BNF for Children 2011-2012

398 7.3.1 Combined hormonal contraceptives BNFC 2011–20127 Obstetrics, gynaecology, and urinary-tract disorderspersistent vomiting or severe diarrhoea lasting morethan 24 hours, additional precautions should be usedduring and for 7 days (9 days for Qlaira c ) after recovery(see also under Missed pill, above). If the vomiting anddiarrhoea occurs during the last 7 tablets, the next pillfreeinterval should be omitted (in the case of ED tabletsthe inactive ones should be omitted).Interactions The effectiveness of combined oralcontraceptives, progestogen-only oral contraceptives(section 7.3.2.1), contraceptive patches, and vaginalrings can be considerably reduced by interaction withdrugs that induce hepatic enzyme activity (e.g. carbamazepine,modafinil, nelfinavir, nevirapine, oxcarbazepine,phenytoin, phenobarbital, primidone, ritonavir,St John’s Wort, topiramate, and, above all,rifabutin and rifampicin). A condom together with along-acting method, such as an injectable contraceptive,may be more suitable for patients with HIV infection orat risk of HIV infection; advice on the possibility ofinteraction with antiretroviral drugs should be soughtfrom HIV specialists.Women taking combined hormonal contraceptives whorequire enzyme-inducing drugs should be advised tochange to a contraceptive method that is unaffected byenzyme-inducers (e.g. some parenteral progestogenonlycontraceptives (p. 404), intra-uterine devices) forthe duration of treatment and for 4 weeks after stopping.If a change in contraceptive method is undesirable orinappropriate the following options should be discussed:. For a short course (2 months or less) of an enzymeinducingdrug (except rifampicin or rifabutin—seebelow), continue with a combined oral contraceptiveproviding ethinylestradiol 30 micrograms dailyand use a ‘tricycling’ regimen (i.e. taking 3 packetsof monophasic tablets without a break followed by ashortened tablet-free interval of 4 days [unlicenseduse]. Additional contraceptive precautions shouldalso be used whilst taking the enzyme-inducingdrug and for 4 weeks after stopping. Another optionis to follow the advice for long-term courses below.For women using combined hormonal contraceptivepatches or vaginal rings, additional contraceptiveprecautions are also required whilst taking theenzyme-inducing drug and for 4 weeks after stopping.If concomitant administration runs beyond the3 weeks of patch or vaginal ring use, a new treatmentcycle should be started immediately, without apatch-free or ring-free break.. For a long-term course (over 2 months) of anenzyme-inducing drug (except rifampicin or rifabutin—seebelow), adjust the dose of combined oralcontraceptive to provide at least ethinylestradiol50 micrograms daily [unlicensed use] and use a‘tricycling’ regimen (as above); continue for theduration of treatment with the enzyme-inducingdrug and for 4 weeks after stopping.If breakthrough bleeding occurs (and all othercauses are ruled out) it is recommended that thedose of ethinylestradiol is increased by incrementsof 10 micrograms up to a maximum of 70 microgramsdaily [unlicensed use], or to use additionalprecautions, or to change to a method unaffected byenzyme-inducing drugs.Contraceptive patches and vaginal rings are notrecommended for women taking enzyme-inducingdrugs over a long period.. For any course of rifampicin or rifabutin, an alternativemethod of contraception (such as an IUD) isalways recommended because they are suchpotent enzyme-inducing drugs. Since enzyme activitydoes not return to normal for several weeks afterstopping an enzyme-inducing drug, appropriatecontraceptive measures are required for 4 to 8weeks after stopping.Latest recommendations are that no additional contraceptiveprecautions are required when combined oralcontraceptives are used with antibacterials that do notinduce liver enzymes (e.g. ampicillin, doxycycline),unless diarrhoea or vomiting occur (see above)It is also recommended that no additional contraceptiveprecautions are required when contraceptive patches orvaginal rings are used with antibacterials that do notinduce liver enzymes. There have been concerns thatsome antibacterials that do not induce liver enzymesreduce the efficacy of combined oral contraceptives byimpairing the bacterial flora responsible for recyclingethinylestradiol from the large bowel; however, there isa lack of evidence to support this interaction.For information on interactions of oral progestogen-onlycontraceptives, see also p. 403; for information on interactionsof parenteral progestogen-only contraceptives,see also p. 404; for information on interactions of theintra-uterine progestogen-only device, see also p. 405;for information on interactions of hormonal emergencycontraception, see also p. 408.Surgery Oestrogen-containing contraceptives shouldpreferably be discontinued (and adequate alternativecontraceptive arrangements made) 4 weeks beforemajor elective surgery and all surgery to the legs orsurgery which involves prolonged immobilisation of alower limb; they should normally be recommenced atthe first menses occurring at least 2 weeks after fullmobilisation. A progestogen-only contraceptive may beoffered as an alternative and the oestrogen-containingcontraceptive restarted after mobilisation, as above.When discontinuation of an oestrogen-containing contraceptiveis not possible, e.g. after trauma or if a patientadmitted for an elective procedure is still on an oestrogen-containingcontraceptive, thromboprophylaxis(with unfractionated or low molecular weight heparinand graduated compression hosiery) is advised. Theserecommendations do not apply to minor surgery withshort duration of anaesthesia, e.g. laparoscopic sterilisationor tooth extraction, or to women using oestrogenfreehormonal contraceptives.Reason to stop immediately Combined hormonalcontraceptives should be stopped (pending investigationand treatment), if any of the following occur:. sudden severe chest pain (even if not radiating to leftarm);. sudden breathlessness (or cough with blood-stainedsputum);. unexplained swelling or severe pain in calf of one leg;. severe stomach pain;. serious neurological effects including unusual severe,prolonged headache especially if first time or gettingprogressively worse or sudden partial or complete lossof vision or sudden disturbance of hearing or otherperceptual disorders or dysphasia or bad fainting attackor collapse or first unexplained epileptic seizure or