DOXYCYCLINE VERSUS TETRACYCLINE THERAPY FOR LYME-DISEASE ASSOCIATED WITH ERYTHEMA MIGRANS

Background: Doxycycline is widely used to treat Lyme disease associate d with erythema migrans. Whether it is comparable to tetracycline is u nknown. Objective: We conducted a two-part retrospective analysis of(1 ) the safety and efficacy of doxycycline compared with tetracycline an d (2) the safety and efficacy of a 14-day versus a 20-day course of do xycycline. Methods: Twenty-seven patients given tetracycline (500 mg f our times a day for 14 days [group 1]) were compared retrospectively w ith 21 patients who received doxycycline (100 mg two or three times a day for 14 days [group 21). The results for group 2 were also compared with that of 38 patients who received doxycycline for 20 days (100 mg three times daily) in a prospective treatment trial (group 3). Result s: There was no significant difference in the incidence of adverse dru g effects or in efficacy at 1 month, but at 1 year there was a trend t oward a better outcome in the group treated with tetracycline (p = 0.0 8). A 14-day course of doxycycline was comparable to a 20-day course i n the incidence of adverse drug effects and in clinical outcome. Concl usion:: The principal advantage of doxycycline over tetracycline for t he treatment of Lyme disease associated with erythema migrans is the c onvenience of less frequent dosing, not enhanced efficacy or safety. T here appears to be no advantage in extending treatment with doxycyclin e from 14 to 20 days.