Benazepril Hydrochloride (Page 3 of 5)

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

Benazepril can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents. When pregnancy is detected, discontinue benazepril as soon as possible.

The estimated background risk of major birth defects and miscarriage for the indicated population are unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the general U.S. population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Clinical Considerations

Disease-associated maternal and/or embryo/fetal risk

Hypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, and post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death. Pregnant women with hypertension should be carefully monitored and managed accordingly.

Fetal/Neonatal Adverse Reactions

Oligohydramnios in pregnant women who use drugs affecting the renin-angiotensin system in the second and third trimesters of pregnancy can result in the following: reduced fetal renal function leading to anuria and renal failure, fetal lung hypoplasia and skeletal deformations, including skull hypoplasia, hypotension, and death. In the unusual case that there is no appropriate alternative to therapy with drugs affecting the renin-angiotensin system for a particular patient, apprise the mother of the potential risk to the fetus.

Perform serial ultrasound examinations to assess the intra-amniotic environment. Fetal testing may be appropriate, based on the week of pregnancy. Patients and physicians should be aware, however, that oligohydramnios may not appear until after the fetus has sustained irreversible injury. Closely observe infants with histories of in utero exposure to benazepril for hypotension, oliguria, and hyperkalemia. If oliguria or hypotension occur in neonates with a history of in utero exposure to benazepril, support blood pressure and renal perfusion. Exchange transfusions or dialysis may be required as a means of reversing hypotension and substituting for disordered renal function.

8.2 Lactation

Minimal amounts of unchanged benazepril and of benazeprilat are excreted into the breast milk of lactating women treated with benazepril. A newborn child ingesting entirely breast milk would receive less than 0.1% of the mg/kg maternal dose of benazepril and benazeprilat.

8.3 Pediatric Use

The antihypertensive effects of benazepril have been evaluated in a double-blind study in pediatric patients 7 to 16 years of age [see Clinical Pharmacology (12.3)] . The pharmacokinetics of benazepril have been evaluated in pediatric patients 6 to 16 years of age [see Clinical Pharmacology (12.3)] . Infants below the age of 1 year should not be given benazepril because of the risk of effects on kidney development.

Safety and effectiveness of benazepril have not been established in pediatric patients less than 6 years of age or in children with glomerular filtration rate < 30 mL/min/1.73m² [see Dosage and Administration (2.1) and Clinical Pharmacology 12.3)].

8.4 Geriatric Use

Of the total number of patients who received benazepril in U.S. clinical studies of benazepril, 18% were 65 or older while 2% were 75 or older. No overall differences in effectiveness or safety were observed between these patients and younger patients, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Benazepril and benazeprilat are substantially excreted by the kidney. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function [see Dosage and Administration (2.2)] .

8.5 Race

ACE inhibitors, including benazepril, as monotherapy, have an effect on blood pressure that is less in Black patients than in non-Blacks.

8.6 Renal Impairment

Dose adjustment of benazepril is required in patients undergoing hemodialysis or whose creatinine clearance is ≤ 30 mL/min. No dose adjustment of benazepril is required in patients with creatinine clearance > 30 mL/min [see Dosage and Administration (2.2) and Clinical Pharmacology (12.3)] .

10 OVERDOSAGE

Single oral doses of 3 g/kg benazepril were associated with significant lethality in mice. Rats, however, tolerated single oral doses of up to 6 g/kg. Reduced activity was seen at 1 g/kg in mice and at 5 g/kg in rats. Human overdoses of benazepril have not been reported, but the most common manifestation of human benazepril overdosage is likely to be hypotension, for which the usual treatment would be intravenous infusion of normal saline solution. Hypotension can be associated with electrolyte disturbances and renal failure.

Benazepril is only slightly dialyzable, but consider dialysis to support patients with severely impaired renal function [see Warnings and Precautions (5.3)].

If ingestion is recent, consider activated charcoal. Consider gastric decontamination (e.g., vomiting, gastric lavage) in the early period after ingestion.

Monitor for blood pressure and clinical symptoms. Supportive management should be employed to ensure adequate hydration and to maintain systemic blood pressure.

In the case of marked hypotension, infuse physiological saline solution; as needed, consider vasopressors (e.g., catecholamines i.v.).

11 DESCRIPTION

Benazepril hydrochloride, USP is a white to off-white crystalline powder, soluble (> 100 mg/mL) in water, in ethanol, and in methanol. Its chemical name is benazepril 3-[[1-(ethoxy-carbonyl)-3-phenyl-(1S)-propyl] amino]-2,3,4,5-tetrahydro-2-oxo-1 H -1-(3S)-benzazepine-1-acetic acid monohydrochloride; its structural formula is

Chemical Structure
(click image for full-size original)

Its molecular formula is C 24 H 28 N 2 O 5 •HCl and its molecular weight is 460.96.
Benazeprilat, the active metabolite of benazepril, is a non-sulfhydryl angiotensin-converting enzyme inhibitor.
Benazepril hydrochloride is supplied as tablets containing 10 mg, 20 mg and 40 mg of benazepril hydrochloride USP for oral administration. The inactive ingredients are colloidal silicon dioxide, crospovidone, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol 400, polysorbate 80, pregelatinized starch (maize) and titanium dioxide. In addition, the 10 mg contains iron oxide yellow and 20 mg and 40 mg contains iron oxide red.
Meets USP Dissolution Test 2.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Benazepril and benazeprilat inhibit angiotensin-converting enzyme (ACE) in human subjects and animals. Benazeprilat has much greater ACE inhibitory activity than does benazepril. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor substance, angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex.

Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and to decreased aldosterone secretion. The latter decrease may result in a small increase of serum potassium.

Removal of angiotensin II negative feedback on renin secretion leads to increased plasma renin activity. In animal studies, benazepril had no inhibitory effect on the vasopressor response to angiotensin II and did not interfere with the hemodynamic effects of the autonomic neurotransmitters acetylcholine, epinephrine, and norepinephrine.

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 benazepril remains to be elucidated. While the mechanism through which benazepril lowers blood pressure is believed to be primarily suppression of the renin-angiotensin-aldosterone system, benazepril has an antihypertensive effect even in patients with low-renin hypertension.

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