Oestrogens Hormonal contraceptives

Drugs with endocrinological functions or side-effects are common, but oestrogenic hormones in oral contraceptives are particularly widely used. Pharmaceuticals and their metabolites eventually find their way into the environment, predominantly via excretion into sewage. ... 

World Health Organization Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception. Effect of different progestagens in low oestrogen oral contraceptives on venous thromboembolic disease. Lancet 1995 346(8990) 1582-8. 

Hormonal contraceptives, which use oral oestrogen and/or progesterone, such as combined hormonal contraceptives and progestogen-only contraceptives. 

NEVIRAPINE OESTROGENS -ETHINYLESTRADIOL Marked si contraceptive effect with nevirapine Induction of metabolism of oestrogens Avoid co-administration, recommend alternative non-hormonal contraceptives - barrier methods are necessary to prevent transmission of infection... 

The oral contraceptives are of two main types the combined hormonal contraceptives containing both an oestrogen and a progestogen (monophasic, biphasie, triphasie, or sequential), available as tablets or a patch, and the progestogen-only contraceptives, which are available as tablets (sometimes ealled mini pills), parenteral preparations (implants, depot injections) and intrauterine devices. 

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. 

A possible explanation for the rise in ethinylestradiol levels is that co-tri-moxazole inhibits the liver enzymes concerned with the metabolism of this oestrogen. Broad-spectrum antibacterials might be expected to interrupt the enterohepatic recirculation of ethinylestradiol leading to contraceptive failure, but the evidence that this is clinically important is scant (see also Hormonal contraceptives + Antibacterials Penicillins , p.981). 

Q10 When choosing an oral contraceptive, a preparation with the lowest oestrogen and progestogen content that can control the cycle is selected. In older women or women with a history of venous thrombosis who require contraception, a progestogen-only preparation may be more suitable than the combined hormonal type, but unfortunately this is not a suitable choice for Shabana s problem. 

UGT activity is modulated by various hormones. Excess thyroid hormone and ethinyl oestradiol (but not other oral contraceptives) inhibit bilirubin glucuronidation. In contrast, the combination of progestational and oestrogenic steroids results in increased enzyme activity. Bihrubin glucuronidation can also be inhibited by certain antibiotics (e.g. novobiocin or gentamicin, at serum concentrations exceeding therapeutic levels) and by chronic hepatitis, advanced cirrhosis and Wilson s disease. 

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