Is a gestagen, without estrogen added, an option for oral contraception in a woman with warfarin tr

Fråga: Is a gestagen, without estrogen added, an option for oral contraception in a woman with warfarin treated pulmonary embolism? A 34-year-old woman, with one child, had a pulmonary embolus recently, but is otherwise healthy. She is treated with warfarin since three months and will continue for another three months. Hormonal contraception is being considered. Are gestagens the best choice for this patient during and after warfarin treatment?

Sammanfattning: For this patient, with a history of pulmonary emboli and ongoing warfarin treatment, hormonal contraceptives are not the first line choice. Instead mechanical contraceptive methods should be used. If these methods not are accepted, hormonal contraceptives containing only gestagens should be chosen but profound menstrual bleedings may occur. When the patient has finished the warfarin treatment primary gestagens may be chosen. Combined oral contraceptives are, for this patient without anticoagulation therapy, contraindicated.

Svar: Women subject to oral contraception have a higher incidence of deep venous thromboses, pulmonary emboli and cerebral thromboses than women using other methods of contraception. The elevated risk of thrombosis is generally ascribed to the estrogen component (1, 2, 6). Gestagens have not been shown to have any effects on the coagulation system or on the prevalence of thrombosis (4). Therefore combined oral contraceptives are contradicted in patients with a medical history of thromboembolism (1). However, in combined oral contraceptives the progesterones might exert a modifying effect on the estrogens (2). An oral contraceptive containing only gestagens is therefore an alternative in this case (1, 3, 7). If there is a distinct heredity for thromboembolic disease also gestagen contraceptives should be avoided (5, 8). A relatively common adverse event of gestagens are spottings. For patients treated with warfarin these bleedings may be more profound (1). Therefore oral contraceptives containing only gestagens are not the ideal contraceptive method for warfarin treated women with pronounced menstruation bleedings. From a pharmacokinetic point of view, the risk of an interaction between gestagens and warfarin should be considered. A literature search failed to reveal any literature supporting the existence of such an interaction.

Thirty-one cases of circulatory adverse events have been reported to SADRAC (The Swedish Adverse Drug Reactions Advisory Committee). Fifteen were of thromboembolic origin, seven of these were judged as at least possibly related to the progesterone containing oral contraceptives. Out of these seven adverse events of thromboembolic origin, four were concerning deep venous thrombosis in the leg, two pulmonary emboli and one venous thrombosis in general. Six of these seven adverse events were reported during the 1970s and beginning of 1980s (9).