Enalapril

VASOTEC ® TABLETS (ENALAPRIL) NDA 018998 Proposed Labeling Page 1 of 20 TABLETS ® VASOTEC (ENALAPRIL) Rx Only

WARNING: FETAL TOXICITY See full prescribing information for complete boxed warning. x When pregnancy is detected, discontinue Vasotec® as soon as possible. x Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. See Warnings: FetalToxicity

DESCRIPTION VASOTEC® (Enalapril Maleate) is the maleate salt of enalapril, the ethyl ester of a long-acting angiotensin converting enzyme inhibitor, enalaprilat. Enalapril maleate is chemically described as (S)-1-[N-[1-(ethoxycarbonyl)-3-phenylpropyl]-L-alanyl]-L-proline, (Z)-2-butenedioate salt (1:1). Its empirical formula is C20H28N2O5•C4H4O4, and its structural formula is:Enalapril maleate is a white to off-white, crystalline powder with a molecular weight of 492.53. It is sparingly soluble in water, soluble in ethanol, and freely soluble in methanol. Enalapril is a pro-drug; following oral administration, it is bioactivated by hydrolysis of the ethyl ester to enalaprilat, which is the active angiotensin converting enzyme inhibitor. Enalapril maleate is supplied as 2.5mg, 5 mg, 10 mg, and 20 mg tablets for oral administration. In addition to the active ingredient enalapril maleate, each tablet contains the following inactive ingredients: lactose, magnesium stearate, sodium bicarbonate, and starch. The 10 mg and 20 mg tablets also contain iron oxides. CLINICAL PHARMACOLOGY Mechanism of Action Enalapril, after hydrolysis to enalaprilat, inhibitsangiotensin-converting enzyme (ACE) in
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SPL Labeling Supplement PAS\Proposed Labeling

Reference ID: 3089266

VASOTEC ® TABLETS (ENALAPRIL) NDA 018998 Proposed Labeling Page 2 of 20 human subjects and animals. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to thevasoconstrictor 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. Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and todecreased aldosterone secretion. Although the latter decrease is small, it results in small increases of serum potassium. In hypertensive patients treated with VASOTEC alone for up to 48 weeks, mean increases in serum potassium of approximately 0.2 mEq/L were observed. In patients treated with VASOTEC plus a thiazide diuretic, there was essentially no change in serum potassium (see PRECAUTIONS). Removalof angiotensin II negative feedback on renin secretion leads to increased plasma renin activity. ACE is identical to kininase, an enzyme that degrades bradykinin. Whether increased levels of bradykinin, a potent vasodepressor peptide, play a role in the therapeutic effects of VASOTEC remains to be elucidated. While the mechanism through which VASOTEC lowers blood pressure is believed to beprimarily suppression of the renin-angiotensin-aldosterone system, VASOTEC is antihypertensive even in patients with low-renin hypertension. Although VASOTEC was antihypertensive in all races studied, black hypertensive patients (usually a low-renin hypertensive population) had a smaller average response to enalapril monotherapy than nonblack patients. Pharmacokinetics and Metabolism Following oraladministration of VASOTEC, peak serum concentrations of enalapril occur within about one hour. Based on urinary recovery, the extent of absorption of enalapril is approximately 60 percent. Enalapril absorption is not influenced by the presence of food in the gastrointestinal tract. Following absorption, enalapril is hydrolyzed to enalaprilat, which is a more potent angiotensin converting enzyme...