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Enhanced Metabolism of Levonorgestrel During Phenobarbital Treatment and Resultant Pregnancy
Author(s) -
ShaneMcWhorter Laura,
Cerveny Joli D.,
MacFarlane Lori L.,
Osborn Carol
Publication year - 1998
Publication title -
pharmacotherapy: the journal of human pharmacology and drug therapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.227
H-Index - 109
eISSN - 1875-9114
pISSN - 0277-0008
DOI - 10.1002/j.1875-9114.1998.tb03161.x
Subject(s) - levonorgestrel , medicine , medroxyprogesterone acetate , family planning , population , gynecology , pregnancy , phenobarbital , medroxyprogesterone , obstetrics , estrogen , pharmacology , research methodology , environmental health , biology , genetics
Levonorgestrel implants (Norplant) are an alternative to oral contraceptives and medroxyprogesterone acetate intramuscular injections. An interaction may exist between levonorgestrel and agents that induce the hepatic microsomal enzyme system. A 21‐year‐old woman with a history of a seizure disorder, treated with phenobarbital, who received levonorgestrel implants became pregnant. After a normal delivery, she took oral contraceptives concomitantly with phenobarbital. Although she was educated about the importance of a backup method of contraception, the woman again became pregnant and delivered twins. A recent national survey of neurologists and obstetricians was conducted evaluating prescriber knowledge of interactions between oral contraceptives and anticonvulsants. Only 4% of neurologists and zero percent of obstetricians knew all the interactions between the six most commonly prescribed anticonvulsants and oral contraceptives. This case supports the importance of continued patient and prescriber education regarding the possibility of drug‐drug interactions in women taking anticonvulsants and hormonal contraceptives.