CHAPTER 2

Application of pharmacology in nursing practice

Our principal goal in this chapter is to answer the question “Why should a nursing student learn pharmacology?” By addressing this question, I want to give you some extra motivation to study. Why do I think you might need some motivation? Because I have known many students who, at the beginning of my pharmacology course, questioned the value of learning the material. With some luck, when you complete the chapter, you will be convinced that understanding drugs is essential for nursing practice, and that putting time and effort into learning about drugs will be a good investment. If you are already convinced that understanding pharmacology is important, then just scan the chapter quickly. However, if you are skeptical, then read it carefully. Hopefully, doing so will help you see the light, and thereby boost your motivation for the job ahead.

Evolution of nursing responsibilities regarding drugs

In the past, a nurse’s responsibility regarding medications focused on the Five Rights of Drug Administration, namely, give the right drug to the right patient in the right dose by the right route at the right time. More recently, a Sixth Right—right documentation—was added. Clearly, the Six Rights are important. However, although these basics are important, much more is required to achieve the therapeutic objective. The Six Rights guarantee only that a drug will be administered as prescribed. Correct administration, without additional interventions, cannot ensure that treatment will result in maximum benefit and minimum harm.

The limitations of the Six Rights can be illustrated with this analogy: The nurse who sees his or her responsibility as being done following correct drug administration would be like a major league baseball pitcher who felt that his responsibility was over once he had thrown the ball toward the batter. As the pitcher must be ready to respond to the consequences of the interaction between ball and bat, you must be ready to respond to the consequences of the interaction between drug and patient. Put another way, although both the nurse and the pitcher have a clear obligation to deliver their respective “pills” in the most appropriate fashion, proper delivery is only the beginning of their responsibilities: Important events will take place after the “pill” is delivered, and these must be responded to. Like the pitcher, the nurse can respond rapidly and effectively only by anticipating (knowing in advance) what the possible reactions to the pill might be.

In order to anticipate possible reactions, both the nurse and the pitcher require certain kinds of knowledge. Just as the pitcher must understand the abilities of the opposing batter, you must understand the patient and the disorder for which he or she is being treated. As the pitcher must know the most appropriate pitch (eg, fast ball, curve, slider) to deliver in specific circumstances, you must know what medications are appropriate for the patient and must check to ensure that the medication ordered is among them. Conversely, as the pitcher must know what pitches not to throw at a particular batter, you must know what drugs are contraindicated for the patient. As the pitcher must know the most likely outcome after the ball and bat interact, you must know the probable consequences of the interaction between drug and patient.

Although this analogy is not perfect (the nurse and patient are on the same team, whereas the pitcher and batter are not), it does help us appreciate that the nurse’s responsibility extends well beyond the Six Rights. Consequently, in addition to the limited information needed to administer drugs in accordance with the Six Rights, you must acquire a broad base of pharmacologic knowledge so as to contribute fully to achieving the therapeutic objective.

In drug therapy today, nurses, together with physicians and pharmacists, participate in a system of checks and balances designed to promote beneficial effects and minimize harm. Nurses are especially important in this system because it is the nurse—not the physician or pharmacist—who follows the patient’s status most closely. As a result, you are likely to be the first member of the healthcare team to observe and evaluate drug responses, and to intervene if required. In order to observe and evaluate drug responses, and in order to intervene rapidly and appropriately, you must know in advance the responses that a medication is likely to elicit. Put another way, in order to provide professional care, you must understand drugs. The better your knowledge of pharmacology, the better you will be able to anticipate drug responses and not simply react to them after the fact.

Within our system of checks and balances, the nurse has an important role as patient advocate. It is your responsibility to detect mistakes made by pharmacists and prescribers—and mistakes will be made. For example, the prescriber may overlook potential drug interactions, or may be unaware of alterations in the patient’s status that would preclude use of a particular drug, or may select the correct drug but may order an inappropriate dosage or route of administration. Because the nurse actually administers drugs, the nurse is the last person to check medications before they are given. Consequently, you are the patient’s last line of defense against medication errors. It is ethically and legally unacceptable for you to administer a drug that is harmful to the patient—even though the medication has been prescribed by a licensed prescriber and dispensed by a licensed pharmacist. In your role as patient advocate, you must protect the patient against medication errors made by other members of the healthcare team. In serving as patient advocate, it is impossible to know too much about drugs.

