Oestrogens Rifampicin

LAMOTRIGINE 1. ANTIBIOTICS -rifampicin 2. OESTROGENS 3. PROGESTOGENS 1 lamotrigine levels t metabolism Monitor levels... 

RIFAMPICIN, RIFABUTIN OESTROGENS Marked 1 contraceptive effect Induction of metabolism of oestrogens Advise patients to use additional contraception for the period of intake and for 1 month after stopping co-administration of these drugs (4-8 weeks after stopping rifabutin or rifampicin)... 

Levonorgestrel is metabolised to inactive substances before it is conjugated, and does not therefore undergo enterohepatic recycling of the active moiety. There is no reason to expect that its efficacy as an emergency contraceptive would be affected by antibacterials that alter gut flora and do not induce liver enzymes. No special precautions are necessary with these antibacterials. However, rifampicin and rifabutin are likely to reduce the efficacy of most forms of hormonal contraceptives, as they induce the metabolism of oestrogens and progestagens, see Hormonal contraceptives + Rifamycins , p. 1001. 

Reimers D, Nocke-Finck L, Breuer H. Rifampicin causes a lowering in efficacy of oral contraceptives by influencing oestrogen excretion. Reports on Rifampicin XXII International Tuberculosis Conference, Tokyo, September 1973, 87-9. 

Effects of rifampicin on the menstrual cycle and on oestrogen excretion in patients taking oral contraceptives. Dtsch. med. Wschr., 98, 1521. 

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