Olmesartan Medoxomil and Hydrochlorothiazide 40 mg; 12.5 mg Tablet, Film Coated, 30-count — NDC 72603-291-01 (Billing 72603-0291-01)

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action Olmesartan medoxomil Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation and renal reabsorption of sodium. Olmesartan blocks the vasoconstrictor effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT 1 receptor in vascular smooth muscle.

Its action is, therefore, independent of the pathways for angiotensin II synthesis. An AT 2 receptor is found also in many tissues, but this receptor is not known to be associated with cardiovascular homeostasis. Olmesartan has more than a 12,500-fold greater affinity for the AT 1 receptor than for the AT 2 receptor.

Blockade of the angiotensin II receptor inhibits the negative regulatory feedback of angiotensin II on renin secretion, but the resulting increased plasma renin activity and circulating angiotensin II levels do not overcome the effect of olmesartan on blood pressure. Hydrochlorothiazide Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts.

Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so co-administration of an angiotensin II receptor antagonist tends to reverse the potassium loss associated with these diuretics. The mechanism of the antihypertensive effect of thiazides is not fully understood.

12.2Pharmacodynamics Olmesartan medoxomil Olmesartan medoxomil doses of 2.5 to 40 mg inhibit the pressor effects of angiotensin I infusion. The duration of the inhibitory effect was related to dose, with doses of olmesartan medoxomil >40 mg giving >90% inhibition at 24 hours. Plasma concentrations of angiotensin I and angiotensin II and plasma renin activity (PRA) increase after single and repeated administration of olmesartan medoxomil to healthy subjects and hypertensive patients.

Repeated administration of up to 80 mg olmesartan medoxomil had minimal influence on aldosterone levels and no effect on serum potassium. Hydrochlorothiazide After oral administration of hydrochlorothiazide, diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours. Drug Interactions Hydrochlorothiazide Alcohol, barbiturates, or narcotics: Potentiation of orthostatic hypotension may occur.

Skeletal muscle relaxants, non-depolarizing (e.g., tubocurarine): Increased responsiveness to the muscle relaxant may occur. Digitalis glycosides : Thiazide-induced hypokalemia or hypomagnesemia may predispose to digoxin toxicity.

12.3Pharmacokinetics Absorption Olmesartan : Olmesartan medoxomil is completely bioactivated by ester hydrolysis to olmesartan during absorption from the gastrointestinal tract. The absolute bioavailability of olmesartan is approximately 26%. After oral administration, the peak plasma concentration (C max ) of olmesartan is reached after 1 to 2 hours.

Food does not affect the bioavailability of olmesartan. Olmesartan shows linear pharmacokinetics following single oral doses of up to 320 mg and multiple oral doses of up to 80 mg. Steady-state levels of olmesartan are achieved within 3 to 5 days and no accumulation in plasma occurs with once-daily dosing.

Hydrochlorothiazide : The estimated absolute bioavailability of hydrochlorothiazide after oral administration is about 70%. Peak plasma hydrochlorothiazide concentrations (C max ) are reached within 2 to 5 hours after oral administration. There is no clinically significant effect of… [Excerpted — this section continues on DailyMed.]

12.1Mechanism of Action Olmesartan medoxomil Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation and renal reabsorption of sodium. Olmesartan blocks the vasoconstrictor effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT 1 receptor in vascular smooth muscle.

Its action is, therefore, independent of the pathways for angiotensin II synthesis. An AT 2 receptor is found also in many tissues, but this receptor is not known to be associated with cardiovascular homeostasis. Olmesartan has more than a 12,500-fold greater affinity for the AT 1 receptor than for the AT 2 receptor.

Blockade of the angiotensin II receptor inhibits the negative regulatory feedback of angiotensin II on renin secretion, but the resulting increased plasma renin activity and circulating angiotensin II levels do not overcome the effect of olmesartan on blood pressure. Hydrochlorothiazide Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts.

Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so co-administration of an angiotensin II receptor antagonist tends to reverse the potassium loss associated with these diuretics. The mechanism of the antihypertensive effect of thiazides is not fully understood.

