A double-blind, multiple-dose, placebo-controlled, cross-over study to compare the incidence of gastrointestinal complaints in healthy subjects given Doryx R and Vibramycin R.

Ninety-eight healthy subjects completed a double-blind, placebo-controlled, multiple-dose cross-over study to compare the incidence of gastrointestinal side effects of Doryx (Parke-Davis, Morris Plains, NJ) capsules (enteric-coated doxycycline hyclate pellets) and Vibramycin (Pfizer, New York, NY) capsules (doxycycline hyclate powder). Doryx produced statistically significantly fewer episodes of nausea, vomiting, stomach of abdominal discomfort, and decreased appetite than did Vibramycin. For every symptom, Vibramycin produced statistically significantly more symptom reports than did placebo. Although Doryx produced significantly more reports of nausea than did placebo, there was no significant difference for the other symptoms. Based on these results, Doryx is superior to Vibramycin when considering the incidence of gastrointestinal side effects.