Amoxicillin and ampicillin are not transferred to gastric juice irrespective of Helicobacter pylori status or acid blockade by omeprazole.
BACKGROUND
The effects of proton pump inhibitors and Helicobacter pylori infection on the distribution of drugs used for the eradication of the bacteria are poorly understood.


OBJECTIVE
The aim of this study was to investigate the effects of a 7-day administration of 20 mg of omeprazole on the pharmacokinetics of amoxicillin and ampicillin in the plasma, saliva and gastric juice of individuals with and without H. pylori infection.


METHODS
Fifty-four healthy volunteers without endoscopic lesions were enrolled. Twenty-six volunteers were included in the amoxicillin study and 28 individuals in the ampicillin study. Each study had an open randomized two-period crossover design and a 21-day washout period between phases. Plasma, saliva and gastric juice concentrations of amoxicillin and ampicillin in subjects with and without omeprazole pre-treatment were measured by reversed-phase HPLC using UV detection.


RESULTS
Neither pre-treatment with omeprazole nor H. pylori infection interfered with the plasma bioavailability of amoxicillin or ampicillin, as assessed by the AUC0-2 h. Neither ampicillin nor amoxicillin were detected in saliva or gastric juice in any study phase.


CONCLUSIONS
Short-term treatment with omeprazole does not interfere with the pharmacokinetics of amoxicillin or ampicillin. Our results also exclude the presence of a transfer mechanism for amoxicillin or ampicillin from the plasma to the gastric lumen.
Ortiz
R A M
RA
Clinical Pharmacology and Gastroenterology Unit, São Francisco University Medical School, Avenue São Francisco de Assis 218, 12916-900 Bragança Paulista, SP, Brazil.
Calafatti
S A
SA
Corazzi
A
A
Souza
J M
JM
Deguer
M
M
De Souza
C A F
CA
Marchioretto
M A M
MA
Bernasconi
G
G
Ferraz
J G P
JG
Pedrazzoli
J
J
D000328:Adult; D000658:Amoxicillin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000667:Ampicillin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005750:Gastric Juice / Q000737:chemistry; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D009853:Omeprazole / Q000494:pharmacology*; D010406:Penicillins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D054328:Proton Pump Inhibitors; D012463:Saliva / Q000737:chemistry
D004791:Enzyme Inhibitors; D010406:Penicillins; D054328:Proton Pump Inhibitors; D000667:Ampicillin; D000658:Amoxicillin; D009853:Omeprazole