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Loestrin Fe 1/20 (28) oral

Estrogens; Contraceptives/Rifamycins

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your body may process estrogen faster.

What might happen:

The effects of your birth control pills may decrease and cause breakthrough bleeding, spotting, or pregnancy. The effects of your estrogen replacement therapy may decrease. The effects of the interaction may last for several weeks after you stop taking rifampin.

What you should do about this interaction:

Talk to your healthcare professional (e.g. doctor, pharmacist) as soon as possible about using a different form of birth control. Contact your doctor if you experience breakthrough bleeding, spotting, or pregnancy.If you are taking estrogen-replacement therapy, let your doctor know if you have any menopausal symptoms.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

References:

1.Altschuler SL, Valenteen JW. Amenorrhea following rifampin administration during oral contraceptive use. Obstet Gynecol 1974 Nov;44(5):771-2.
2.Skolnick JL, Stoler BS, Katz DB, Anderson WH. Rifampin, oral contraceptives, and pregnancy. JAMA 1976 Sep 20;236(12):1382.
3.Back DJ, Breckenridge AM, Crawford F, MacIver M, Orme ML, Park BK, Rowe PH, Smith E. The effect of rifampicin on norethisterone pharmacokinetics. Eur J Clin Pharmacol 1979 Apr 17;15(3):193-7.
4.Joshi JV, Joshi UM, Sankolli GM, Gupta K, Rao AP, Hazari K, Sheth UK, Saxena BN. A study of interaction of a low-dose combination oral contraceptive with anti-tubercular drugs. Contraception 1980 Jun; 21(6):617-29.
5.Back DJ, Breckenridge AM, Crawford FE, Hall JM, MacIver M, Orme ML, Rowe PH, Smith E, Watts MJ. The effect of rifampicin on the pharmacokinetics of ethynylestradiol in women. Contraception 1980 Feb;21(2):135-43.
6.Gupta KC, Ali MY. Failure of oral contraceptive with rifampicin. Med J Zambia 1980 Dec-1981 Jan;15(1):23.
7.Baciewicz AM, Self TH. Rifampin drug interactions. Arch Intern Med 1984 Aug;144(8):1667-71.
8.Barnett ML. Inhibition of oral contraceptive effectiveness by concurrent antibiotic administration. A review. J Periodontol 1985 Jan;56(1):18-20.
9.Baciewicz AM. Oral contraceptive drug interactions. Ther Drug Monit 1985; 7(1):26-35.
10.Szoka PR, Edgren RA. Drug interactions with oral contraceptives: compilation and analysis of an adverse experience report database. Fertil Steril 1988 May;49(5 Suppl 2):31S-38S.
11.Nor-Q-D (norethindrone) US prescribing information. WatsonPharma March, 2005.
12.Barditch-Crovo P, Trapnell CB, Ette E, Zacur HA, Coresh J, Rocco LE, Hendrix CW, Flexner C. The effects of rifampin and rifabutin on the pharmacokinetics and pharmacodynamics of a combination oral contraceptive. Clin Pharmacol Ther 1999 Apr;65(4):428-38.
13.LeBel M, Masson E, Guilbert E, Colborn D, Paquet F, Allard S, Vallee F, Narang PK. Effects of rifabutin and rifampicin on the pharmacokinetics of ethinylestradiol and norethindrone. J Clin Pharmacol 1998 Nov; 38(11):1042-50.
14.Buss WC. Induction of hepatic drug metabolizing enzymes and pregnancy while taking oral contraceptives. J Antimicrob Chemother 1979 Jan; 5(1):4-5.
15.Gelbke HP, Gethmann U, Knuppen R. Influence of rifampicin treatment on the metabolic fate of. Horm Metab Res 1977 Sep;9(5):415-9.
16.Bolt HM, Bolt M, Kappus H. Interaction of rifampicin treatment with pharmacokinetics and metabolism of ethinyloestradiol in man. Acta Endocrinol (Copenh) 1977 May;85(1):189-197.
17.Bessot JC, Vandevenne A, Petitjean R, Burghard G. Antagonistic action of rifampicin and isoniazid on the metabolism of oral contraceptives. Nouv Presse Med 1977 Apr 30;6(18):1568.
18.Dommisse J. Letter: Oral contraceptive failure due to drug interaction. S Afr Med J 1976 May 15;50(21):796.
19.Bolt HM, Kappus H, Bolt M. Effect of rifampicin treatment on the metabolism of oestradiol and 17alpha-ethinyloestradiol by human liver microsomes. Eur J Clin Pharmacol 1975 Jun 13;8(5):301-7.
20.Priftin (rifapentine) US prescribing information. Sanofi-Aventis U.S. LLC July, 2010.

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