Enteric Coating Reduces Upper Gastrointestinal Adverse Reactions to Doxycycline.

A new doxycycline formulation consisting of enteric-coated doxycycline hyclate pellets in capsules is aimed at reducing gastrointestinal adverse reactions related to doxycycline therapy. In this randomised, double-blind, 3-way crossover study, adverse reactions caused by short term treatment with enteric-coated doxycycline hyclate pellets in capsules were compared with placebo and doxycycline monohydrate tablets. The latter are generally considered to be better tolerated than older formulations of doxycycline hyclate. 111 healthy volunteers completed the study. They were given 150mg of doxycycline once daily over 3 consecutive days with a washout of 4 to 10 days between the study periods. The medication was administered after an overnight fast (10 hours) with 200ml of tap water. An upright position was maintained for 1 hour and no food was allowed for 2 hours after drug administration. Participants recorded adverse reactions daily. Adverse reactions were reported by 66% of the subjects during treatment with doxycycline monohydrate, while 43% reported adverse reactions during treatment with enteric-coated doxycycline hyclate and 30% during placebo. Compared with the 2 other groups, doxycycline monohydrate caused significantly more adverse reactions in general, and abdominal pain, nausea and vomiting in particular. It is concluded that enteric-coated doxycycline hyclate pellets in capsules have significantly better gastrointestinal tolerability compared with doxycycline monohydrate.