Application of pharmacology in patient care

The two major areas in which you can apply pharmacologic knowledge are patient care and patient education. Patient care is considered in this section. Patient education is considered in the section that follows. In discussing the applications of pharmacology in patient care, we focus on seven aspects of drug therapy: (1) preadministration assessment, (2) dosage and administration, (3) evaluating and promoting therapeutic effects, (4) minimizing adverse effects, (5) minimizing adverse interactions, (6) making PRN decisions, and (7) managing toxicity.

Preadministration assessment

All drug therapy begins with assessment of the patient. Assessment has three basic goals: (1) collecting baseline data needed to evaluate therapeutic and adverse responses, (2) identifying high-risk patients, and (3) assessing the patient’s capacity for self-care. The first two goals are highly specific for each drug. Accordingly, we cannot achieve these goals without understanding pharmacology. The third goal applies generally to all drugs, and hence it does not usually require specific knowledge of the drug you are about to give. Preadministration assessment is discussed here and again under Application of the Nursing Process in Drug Therapy.

Collecting baseline data.

Baseline data are needed to evaluate drug responses, both therapeutic and adverse. For example, if we plan to give a drug to lower blood pressure, we must know the patient’s blood pressure prior to treatment. Without these data, we would have no way of determining the effectiveness of our drug. Similarly, if we are planning to give a drug that can damage the liver, we need to assess baseline liver function in order to evaluate this potential toxicity. Obviously, in order to collect appropriate baseline data, we must first know the effects that our drug is likely to produce.

Identifying high-risk patients.

Multiple factors can predispose an individual to adverse reactions from specific drugs. Important predisposing factors are pathophysiology (especially liver and kidney impairment), genetic factors, drug allergies, pregnancy, old age, and extreme youth.

Patients with penicillin allergy provide a dramatic example of those at risk: Giving penicillin to such a patient can be fatal. Accordingly, whenever treatment with penicillin is under consideration, we must determine if the patient has had an allergic reaction to a penicillin in the past. If there is a history of penicillin allergy, an alternative antibiotic should be employed. If there is no effective alternative, facilities for managing a severe reaction should be in place before the drug is given.

From the preceding example, we can see that, when planning drug therapy, we must identify patients who are at high risk of reacting adversely. To identify such patients, we use three principal tools: the patient history, physical examination, and laboratory data. Of course, if identification is to be successful, you must know what to look for (ie, you must know the factors that can increase the risk of severe reactions to the drug in question). Once the high-risk patient has been identified, we can take steps to reduce the risk. We might select an alternative drug, or, if no alternative is available, we can at least prepare in advance to manage a possible adverse event.

Dosage and administration

Earlier we noted the Six Rights of Drug Administration and agreed on their importance. Although you can implement the Six Rights without a detailed knowledge of pharmacology, having this knowledge can help reduce your contribution to medication errors. The following examples illustrate this point:

• Certain drugs have more than one indication, and dosage may differ depending on which indication the drug is used for. Aspirin, for example, is given in low doses to relieve pain and in high doses to suppress inflammation (eg, in patients with arthritis). If you don’t know about these differences, you might administer too much aspirin to the patient with pain or too little to the patient with inflammation.

• Many drugs can be administered by more than one route, and dosage may differ depending upon the route selected. Morphine, for example, may be administered by mouth or by injection (eg, subcutaneous, intramuscular, intravenous). Oral doses are generally much larger than injected doses. Accordingly, if a large dose intended for oral use were to be mistakenly administered by injection, the result could prove fatal. The nurse who understands the pharmacology of morphine is unlikely to make this error.

• Certain intravenous agents can cause severe local injury if the line through which they are being infused becomes extravasated. Accordingly, when such drugs are given, special care must be taken to prevent extravasation. The infusion must be monitored closely, and, if extravasation occurs, corrective steps must be taken immediately. The nurse who doesn’t understand these drugs will be unprepared to work with them safely.

The following basic guidelines can help ensure correct administration:

• Read the medication order carefully. If the order is unclear, verify it with the prescriber.

• Verify the identity of the patient by comparing the name on the wristband with the name on the drug order or medication administration record.

• Read the medication label carefully. Verify the identity of the drug, the amount of drug (per tablet, volume of liquid, etc.), and its suitability for administration by the intended route.

• Verify dosage calculations.

• Implement any special handling the drug may require.

• Don’t administer any drug if you don’t understand the reason for its use.

Measures to minimize medication errors are discussed further in Chapter 7 (Adverse Drug Reactions and Medication Errors).

Evaluating and promoting therapeutic effects

Evaluating therapeutic responses.

Evaluation is one of the most important aspects of drug therapy. After all, this is the process that tells us whether or not a drug is doing anything useful. Because the nurse follows the patient’s status most closely, the nurse is in the best position to evaluate therapeutic responses.