12.3Pharmacokinetics Absorption Olmesartan : Olmesartan medoxomil is completely bioactivated by ester hydrolysis to olmesartan during absorption from the gastrointestinal tract. The absolute bioavailability of olmesartan is approximately 26%. After oral administration, the peak plasma concentration (C max ) of olmesartan is reached after 1 to 2 hours.

Food does not affect the bioavailability of olmesartan. Olmesartan shows linear pharmacokinetics following single oral doses of up to 320 mg and multiple oral doses of up to 80 mg. Steady-state levels of olmesartan are achieved within 3 to 5 days and no accumulation in plasma occurs with once-daily dosing.

Hydrochlorothiazide : The estimated absolute bioavailability of hydrochlorothiazide after oral administration is about 70%. Peak plasma hydrochlorothiazide concentrations (C max ) are reached within 2 to 5 hours after oral administration. There is no clinically significant effect of food on the bioavailability of hydrochlorothiazide.

The pharmacokinetics of hydrochlorothiazide is dose proportional in the range of 12.5 to 75 mg. Distribution Olmesartan : The volume of distribution of olmesartan is approximately 17 L. Olmesartan is highly bound to plasma proteins (99%) and does not penetrate red blood cells.

The protein binding is constant at plasma olmesartan concentrations well above the range achieved with recommended doses. In rats, olmesartan crossed the blood-brain barrier poorly, if at all. Olmesartan passed across the placental barrier in rats and was distributed to the fetus.

Olmesartan was distributed to milk at low levels in rats. Hydrochlorothiazide : Hydrochlorothiazide binds to albumin (40 to 70%) and distributes into erythrocytes. Following oral administration, plasma hydrochlorothiazide concentrations decline bi-exponentially, with a mean distribution half-life of about 2 hours and an elimination half-life of about 10 hours.

Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk. Metabolism Olmesartan : Olmesartan does not undergo further metabolism. Hydrochlorothiazide : Hydrochlorothiazide is not metabolized.

Elimination Olmesartan: Olmesartan appears to be eliminated in a biphasic manner with a terminal elimination half-life of approximately 13 hours. Total plasma clearance of olmesartan is

1.3 L/h, with a renal clearance of

0.6L/h. Approximately 35% to 50% of the absorbed dose is recovered in urine while the remainder is eliminated in feces via the bile. Hydrochlorothiazide : About 70% of an orally administered dose of hydrochlorothiazide is eliminated in the urine as unchanged drug.

Specific populations Olmesartan medoxomil Pediatric: The pharmacokinetics of olmesartan were studied in pediatric hypertensive patients aged 1 to16 years. The clearance of olmesartan in pediatric patients was similar to that in adult patients when adjusted by the body weight. Olmesartan pharmacokinetics have not been investigated in pediatric patients less than 1 year of age.

Geriatric : The pharmacokinetics of olmesartan were studied in the elderly (≥65 years). Overall, maximum plasma concentrations of olmesartan were similar in young adults and the elderly. Modest accumulation of olmesartan was observed in the elderly with repeated dosing; AUC ss , τ was 33% higher in elderly patients, corresponding to an approximate 30% reduction in CL R .

Gender: Minor differences were observed in the pharmacokinetics of olmesartan in women compared to men. AUC and C max were 10-15% higher in women than in men. Renal insufficiency : In patients with renal insufficiency, serum concentrations of olmesartan were elevated compared to subjects with normal renal function.

After repeated dosing, the AUC was approximately tripled in patients with severe renal impairment (creatinine clearance <20 mL/min). The pharmacokinetics of olmesartan in patients undergoing hemodialysis has not been studied. Hepatic insufficiency : Increases in AUC 0-∞ and C max… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics Olmesartan medoxomil Olmesartan medoxomil doses of 2.5 to 40 mg inhibit the pressor effects of angiotensin I infusion. The duration of the inhibitory effect was related to dose, with doses of olmesartan medoxomil >40 mg giving >90% inhibition at 24 hours. Plasma concentrations of angiotensin I and angiotensin II and plasma renin activity (PRA) increase after single and repeated administration of olmesartan medoxomil to healthy subjects and hypertensive patients.

