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 degrees 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 > or = 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.
Background: Subsidizing the cost of medicines through insurance schemes increases consumption of medicines and may contribute to irrational use of antibiotics. Objectives: To describe the systemic antibiotics prescriptions patterns and analyze the determinants of their utilization in the National Health insurance Scheme (NHIS).Methods: Established WHO guideline was followed to conduct this cross-sectional retrospective study at University of Nigeria Teaching Hospital, Nigeria. Data were collected from randomly sampled prescription sheets of one year duration. Logistic regression analysis was performed to determine the predictors of antibiotics prescriptions.Results: The results are based on 802 sampled out-patients NHIS prescriptions. Average number of medicines per encounter was 4.0 ± 1.8, whereas 46.9% of antibiotics were prescribed by generic name. Penicillins (most frequently amoxicillin/clavulanate), and nitroimidazole (most frequently metronidazole) were the most commonly prescribed antibiotics with percentage share of 43.3% and 22.2%. Being <5 years old, and taking more than 4 medicines (OR 2.20, 95% CI 1.37-3.55) were the factors associated with the highest risk of antibiotics exposure.Conclusion: There were poly-pharmacy, and non-adherence to generic antibiotic prescriptions. Penicillins (amoxicillin/clavulanate) were the most commonly prescribed antibiotic class. Being < 5 years old, and taking more than 4 medicines were significant predictors of antibiotics exposure.Keywords: Antibiotics; national health insurance scheme; Nigeria; poly-pharmacy; prescription.
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