Contraceptives interaction with other drugs

Interactions of Oral Contraceptives (PCs) with Other Drugs... 

The contraceptive efficacy of depot medroxyprogesterone acetate does not appear to be affected by interactions with other drugs some interactions are known (6), but the doses used for contraceptive purposes are sufficient to remain effective even if metabolism is increased, for example by aminoglutethimide or phenytoin. 

These batteries of preclinical tests will often generate questions that can only be answered by studying potential interactions in humans. Understanding whether a new drug will interact with other drugs that are likely to be co-prescribed for the disease of interest is essential for good product labeling. Oral contraceptives are used by about 50% of women in their reproductive years in the developed world, and must always be considered as a concomitant medication. 

Drug Interactions. Lamotrigine does not inhibit or induce liver enzymes and has a low potential for pharmacokinetic interactions with other drugs. Lamotrigine does not interfere with oral contraceptives. 

St John s wort may help in mild/moderate depression, but advise caution preparations often have unclear doses and can interact with other drugs, e.g. oral contraceptives, anticoagulants, anticonvulsants. 

The study described above did not study interactions with other active components of oral contraceptives whose pharmacokinetics could also be altered by concomitant dosing with Drug XYZ. 

Pharmacokinetics. Carbamazepine is extensively metabolised one of the main products, an epoxide (a chemically reactive form), has anticonvulsant activity similar to that of the parent drug but may also cause some of its adverse effects. The t) of carbamazepine falls from 35 h to 20 h over the first few weeks of therapy due to induction of hepatic enzymes that metabolise it as well as other drugs, including corticosteroids (adrenal and contraceptive), theophylline and warfarin. Cimetidine and valproate inhibit its metabolism. There are complex interactions with other antiepilepsy drugs, which constitute a reason for monodrug therapy. 

Drug Interactions. Levetiracetam neither inhibits nor indnces the CYP450, UGT, or epoxide hydrolase enzyme systems, and in vitro data predict a low potential for pharmacokinetic interactions. Levetiracetam does not appear to interact with other AEDs, warfarin, digoxin, or oral contraceptive drngs. ° ... 

Interactions in which oral contraceptives interfere with the metabolism of other drugs... 

Sulfonylureas In acute poisoning with sulfonylureas, the stomach should be washed and treated with activated charcoal, and hypoglycemia must be treated. Sulfonylureas interact with oral contraceptives, thiazide diuretics, corticosteroids, adrenaline, chlorpromazine, ACE inhibitors, some NSAIDs, antihistamines, anticoagulants, MAOIs, antidepressants, and many other drugs. Care must be exercised when treating with sulfonylureas. 

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