A thorough understanding of the ways patients metabolize drugs is essential for both NP students and practicing clinicians. By developing well-rounded knowledge of pharmacology, you can help avoid adverse drug reactions, enhance medication efficacy, and help patients feel better faster. In this article, we break down the fundamentals of pharmacokinetics and pharmacodynamics, two important tenets of pharmacological theory.
If you’re an NP faculty member looking for comprehensive ways to help your students become astute prescribers, join Dr. Margaret Fitzgerald for a faculty-tailored pharmacokinetics webinar on May 27, 2025, at 7PM EST.
What are pharmacokinetics and pharmacodynamics?
Pharmacokinetics is a branch of pharmacology which studies how specific drugs move through the body. This field specifically focuses on the course of a medication’s absorption, bioavailability, distribution, metabolism, and excretion. Drug pharmacokinetics determines the onset, duration, and intensity of a drug’s effect (Merck Manual, 2024). Clinicians often use formulas to understand the pharmacokinetics of most drugs. A comprehensive table covering commonly used medications can be found here.
Conversely, pharmacodynamics describes how drugs effect the body. Pharmacodynamics often considers receptor binding and chemical interactions when determining the potential metabolic responses, side effects, and adverse reactions to a drug. A drug’s pharmacodynamics can be affected by the unique demographics and conditions of a patient, including age, underlying pathologies, and the other drugs they are taking.
Pharmacodynamics is used in tandem with pharmacokinetic theory to explain the relationship between the dose and response, i.e., the drug’s effects.
Related: Clinical Pharmacology for NPs & Adv Practice Clinicians
How can an understanding of pharmacokinetics and pharmacodynamics help NPs prescribe appropriately?
Pharmacokinetic and pharmacodynamic principles are essential for NPs to develop safe and effective treatment plans to address a variety of conditions. Not only will this knowledge help you prevent drug-drug and drug-supplement interactions, it can also help you prescribe the right medication on the first try, improving outcomes and boosting quality of life.
Tailoring drugs according to the individual
If you have a patient with a preexisting condition, including compromised kidney or liver function, drug allergies, or obesity, being aware of the specific ways a drug is absorbed and excreted can be crucial when determining dosage.
Interactions and adverse effect detection
When a clinician is aware of how a drug affects body systems, nurse practitioners can make informed decisions about what to prescribe and when. Additionally, knowing all the potential side effects of a drug can help tailor the treatment regimen accordingly and prevent medication-related symptoms.
Evaluating efficacy
If an NP knows how quickly a drug begins working and what it specifically does to the body to address symptoms of a disease, they can determine whether the treatment plan is effective or not.
Related: Family Nurse Practitioner Pharmacology Package
“Current and comprehensive knowledge of the pharmacokinetics and pharmacodynamics of drugs have implications for nursing management of patient care,” says Karen-Leigh Edward, director and chair of St. Vincent’s Private Hospital in Melbourne, Australia. “Medication competence in nursing is multifaceted, requiring broader understanding of medication management than that currently taught in undergraduate nursing curriculum, which focuses on drug administration and drug calculations, adherence and legal considerations. Using the nursing process (assessment, planning, intervention and evaluation) nurse practitioners can identify and monitor factors that may affect or alter drug absorption and consequent action.”
