ATACAND (Page 5 of 7)

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

There was no evidence of carcinogenicity when candesartan cilexetil was orally administered to mice and rats for up to 104 weeks at doses up to 100 and 1000 mg/kg/day, respectively. Rats received the drug by gavage, whereas mice received the drug by dietary administration. These (maximally-tolerated) doses of candesartan cilexetil provided systemic exposures to candesartan (AUCs) that were, in mice, approximately 7 times and, in rats, more than 70 times the exposure in man at the maximum recommended daily human dose (32 mg).

Candesartan and its O-deethyl metabolite tested positive for genotoxicity in the in vitro Chinese hamster lung (CHL) chromosomal aberration assay. Neither compound tested positive in the Ames microbial mutagenesis assay or the in vitro mouse lymphoma cell assay. Candesartan (but not its O-deethyl metabolite) was also evaluated in vivo in the mouse micronucleus test and in vitro in the Chinese hamster ovary (CHO) gene mutation assay, in both cases with negative results. Candesartan cilexetil was evaluated in the Ames test, the in vitro mouse lymphoma cell and rat hepatocyte unscheduled DNA synthesis assays and the in vivo mouse micronucleus test, in each case with negative results. Candesartan cilexetil was not evaluated in the CHL chromosomal aberration or CHO gene mutation assay.

Fertility and reproductive performance were not affected in studies with male and female rats given oral doses of up to 300 mg/kg/day (83 times the maximum daily human dose of 32 mg on a body surface area basis).

14 CLINICAL STUDIES

14.1 Hypertension

Adult

The antihypertensive effects of ATACAND were examined in 14 placebo-controlled trials of 4- to 12-weeks duration, primarily at daily doses of 2 to 32 mg per day in patients with baseline diastolic blood pressures of 95 to 114 mm Hg. Most of the trials were of candesartan cilexetil as a single agent, but it was also studied as add-on to hydrochlorothiazide and amlodipine. These studies included a total of 2350 patients randomized to one of several doses of candesartan cilexetil and 1027 to placebo. Except for a study in diabetics, all studies showed significant effects, generally dose related, of 2 to 32 mg on trough (24 hour) systolic and diastolic pressures compared to placebo, with doses of 8 to 32 mg giving effects of about 8-12/4-8 mm Hg. There were no exaggerated first-dose effects in these patients. Most of the antihypertensive effect was seen within 2 weeks of initial dosing and the full effect in 4 weeks. With once-daily dosing, blood pressure effect was maintained over 24 hours, with trough to peak ratios of blood pressure effect generally over 80%. Candesartan cilexetil had an additional blood pressure lowering effect when added to hydrochlorothiazide.

The antihypertensive effects of candesartan cilexetil and losartan potassium at their highest recommended doses administered once-daily were compared in two randomized, double-blind trials. In a total of 1268 patients with mild to moderate hypertension who were not receiving other antihypertensive therapy, candesartan cilexetil 32 mg lowered systolic and diastolic blood pressure by 2 to 3 mm Hg on average more than losartan potassium 100 mg, when measured at the time of either peak or trough effect. The antihypertensive effects of twice daily dosing of either candesartan cilexetil or losartan potassium were not studied.

The antihypertensive effect was similar in men and women and in patients older and younger than 65. Candesartan was effective in reducing blood pressure regardless of race, although the effect was somewhat less in blacks (usually a low-renin population). This has been generally true for angiotensin II antagonists and ACE inhibitors.

In long-term studies of up to 1 year, the antihypertensive effectiveness of candesartan cilexetil was maintained, and there was no rebound after abrupt withdrawal.

There were no changes in the heart rate of patients treated with candesartan cilexetil in controlled trials.

Pediatric

The antihypertensive effects of ATACAND were evaluated in hypertensive children 1 to < 6 years old and 6 to < 17 years of age in two randomized, double-blind multicenter, 4-week dose ranging studies. There were 93 patients 1 to < 6 years of age, 74% of whom had renal disease, that were randomized to receive an oral dose of candesartan cilexetil suspension 0.05, 0.20 or 0.40 mg/kg once daily. The primary method of analysis was slope of the change in systolic blood pressure (SBP) as a function of dose. Since there was no placebo group, the change from baseline likely overestimates the true magnitude of blood pressure effect. Nevertheless, SBP and diastolic blood pressure (DBP) decreased 6.0/5.2 to 12.0/11.1 mmHg from baseline across the three doses of candesartan.

