Antibiotics and oral contraceptives: new considerations for dental practice

changes in advice that should be given to VERIFIABLE CPD PAPER
The aim of this paper is to highlight a change in guidance relating to possible interactions between antibiotics and oral contraceptives. Until recently, dentists have been advised to warn women taking the combined oral contraceptive pill of the routine need to use additional contraceptive measures while taking courses of broad spectrum antibiotics. Recent guid-ance relating to this issue has changed and dentists may not be aware of this. This paper reminds dentists of the previous guidelines and related evidence, reviews the pharmacokinetics of hormonal contraception and presents them with the latest evidence-based guidance. This should change their clinical practice.
CLINICAL SCENARIO
prescribed to them may interfere with the contraceptive effects of the combined oral contraceptive pill and that additional con- tal periapical infection associated with traceptive methods should be used while the upper left first premolar. You obtain taking the antibiotics and for seven days contraception is available as an oral pill, drainage by accessing the root canal, after stopping.1 This advice was based on however, due to the facial swelling and our understanding at the time and further oral pills may be taken on a 21 day cycle the patient’s associated malaise and publications reminded dentists of their with a 7 day break or taken continuously. reported pyrexia, you prescribe 500 mg professional obligations in this area and The progestogen-only contraceptive is amoxicillin to be taken three times a day the possible medico-legal implications of available as an oral pill, an intramuscu- for five days. Her medical history reveals not following current guidance.2 Various she is taking the contraceptive pill. What mechanisms for delivering the advice to terine device. The progestogen-only oral patients, including a patient information pills are taken on a continuous basis and PREVIOUS RECOMMENDATIONS
HORMONAL CONTRACEPTION
trial lining. They are usually used when nario faced by dentists on a daily basis There are two main types of hormonal oestrogens are contra-indicated.
and has been for many years. In 1994, contraception. These are the combined the British Dental Journal published a hormonal contraceptive and the pro- paper reviewing the possible interactions gestogen-only contraceptive. Combined combined oral contraceptive in the UK.3 tives emphasising the need for dentists to trogen and a progestogen component. according to instructions.4 follow current national guidelines as part Factors affecting the reliability of oral of good dental practice.1 At the time the gestogen is fixed they are know as ‘mono- guidance was that as a dentist you needed phasic’. When the amount of hormone 1. Diarrhoea and vomiting: vomiting to warn the patient that the antibiotics varies according to the stage of cycle, they are known as ‘phasic.’ The oestro- gen component is usually ethinylestradiol Specialist Registrar in Oral Medicine; 2Consultant in Oral Medicine, Department of Oral Medicine, University Dental Hospital of Manchester, Higher Cambridge Refereed Paper
Accepted 15 March 2012
DOI: 10.1038/sj.bdj.2012.414
British Dental Journal 2012; 212: 481-483
BRITISH DENTAL JOURNAL VOLUME 212 NO. 10 MAY 26 2012
2012 Macmillan Publishers Limited. All rights reserved. PRACTICE
Table 1 Enzyme-inducing and non-enzyme-inducing antibiotics
illness and for a period of time after recovery5 Enzyme-inducing antibiotics
Non-enzyme-inducing antibiotics
component. Oral ethinylestradiol is absorbed from the small intestine in the British Dental Journal in 2011 Absorption
antibacterial drugs prescribed by dentists in Wales. Other antimicrobials prescribed included clindamycin, macrolides and tet- racyclines.9 In dentistry, enzyme-inducing Metabolism (first pass)
antibiotics appear to be only very rarely used if at all, hence interactions of com- inducing antibiotics is unlikely to be a The most important hepatic enzyme is cytochrome p-450 mixed function CURRENT RECOMMENDATIONS
Large Intestine
ENTEROHEPATIC CIRCULATION
ics. Several studies and trials have looked at levels of ethinylestradiol in patients rifabutin) are the only antibiotics that pill (COCP) and antibiotics and have not found decreased levels of ethinylestradiol Medical eligibility criteria for contracep- Fig. 1 Metabolism of oral contraceptives
tive use in 2010 to include evidence-based CONCLUSION
interactions.14 On the basis of this, in The recent change in the evidence base January 2011 the Clinical Effectiveness has implications for dentistry. When pre- Unit of the Faculty of Sexual and scribing non-enzyme-inducing antibiot- Reproductive Healthcare (Royal College ics to patients using combined hormonal of Obstetricians and Gynaecologists) contraception, the current guidance is that produced new clinical guidance which there is now no need to tell patients that now states that ‘additional contracep- they should use additional contraceptive tive precautions are not required even methods while they take the antibiotics. for short courses of antibiotics that For patients on any form of oral contra- are not enzyme inducers when taken ception, however, the guidance remains with combined oral contraception’.6 that they should be aware that additional This new advice has been incorporated contraceptive precautions are needed into the guidance given in the British should they suffer diarrhoea or vomiting National Formulary.5 as a result of their illness or as a side effect ANTIBIOTICS AND DENTISTRY
If the antibiotics (or indeed the illness) of the antibiotics.
