Pharmacotherapeutics for Advanced Practice Nurse Prescribers and Registered Nurses

Faith Selchick, DNP, AGPCNP-BC, OCN, AOCNP

Faith Selchick, DNP, AGPCNP-BC, OCN, AOCNP

There is an increased reliance on medication therapy in modern-day healthcare to support vital physiological processes and remedy illnesses. More than 10,000 prescription medications are available in the US, and approximately one-third of adults take at least five medications simultaneously. Nurses’ primary responsibility in patient care and mediation therapy is to uphold and preserve patient safety. Medication administration is a core aspect of nursing practice, but nursing responsibilities extend well beyond medication administration.

At a basic level, nurses must learn the various classes of medications, understand how medications work, recognize both the generic and brand name of medications, comprehend the restrictions regarding controlled substances, be familiar with credible resources to obtain specific information about medications (e.g., drug handbooks, online resources), and ensure patients are adequately educated on potential side effects, precautions, and drug interactions. Nurses must ascertain a comprehensive understanding of drugs and their effects on the body to determine if the intended medication effects are achieved and recognize adverse or unintended effects. 

The goal of medication therapy is to achieve a desired therapeutic effect with minimal adverse effects or toxicity. The safety and efficacy of medications rely on the principles of pharmacokinetics and pharmacodynamics. Nurses must master these concepts to attain a higher-level understanding of the principles of medication therapy.  

Put simply, pharmacokinetics is the study of what the body does to the drug, and pharmacodynamics is the study of what the drug does to the body. Pharmacokinetics includes four primary stages: absorption, distribution, metabolism, and excretion (or ADME). Pharmacodynamics refers to the biochemical changes in the body due to the drug’s concentration at the target site and its post-receptor effects, including therapeutic effects, adverse effects, and interactions.

 (Scivit, 2020)

For most drugs, the concentration at the receptor site determines the intensity of its effect. Understanding a medication’s mechanism of action (how it functions within the body) is vital to comprehend the processes leading to its intended effects. A drug’s half-lifeor the time it takes to decrease in amount by half after a drug enters the body, is essential when determining drug clearance and dosing intervals.

Nurses should understand the process of monitoring peak (when a drug is at its highest concentration) and trough (when the drug is at its lowest concentration) levels of specified drugs to prevent and manage an overdose or under-dose. If the peak level is too high, the patient is at risk for toxicity, and if it is too low, the patient is at risk for a non-therapeutic response, thereby mitigating its intended effect.

In a 2016, a study by Johns Hopkins University, researchers compared medical errors to the Centers for Disease Control and Prevention’s annual list of the most common causes of death in the US. They demonstrated that 10% of all deaths in the US are attributable to medical errors, establishing this as the third-highest cause of death in the US. To date, the FDA receives at least 100,000 reports annually of suspected medication errors, and up to 9,000 people die annually due to a medication error. The World Health Organization estimates that the global cost associated with medication errors is $42 billion annually.

According to the Agency for Healthcare Research and Quality (AHRQ), a medication error is a preventable event defined as “an error (of commission or omission) at any step along the pathway that begins when a clinician prescribes a medication and ends when the patient receives the medication.” An adverse drug event (ADE) refers to harm experienced by a patient due to exposure to a medication. ADEs account for nearly 700,000 emergency department visits and 100,000 hospitalizations in the US each year. Almost 5% of hospitalized patients experience an ADE, making them one of the most common types of inpatient medical errors (AHRQ, 2019).

Nurses must be knowledgeable of all drugs they administer. It is essential to understand the pharmacokinetics and pharmacodynamics of a drug to safely administer it while monitoring for adverse effects and signs of toxicity. Patient characteristics such as age, health alterations, and liver or kidney function must also be considered regarding the risk for side and adverse effects. As the last line of defense, nurses should routinely and meticulously review all drugs prescribed to a patient to ensure accuracy, safety, and avert drug interactions.

Nurses are responsible for safeguarding patient care by serving as the patient’s advocate. Education and proper communication can help avoid many medication errors and adverse effects. For a comprehensive overview of the principles of pharmacology, pharmacokinetics, pharmacodynamics, and safe medication administration, refer to the recently updated NursingCE courses:


  • Agency for Healthcare Research and Quality. (2019). Medication errors and adverse drug events.
  • Frandsen, G., & Pennington, S. S. (2018). Abrams’ clinical drug therapy: Rationales for nursing practice(11th ed.). Wolters Kluwer.
  • Katzung, B. G. (2018). Basic & clinical pharmacology (14th ed.). McGraw-Hill Education.
  • Makary, M. A., & Daniel, M. (2016). Medical error—the third leading cause of death in the US. BMJ, 353, i2139.
  • Scivit. (2020). Graphic depiction of pharmacokinetics vs. pharmacodynamics [image].
  • US Food & Drug Administration. (2019). Working to reduce medication errors.
  • World Health Organization. (n.d.). Medication without harm. Retrieved May 30, 2021, from,

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