In children 6 to < 17 years, 240 patients were randomized to receive either placebo or low, medium, or high doses of ATACAND in a ratio of 1: 2: 2: 2. For children who weighed < 50 kg the doses of ATACAND were 2, 8, or 16 mg once daily. For those > 50 kg the ATACAND doses were 4, 16 or 32 mg once daily. Those enrolled were 47% Black and 29% were female; mean age +/- SD was 12.9 +/- 2.6 years.

The placebo subtracted effect at trough for sitting systolic blood pressure/sitting diastolic blood pressure for the different doses were from 4.9/3.0 to 7.5/6.2 mmHg.

In children 6 to < 17 years there was a trend for a lesser blood pressure effect for Blacks compared to other patients. There were too few individuals in the age group of 1 — 6 years old to determine whether Blacks respond differently than other patients to ATACAND.

14.2 Heart Failure

Candesartan was studied in two heart failure outcome studies: 1. The Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity trial in patients intolerant of ACE inhibitors (CHARM–Alternative), 2. CHARM–Added in patients already receiving ACE inhibitors. Both studies were international double-blind, placebo-controlled trials in patients with NYHA class II — IV heart failure and LVEF ≤40%. In both trials, patients were randomized to placebo or ATACAND (initially 4-8 mg once daily, titrated as tolerated to 32 mg once daily) and followed for up to 4 years. Patients with serum creatinine > 3 mg/dL, serum potassium > 5.5 mEq/L, symptomatic hypotension or known bilateral renal artery stenosis were excluded. The primary end point in both trials was time to either cardiovascular death or hospitalization for heart failure.

CHARM–Alternative included 2028 subjects not receiving an ACE inhibitor due to intolerance. The mean age was 67 years and 32% were female, 48% were NYHA II, 49% were NYHA III, 4% were NYHA IV, and the mean ejection fraction was 30%. Sixty-two percent had a history of myocardial infarction, 50% had a history of hypertension, and 27% had diabetes. Concomitant drugs at baseline were diuretics (85%), digoxin (46%), beta-blockers (55%), and spironolactone (24%). The mean daily dose of ATACAND was approximately 23 mg and 59% of subjects on treatment received 32 mg once daily.

After a median follow-up of 34 months, there was a 23% reduction in the risk of cardiovascular death or heart failure hospitalization on ATACAND (p<0.001), with both components contributing to the overall effect (Table 1).

Table 1. CHARM — Alternative: Primary Endpoint and its Components

Endpoint (time to first event)

ATACAND

(n= 1013)

Placebo

(n=1015)

Hazard Ratio

(95% CI)

p-value

(logrank)

CV death or heart failure hospitalization

334

406

0.77

(0.67–0.89)

<0.001

CV death

219

252

0.85

(0.71–1.02)

0.072

Heart failure hospitalization

207

286

0.68

(0.57–0.81)

<0.001

In CHARM–Added, 2548 subjects receiving an ACE inhibitor were randomized to ATACAND or placebo. The specific ACE inhibitor and dose were at the discretion of the investigators, who were encouraged to titrate patients to doses known to be effective in clinical outcome trials, subject to patient tolerability. Forced titration to maximum tolerated doses of ACE inhibitor was not required.

The mean age was 64 years and 21% were female, 24% were NYHA II, 73% were NYHA III, 3% were NYHA IV, and the mean ejection fraction was 28%. Fifty-six percent had a history of myocardial infarction, 48% had a history of hypertension, and 30% had diabetes. Concomitant drugs at baseline in addition to ACE inhibitors were diuretics (90%), digoxin (58%), beta-blockers (55%), and spironolactone (17%). The mean daily dose of ATACAND was approximately 24 mg and 61% of subjects on treatment received 32 mg once daily.

After a median follow-up of 41 months, there was a 15% reduction in the risk of cardiovascular death or heart failure hospitalization on ATACAND (p=0.011), with both components contributing to the overall effect (Table 2). There was no evident relationship between dose of ACE inhibitor and the benefit of ATACAND.

Table 2. CHARM — Added: Primary Endpoint and its Components

Endpoint (time to first event)

ATACAND (n=1276)

Placebo (n=1272)

Hazard Ratio (95% CI)

p-value (logrank)

CV death or heart failure hospitalization

483

538

0.85 (0.75–0.96)

0.011

CV death

302

347

0.84 (0.72–0.98)

0.029

Heart failure hospitalization

309

356

0.83 (0.71–0.96)

0.014

In these two studies, the benefit of ATACAND in reducing the risk of CV death or heart failure hospitalization (18% p<0.001) was evident in major subgroups (see Figure), and in patients on other combinations of cardiovascular and heart failure treatments, including ACE inhibitors and beta-blockers.

Figure. CV Death or Heart Failure Hospitalization in Subgroups – LV Systolic Dysfunction Trials

Graph-1
(click image for full-size original)

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