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Recommendations for Contraceptive Use |
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Combined Oral Contraceptives (COCs) |
Q.7. Are back-up methods advisable
in the following situations:
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| a) If the client is taking antibiotics?
No - except rifampin or griseofulvin (an antifungal
medication). |
a) Rifampin, rifampicin, and
griseofulvin require use of a back-up method (or increased COC dose if back-up is not
possible) to compensate for hepatic micro-enzyme induction. Hepatic micro-enzyme induction
by rifampin lasts for 4 weeks for short-term use and for 8 weeks for long-term use.
Although anecdotal reports of failure to prevent pregnancy exist for other antibiotics,
epidemiologic evidence suggests that antibiotics (except rifampin and griseofulvin) do not
require a back-up method.
- Orme M, Back DJ. Oral contraceptive
steroids - Pharmacological issues of interest to the prescribing physician. Advances in
Contraception 1991;7: 325-331.
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| b) If the client is taking anticonvulsants
(except valproic acid)? Use of one of the following
may be necessary:
- switch to Depo Provera® or an effective
non-hormonal method;
- a back-up method (for short-term anti-convulsant use);
- higher dose COCs (i.e., 50 mcg ethinyl estradiol (EE), or
two 30 to 35 mcg EE COCs per day for more efficient contraception and/or to produce
regular menses without breakthrough bleeding).
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b) Anticonvulsants include
phenobarbitol/ phenobarbitone, primidone, carbamezepine, and ethosuximide.
Anticonvulsants, except valproic acid, significantly increase liver metabolism of estrogen
and progestins, which decreases the effectiveness of COCs. Taking two 30 to 35 mcg COCs per day will provide adequate estrogen
to compensate for increased metabolism. Levonorgestrel levels are also reduced by
phenytoin (and presumably other anti-epileptics). Therefore, doubling up on COCs which
contain Levonorgestrel is particularly important.
- Orme M, Back DJ. Oral contraceptive
steroids - Pharmacological issues of interest to the prescribing physician. Advances in
Contraception 1991;7:325-331.
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| c) If it is the client's first
cycle of COCs? If she is in the first 7 days of her cycle, but is not menstruating,
some programs may recommend use of a back-up method for 1 week. COCs may be started
anytime you can be reasonably sure the woman is not pregnant (see definition).
However, if COCs are started after day 7 of a regular cycle, the woman should also be
counseled that her regular bleeding pattern may be altered and that additional
contraceptive protection (or abstinence) is needed for the first 7 days. Dispensing a
back-up method, however, especially condoms, is a good idea in case of failures of correct
use, as well as for sexually transmitted disease protection when needed. |
c) The COC effect on cervical
mucus is not as strong as the effect of progestin-only methods. COCs require 7 days to
suppress follicular development.
- Sparrow MJ. Pregnancies in reliable
pill takers. New Zealand Medical Journal 1989;102(879):575-577.
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| d) If the client has missed
pills? Back-up is needed only if 2 or more
pills are missed, and back-up must be used until the client has taken 7 active pills (one
active pill per day for 7 days). |
d) If two or more pills are
missed, a back-up must be used until the client has taken 7 active pills. Missed pills may
occur at the beginning of the cycle (extending the pill-free interval from 7 to 9 days and
perhaps allowing escape ovulation to occur).
- Killick SR, Bancroft K, Oelbaums MJ,
Elstein M. Extending the duration of the pill-free interval during combined oral
contraception. Advances in Contraception 1990;6:33-40.
- Family Health International. New
simplified OC instructions. April 1992.
Seven days of exposure to COCs are required to suppress
follicular development.
- Molloy BG, Coulson KA, Lee JM, Watters
JK. "Missed pill" conception: fact or fiction? British Medical Journal 1985;290:1474-1475.
- Guillebaud J. The forgotten pill - and
the paramount importance of the pill free week. British Journal of Family Planning
1987;12:35-43.
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| e) If the client has diarrhea
and/or vomiting? Back-up may be advisable
whenever vomiting or severe diarrhea occurs within one hour after taking the tablet. If
vomiting or severe diarrhea persists for more than 24 hours (then two pills will have been
missed), a back-up method will be needed (until client has taken one active pill per day
for 7 days). |
e) Acute vomiting and severe
diarrhea may interfere with the effectiveness of the pill. In these cases, a back-up
method is reasonable.
- Orme M, Back DJ. Oral contraceptive
steroids - Pharmacological issues of interest to the prescribing physician. Advances in
Contraception 1991;7:325-331.
- Orme M, Back D, Breckenridge A.
Clinical pharmacokinetics of oral contraceptive steroids. Clinical Pharmacokinetics
1983;8:95-136.
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| f) If the client is taking anti-malarial
medication? No back-up is needed. |
f) Anti-malarials studied to
date have not been found to decrease the efficacy of COCs. Chloroquine and primaquine have
not demonstrated an effect on plasma COC hormonal levels or on ovulation inhibition.
Tetracycline (which is used at low dosage in combination with quinine) has not been found
to compromise the effect of COCs.
- Back DJ, Breckenridge AM, Grimer S,
Orme M, Purba H.Pharmacokinetics of oral contraceptive steroids following the
administration of anti-malarial drugs primaquine and chloroquine.Contraception
1984;30(3):289-295.
- Gupta KC, Joshi JV, Desai NK, Sankolli
GM, Chowdhary VN, Joshi UM, Chitalange S, Satoskar RS.Kinetics of chloroquine and
contraceptive steroids in oral contraceptive users during concurrent chloroquine
prophylaxis.Indian Journal of Medical Research 1984;80:658-662.
- Murphy A, Zacur H, Charache P, Burkman
R.The effect of tetracycline on levels of oral contraceptives.American Journal of
Obstetrics and Gynecology 1991;164:28-32.
- D'Arcy PF.Drug interaction and
reaction:Update:Drug interactions with oral contraceptives.Drug Intelligence and
Clinical Pharmacy 1986;20: 353-362.
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