To evaluate physician and pharmacist knowledge on potential drug
interactions between combined oral contraceptives (COC) and broad-spectrum
antibiotics and determine if any difference exists between responses.
Methods: Two hundred licensed retail pharmacists and 200 licensed
family practice physicians in the states of Virginia, West Virginia,
and Maryland were mailed an anonymous survey between August 2007
and November 2007. The survey consisted of 3 short questions asking
practitioners about their current opinion on drug interactions
with COCs and whether an alternative form of contraception is
needed for patients taking COC and concomitant broad-spectrum
antibiotics. The main outcome measure of the survey included:
identifying how physicians and pharmacists handle prescribing
or dispensing COCs along with broad-spectrum antibiotics. Gender,
educational degree, and years in practice were also collected.
Results: A total of 182 participants returned the surveys (57%
were physicians and 43% were pharmacists). When asked if broad-spectrum
antibiotics have a clinically significant interaction with COCs,
82.7% of physicians and 88.5% of pharmacists answered, “yes”.
Of the respondents, 84.6% stated that the drug interaction warrants
the patient to be advised to use back-up contraception. A total
of 90.1% stated that they currently instruct patients to use back-up
contraception when prescribing or dispensing antibiotics to a
patient who is on COC, with no statistically significant difference
existing between the responses of the pharmacists and the physicians.
Conclusion: Physicians and pharmacists believe that broad-spectrum
antibiotics decrease the effectiveness of COCs. These practitioners
warn their patients of this interaction and advise the use of
back-up contraception. More education should be provided to practitioners
regarding the data concerning COCs and broad spectrum antibiotics
and lack of a proven interaction.