Chapter 5 IM

Chapter 5 Adverse Drug Effects and Drug Interactions Learning Outcomes 1. Differentiate between adverse effects and side effects. Suggested Classroom Activity: Divide students into three to four groups. Assign each group a different drug (e.g., ciprofloxacin, atenolol, pantoprazole, lisinopril). Have them present some predictable side effects of the drug and then discuss what would be considered adverse effects. Suggested Classroom Activity: Compare and contrast the different side effects and adverse effects for furosemide (Lasix). Suggested Clinical Activity: Have each student evaluate the medications of an assigned patient and determine if the patient is experiencing any side effects or adverse effects of any of the medications. 2. Create a plan to minimize or prevent adverse drug events in patients. Suggested Classroom Activity: Using the same groups and drugs as in Learning Outcome 1, have students identify what they can do to reduce or prevent the side effects of the drugs. Suggested Clinical Activity: Select a patient who is experiencing side effects of a drug and discuss what the nurse can do to minimize the effect. Discuss if anything could be done to prevent the side effect from occurring in the future. 3. Explain the advantages and disadvantages of the Adverse Event Reporting System. Suggested Classroom Activity: Have students research the Adverse Event Reporting System on the Internet. Discuss the processes involved in making a report. Suggested Clinical Activity: Have students review the medications being given to clinical patients for black box warnings. Discuss the implications of using this medication or not using this medication. 4. Describe the incidence and characteristics of drug allergies. Suggested Classroom Activity: Present a scenario where a patient states, “I am allergic to sulfa. It makes me so sick to my stomach and I get diarrhea.” Discuss why this may not be a true allergy. Explore what questions should be asked to determine if a true allergy exists. Suggested Classroom Activity: Present a scenario where a patient develops an anaphylactic reaction. Outline steps the nurse would take to treat the reaction. Suggested Clinical Activity: Check the chart of patients assigned to the students and identify one or two who have a reported allergy. Have students assess patients to determine what occurs when the patient takes the medication. Discuss if the symptoms reflect a true allergic response. 5. Explain how idiosyncratic reactions differ from other types of adverse effects. Suggested Classroom Activity: Discuss how to differentiate a side effect from an idiosyncratic effect. Suggested Clinical Activity: Review drug therapies with staff at the clinical site to identify if any patients are experiencing, or have recently experienced, any idiosyncratic reactions and share these with the students. 6. Explain why certain drugs with carcinogenic or teratogenic potential are used in pharmacotherapy. Suggested Classroom Activity: Divide students into four to five groups, assigning each group a different drug to check the pregnancy risk category. Be sure to include drugs from a safe category (such as acetaminophen) as well as those with known teratogenic effects (isotretinoin [Accutane] and finasteride [Proscar]). Suggested Classroom Activity: Illustrate how the drugs with known carcinogen effects can provide therapeutic benefits (e.g., doxorubicin [Adriamycin] and methotrexate). Suggested Clinical Activity: Check patients to determine if any are receiving a medication with a known carcinogenic or teratogenic effect. (If not on an oncology unit, look for immunosuppressant drugs or hormones and hormone antagonists.) Discuss why the patient is receiving the drug and why the benefits may outweigh the risks. 7. Report the characteristic signs, symptoms, and treatment for each of the following organ-specific adverse events: nephrotoxicity, neurotoxicity, hepatotoxicity, dermatologic toxicity, bone marrow toxicity, cardiotoxicity, and skeletal muscle toxicity. Suggested Classroom Activity: Divide students into six groups and assign each a drug class with a known toxicity for each system. Have each group present what specific toxic effect can occur with the drug classification assigned to them. Suggestions for classifications are: Renal toxicity: aminoglycosides Hepatotoxicity: antifungals Muscle toxicity: HmG co-reductase inhibitors (statins) Bone marrow toxicity: folic acid antagonists Neurotoxicity: anticonvulsants Dermatologic toxicity: sulfonamides Suggested Classroom Activity: Discuss the relevance of doing peak and trough levels for drugs with potential toxicities, such as vancomycin. Suggested Clinical Activity: Have students review all medications their assigned patients are receiving and identify any that have potential for toxicities. Discuss what parameters should be closely monitored in the patient. 8. Use examples to explain the importance of drug interactions to pharmacology. Suggested Classroom Activity: Select a common drug and examine the various types of interactions that can potentially occur with this drug. Involve students by using a drug guide and having them follow which are food–drug interactions and which are drug–drug interactions. Suggested Clinical Activity: Have each student choose one drug an assigned patient is receiving. Have them identify what drug or food interactions are possible with that drug. Have them assess whether the patient is at risk for any of the interactions. Suggested Clinical Activity: Develop a teaching plan that addresses the food–drug interactions of warfarin (Coumadin). 