. Usual maintenance dose is 20 mg daily in 1-2 divided doses
Interaction
Combination with other antihypertensive agents such as b blockers, Methyldopa, calcium antagonists and diuretics may increase the antihypertensive efficacy. Adrenergic blocking drugs should only be combined with Enalapril under careful supervision. Concomitant Propranolol may reduce the bioavailability of Enalapril, but this does not appear to be of any clinical significance. Concomitant therapy with Lithium may increase the serum Lithium concentration.
Contraindications
Aortic stenosis or outflow tract obstruction. Renovascular disease. Severe resistant HTN. Peripheral vascular disease or generalized atherosclerosis.
Side Effects
Dizziness and headache are more commonly reported side effects. Fatigue and asthenia were reported in 2-3% of patients. Other side effects occurred in less than 2% of patients and included hypotension, orthostatic hypotension, syncope, nausea, diarrhoea, muscle cramps, rash and cough.

Less frequently renal dysfunction, renal failure and oliguria have been reported. Angioedema, hyperkalemia and hyponatremia have also been reported rarely
Pregnancy & Lactation
Category D: Contraindicated in pregnancy. The drug is excreted in trace amount in human milk and caution should be exercised if given to nursing mothers.
Precautions & Warnings
Assess renal function; regular WBC counts in patient w/ collagen vascular disease eg SLE & scleroderma. Patient receiving immunosuppressive therapy; those prone to salt or water depletion. Pregnancy.
Use in Special Populations
Use in the elderly (over 65 years): The starting dose should be 2.5 mg. Enaril is effective in the treatment of hypertension in the elderly. The dose should be titrated according to need for the control of blood pressure.
Overdose Effects
symptoms-

    Lightheadedness, dizziness, or fainting
    Decrease in urine output
    Drowsiness, headache, or back pain
    Slow or irregular heartbeat.

Management-

    Fluids through an intravenous line (IV)
    Medications to increase blood pressure
    Other treatments based on complications that occur
    Closely monitoring the heart and lungs.