Ranitidine Doxycycline

A 27-year-old man with an 8-day history of dysphagia and retrosternal pain was taking doxycycline prophylaxis and occasional terfenadine (doses not stated). He recalled no problems with taking any of his doxycycline prophylaxis. He had an esophagoscopy, which showed a 1 cm esophageal ulcer. He improved with ranitidine. 

Deppermann K-M, Lode H, HofQ en G, Tschink G, Kalz C, Koeppe P. Influence of ranitidine, pirenzepine, and aluminum magnesium hydroxide on the bioavailability of various antibiotics, including amoxicillin, cephalexin, doxycycline and amoxicillin-clavulanic acid. Antmdcrob Agents Chemodier( 9Z9) 33,1901-1907. 

Cimetidine reduces the absorption of tetracycline but does not appear to affect its serum levels. Ranitidine seems not to affect the bioavailability of doxycycline. Information about other tetracyclines and H2-receptor antagonists is lacking, but there would seem to be no reason to suspect that they will interact. 

In 10 healthy subjects, the bioavailability of doxycycline 200 mg was not altered by three 150-mg doses of ranitidine. 

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