OBJECT DRUGS
PRECIPITANT DRUGS
Comment:
Cosevelam has been shown to reduce the AUC of ethinyl estradiol when given concurrently, probably due to binding of the estrogen in the GI tract. The effect was less when the drugs were separated by 4 hours. Estrogens other than ethinyl estradiol might be similarly affected. Also, one should be alert for the possibility that other binding agents such as colestipol (Colestid) might also interact.
Class 3: Assess Risk & Take Action if Necessary
- Circumvent/Minimize: Minimize interactions by giving the oral contraceptive at least 2 hours before or 6 hours after the colesevelam. Some reduction in ethinyl estradiol levels may still occur due to enterohepatic circulation of the estrogen.
- Monitor: Menstrual irregularities (spotting, breakthrough bleeding) may be a sign of inadequate contraceptive hormone levels, but absence of menstrual problems does not guarantee adequate contraception.