Repeated administration of up to 80 mg olmesartan medoxomil had minimal influence on aldosterone levels and no effect on serum potassium. Hydrochlorothiazide After oral administration of hydrochlorothiazide, diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours. Drug Interactions Hydrochlorothiazide Alcohol, barbiturates, or narcotics: Potentiation of orthostatic hypotension may occur.

Skeletal muscle relaxants, non-depolarizing (e.g., tubocurarine): Increased responsiveness to the muscle relaxant may occur. Digitalis glycosides : Thiazide-induced hypokalemia or hypomagnesemia may predispose to digoxin toxicity.

14 CLINICAL STUDIES Olmesartan medoxomil and hydrochlorothiazide In clinical trials 1230 patients were exposed to the combination of olmesartan medoxomil (2.5 mg to 40 mg) and hydrochlorothiazide (12.5 mg to 25 mg). These trials included one placebo-controlled factorial trial in mild-moderate hypertensive patients (n=502) with combinations of olmesartan medoxomil (10 mg, 20 mg, 40 mg, or placebo) and hydrochlorothiazide (12.5 mg, 25 mg, or placebo). The antihypertensive effect of the combination on trough blood pressure was related to the dose of each component (see Table 2).

Once-daily dosing with 20 mg olmesartan medoxomil and 12.5 mg hydrochlorothiazide, 40 mg olmesartan medoxomil and 12.5 mg hydrochlorothiazide or 40 mg olmesartan medoxomil and 25 mg hydrochlorothiazide produced mean placebo-adjusted blood pressure reductions at trough (24 hours post-dosing) ranging from 17/8 to 24/14 mm Hg. Table 2: Placebo-Adjusted Reductions in Sitting Systolic/Diastolic Blood Pressure (mmHg) HCTZ Olmesartan Medoxomil 0 mg 10 mg 20 mg 40 mg 0 mg -- 7/5 12/5 13/7 12.5 mg 5/1 17/8 17/8 16/10 25 mg 14/5 19/11 22/11 24/14 The antihypertensive effect had onset within 1 week and was near maximal at 4 weeks.

The antihypertensive effect was independent of gender, but there were too few subjects to identify response differences based on race or age greater than or less than 65 years. No appreciable changes in trough heart rate were observed with combination therapy. There are no trials of olmesartan medoxomil and hydrochlorothiazide tablets demonstrating reductions in cardiovascular risk in patients with hypertension, but at least one drug pharmacologically similar to olmesartan medoxomil has demonstrated such benefits, and hydrochlorothiazide demonstrated reduction of cardiovascular risk in patients with hypertension.

Olmesartan medoxomil The antihypertensive effects of olmesartan medoxomil have been demonstrated in seven placebo-controlled studies at doses ranging from 2.5 to 80 mg for 6 to 12 weeks, each showing statistically significant reductions in peak and trough blood pressure. A total of 2693 patients (2145 olmesartan medoxomil; 548 placebo) with essential hypertension were studied. Olmesartan medoxomil once daily (QD) lowered diastolic and systolic blood pressure.

The response was dose-related. An olmesartan medoxomil dose of 20 mg daily produced a trough sitting BP reduction over placebo of about 10/6 mm Hg and a dose of 40 mg daily produced a trough sitting BP reduction over placebo of about 12/7 mm Hg. Olmesartan medoxomil doses greater than 40 mg had little additional effect.

The onset of the antihypertensive effect occurred within 1 week and was largely manifest after 2 weeks. The blood pressure lowering effect was maintained throughout the 24-hour period with olmesartan medoxomil once daily, with trough-to-peak ratios for systolic and diastolic response between 60 and 80%. The blood pressure lowering effect of olmesartan medoxomil, with and without hydrochlorothiazide, was maintained in patients treated for up to 1 year.

There was no evidence of tachyphylaxis during long-term treatment with olmesartan medoxomil or rebound effect following abrupt withdrawal of olmesartan medoxomil after 1 year of treatment. The antihypertensive effect of olmesartan medoxomil was similar in men and women and in patients older and younger than 65 years. The effect was smaller in black patients (usually a low-renin population), as has been seen with other ACE inhibitors, angiotensin receptor blockers, and beta-blockers.