In 2010, general dental practitioners in should cause diarrhoea or vomiting, then England prescribed over 3.8 million items the usual additional precautions relating to under the infections chapter of the British these conditions should be observed.
implications for dental practitioners.
BRITISH DENTAL JOURNAL VOLUME 212 NO. 10 MAY 26 2012
2012 Macmillan Publishers Limited. All rights reserved. PRACTICE
1. Gibson J, McGowan D A. Oral contraceptives and clinical guidance: drug interactions with hormonal 11. Abrams L S, Skee D M, Natarajan J, Hutman W, antibiotics: important considerations for dental contraception. London: Royal College of Wong F A. Tetracycline HCL does not affect the practice. Br Dent J 1994; 177: 419–422.
Obstetricians and Gynaecologists, 2011.
pharmakokinetics of a contraceptive patch. Int J 2. Stephens I F, Binnie V I, Kinane D F. Dentists, pills 7. Seymour R A. Drug interactions in dentistry Dent Gynaecol Obstet 2000; 70: 57–58.
and pregnancies. Br Dent J 1996; 181: 236–239.
Update 2009; 36: 458–460, 463–436, 469–470.
12. Neely J L, Abate M, Swinker M, D’Angio R. The effect 3. The Office for National Statistics. Contraception 8. The NHS Information Centre, Dental and Eye of doxycycline on serum levels of ethinylestradiol, and sexual health, 2005-06. London: ONS, 2006. Care Team, Prescribing Support Unit. Prescribing norethindrone, and endogenous progesterone. Online article available at http://www.ons.gov.
by dentists, 2010. England: NHS Information Obstet Gynecol 1991; 77: 416–420.
uk/ons/rel/lifestyles/contraception-and-sexual- 13. Dogterom P, van den Heuvel M W, Thomson T. health/2005-06/index.html (accessed March 2012).
9. Karki A J, Holyfield G, Thomas D. Dental prescribing Absence of pharmacokinetic interactions of the 4. Family Planning Association. Online information in Wales and associated public health issues. combined contraceptive vaginal ring Nuvaring with available at www.fpa.org.uk (accessed March 2012).
Br Dent J 2011; 210: E21.
oral amoxicillin or doxycycline in two randomised British National Formulary 61. London: 10. Murphy A A, Zacur H A, Charace P, Burkman trials. Clin Pharmacokinet 2005; 44: 429–438.
R T. The effect of tetracycline on levels of oral 14. World Health Organization. Medical eligibility 6. Faculty of Sexual and Reproductive Healthcare. contraceptives. Am J Obstet Gynecol 1991; criteria for contraceptive use, 4th ed. Geneva: Faculty of Sexual and Reproductive Healthcare 164: 28–33.
Erratum
Obituary (BDJ 2012; 212: 399)
‘Peter Douglas Bird’In the above obituary, the author’s name should have read as follows:John R. DaveyWe apologise for any misunderstanding caused.
BRITISH DENTAL JOURNAL VOLUME 212 NO. 10 MAY 26 2012
2012 Macmillan Publishers Limited. All rights reserved.

Source: http://www.laboral.info/site/files/ab_and_contraceptives_bdj_2012.pdf