The stability of amoxycillin, clarithromycin and metronidazole in gastric juice: Relevance to the treatment of Helicobacter pylori infection

Erah, P.O., Goddard, A.F., Barrett, D.A., Shaw, P.N. and Spiller, R.C. (1997) The stability of amoxycillin, clarithromycin and metronidazole in gastric juice: Relevance to the treatment of Helicobacter pylori infection. Journal of Antimicrobial Chemotherapy, 39 1: 5-12. doi:10.1093/jac/39.1.5


Author Erah, P.O.
Goddard, A.F.
Barrett, D.A.
Shaw, P.N.
Spiller, R.C.
Title The stability of amoxycillin, clarithromycin and metronidazole in gastric juice: Relevance to the treatment of Helicobacter pylori infection
Journal name Journal of Antimicrobial Chemotherapy   Check publisher's open access policy
ISSN 0305-7453
1460-2091
Publication date 1997-01
Sub-type Article (original research)
DOI 10.1093/jac/39.1.5
Volume 39
Issue 1
Start page 5
End page 12
Total pages 8
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Language eng
Abstract Although omeprazole is an important component in anti-Helicobacter pylori therapeutic regimes using clarithromycin, amoxycillin and metronidazole, the mechanism by which it enhances antimicrobial action is unknown. One potential explanation for this effect is increased antibiotic chemical stability resulting from gastric pH changes induced by co-administration of omeprazole. The chemical stability of clarithromycin, amoxycillin and metronidazole was investigated in aqueous solutions and in human gastric juice collected before and after a 7-day course of omeprazole. Amoxycillin, clarithromycin and metronidazole were prepared in buffered aqueous solutions of pH 1.0 to 8.0 and in gastric juice of pH 2.0 and 7.0. The gastric juice samples were obtained from fasted H. pylori-negative volunteers before and after they had received a 7-day course of omeprazole. All the samples were incubated at 37°C and analysed at intervals by HPLC. Amoxycillin, clarithromycin and metronidazole were stable in aqueous solutions of pH 4.0-7.0, pH 5.0-8.0 and pH 2.0-7.0, respectively. At pH 2.0, the degradation half-lives were 19.0 ± 0.2 h, 1.3 ± 0.05 h and 2200 ± 1100 h, respectively. In gastric juice samples of pH 2.0, the degradation half-lives were 15.2 ± 0.3 h, 1.0 ± 0.04 h and ≤ 800 h, respectively. The half-lives of the drugs in the gastric juice samples of pH 7.0 were all > 68 h. The co-administration of omeprazole with amoxycillin or clarithromycin is likely to increase the chemical stability of amoxycillin and clarithromycin in gastric juice. Clarithromycin degrades rapidly at normal gastric pH (1.0-2.0) but amoxycillin and metronidazole are sufficiently stable at this pH to maintain an antibacterial concentration in the stomach.
Keyword Peptic-ulcer disease
Physicochemical properties
Campylobacter-pylori
Omeprazole
Amoxicillin
Eradication
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Pharmacy Publications
 
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