Inhibition of enoxacin absorption by antacids or ranitidine.
Ten normal volunteers participated in a randomized, five-way crossover study to determine the effect of concurrent enoxacin and antacid or ranitidine administration on enoxacin absorption. The bioavailability of a single oral 400-mg enoxacin dose was significantly decreased, by 73 and 49%, when Maalox TC was administered 0.5 and 2 h before enoxacin, respectively. Enoxacin bioavailability was not significantly altered when the antacid was given 8 h before or 2 h after enoxacin administration. Ranitidine, administered intravenously 2 h before enoxacin, also significantly decreased enoxacin bioavailability, by 40%. The correlation between the proximity of antacid administration and the magnitude of the decrease in enoxacin bioavailability supports complexation as the mechanism of the antacid-enoxacin interaction. However, reduction of enoxacin bioavailability by ranitidine suggests that elevated gastric pH may also play a role in the antacid-enoxacin drug-drug interaction.
Grasela
T H
TH
School of Pharmacy, State University of New York, New York.
Schentag
J J
JJ
Sedman
A J
AJ
Wilton
J H
JH
Thomas
D J
DJ
Schultz
R W
RW
Lebsack
M E
ME
Kinkel
A W
AW
D000293:Adolescent; D000536:Aluminum Hydroxide / Q000494:pharmacology; D000863:Antacids / Q000494:pharmacology*; D004338:Drug Combinations / Q000494:pharmacology; D004347:Drug Interactions; D015365:Enoxacin / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D008276:Magnesium Hydroxide / Q000494:pharmacology; D008297:Male; D011899:Ranitidine / Q000494:pharmacology*
D000863:Antacids; D004338:Drug Combinations; D015365:Enoxacin; C013591:aluminum hydroxide, magnesium hydroxide, drug combination; D000536:Aluminum Hydroxide; D011899:Ranitidine; D008276:Magnesium Hydroxide