In order to make an evaluation, you must know the rationale for treatment and the nature and time course of the intended response. If you lack this knowledge, you will be unable to evaluate the patient’s progress. When beneficial responses develop as hoped for, ignorance of expected effects might not be so bad. However, when desired responses do not occur, it may be essential to identify the failure quickly, so that timely implementation of alternative therapy may ordered.

When evaluating responses to a drug that has more than one application, you can do so only if you know the specific indication for which the drug is being used. Nifedipine, for example, is given for two cardiovascular disorders: hypertension and angina pectoris. When the drug is used for hypertension, you should monitor for a reduction in blood pressure. In contrast, when this drug is used for angina, you should monitor for a reduction in chest pain. Clearly, if you are to make the proper evaluation, you must understand the reason for drug use.

Promoting patient adherence.

Adherence—also known as compliance or concordance—may be defined as the extent to which a patient’s behavior coincides with medical advice. If we are to achieve the therapeutic objective, adherence is essential. Drugs that are self-administered in the wrong dose, by the wrong route, or at the wrong time cannot produce maximum benefit—and may even prove harmful. Obviously, successful therapy requires active and informed participation by the patient. By educating patients about the drugs they are taking, you can help elicit the required participation.

Implementing nondrug measures.

Drug therapy can often be enhanced by nonpharmacologic measures. Examples include (1) enhancing drug therapy of asthma through breathing exercises, biofeedback, and emotional support; (2) enhancing drug therapy of arthritis through exercise, physical therapy, and rest; and (3) enhancing drug therapy of hypertension through weight reduction, smoking cessation, and sodium restriction. As a nurse, you may provide these supportive measures directly, through patient education, or by coordinating the activities of other healthcare providers.

Minimizing adverse effects

All drugs have the potential to produce undesired effects. Common examples include gastric erosion caused by aspirin, sedation caused by older antihistamines, hypoglycemia caused by insulin, and excessive fluid loss caused by diuretics. When drugs are employed properly, the incidence and severity of such events can be reduced. Measures to reduce adverse events include identifying high-risk patients through the patient history, ensuring proper administration through patient education, and forewarning patients about activities that might precipitate an adverse event.

When untoward effects cannot be avoided, discomfort and injury can often be minimized by appropriate intervention. For example, timely administration of glucose will prevent brain damage from insulin-induced hypoglycemia. In order to help reduce adverse effects, you must know the following about the drugs you are working with:

• The major adverse effects the drug can produce

• When these reactions are likely to occur

• Early signs that an adverse reaction is developing

• Interventions that can minimize discomfort and harm

Minimizing adverse interactions

When a patient is taking two or more drugs, those drugs may interact with one another to diminish therapeutic effects or intensify adverse effects. For example, the ability of oral contraceptives to protect against pregnancy can be reduced by concurrent therapy with carbamazepine (an antiseizure drug), and the risk of thromboembolism from oral contraceptives can be increased by smoking cigarettes.

As a nurse, you can help reduce the incidence and intensity of adverse interactions in several ways. These include taking a thorough drug history, advising the patient to avoid over-the-counter drugs that can interact with the prescribed medication, monitoring for adverse interactions known to occur between the drugs the patient is taking, and being alert for as-yet unknown interactions.

Making PRN decisions

A PRN medication order is one in which the nurse has discretion regarding how much drug to give and when to give it. (PRN stands for pro re nata, a Latin phrase meaning as needed or as the occasion arises.) PRN orders are common for drugs that promote sleep, relieve pain, and reduce anxiety. In order to implement a PRN order rationally, you must know the reason for drug use and be able to assess the patient’s medication needs. Clearly, the better your knowledge of pharmacology, the better your PRN decisions are likely to be.

Managing toxicity

Some adverse drug reactions are extremely dangerous. Hence, if toxicity is not diagnosed early and responded to quickly, irreversible injury or death can result. In order to minimize harm, you must know the early signs of toxicity and the procedure for toxicity management.

Application of pharmacology in patient education

Very often, the nurse is responsible for educating patients about medications. In your role as educator, you must give the patient the following information:

• Drug name and therapeutic category (eg, penicillin: antibiotic)

• Dosage size

• Dosing schedule

• Route and technique of administration

• Expected therapeutic response and when it should develop

• Nondrug measures to enhance therapeutic responses

• Duration of treatment

• Method of drug storage

• Symptoms of major adverse effects, and measures to minimize discomfort and harm

• Major adverse drug-drug and drug-food interactions

• Whom to contact in the event of therapeutic failure, severe adverse reactions, or severe adverse interactions

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