Olmesartan medoxomil had an additional blood pressure lowering effect when added to hydrochlorothiazide.

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Olmesartan medoxomil and hydrochlorothiazide No carcinogenicity studies with olmesartan medoxomil and hydrochlorothiazide have been conducted. Olmesartan medoxomil and hydrochlorothiazide in a ratio of 20:12.5 were negative in the Salmonella-Escherichia coli /mammalian microsome reverse mutation test up to the maximum recommended plate concentration for the standard assays. Olmesartan medoxomil and hydrochlorothiazide were tested individually and in combination ratios of 40:12.5, 20:12.5 and 10:12.5, for clastogenic activity in the in vitro Chinese hamster lung (CHL) chromosomal aberration assay.

A positive response was seen for each component and combination ratio. However, no synergism in clastogenic activity was detected between olmesartan medoxomil and hydrochlorothiazide at any combination ratio. Olmesartan medoxomil and hydrochlorothiazide in a ratio of 20:12.5, administered orally, tested negative in the in vivo mouse bone marrow erythrocyte micronucleus assay at administered doses of up to 3144 mg/kg.

No studies of impairment of fertility with olmesartan medoxomil and hydrochlorothiazide have been conducted. Olmesartan medoxomil Olmesartan medoxomil was not carcinogenic when administered by dietary administration to rats for up to 2 years. The highest dose tested (2000 mg/kg/day) was, on a mg/m 2 basis, about 480 times the maximum recommended human dose (MRHD) of 40 mg/day.

Two carcinogenicity studies conducted in mice, a 6-month gavage study in the p53 knockout mouse and a 6-month dietary administration study in the Hras2 transgenic mouse, at doses of up to 1000 mg/kg/day (about 120 times the MRHD), revealed no evidence of a carcinogenic effect of olmesartan medoxomil. Both olmesartan medoxomil and olmesartan tested negative in the in vitro Syrian hamster embryo cell transformation assay and showed no evidence of genetic toxicity in the Ames (bacterial mutagenicity) test. However, both were shown to induce chromosomal aberrations in cultured cells in vitro (Chinese hamster lung) and both tested positive for thymidine kinase mutations in the in vitro mouse lymphoma assay.

Olmesartan medoxomil tested negative in vivo for mutations in the MutaMouse intestine and kidney, and for clastogenicity in mouse bone marrow (micronucleus test) at oral doses of up to 2000 mg/kg (olmesartan not tested). Fertility of rats was unaffected by administration of olmesartan medoxomil at dose levels as high as 1000 mg/kg/day (240 times the MRHD) in a study in which dosing was begun 2 (female) or 9 (male) weeks prior to mating. Hydrochlorothiazide Two-year feeding studies in mice and rats conducted under the auspices of the National Toxicology Program (NTP) uncovered no evidence of a carcinogenic potential of hydrochlorothiazide in female mice (at doses of up to approximately 600 mg/kg/day) or in male and female rats (at doses of up to approximately 100 mg/kg/day).

The NTP, however, found equivocal evidence for hepatocarcinogenicity in male mice. Hydrochlorothiazide was not genotoxic in vitro in the Ames mutagenicity assay of Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538, or in the Chinese Hamster Ovary (CHO) test for chromosomal aberrations. It was also not genotoxic in vivo in assays using mouse germinal cell chromosomes, Chinese hamster bone marrow chromosomes, or the Drosophila sex-linked recessive lethal trait gene.

Positive test results were obtained in the in vitro CHO Sister Chromatid Exchange (clastogenicity) assay, the Mouse Lymphoma Cell (mutagenicity) assay and the Aspergillus nidulans non-disjunction assay. Hydrochlorothiazide had no adverse effects on the fertility of mice and rats of either sex in studies wherein these species were exposed, via their diet, to doses of up to 100 and 4 mg/kg, respectively, prior to mating and throughout gestation.

13.3Developmental Toxicity Olmesartan medoxomil and hydrochlorothiazide… [Excerpted — this section continues on DailyMed.]