Meloxicam inhibits ovulation in non-human primates when administered during the follicular phase of the menstrual cycle to simulate emergency contraception

Abstract

OBJECTIVE: To determine if a 5 day course of oral administration of the cyclooxygenase inhibitor meloxicam can prevent ovulation while maintaining normal menstrual cycles in nonhuman primates. DESIGN: Adult cynomolgus monkeys were studied in each of 4 menstrual cycles. In cycle 1, serum obtained each day was assayed for estradiol, progesterone, and luteinizing hormone (LH); first menses was also noted. In cycle 2, meloxicam was administered orally once each day for 5 days beginning at either mid follicular, late follicular, or periovulatory stage of the menstrual cycle; serum and menses were assessed as in cycle 1. In cycle 3, the ovary bearing the ovulatory follicle was removed 2 days after the expected day of ovulation. In cycle 4, monkeys received 5 days of oral meloxicam beginning at either mid follicular, late follicular, or periovulatory stage; the remaining ovary was removed 2 days after the expected day of ovulation. Ovarian sections were examined for the presence of an oocyte within the follicle. MATERIALS AND METHODS: Estradiol and progesterone were assessed by immunoassay; LH was assayed by RIA. Hormones levels were compared by ANOVA. Menstrual cycle length was compared by paired t-test. Ovaries were fixed, serial sectioned, and stained. RESULTS: All monkeys showed the expected pattern of changing estradiol, progesterone, and LH levels during cycle 1; meloxicam treatment in cycle 2 did not alter hormone levels or luteal phase length. Ovaries removed in cycle 3 did not contain oocytes within follicles, indicating successful ovulation. In contrast, large follicles did contain oocytes, indicating ovulation failure, after treatment with meloxicam during the mid follicular (67%), late follicular (100%), or periovulatory (50%) stage of cycle 4. CONCLUSIONS: A 5 day course of oral meloxicam can reduce the rate of oocyte release without alteration of reproductive hormones or menstrual cycle length. Meloxicam may be an effective emergency contraceptive.