<p><strong>Interaction with laboratory tests</strong>: The use of sex steroids may influence biochemical parameters of, for example, liver, thyroid, adrenal and renal function, plasma levels of (carrier) proteins such as corticosteroid-binding globulin and lipid/lipoprotein fractions, parameters of carbohydrate metabolism, and parameters of coagulation and fibrinolysis.<br />
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<strong>Interactions with other medicines</strong>: Long-term treatment with hepatic enzyme-inducing drugs (e.g. several anticonvulsants and antimicrobials) can increase the clearance of sex hormones and may reduce clinical efficacy. Such hepatic enzyme-inducing properties have been established for hydantoins, barbiturates, primidone, carbamazepine, and rifampicin and are also suspected for oxcarbazepine, topiramate, felbamate, griseofulvin and the herbal remedy St John&rsquo;s Wort (hypericum perforatum). Maximal enzyme induction is generally not seen before 2-3 weeks but may be sustained for at least 4 weeks after cessation of drug therapy. In rare cases, reduced oestradiol levels have been observed under the simultaneous use of certain antibiotics (e.g. penicillins and tetracycline). Substances which undergo substantial conjugation (e.g. paracetamol) may increase the bioavailability of oestradiol by competitive inhibition of the conjugation system during absorption. In individual cases, the requirement for oral antidiabetics or insulin can change as a result of the effect on glucose tolerance.</p>