Amlodipine 2.5 mg, Benazepril 10 mg Hard-gelatin capsules

Benazepril — Benazepril and benazeprilat inhibit ACE in human subjects and in animals. 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. Hypertensive patients treated with benazepril and amlodipine for up to 56 weeks had elevations of serum potassium up to 0.2 mEq/L [see Warnings and Precautions (5.6)].

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 amlodipine and benazepril hydrochloride capsules 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.

The rate and extent of absorption of benazepril and amlodipine from amlodipine and benazepril hydrochloride capsules are the same as when administered as individual tablets. Absorption from the individual tablets is not influenced by the presence of food in the gastrointestinal tract; food effects on absorption from amlodipine and benazepril hydrochloride capsules have not been studied.

Absorption: Following oral administration of amlodipine and benazepril hydrochloride capsules, peak plasma concentrations of amlodipine are reached in 6 to 12 hours. Absolute bioavailability has been calculated as between 64% and 90%. Following oral administration of amlodipine and benazepril hydrochloride capsules, the peak plasma concentrations of benazepril are reached in 0.5 to 2 hours. The cleavage of the ester group (primarily in the liver) converts benazepril to its active metabolite, benazeprilat, which reaches peak plasma concentrations in 1.5 to 4 hours. The extent of absorption of benazepril is at least 37%. Amlodipine and benazepril exhibit dose proportional pharmacokinetics between the therapeutic dose range of 2.5 and 10 mg and 10 and 20 mg, respectively.

Distribution: The apparent volume of distribution of amlodipine is about 21 L/kg. In vitro studies indicate that

approximately 93% of circulating amlodipine is bound to plasma proteins in hypertensive patients. The apparent volume of distribution of benazeprilat is about 0.7 L/kg. Approximately 93% of circulating amlodipine is bound to plasma proteins, and the bound fraction of benazeprilat is slightly higher. On the basis of in vitro studies, benazeprilat’s degree of protein binding should be unaffected by age, by hepatic dysfunction, or—over the therapeutic concentration range—by concentration.

Metabolism: Amlodipine is extensively (approximately 90%) metabolized in the liver to inactive metabolites. Benazepril is extensively metabolized to form benazeprilat as the main metabolite, which occurs by enzymatic hydrolysis, mainly in the liver. Two minor metabolites are the acyl glucuronide conjugates of benazepril and benazeprilat.

Elimination: Amlodipine elimination from plasma is biphasic with a terminal elimination half-life of approximately 30 to 50 hours. Steady-state plasma levels are reached after once-daily dosing for 7 to 8 days. Ten percent of unchanged drug and 60% of amlodipine metabolites are excreted in urine. Effective elimination half-life of amlodipine is 2 days. Benazepril is eliminated mainly by metabolic clearance. Benazeprilat is eliminated via the kidneys and the bile; renal excretion is the main route in patients with normal renal function. In the urine, benazepril accounts for less than 1 % and benazeprilat for about 20% of an oral dose. Elimination of benazeprilat is biphasic with an initial half-life of about 3 hours and a terminal half-life of about 22 hours. Benazeprilat’s effective elimination half-life is 10 to 11 hours, while that of amlodipine is about 2 days, so steady-state levels of the 2 components are achieved after about a week of once-daily dosing.

Specific Populations — Geriatric Patients: No specific clinical studies were performed to understand the impact of age on the pharmacokinetics of amlodipine and benazepril as fixed dose combination. As individual component amlodipine is extensively metabolized in the liver. In the elderly, clearance of amlodipine is decreased with resulting increases in peak plasma levels, elimination half-life and area-under-the-plasma-concentration curve [see Use in Specific Populations (8.5)].

Hepatic Impairment: Patients with hepatic insufficiency have decreased clearance of amlodipine with a resulting increase in AUC of approximately 40% to 60%. Pharmacokinetics of benazepril is not significantly influenced by hepatic impairment [see Use in Specific Populations (8.6)].

Renal Impairment: The disposition of benazepril and benazeprilat in patients with mild-to-moderate renal insufficiency (CrCl greater than 30 mL/min) is similar to that in patients with normal renal function. In patients with CrCl less than or equal to 30 mL/min, peak benazeprilat levels and the effective half-life increase, resulting in higher systemic exposures. Pharmacokinetics of amlodipine is not significantly influenced by renal impairment [see Dosage and Administration (2.2), Use in Specific Populations (8.7) and Warnings and Precautions (5.7)].