Lansoprazole (Page 8 of 12)

12.4 Microbiology

Microbiology
Lansoprazole, clarithromycin and/or amoxicillin have been shown to be active against most strains of Helicobacter pylori in vitro and in clinical infections [ see Indications and Usage ( 1.2)].

Helicobacter pylori Pre-treatment Resistance Clarithromycin pre-treatment resistance (≥2.0 mcg/mL) was 9.5% (91/960) by E-test and 11.3% (12/106) by agar dilution in the dual and triple therapy clinical trials (M93-125, M93-130, M93-131, M95-392, and M95-399).

Amoxicillin pre-treatment susceptible isolates (≤0.25 mcg/mL) occurred in 97.8% (936/957) and 98.0% (98/100) of the patients in the dual and triple therapy clinical trials by E-test and agar dilution, respectively. Twenty one of 957 patients (2.2%) by E-test, and two of 100 patients (2.0%) by agar dilution, had amoxicillin pre-treatment MICs of greater than 0.25 mcg/mL. One patient on the 14 day triple therapy regimen had an unconfirmed pre-treatment amoxicillin minimum inhibitory concentration (MIC) of greater than 256 mcg/mL by E-test and the patient was eradicated of H. pylori ( Table 8).

Table 8. Clarithromycin Susceptibility Test Results and Clinical/Bacteriological Outcomes*
Clarithromycin Pre-treatment Results		Clarithromycin Post-treatment Results
		H. pylori negative- ­ eradicated	H. pylori positive – not eradicated Post-treatment susceptibility results
			S †	I †	R †	No MIC
Triple Therapy 14 Day (lansoprazole 30 mg twice daily/amoxicillin 1 g twice daily/clarithromycin 500 mg twice daily) (M95-399, M93-131, M95-392)
Susceptible †	112	105				7
Intermediate †	3	3
Resistant †	17	6			7	4
Triple Therapy 10 Day (lansoprazole 30 mg twice daily/amoxicillin 1 g twice daily/clarithromycin 500 mg twice daily) (M95-399)
Susceptible †	42	40	1		1
Intermediate †
Resistant †	4	1			3

*Includes only patients with pre-treatment clarithromycin susceptibility test results † Susceptible (S) MIC ≤0.25 mcg/mL, Intermediate (I) MIC 0.5 to 1.0 mcg/mL, Resistant (R) MIC ≥2 mcg/mL

Patients not eradicated of H. pylori following lansoprazole/amoxicillin/clarithromycin triple therapy will likely have clarithromycin resistant H. pylori. Therefore, for those patients who fail therapy, clarithromycin susceptibility testing should be done when possible. Patients with clarithromycin resistant H. pylori should not be treated with lansoprazole/amoxicillin/clarithromycin triple therapy or with regimens which include clarithromycin as the sole antimicrobial agent.

Amoxicillin Susceptibility Test Results and Clinical/Bacteriological Outcomes: In the dual and triple therapy clinical trials, 82.6% (195/236) of the patients that had pre-treatment amoxicillin susceptible MICs (≤0.25 mcg/mL) were eradicated of H. pylori. Of those with pre-treatment amoxicillin MICs of greater than 0.25 mcg/mL, three of six had the H. pylori eradicated. A total of 30% (21/70) of the patients failed lansoprazole 30 mg three times daily/amoxicillin 1 g three times daily dual therapy and a total of 12.8% (22/172) of the patients failed the 10 and 14 day triple therapy regimens. Post-treatment susceptibility results were not obtained on 11 of the patients who failed therapy. Nine of the 11 patients with amoxicillin post treatment MICs that failed the triple therapy regimen also had clarithromycin resistant H. pylori isolates.

Susceptibility Test for Helicobacter pylori: For susceptibility testing information about Helicobacter pylori , see Microbiology section in prescribing information for clarithromycin and amoxicillin.

