Amlodipine 5 mg, Perindopril 4 mg Tablets

Perindopril — Perindopril, a pro-drug, is hydrolyzed to perindoprilat, which inhibits ACE in humans and in animals. 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, which stimulates aldosterone secretion by the adrenal cortex, and provides negative feedback on renin secretion. Inhibition of ACE results in decreased plasma angiotensin II, leading to decreased vasoconstriction, increased plasma renin activity and decreased aldosterone secretion. The latter results in diuresis and natriuresis and may be associated with an increase in serum potassium [see Warnings and Precautions (5.6)].

ACE is identical to kininase II, an enzyme that degrades bradykinin. Whether increased levels of bradykinin, a potent vasodepressor peptide, play a role in the therapeutic effects of perindopril remains to be elucidated.

While the principal mechanism of perindopril in blood pressure reduction is believed to be through the renin-angiotensin-aldosterone system, ACE inhibitors have some effect even in apparent low-renin hypertension. Perindopril has been studied in relatively few black patients, usually a low-renin population, and the average response of diastolic blood pressure to perindopril was about half the response seen in nonblack patients, a finding consistent with previous experience of other ACE inhibitors.

Prestalia — Following administration of PRESTALIA, peak plasma concentration of perindopril, perindoprilat and amlodipine occur at approximately 1 hour, 4 hours and 6-12 hours, respectively. The mean half-life of perindopril is approximately 1.3 hours. The decline in the plasma concentration of perindoprilat is multiphasic and shows a terminal elimination half-life of approximately 100 hours, resulting from slow dissociation of perindoprilat from plasma/tissue ACE binding sites. Amlodipine elimination from plasma is biphasic with a terminal elimination half-life of approximately 30 to 50 hours.

When PRESTALIA is administered with food, the exposure to perindopril, perindoprilat and amlodipine is not impacted.

Perindopril — Following administration of PRESTALIA, perindopril is rapidly absorbed, with peak plasma concentrations occurring at approximately 1 hour. The absolute oral bioavailability of perindopril is approximately 75%. Following absorption, approximately 30% to 50% of systemically available perindopril is hydrolyzed to its active metabolite, perindoprilat, which has a mean bioavailability of approximately 25%. Peak plasma concentrations of perindoprilat are attained approximately 4 hours after PRESTALIA administration. Food had no effect on the extent of absorption of perindopril or perindoprilat, but slightly reduced the rate of absorption of perindopril and perindoprilat by 18% and 14%, respectively.

The Cmax and AUC of perindopril and perindoprilat increase in a linear and dose proportional manner following both single oral dosing and at steady state during an once-a-day multiple dosing regimen. Perindopril exhibits multiexponential pharmacokinetics following oral administration. The mean half-life of perindopril associated with most of its elimination is approximately 0.8 to 1 hours.

Perindopril is extensively metabolized following oral administration, with only 4% to 12% of the dose recovered unchanged in the urine. Six metabolites resulting from hydrolysis, glucuronidation, and cyclization via dehydration have been identified. These include the active ACE inhibitor perindoprilat (hydrolyzed perindopril), perindopril, and perindoprilat glucuronides, dehydrated perindopril, and the diastereoisomers of dehydrated perindoprilat. In humans, hepatic esterase appears to be responsible for the hydrolysis of perindopril.

The active metabolite, perindoprilat, also exhibits multiexponential pharmacokinetics following the oral administration of perindopril. Formation of perindoprilat is gradual with peak plasma concentrations occurring between 3 and 7 hours. The subsequent decline in plasma concentration shows a prolonged terminal elimination half-life of 120 hours resulting from slow dissociation of perindoprilat from plasma/tissue ACE binding sites. During repeated oral once-daily dosing with perindopril, perindoprilat accumulates about 1.5- to 2-fold and attains steady state plasma levels in 3 to 6 days. The clearance of perindoprilat and its metabolites is almost exclusively renal.

Approximately 60% of circulating perindopril is bound to plasma proteins, and only 10% to 20% of perindoprilat is bound. Therefore, drug interactions mediated through effects on protein binding are not anticipated.

Amlodipine — Absolute bioavailability of amlodipine has been estimated between 64% and 90%. Ex vivo studies indicate that approximately 93% of circulating amlodipine is bound to plasma proteins in hypertensive patients.

Amlodipine is extensively (approximately 90%) metabolized in the liver to inactive metabolites. Steady-state plasma levels are reached after once-daily dosing for 7 to 8 days. 10% of unchanged drug and 60% of amlodipine metabolites are excreted in urine.