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Active ingredient: Moexipril - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Angiotensin-Converting Enzyme Inhibitors

Dosage Forms

  • Tablets (scored, coated, containing 7.5 mg or 15 mg of moexipril hydrochloride for oral administration)

Brands / Synonyms

Moexipril HCL; Moexiprilum [INN-Latin]; Uniretic; Univasc; Univasc

Indications

For treatment of patients with hypertension.

Pharmacology

Moexipril is a non-sulfhydryl containing precursor of the active angiotensin-converting enzyme (ACE) inhibitor moexiprilat. It is used to treat high blood pressure (hypertension). It works by relaxing blood vessels, causing them to widen. Lowering high blood pressure helps prevent strokes, heart attacks and kidney problems.

Mechanism of Action

Moexipril is a prodrug for moexiprilat, which inhibits ACE in humans and animals. The mechanism through which moexiprilat lowers blood pressure is believed to be primarily inhibition of ACE activity. ACE is a peptidyl dipeptidase that catalyzes the conversion of the inactive decapeptide angiotensin I to the vasoconstrictor substance angiotensin II. Angiotensin II is a potent peripheral vasoconstrictor that also stimulates aldosterone secretion by the adrenal cortex and provides negative feedback on renin secretion. ACE is identical to kininase II, an enzyme that degrades bradykinin, an endothelium-dependent vasodilator. Moexiprilat is about 1000 times as potent as moexipril in inhibiting ACE and kininase II. Inhibition of ACE results in decreased angiotensin II formation, leading to decreased vasoconstriction, increased plasma renin activity, and decreased aldosterone secretion. The latter results in diuresis and natriuresis and a small increase in serum potassium concentration (mean increases of about 0.25 mEq/L were seen when moexipril was used alone). Whether increased levels of bradykinin, a potent vasodepressor peptide, play a role in the therapeutic effects of moexipril remains to be elucidated. Although the principal mechanism of moexipril in blood pressure reduction is believed to be through the renin-angiotensin-aldosterone system, ACE inhibitors have some effect on blood pressure even in apparent low-renin hypertension.

Absorption

Moexipril is incompletely absorbed, with bioavailability as moexiprilat of about 13% compared to intravenous (I.V.) moexipril (both measuring the metabolite moexiprilat), and is markedly affected by food, which reduces Cmax and AUC by about 70% and 40% respectively after the ingestion of a low-fat breakfast or by 80% and 50% respectively after the ingestion of a high-fat breakfast.

Toxicity

Human overdoses of moexipril have not been reported. In case reports of overdoses with other ACE inhibitors, hypotension has been the principal adverse effect noted. Single oral doses of 2 g/kg moexipril were associated with significant lethality in mice. Rats, however, tolerated single oral doses of up to 3 g/kg.

Biotrnasformation / Drug Metabolism

Rapidly converted to moexiprilat, the active metabolite. Conversion to the active metabolite is thought to require carboxyesterases and is likely to occur in organs or tissues, other than the gastrointestinal tract, in which carboxyesterases occur. The liver is thought to be one site of conversion, but not the primary site.

Contraindications

UNIVASC® is contraindicated in patients who are hypersensitive to this product and in patients with a history of angioedema related to previous treatment with an ACE inhibitor.

Drug Interactions

Diuretics: Excessive reductions in blood pressure may occur in patients on diuretic therapy when ACE inhibitors are started. The possibility of hypotensive effects with UNIVASC® can be minimized by discontinuing diuretic therapy for several days or cautiously increasing salt intake before initiation of treatment with UNIVASC®. If this is not possible, the starting dose of moexpril should be reduced..

Potassium Supplements and Potassium-Sparing Diuretics: UNIVASC® can increase serum potassium because it decreases aldosterone secretion. Use of potassium-sparing diuretics (spironolactone, triamterene, amiloride) or potassium supplements concomitantly with ACE inhibitors 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.

Oral Anticoagulants: Interaction studies with warfarin failed to identify any clinically important effect on the serum concentrations of the anticoagulant or on its anticoagulant effect.

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 coadministered 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.

Other Agents: No clinically important pharmacokinetic interactions occurred when UNIVASC® was administered concomitantly with hydrochlorothiazide, digoxin, or cimetidine. UNIVASC® has been used in clinical trials concomitantly with calcium-channel-blocking agents, diuretics, H2 blockers, digoxin, oral hypoglycemic agents, and cholesterol-lowering agents. There was no evidence of clinically important adverse interactions.

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