Carbamazepine + oral contraceptive — enzyme induction
- Carbamazepine induces CYP3A + UGT
- estrogen/progestin exposure falls
- Breakthrough bleeding ≠ reliable warning
- Contraceptive failure risk rises
- Prefer nonhormonal/unaffected contraception
- Also affects implants + some progestins
Interaction at a glance
- Carbamazepine induces CYP3A + UGT
- estrogen/progestin exposure falls
- Prefer nonhormonal/unaffected contraception
Magnitude / time course
- Carbamazepine induces CYP3A + UGT
- estrogen/progestin exposure falls
- Also affects implants + some progestins
Clinical consequence
- Breakthrough bleeding ≠ reliable warning
- Contraceptive failure risk rises
Management
- Prefer nonhormonal/unaffected contraception
Self-check
- Key risk with Carbamazepine + oral contraceptive?
Contraceptive failure risk rises. - Preferred alternative for Carbamazepine + oral contraceptive?
Nonhormonal/unaffected contraception.
Drugs in this interaction (8)
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