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

In two 24-month carcinogenicity studies, Sprague-Dawley rats were treated with oral lansoprazole doses of five to 150 mg/kg/day, about one to 40 times the exposure on a body surface (mg/m ²) basis of a 50 kg person of average height [1.46 m ² body surface area (BSA)] given the recommended human dose of 30 mg/day. Lansoprazole produced dose-related gastric enterochromaffin-like (ECL) cell hyperplasia and ECL cell carcinoids in both male and female rats. It also increased the incidence of intestinal metaplasia of the gastric epithelium in both sexes. In male rats, lansoprazole produced a dose-related increase of testicular interstitial cell adenomas. The incidence of these adenomas in rats receiving doses of 15 to 150 mg/kg/day (four to 40 times the recommended human dose based on BSA) exceeded the low background incidence (range = 1.4 to 10%) for this strain of rat.

In a 24-month carcinogenicity study, CD-1 mice were treated with oral lansoprazole doses of 15 to 600 mg/kg/day, two to 80 times the recommended human dose based on BSA. Lansoprazole produced a dose-related increased incidence of gastric ECL cell hyperplasia. It also produced an increased incidence of liver tumors (hepatocellular adenoma plus carcinoma). The tumor incidences in male mice treated with 300 and 600 mg/kg/day (40 to 80 times the recommended human dose based on BSA) and female mice treated with 150 to 600 mg/kg/day (20 to 80 times the recommended human dose based on BSA) exceeded the ranges of background incidences in historical controls for this strain of mice. Lansoprazole treatment produced adenoma of rete testis in male mice receiving 75 to 600 mg/kg/day (10 to 80 times the recommended human dose based on BSA).

A 26-week p53 (+/-) transgenic mouse carcinogenicity study was not positive.

Lansoprazole was positive in the Ames test and the in vitro human lymphocyte chromosomal aberration assay. Lansoprazole was not genotoxic in the ex vivo rat hepatocyte unscheduled DNA synthesis (UDS) test, the in vivo mouse micronucleus test, or the rat bone marrow cell chromosomal aberration test.

Lansoprazole at oral doses up to 150 mg/kg/day (40 times the recommended human dose based on BSA) was found to have no effect on fertility and reproductive performance of male and female rats.

14 CLINICAL STUDIES

14.1 Duodenal Ulcer

In a U.S. multicenter, double-blind, placebo-controlled, dose-response (15, 30, and 60 mg of lansoprazole once daily) study of 284 patients with endoscopically documented duodenal ulcer, the percentage of patients healed after two and four weeks was significantly higher with all doses of lansoprazole than with placebo. There was no evidence of a greater or earlier response with the two higher doses compared with lansoprazole 15 mg. Based on this study and the second study described below, the recommended dose of lansoprazole in duodenal ulcer is 15 mg per day ( Table 9).

Table 9. Duodenal Ulcer Healing Rates
Week	Lansoprazole			Placebo (N=72)
	15 mg daily (N=68)	30 mg daily (N=74)	60 mg daily (N=70)
2	42.4%*	35.6%*	39.1%*	11.3%
4	89.4%*	91.7%*	89.9%*	46.1%

* (p≤0.001) versus placebo.

Lansoprazole 15 mg was significantly more effective than placebo in relieving day and nighttime abdominal pain and in decreasing the amount of antacid taken per day.

In a second U.S. multicenter study, also double-blind, placebo-controlled, dose-comparison (15 and 30 mg of lansoprazole once daily), and including a comparison with ranitidine, in 280 patients with endoscopically documented duodenal ulcer, the percentage of patients healed after four weeks was significantly higher with both doses of lansoprazole than with placebo. There was no evidence of a greater or earlier response with the higher dose of lansoprazole. Although the 15 mg dose of lansoprazole was superior to ranitidine at four weeks, the lack of significant difference at two weeks and the absence of a difference between 30 mg of lansoprazole and ranitidine leaves the comparative effectiveness of the two agents undetermined (Table 10) [see Indications and Usage ( 1.1)]

Table 10. Duodenal Ulcer Healing Rates
Week	Lansoprazole		Ranitidine	Placebo (N=41)
	15 mg daily (N=80)	30 mg daily (N=77)	300 mg h.s. (N=82)
2	35.0%	44.2%	30.5%	34.2%
4	92.3%*	80.3% †	70.5% †	47.5%

* (p≤0.05) versus placebo and ranitidine. ^† (p≤0.05) versus placebo.