Further investigation on meloxicam contraceptivity in female rabbits: luteinizing unruptured follicles, a microscopic evidence.

Meloxicam, a selective cyclooxygenase-2 inhibitor, was administered orally or intravaginally, to sperm-positive female rabbits to assess its effect on ovulation. A single oral dose (20 mg/kg), administered 5 h postcoitus resulted in 100% contraceptive rate. On the other hand, for females receiving meloxicam suppositories (14.9 mg/kg), 5 h postcoitus, the contraceptive rate was 62.5% compared to placebo. The decrease in the contraceptive effect of meloxicam suppository may be due to the rejection of the dose by some females. Corpora lutea, maternal plasma progesterone, ovary fresh weight and maternal body weight gain were not affected by meloxicam treatment compared to placebo. Histopathologically, the surface of the ovary of meloxicam-treated females appears irregular and dilated due to the presence of different-sized cysts. Some of the cystic follicles were retained ova. Further, immunohistochemical stains for estrogen and progesterone receptors showed positive staining in granulosa cells and the wall of the unruptured follicle. It is concluded that contraceptive effect of meloxicam in female rabbits resulted in a failure of follicular rupturing.