Use of the widely used birth control pill, Ortho Tri-Cyclen LO (norgestimate/ethinyl estradiol) tablets, resulted in significantly lower rates of breakthrough bleeding and spotting in a broad range of women compared to another low-dose combination birth control pill, according to data presented at the 55th Annual Clinical Meeting of The American College of Obstetricians and Gynaecologists (ACOG).

This analysis compared the breakthrough bleeding and spotting profiles of two low-dose birth control pills, containing either 25 mcg or 20 mcg of ethinyl estradiol and differing progestins, in women across a range of ages and weights.

Breakthrough bleeding and spotting, which refers to irregular or unexpected bleeding between periods, is a side effect associated with the use of birth control pills, especially low-dose pills, and is the leading cause of dissatisfaction and discontinuation of oral contraceptive use. It most commonly occurs in the first few months of taking a new pill, and often ceases once the body adjusts to the hormonal dosage.

"Breakthrough bleeding is a bothersome side effect of using the Pill," said, lead investigator Raymond Moss Hampton, MD, Texas Tech University School of Medicine. "These data demonstrate that women using Ortho Tri-Cyclen LO, an effective, low dose combination birth control pill, have significantly less breakthrough bleeding, regardless of age or weight."

The findings are based on a retrospective analysis of data from a randomised clinical trial evaluating the safety and efficacy of Ortho Tri-Cyclen LO (norgestimate/ 25 mcg ethinyl estradiol) compared to Loestrin Fe 1/20 (norethindrone acetate/20 mcg ethinyl estradiol) tablets. The study evaluated the incidence of breakthrough bleeding and spotting in 1,506 women using Ortho Tri-Cyclen LO versus 1,057 women using norethindrone acetate/20 mcg ethinyl estradiol tablets for up to 13 continuous menstrual cycles.

All women were between the ages of 18 and 45 and weighed between 90 and 240 pounds. Women were stratified by age and by weight, and all groups were analysed to determine the incidence of breakthrough bleeding and spotting by cycle. Cycle six data were presented as representative data for this analysis.

Based on this study analysis, a lower incidence of breakthrough bleeding and spotting was observed for women using Ortho Tri-Cyclen LO versus norethindrone acetate/ethinyl estradiol regardless of age or weight.

Ortho Tri-Cyclen LO (norgestimate/ethinyl estradiol) is indicated for the prevention of pregnancy in women who elect to use oral contraceptives as their method of contraception. It is a low-dose, tri-phasic hormonal birth control pill that provides high efficacy in pregnancy prevention with a low incidence of common side effects.

Barr Pharmaceuticals, Inc markets Loestrin Fe 1/20.