9. Describe the mechanisms of drug interactions that alter absorption, distribution, metabolism, or excretion. Suggested Classroom Activity: Divide students into four to five groups and assign each group a different drug. Have students look up interactions for that given drug and identify which phase of pharmacokinetics is affected. Suggested Clinical Activity: Have each student choose the drugs an assigned patient is receiving and identify if the drugs have any interactions and what phase of pharmacokinetics is affected by the interaction. 10. Differentiate among additive, synergistic, and antagonistic drug interactions. Suggested Classroom Activity: Discuss the implications of administering drugs with each of these effects. Are there instances when these effects are undesirable? Are there instances in which a drug is given for a specific additive, synergistic, or antagonistic effect, but giving the drug has other undesired effects? Suggested Clinical Activity: Identify a drug with each of these implications among those being taken by assigned patients. What is the specific reason this drug was chosen for this patient? 11. Identify examples of drug–food interactions that may impact pharmacotherapeutic outcomes. Suggested Classroom Activity: Divide students into four to five groups and assign each group a different drug. Have students look up interactions for that given drug and identify which ones are drug–food interactions. Have them explain if the drug should be given with or without food and why. Suggested Clinical Activity: Have students identify any food–drug interactions that are indicated with the medications being taken by their assigned patients. Discuss if this posed any problems with administration of the medications (for example, ciprofloxacin may be ordered along with an antacid and several other a.m. medications; it is sometimes inconvenient to hold one medication and administer it 2 hours later). Concepts for Lecture Adverse events, also called adverse effects, are undesirable and possibly harmful actions that occur secondary to a medication. All drugs have a potential to produce adverse events, including OTC drugs, herbals, and dietary supplements. Side effects are predictable and can occur at therapeutic doses. The distinction between adverse effects and side effects is in the severity of the symptoms. According to the FDA, serious drug effects are those that can result in death, can cause congenital abnormalities, can cause life-threatening events, and/or require interventions to prevent serious consequences. Adverse events may be an extension of a drug’s pharmacologic action. Knowing the drug’s expected therapeutic action enables the nurse to predict potential adverse effects. Nurses play a critical role in minimizing the severity and occurrence of adverse drug events. Adverse effects cannot always be predicted or prevented, but nurses should take measures to minimize or prevent them. A thorough health history/assessment of the patient provides valuable information that can identify potential drug interactions. It alerts the nurse to allergies and to metabolic and excretion problems that may impact drug effects. Giving medications accurately helps to reduce unnecessary adverse effects. A thorough knowledge of drug doses, actions, and potential adverse effects is necessary for early recognition of harmful drug effects. Nurses must anticipate unusual and unexpected drug effects. The nurse should question unusual orders. The nurse should teach the patient about adverse effects. The FDA’s MedWatch Safety Information and Adverse Event Reporting System (FAERS) is a voluntary program that encourages health care providers and consumers to report suspected adverse effects to the FDA or product manufacturer. Data from the FAERS are analyzed by clinical reviewers at the Center for Drug Evaluation and Research of the FDA. If a potential safety concern is identified, the FDA may conduct additional studies to determine the validity or extent of safety concerns, require changes to a product’s labeling, require a black box warning that warns prescribers the drug carries a risk of serious or even fatal adverse effects, restrict use of the drug in specific populations, communicate safety information to health care providers and consumers, or recall or remove the product from the market. The FDA disseminates changes in safety information through its MedWatch website. Some patients experience a placebo effect. Thus when examining drug information, the nurse should always examine the incidence of adverse effects that occur over and above that caused by a placebo. Patients exhibit many different types of symptoms with allergies, but they are all caused by a hyper-response of the immune system. Allergy symptoms are unrelated to the pharmacologic action of a drug. Anaphylactic reactions have the same symptoms regardless of the drug. Drug classes more likely to cause allergic reactions include penicillin and related antibiotics, radiologic contrast dyes, insulin, NSAIDs, sulfonamides, cancer chemotherapy