Itokazu GS, Fischer JH, Manitpisitkul P, Hariharan R, Danziger LH. Lack of effect of nizatidine-induced elevation of gastric pH on the oral bioavailability of dapsone in healthy volunteers.
Pharmacotherapy 2002;
22:1420-5. [PMID:
12432968 DOI:
10.1592/phco.22.16.1420.33698]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE
To investigate the effect of histamine2 (H2)-receptor antagonist-induced elevation of gastric pH on oral bioavailability of a single dose of dapsone 100 mg.
DESIGN
Prospective, randomized, crossover, open-label, single-dose pharmacokinetic study.
SETTING
Teaching hospital.
PATIENTS
Sixteen men were enrolled in the study; data from 11 subjects were evaluable.
INTERVENTIONS
Participants received two treatments separated by at least 14 days. Treatment A consisted of a single dose of dapsone 100 mg. Treatment B consisted of a single dose of dapsone 100 mg plus two doses of oral nizatidine 300 mg administered 3-4 hours apart to maintain gastric pH above 6.0. Plasma samples collected before and up to 120 hours after dapsone administration were analyzed for dapsone and monoacetyldapsone (MADDS) by high-performance liquid chromatography. Pharmacokinetic parameters were determined by noncompartmental analysis.
MEASUREMENTS AND MAIN RESULTS
Gastric pH in the first 6 hours after dapsone administration was above 6.0 for a mean +/- SD of 1.1% +/- 2.9% of the time in the absence of nizatidine and 69.5% +/- 18.0% of the time during nizatidine therapy. The geometric mean dapsone maximum plasma concentration (Cmax) declined by 13% (p<0.01), and median time to Cmax occurred 2 hours later (p<0.01) with nizatidine coadministration compared with dapsone alone. Inclusion of the 90% confidence interval for the mean Cmax ratio within the equivalence interval of 0.8-1.25 demonstrated the lack of clinical significance for this modest decrease in Cmax. Neither the area under the dapsone plasma concentration-time curve from zero to infinity nor the elimination half-life of dapsone were significantly altered by nizatidine. No clinically significant changes were observed in the pharmacokinetics of MADDS with regard to coadministration of nizatidine.
CONCLUSION
Elevation of gastric pH by H2-receptor antagonists, such as nizatidine, does not result in clinically important changes in the rate or extent of oral dapsone absorption.
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