McKenna's Pharmacology, 2e

32

P A R T 1  Introduction to nursing pharmacology

These terms were first introduced from the field of pharmacovigilance , the study of drug related injury. Several studies have reported adverse drug reactions to be among leading causes of morbidity and mortality. An adverse drug reaction is defined as “an apprecia­ bly harmful or unpleasant reaction, resulting from an intervention related to the dose of a medicinal product, which predicts hazards from future administration and warrants prevention or specific treatment, or alteration of the dosage regimen or withdrawal of the product” (Edwards & Aronson, 2000). The nurse or midwife, as the caregivers who most frequently administer medications, must be constantly alert for signs of drug reactions of various types. People and their families need to be taught what to look for when taking drugs at home. Some adverse drug effects can be countered with specific comfort measures or precautions. Knowing that these effects may occur and what actions can be taken to prevent or cope with them may be the most critical factor in helping the person to comply with drug therapy. Adverse effects can be one of several types: primary actions, secondary actions and hypersensitivity reactions. The Australian Commission on Safety and Quality in Health Care (ACSQHC) has developed 10 National Safety and Quality Health Service Standards. These Standards aim to improve the quality of health service provision across Australia and provide a national state­ ment of the level of care consumers should be able to expect from health services. Awareness and knowledge of Standard 4 on Medication Safety is an important part of the nurse’s and midwife’s clinical repertoire. For more information, see www.safetyandquality.gov.au/ our-work/accreditation/nsqhss. ADVERSE DRUG EFFECTS Adverse drug effects are undesired effects that may be unpleasant or even dangerous. They can occur for many reasons, including the following: • The drug may have other effects on the body besides the therapeutic effect. • The person may be sensitive to the drug being given. • The drug’s action on the body may cause other responses that are undesirable or unpleasant. • The person may be taking too much or too little of the drug, leading to adverse effects. • The person may be taking a complementary product interacting with the drug leading to adverse effects. • The person may be taking many drugs (polypharmacy). Primary actions One of the most common occurrences in drug therapy is the development of adverse drug effects from simple

Safe medication administration

overdose. In such cases, the person suffers from effects that are merely an extension of the desired effect. This is sometimes known as “predictable side effects”. For example, an anticoagulant may act so effectively that the person experiences excessive and spontaneous bleeding. This type of adverse drug effect can be avoided by moni­ toring the person carefully and adjusting the prescribed dose to fit that particular person’s needs. In the same way, a person taking an antihyper­ tensive drug may become dizzy, weak or faint when taking the “recommended dose” but will be able to adjust to the drug therapy with a reduced dose. These effects can be caused by individual response to the drug, high or low body weight, age or underlying pathology that alters the effects of the drug. Secondary actions Drugs can produce a wide variety of effects in addition to the desired pharmacological effect. Sometimes the drug dose can be adjusted so that the desired effect is achieved without producing undesired secondary reac­ tions. Sometimes this is not possible and the adverse effects are almost inevitable. In such cases, the person needs to be informed that these effects may occur and counselled about ways to cope with the undesired effects. For example, many antihistamines are very effective in drying up secretions and helping breathing, but they also cause drowsiness. The person who is taking anti­ histamines needs to know that driving a car or operating power tools or machinery should be avoided because the drowsiness could pose a serious problem. A person taking an oral antibiotic needs to know that frequently the effects of the antibiotic on the gastrointestinal tract result in diarrhoea, nausea and sometimes vomiting. The person should be advised to eat small, frequent meals to help alleviate this problem. Before administering any drug to a person, it is important to review the contraindications and cautions associated with that drug, as well as the anticipated adverse effects of the drug. This information will direct your assessment of the person, helping you to focus on particular signs and symptoms that would alert you to contraindications or to proceed cautiously, and help you to establish a baseline for that person so that you will be able to identify adverse effects that occur. When teaching the person about a drug, you should list the adverse drug effects that should be anticipated, along with appropriate actions that can be taken to alleviate any discomfort associated with these effects. Being alert to adverse drug effect—what to assess and how to intervene appropriately—can increase the effectiveness of a drug regimen, provide for a person’s safety and improve their compliance.