Women are being recruited for a drug trial to prevent menstrual bleeding while on continuous birth control pills.

Dr. Bliss Kaneshiro, an obstetrician-gynecologist at the University of Hawaii John A. Burns School of Medicine, is evaluating use of a low dose of doxycycline to prevent what is called “;breakthrough”; bleeding in the first months of using a continuous oral contraceptive pill.

Doxycycline is an antibiotic used to treat conditions such as acne, and it also inhibits enzymes believed to play a role in the menstrual process, Kaneshiro said.

“;It is a very safe medication,”; she said. “;A lot of doctors are comfortable using it with minimal side effects.”;

Women using a regular birth control pill have a scheduled menstrual period at the end of a month, but many women starting continuous birth control pills experience unscheduled bleeding in the first three months, she said.

The idea of a continuous oral contraceptive is not to have any periods while taking it, so women are caught unaware and unprepared if bleeding does occur, she said.

Kaneshiro began the study with about 75 women while in Oregon and hopes to have 66 in the second phase between Hawaii and Oregon. So far, she has enrolled 20 in Hawaii and 20 in Oregon, she said.

Participants take a continuous birth control pill and a second medication — either a placebo pill or a “;very small dose”; of doxycycline, she said.

If the study shows doxycycline is successful in stopping unscheduled bleeding, it will give women the option of not having a period, she said.

Continuous birth control pills initially were for women with menstrual-related problems such as endometriosis or menstrual headaches, she said. However, more women have shown interest in not having a period, she said.

Continuous birth control does not affect long-term fertility, cause cancer or have any long-term health consequences, Kaneshiro said.

Women 18 and older interested in participating in the drug trial should contact the UH Clinical Research Center at 983-6243 or e-mail .(JavaScript must be enabled to view this email address).