The effect of activated dimethicone and a proprietary antacid preparation containing this agent on the absorption of phenytoin.

J C McElnay, G Uprichard, P S Collier

British journal of clinical pharmacology 1982 Apr

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1 The bioavailabilty of phenytoin sodium (Epanutin both alone and in combination with activated dimethicone and Asilone (a proprietary antacid preparation containing activated dimethicone) was examined in six healthy male volunteers. 2 The bioavailability of phenytoin when given concomitantly with Asilone was decreased in five of six volunteer subjects (by greater than 30% in three subjects) although this decrease was not shown to be statistically significant. 3 Dimethicone, which has been shown to decrease phenytoin absorption in vitro did not affect phenytoin bioavailability in vivo. 4 It is recommended that when treating patients stabilised on phenytoin one should exercise caution with concomitant phenytoin and antacid therapy to guard against possible changed drug absorption.

Citation

J C McElnay, G Uprichard, P S Collier. The effect of activated dimethicone and a proprietary antacid preparation containing this agent on the absorption of phenytoin. British journal of clinical pharmacology. 1982 Apr;13(4):501-5