Objective: To evaluate the teratogenic effects of clarithromycin on developing rabbit.
Design: Randomized controlled study. Animals: Twenty one female New Zealand rabbits. Procedure: The pregnant female rabbits (21) were allocated into 4 groups. Control group (G1) (6 rabbits) received placebo. Other groups received clarithromycin (at a dose of 30 mg/kg b.wt orally) for ten days during the first stage (group2, n=6), the second stage (group3, n=6) or the third stage (group 4, n=3) of pregnancy. Three rabbits from each group were slaughtered on 20th and 30th days of pregnancy. Teratogenic effects were evaluated morphologically and histopathologically. Results: The therapeutic dose of clarithromycin exhibited morphological malformations, significant decrease (P≤0.05) in viable foeti mean, the mean values of the body weight and the fetal crown-rump length. However there was significant increase (P≤0.05) in dead foeti, fetal resorption rate, pre and post-implantation death in different stages of pregnancy. Visceral fetal abnormalities revealed dilatation of lateral ventricles of brain, thickening of the ventricular wall of the heart, and slight unilateral or bilateral widening of the renal pelvis. Skeleton fetal malformations showed incomplete ossification of 5th sternipri with absence of last ribs. Histopathological examination confirm teratogenic effects of clarithromycin. Conclusion and clinical relevance: The use of clarithromycin during pregnancy should be prohibited.