Drug-Drug Interaction

ANTICONVULSANTS/CONTRACEPTIVES

MECHANISM OF ACTION
It is speculated that barbiturates, hydantoins, and primidone may increase the metabolism of the contraceptives via hepatic enzyme induction. Contraceptives may also reduce hydantoin metabolism.

DISCUSSION
Decreased effectiveness of oral contraceptives, characterized by breakthrough bleeding and amenorrhea have been documented. Decreased effectiveness of hydantoin with loss of seizure control has also been reported but not confirmed.

CLINICAL EFFECTS
May observe reduced contraceptive effects such as breakthrough bleeding, spotting, or pregnancy. Effects may be seen several days after discontinuation of the anticonvulsant.

SEVERITY LEVEL
2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

PATIENT MANAGEMENT
An alternative form of contraception may be required during concomitant administration with anticonvulsants.

PREDISPOSING FACTORS
None determined.

REFERENCES

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