McKenna's Pharmacology for Nursing, 2e

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P A R T 2  Chemotherapeutic agents

is scheduled. She states that she has successfully used low-dose oral contraceptives for 4 years and plans to continue this method of birth control. CRITICAL THINKING How do doxycyclines and some other antibiotics and oral contraceptives interact? What are the possible ramifications of continuing to take oral contraceptives during a pregnancy? What care interventions are appropriate for G.S.? What teaching points should be stressed with G.S.? Think about the nature of her personality and the problems that an unplanned pregnancy might cause. How can you help G.S. to cope with her infection, her drug regimen and her rigorous schedule? DISCUSSION Several antibiotics, including tetracycline, are known to lead to the failure of oral contraceptives as evidenced by breakthrough bleeding and unplanned pregnancy. Although the exact way in which these drugs interact is incompletely understood, it is thought that the antibiotics destroy certain bacteria in the normal flora of the gastro ­ intestinal (GI) tract. These bacteria are necessary for the breakdown and eventual absorption of the female hormones contained in the contraceptives. The 5 days of antibiotic treatment together with the time necessary for rebuilding the normal flora can be long enough for the hypothalamus to lose the negative feedback signal provided by the contraceptives that prevents ovulation and preparation of the uterus. Sensing the low hormone levels, the hypothalamus releases gonadotropin-releasing hormone, which leads to the release of follicle-stimulating hormone and luteinising hormone, with subsequent ovulation. G.S. will need a clear explanation and follow-up in written form about the risks of oral contraceptive failure while she is receiving doxycycline therapy. She should be encouraged to use an additional form of birth control during the course of her antibiotic use and to read all of the literature that comes with oral contraceptives, as well as teaching information that should be provided with the antibiotic. G.S. also may need a great deal of support and encouragement at this time. The sinus infection may increase her stress by interfering with her ability to stick to her rigid schedule. Discussing the possibility of an unplanned pregnancy may cause even more stress. The health clinic visit could be used as an opportunity to allow G.S. to talk, to vent any frustrations and stress, and then to encourage her to make time for herself. The nurse should stress the importance of a good diet, which will ensure that her body has the components she will need to fight this infection, to heal and to ward off other infections, as well as the importance of

adequate rest and exercise. The nurse should also make sure that G.S. is receiving annual gynaecological examinations and has been advised not to smoke. All healthcare professionals who are involved with G.S. should consider the impact that an unplanned pregnancy could have on this very organised woman and use this as an example of the importance of clear, concise teaching in the administration of drug therapy. CARE GUIDE FOR G.S.: TETRACYCLINES Assessment: History and examination Allergy to any doxycycline Hepatic or renal dysfunction Pregnancy or breastfeeding Concurrent use of oral contraceptives, antacids, iron products, digoxin or penicillins General: site of infection, culture and sensitivity Skin: colour, lesions Respiratory: respiration, adventitious sounds GI: liver evaluation, bowel sounds, usual output Laboratory data: liver and renal function tests, urinalysis Implementation Perform culture and sensitivity tests before beginning therapy. Administer drug on an empty stomach, 1 hour before or 2 to 3 hour after meals. Do not give with antacids, milk or iron products. Do not use outdated drug because of the risk of nephrotoxicity. Monitor for and provide hygiene measures and treatment if superinfections occur. Monitor nutritional status and fluid intake. Provide ready access to bathroom facilities if diarrhoea is a problem. Provide support and reassurance for dealing with the drug effects and infection. Provide teaching regarding drug name, dosage, adverse effects, precautions, warnings to report and drugs that might cause a drug–drug interaction, including the need to use a second form of contraception if using oral contraceptives. Evaluation Evaluate drug effects: resolution of bacterial infections. Monitor for adverse effects: GI effects, superinfections, CNS effects. Monitor for drug–drug interactions: lack of effectiveness of oral contraceptives, lack of antibacterial effect with antacids or iron. Evaluate effectiveness of teaching program. Evaluate effectiveness of comfort and safety measures. Teaching for G.S. • Doxycycline is an antibiotic that is specific for your infection. You should take it throughout the day for best results.