Contraceptive patch, efficacy

As the LNG-IUD has a local contraceptive action progestogenic interactions are less likely to occur. The efficacy of the contraceptive patch may be reduced by enzyme-inducing drugs [3, 11, 19]. 

A combination contraceptive is available as a transdermal patch (Ortho Evra), which may have improved adherence compared to OCs. Efficacy seems to be compromised in women over 198 lb (90 kg). The patch should be applied to the abdomen, buttocks, upper torso, or upper arm at the beginning of the menstrual cycle and replaced every week for 3 weeks. 

A new combination contraceptive is available as a transdermal patch (Ortho Evra), which includes 0.75 mg EE and 6 mg norelgestromin, the active metabolite of norgestimate. In comparative trials, it has been shown to be as effective as combined OCs. Of the 15 pregnancies reported with the patch, 5 were among women with a baseline weight of greater than 90 kg, so efficacy may be compromised as weight increases. Some patients experience application-site reactions, but other side effects are similar to OCs (i.e., breast discomfort, headache, nausea, and menstrual cramps). 

Not established. The pharmaeokinetie and pharmacodynamic evidence in-dieates that eo-trimoxazole is not likely to reduce the effectiveness of combined oral eontraeeptives. Although there are a number of reports of contraceptive failure attributed to co-trimoxazole, these are anecdotal and unconfirmed, whereas the studies suggest increased contraceptive efficacy (but see below). It is possible that the cases are coincidental, and fit within the normal failure rate of combined oral contraceptives. The UK Family Planning Authority considered that it was almost certain that co-trimoxazole and sulphonamides did not interact with combined oral contraceptives. However, the Faculty of Family Planning and Reproductive Health Care (FFPRHC) Clinical Effectiveness Unit has issued guidance on the use of antibacterials with hormonal contraceptives. Although they recognise that there is poor evidence for contraceptive failure, they recommend that additional contraceptives, such as condoms, should be used for short courses of antibacterials, see Hormonal contraceptives + Antibacterials Penicillins , p.981, for more detailed information. This applies to both the oral and the patch form of the combined contraceptive. This advice has usually been applied to only broad-spectrum antibacterials that do not induce liver enzymes but the FFPRHC notes that some confusion has occurred over which antibacterials are considered to be broad-spectrum , and thus they recommend that this advice is applied to all antibacterials that do not induce liver enzymes, which would include co-trimoxazole, sulfonamides and trimethoprim. ... 

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