Effect of ormeloxifene, a nonsteroidal once-a-week oral contraceptive, on systemic hemodynamics in adult female rats

OBJECTIVE: To investigate the short-term effects of ormeloxifene on systemic hemodynamics, coagulation profile, and serum antioxidant activity in vivo in comparison with raloxifene. MATERIALS AND METHODS: Colony-bred adult female Sprague-Dawley rats were randomized into 19 groups of 10 each and received either ormeloxifene or raloxifene (0.25, 1.25, or 3 mg/kg/day) for 7, 15, or 30 days by the oral route. Animals of control group received vehicle (gum-acacia in distilled water) alone in a similar manner. Systemic hemodynamics and serum total antioxidant activity were assessed 24 h after the last treatment. RESULTS: There was no significant effect of ormeloxifene administered at these doses and schedules on hemodynamic parameters or antioxidant activity, except for increase in amplitude of R wave in rats treated with 3 mg/kg/day dose for 30 days. This effect with raloxifene was evident only 7 days after treatment at this dose. Overall response was, however, almost similar with both the agents. CONCLUSION: The findings demonstrate comparable pharmacological profile of ormeloxifene and raloxifene on short-term administration to rats. Based on changes observed in the ECG (R wave), long-term studies may lead to justifiable comparison of beneficial and harmful effects of ormeloxifene and raloxifene in relation to cardiovascular effects.