When to use backup with OCs? Tips from our board
Are you curious about when backup is required when switching birth control pills? How about when switching antibiotic therapy?
Contraceptive Technology Update reader Eileen Swanson, RN, recently filed these questions with the publication. A registered nurse with Kansas State University’s Lafene Student Health Center in Manhattan, KS, Swanson was seeking answers to aid the center’s medical staff in developing a consistent protocol.
Four members of CTU’s editorial advisory board participated in the response: Andrew Kaunitz, MD, professor and assistant chair in the Department of OB/GYN at the University of Florida Health Sciences Center in Jacksonville; Anita Nelson, MD, medical director of the Women’s Health Care Program at Harbor-UCLA Medical Center in Torrance, CA; Michael Rosenberg, MD, MPH, clinical associate professor of OB/GYN and Epidemiology at the University of North Carolina at Chapel Hill and president of Health Decisions, a private research firm; and Sharon Schnare, FNP, CNM, a Seattle-based family planning clinician and consultant.
Q. When is backup required when switching birth control pills?
Kaunitz: If no pills are missed, no backup is needed.
Nelson: There is no need for a backup method when switching between brands outside the routine situations that would require a backup method. For example, if a patient is late starting her oral contraceptives (OCs), she needs to use a backup method for seven days. If she forgets one of her first seven pills, she needs to use a backup method for seven days. If she misses more than seven pills after the first week, she needs to use a backup for the rest of the cycle. (Nelson cites Contraception: Your Questions Answered1 by John Guillebaud, MA, FRCSE, FRCOG, in posing this comment. See reference at end of article.)
Rosenberg: When switching OCs, as in from one brand or type to another, no backup is needed. Just remember to take all the pills from one cycle, then start the following cycle from the first pack.
Schnare: A backup method is not required when patients switch from one combination pill brand to another, as long as there are no breaks in pill-taking continuity and no extension of the pill-free interval and no pills have been missed during the preceding cycle. It is essential that the pill-free interval not be extended, because, according to Guillebaud, up to 30% of women may ovulate if the pill-free interval is extended two or more days.
I usually switch patients to different types of oral contraceptives in this way: Have the patient start a new brand of pills on the first day of the pill-free interval. She will have withdrawal bleeding at the next interval. This timing will work whether you are switching the patient from a higher to a lower dose or vice versa. This timing works just as well when switching to triphasics or monophasics or progestin-only pills. If the patient wants to switch brands immediately within the midcycle from a higher to a lower dose pill, I simply switch brands and have her use a backup method for two weeks.
I always discuss and promote condom use with patients for sexually transmitted infection prevention, as well as to increase the effectiveness of methods.
Q. When is a backup required in switching antibiotic therapy?
Kaunitz: Kaunitz refers to a section of the October 1994 technical bulletin, Hormonal Contraception, released by the American College of Obstetricians and Gynecologists of Washington, DC.2 The section on concomitant medications states:
"Anticonvulsants and antibiotics that induce hepatic enzymes (phenytoin, phenobarbital, carbamazepine, primidone, and rifampin) can reduce the contraceptive efficacy of OCs and implants."3,4
"Pharmacokinetic studies suggest that the anticonvulsant valproic acid and the antibiotics doxycycline and tetracycline do not appear to reduce OC efficacy and presumably do not impair implant efficacy."5,6,7
Nelson: There is no need for barrier methods to be used with antibiotic therapy unless the antibiotic induces vomiting or diarrhea, which reduces sex steroid absorption, or unless the patient is using rifampin or griseofulvin.
Rosenberg: I presume this question means "using" rather than switching antibiotics. The rule of thumb that I follow (recognizing that it’s an oversimplification) is to try to take OCs at least four hours apart from antibiotics, in which case no backup is required. Otherwise for example, if OCs and antibiotics are used at the same time, as may be the case for a QID preparation use a backup for the rest of that cycle. This is pretty conservative, but I have found it simple enough to follow easily.
Schnare: Some antibiotics may decrease the contraceptive effect of combination OCs by increasing the liver metabolism of OCs. Antibiotics that may decrease combination OC effectiveness are listed in Contraceptive Technology and include rifampin.8
Rifampin clearly increases the clearance of OCs; however, the use of backup methods is controversial with ampicillin and tetracycline. I suggest using a backup method to maintain the highest efficacy possible for the patient. I would rather err on the side of prevention.
Concomitant use of these antibiotics, especially rifampin, with OCs is possible by increasing the OC dose to 50 mcg or by having the patient delete the pill-free interval, or "tricycling," according to Guillebaud. A backup method also may be used during the course of antibiotic therapy. The patient also may switch to another method of contraception (DMPA, IUD, spermicides and condoms, cervical cap, or diaphragm). If breakthrough bleeding occurs during OC and antibiotic use, this may suggest breakthrough ovulation and the need to use a backup method or switch to another contraceptive method.
References
1. Guillebaud J. Contraception: Your Questions Answered. New York, NY: Pitman; 1985.
2. American College of Obstetricians and Gynecologists. Hormonal Contraception. ACOG Technical Bulletin 198. Washington, DC; 1994.
3. Back DJ, Orme ML’E. Pharmacokinetic drug interactions with oral contraceptives. Clin Pharmacokinet 1990; 18:472-484.
4. Haukkamaa M. Contraception by Norplant subdermal capsules is not reliable in epileptic patients on anti- convulsant treatment. Contraception 1986; 33:559-565.
5. Crawford P, Chadwick D, Cleland P, et al. The lack of effect of sodium valproate on the pharmacokinetics of oral contraceptive steroids. Contraception 1986; 33:23-29.
6. Neely JL, Abate M, Swinker M, et al. The effect of doxycycline on serum levels of ethinyl estradiol, norethindrone, and endogenous progesterone. Obstet Gynecol 1991; 77:416-420.
7. Murphy AA, Zacur HA, Charache P, et al. The effect of tetracycline on levels of oral contraceptives. Am J Obstet Gynecol 1991; 164:28-33.
8. Hatcher RA, Trussell J, Stewart F, et al. Contraceptive Technology. New York, NY: Irvington; 1994.
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