agents, preservatives, and certain antiseizure drugs. Idiosyncratic responses are rare drug events but are not considered to be expected side effects or allergic responses. They are unrelated to pharmacologic action of the drug. Idiosyncratic responses are often attributed to genetic differences that affect drug metabolism. Some drugs are approved for use in humans even though they were shown to produce cancer in laboratory animals. The risk–benefit ratio of these drugs demonstrates that the benefits of the drug outweigh its long-term risks. Many of the drugs with a risk–benefit ratio are those used to treat cancer. Treatment with such drugs often prolongs life. Immunosuppressants may cause cancer. Hormone or hormone antagonists may cause cancer. Drugs known to cause birth defects are called teratogens. These drugs are only dangerous to pregnant women. When drugs with known teratogenic effects are used in women of childbearing years, the nurse must be diligent in educating patients to avoid pregnancy. Drugs are not tested in pregnant humans. No woman should take a drug, herbal product, or dietary supplement during pregnancy unless approved by the patient’s health care provider. Since the majority of drugs are excreted by the kidneys, the renal tubule is exposed to high drug concentrations. It is important to identify drugs that have nephrotoxicity potential and recognize risk factors for impaired renal function in the patient, which include dehydration, abnormal urinary lab values, and history of renal impairment. Drugs with the ability to cross the blood–brain barrier (BBB) can cause neurotoxicity, so patients need to be assessed for CNS effects. Patients receiving these drugs need to be taught safety precautions. A common adverse effect is hepatotoxicity, since the majority of drugs are detoxified in the liver. Liver function tests must be monitored when known hepatotoxic drugs are being administered. Some of the most common drug adverse events include skin reactions, such as rashes with pruritus. More serious, and even fatal, skin reactions include urticaria, which may lead to anaphylaxis; angioedema; and Stevens–Johnson syndrome. Photosensitivity can also occur. Since the bone marrow is the source of RBC, WBC, and platelet production, toxicity can result in serious and life-threatening conditions, including pancytopenia, aplastic anemia, agranulocytosis, and neutropenia. Such conditions are often associated with antineoplastic treatment. Some drugs damage the muscle cells of the heart, reducing cardiac output. The nurse must monitor for excessive fatigue, cough, shortness of breath, weight gain, and peripheral edema, which may be associated with heart failure. Although muscle tissue is quite resistant to drug effects, skeletal muscle myopathy and toxicity to cardiac muscle can occur. Abnormal muscle pain should always be evaluated, and CK levels should be monitored. Drugs can interact with other substances such as foods, dietary supplements, herbal products, or another drug, affecting the drug’s action. Drug interactions are ongoing and can often go unnoticed because therapy is not affected. Drug interactions can inhibit, enhance, or change the therapeutic effect of a drug. Absorption of drugs can be affected by stomach pH, peristalsis, and concurrent administration with other drugs or foods. Interactions can occur when a drug is displaced from protein-binding sites or an altered plasma pH affects the ability of drugs to cross membranes. Drugs that are inhibitors, inducers, and substrates of CYP enzymes have potential to cause drug interactions. Inducers can increase drug metabolism; inhibitors can decrease drug metabolism. Most drugs are excreted via the kidneys. Interactions can be influenced by cardiac output, glomerular filtration rate (GFR), competition for reabsorption or excretion in the tubule, biliary drug excretion, effects on aging, and urinary pH. When pharmacodynamic drug interactions occur, the drug action is enhanced or inhibited. In addition, the drug interactions are either desirable—with increased therapeutic response or decreased adverse effects—or undesirable—with decreased therapeutic responses or increased adverse effects. When two drugs are given to produce a therapeutic response that is greater than that of each drug given separately, it is called an additive effect. When the effect of two drugs given together is greater than the effect expected from simply adding the two drugs’ responses, it is called a synergistic effect. When one drug diminishes the pharmacologic response of another drug, it is called an antagonistic effect. Pharmacologic interactions can also be indirect. In this situation, one drug does not directly affect the pharmacologic action of another drug, but produces adverse effects that indirectly impact the second drug. Many drug–food and drug–herb interactions can impact pharmacotherapeutic outcomes. Grapefruit juice inhibits the CYP3A4 enzyme, which can increase blood levels of benzodiazepines, calcium channel blockers, and statins. Absorption and bioavailability of drugs can be increased or decreased. To avoid interactions, separate drugs and food. Some drugs are better absorbed if given with food. Adams and Urban, Pharmacology: Connections to Nursing Practice, 3e Instructor’s Resource Manual Copyright 2016 by Education, Inc.