Esomeprazole Magnesium (Page 9 of 12)

13.2 Animal Pharmacology & OR Toxicology

Reproduction Studies
Reproduction studies have been performed in rats at oral doses up to 280 mg/kg/day (about 68 times an oral human dose of 40 mg on a body surface area basis) and in rabbits at oral doses up to 86 mg/kg/day (about 42 times an oral human dose of 40 mg on a body surface area basis) and have revealed no evidence of impaired fertility or harm to the fetus due to esomeprazole [see Use in Specific Populations ( 8.1)].
Juvenile Animal Study
A 28-day toxicity study with a 14-day recovery phase was conducted in juvenile rats with esomeprazole magnesium at doses of 70 to 280 mg /kg/day (about 17 to 68 times a daily oral human dose of 40 mg on a body surface area basis). An increase in the number of deaths at the high dose of 280 mg/kg/day was observed when juvenile rats were administered esomeprazole magnesium from postnatal day 7 through postnatal day 35. In addition, doses equal to or greater than 140 mg/kg/day (about 34 times a daily oral human dose of 40 mg on a body surface area basis), produced treatment-related decreases in body weight (approximately 14%) and body weight gain, decreases in femur weight and femur length, and affected overall growth. Comparable findings described above have also been observed in this study with another esomeprazole salt, esomeprazole strontium, at equimolar doses of esomeprazole.

14 CLINICAL STUDIES

14.1 Healing of Erosive Esophagitis

The healing rates of esomeprazole magnesium delayed-release capsules 40 mg, esomeprazole magnesium delayed-release capsules 20 mg, and omeprazole 20 mg (the approved dose for this indication) were evaluated in patients with endoscopically diagnosed erosive esophagitis in four multicenter, double-blind, randomized studies. The healing rates at Weeks 4 and 8 were evaluated and are shown in the Table 9: Table 9: Erosive Esophagitis Healing Rate (Life-Table Analysis)

Study No. of patients Treatment group Week 4 Week 8 Significance Level 1
1 588 588 Esomeprazole magnesium delayed-release capsules 20 mg Omeprazole 20 mg 68.7% 69.5% 90.6% 88.3% N.S.
2 654 656 650 Esomeprazole magnesium delayed-release capsules 40 mg Esomeprazole magnesium delayed-release capsules 20 mg Omeprazole 20 mg 75.9% 70.5% 64.7% 94.1% 89.9% 86.9% p < 0.001 p < 0.05
3 576 572 Esomeprazole magnesium delayed-release capsules 40 mg Omeprazole 20 mg 71.5% 68.6% 92.2% 89.8% N.S.
4 1216 1209 Esomeprazole magnesium delayed-release capsules 40 mg Omeprazole 20 mg 81.7% 68.7% 93.7% 84.2% p < 0.001

1. log-rank test vs. omeprazole 20 mg
N.S. = not significant (p > 0.05)

In these same studies of patients with erosive esophagitis, sustained heartburn resolution and time to sustained heartburn resolution were evaluated and are shown in the Table 10: Table 10: Sustained Resolution1 of Heartburn (Erosive Esophagitis Patients)

Cumulative Percent 2 with Sustained Resolution
Study No. of Patients Treatment Groups Day 14 Day 28 Significance Level 3
1 573 Esomeprazole magnesium delayed-release capsules 20 mg 64.3% 72.7% N.S.
555 Omeprazole 20 mg 64.1% 70.9%
2 621 Esomeprazole magnesium delayed-release capsules 40 mg 64.8% 74.2% p <0.001
620 Esomeprazole magnesium delayed-release capsules 20 mg 62.9% 70.1% N.S.
626 Omeprazole 20 mg 56.5% 66.6%
3 568 Esomeprazole magnesium delayed-release capsules 40 mg 65.4% 73.9% N.S.
551 Omeprazole 20 mg 65.5% 73.1%
4 1187 Esomeprazole magnesium delayed-release capsules 40 mg 67.6% 75.1% p <0.001
1188 Omeprazole 20 mg 62.5% 70.8%

1. Defined as 7 consecutive days with no heartburn reported in daily patient diary.
2. Defined as the cumulative proportion of patients who have reached the start of sustained resolution.
3. log-rank test vs. omeprazole 20 mg.
N.S. = not significant (p > 0.05).
In these four studies, the range of median days to the start of sustained resolution (defined as 7 consecutive days with no heartburn) was 5 days for esomeprazole magnesium delayed-release capsules 40 mg, 7 to 8 days for esomeprazole magnesium delayed-release capsules 20 mg and 7 to 9 days for omeprazole 20 mg.
There are no comparisons of 40 mg of esomeprazole magnesium delayed-release capsules with 40 mg of omeprazole in clinical trials assessing either healing or symptomatic relief of erosive esophagitis.
Long-Term Maintenance of Healing of Erosive Esophagitis
Two multicenter, randomized, double-blind placebo-controlled 4-arm trials were conducted in patients with endoscopically confirmed, healed erosive esophagitis to evaluate esomeprazole magnesium delayed-release capsules 40 mg (n=174), 20 mg (n=180), 10 mg (n=168) or placebo (n=171) once daily over six months of treatment.
No additional clinical benefit was seen with esomeprazole magnesium delayed-release capsules 40 mg over esomeprazole magnesium delayed-release capsules 20 mg. The percentages of patients that maintained healing of erosive esophagitis at the various time points are shown in the Figures 2 and 3:

Figure 2: Maintenance of Healing Rates by Month (Study 177)

image1
(click image for full-size original)

s= scheduled visit
Figure 3: Maintenance of Healing Rates by Month (Study 178)
image2
(click image for full-size original)

s= scheduled visit
Patients remained in remission significantly longer and the number of recurrences of erosive esophagitis was significantly less in patients treated with esomeprazole magnesium delayed-release capsules compared to placebo.
In both studies, the proportion of patients on esomeprazole magnesium delayed-release capsules who remained in remission and were free of heartburn and other GERD symptoms was well differentiated from placebo.
In a third multicenter open label study of 808 patients treated for 12 months with esomeprazole magnesium delayed-release capsules 40 mg, the percentage of patients that maintained healing of erosive esophagitis was 93.7% for six months and 89.4% for one year.

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