Do Anticonvulsants Reduce the Efficacy of Oral Contraceptives?

Epilepsia (Impact Factor: 4.57). 11/1979; 20(5):519-25. DOI: 10.1111/j.1528-1157.1979.tb04834.x
Source: PubMed


Women in our area with epilepsy who were also taking oral contraceptives were identified. Of 82 patients taking oral contraceptives, 41 had used both anticonvulsants and oral contraceptives for a total of 955 months. Three documented oral contraceptive (pill) failures occurred during this period, whereas the expected number was 0.12 (relative risk, 25; 95% confidence interval, 5 to 73). No pill failures were observed in 2,278 months among women with epilepsy who were taking oral contraceptives but who were not taking anticonvulsants at this time. Thus our data support the suggestion that there is an increased rate of pill failure among women taking anticonvulsants. In view of this diminished effectiveness, the advisability of using oral contraceptives rather than one of the other forms of contraception when anticonvulsant medication is being used concurrently may need to be reevaluated.
Les femmes épileptiques de notre région qui utilisent un contraceptif oral ont été recensées. La moitié D'entre elles (41 sur 82) ont utilisé la pilule associée à des anticonvulsivants pour un total de 955 mois. Trois échecs de la contraception ont été observés pendant cette période au lieu du chiffre 0.12 qui était prévisible. Aucun échec de la pilule n'a été observé pour un total de 2,278 mois chez les femmes épileptiques qui utilisaient la pilule mais ne prenaient pas D'antiépileptiques. Ces données confirment L'opinion suivant laquelle les échecs de la pilule sont plus fréquents parmi les femmes qui utilisent des anticonvulsivants. Dans ces conditions il convient D'envisager à nouveau les indications de la pilule plutôt que D'autres formes de contraception chez les femmes qui recoivent des anticonvulsivants.
Se nan identificado en nuestra zona de epilepsía las mujeres que, además, tomaban contraceptivos orales. De 82 enfermas que los tomaban, 41 los habían combinado con anticonvulsivos durante un total de 955 meses. Se registraron 3 fallos bien docu-mentados el del anticonceptivo (píldora) durante este periodo de tiempo, mientras que el número previsto era de 0.12 (riesgo relativo, 25; 95% intervalo de confianza, 5 a 73): No existieron fallos en 2,278 meses en las mujeres con epilepsía que tomaban anticoncep-tivos orales pero que no tomaban anticonvulsivos en ese momento. Asi pues, nuestra información apoya la sugerencia de que existe un aumento del fallo de la pildora en las mujeres que toman anticonvulsivos. En vista de esta reducción de efectividad, se estima que la sugerencia de utilización de anticonceptivos orales en vez de otras formas de concentración cuando se toman, simultáneamente, anticonceptivos, debe ser reconsiderada.
Im Einzugsgebiet der Klinik wurden Frauen mit Epilepsien gesucht, die auch orale Contraceptiva nahmen. Von 82 Patienten mit oralen Contraceptiva benutzten 41 sowohl Antikonvulsiva als Contraceptiva far einen Gesamtzeitraum von 955 Monaten. Während dieser Periode versagte die orale Contraception 3mal; die Erwartungsrate betrug 0.12 (relatives Risoko 25; 95% Vertrauensgrenzen: 5–73). Kein Versagen der Pille wurde während 2,278 Monaten beobachtet, die von Frauen mit Epilepsie gewonnen wurden, die wohl orale Contraceptiva aber keine Antikonvulsiva während dieser Zeit eingenommen haben. Damit unterstützt unsere Beobachtung die Meinung, daß bei Frauen unter antikonvulsiver Therapie eine höhere Versagensagensrate der Pille zu erwarten ist. An-gesichts dieser verminderten Wirksamkeit muß erneut überprüft werden, ob es ratsam ist, orale Contraceptiva zu empfehlen anstelle einer der anderen Möglichkeiten der Contraception, solange antikonvulsive Medikation verordnet wird.

1 Follower
10 Reads
  • Source
    • "As a result of case reports and clinical studies (Kenyon, 1972; Hempel et al., 1973; Janz & Schmidt, 1974; Gagnaire et al., 1975; Coulam & Annegers, 1979; Diamond et al., 1985; Mattson et al., 1986) the potential for a number of antiepileptic drugs to interact adversely with oral contraceptives (OCS) has been widely recognised. Most reports have concerned phenytoin, phenobarbitone , carbamazepine and primidone which are all recognised as inducers of hepatic microsomal drug metabolising enzymes in man (Park & Breckenridge, 1981). "
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. We have searched the adverse reactions register for the years 1968-84 in an attempt to evaluate data relating to reported pregnancies in women on oral contraceptive steroids (OCS) who concurrently received either an antiepileptic drug or an antibiotic. 2. A total of 43 pregnancies were reported in women on OC therapy who concurrently received antiepileptic drugs and 63 pregnancies in women receiving antibiotics. In addition the number of prescriptions for both antiepileptics and antibiotics in England are reported for the years 1973-84.
    Full-text · Article · Jun 1988 · British Journal of Clinical Pharmacology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Drug interactions with phenytoin are a frequent occurrence, although their clinical relevance has often been overemphasised. Probably the most important of such interactions are those resulting in inhibition of phenytoin metabolism: due to the saturable nature of phenytoin biotransformation even minor degrees of inhibition can produce disproportionate changes in both steady-state serum concentration and the magnitude of pharmacological effect. Phenytoin has marked enzyme-inducing properties and can stimulate the metabolism of many concurrently administered drugs, thereby reducing their therapeutic efficacy. Clinically important examples of such interactions include a reduction of the anticoagulant effect of dicoumarol, a decrease in the prophylactic efficacy of the contraceptive pill and failure of response to various corticosteroid agents when administered therapeutically or diagnostically. Unless complicated by additional mechanisms, plasma protein binding interactions with phenytoin are seldom of clinical significance. However, they may alter considerably the relationship between serum drug concentration and clinical response, a possibility which needs to be taken into account when interpreting serum phenytoin levels in clinical practice.
    No preview · Article · Aug 1980 · Medizinische Monatsschrift für Pharmazeuten

  • No preview · Article · Oct 1980 · Journal of Obstetrics and Gynaecology
Show more