1.0 Introduction to Pharmacology V2

Introduction

To be able to administer medications safely and effectively, registered nurses require specific knowledge, skill, and judgment to ensure safe, client-centred care. To provide this safe care, nurses need a strong foundation in pharmacology, which can be defined as “the study of drugs and their interactions with living systems” (Burcham & Rosenthal, 2019), which includes learning about:

• the physical and chemical properties of drugs;
• how the drug works in the body;
• the uses of drugs for different health conditions;
• the intended and adverse effects;
• drug interactions; and
• important assessments and monitoring following administration.

The topic of pharmacology is expansive, with thousands of medications available, not including combination formulas and natural health products (Government of Canada, 2015), and each have their own therapeutic applications and characteristics. As such, this text will focus on what information is clinically relevant for nurses by learning about different medication classifications, key information about each med, and nursing considerations for safe medication administration.

Is It a Drug or a Medication?

These two terms are often used interchangeably, but they have distinct definitions. A drug is a chemical agent that is capable of producing a biological response within the body (Adams et al., 2018). A drug is considered a medication if it is medically therapeutic. This definition excludes food and other agents such as cosmetics. In most of the literature and in this text, you will see drug and medication both used and sometimes interchangeably.

The Ideal Medication

If you were developing a new medication, what would be important characteristics? You will likely consider a medication that is safe (no harmful effects to the client), effective (treats or prevents the condition 100% of the time), and selective (does exactly what it is intended to do and nothing else). Other qualities you might consider would be whether the medication is easily accessible, inexpensive, convenient, or fast acting with no drug interactions. These qualities would be ideal, but unfortunately, no medication has all these characteristics. No medication is 100% effective all the time with no negative effects. All medications have the potential to produce harmful effects regardless if they are used correctly or incorrectly. For example, if a prescriber does not consider a client’s impaired renal function and prescribes a larger dose, this can lead to adverse effects. Sometimes, medications prescribed are used correctly but have a different effect than what was expected (adverse reactions or idiosyncratic reactions). Some medications are over-the-counter (OTC), making them highly accessible and inexpensive but open to incorrect usage. For example, Ibuprofen is a highly effective pain reliever and anti-inflammatory. However, if dosages exceed recommendations or someone takes the medication for a long time, it can lead to a risk of gastric issues and drug interactions.

If there is no ideal drug, what factors determine how well a drug meets its therapeutic objective? In the upcoming units on pharmacokinetics and pharmacodynamics, we will examine many factors that influence a drug’s capability and how the same drug can work differently in different people.

To improve the client outcomes when taking any medications, a collaborative health care team approach is needed that includes the prescriber, such as a physician or nurse practitioner, the pharmacist, the nurse, and other allied health members. In Chapter 2.7 Deprescribing Medications, we will explore the implications of overprescribing, especially in the older population, and the role that all health care team members have in minimizing polypharmacy.

Safe Medication Administration in Action

Nurses need to make many decisions about medications that have a significant impact on client well-being. This begins with taking the best medication history for a new admission (see Chapter 2 Safety and Ethics) and ends with completing health teaching prior to discharge. Other examples of decisions that a nurse might make during client care include:

• Is my client’s heart rate within the correct range to receive this beta-blocker medication?
• Does my client have adequate renal function prior to administering this dose of antibiotic?
• Is this pain medication effective in controlling my client’s discomfort?
• My client is going home; what health teaching about this medication is important for ensuring the client uses it safely?

In summary, in order to make safe medication administration decisions, the nurse must have a strong understanding of pharmacology. The use of medications is strongly connected to a client’s treatment plan, including symptom management, physical recovery, and individual well-being. Before a nurse reviews a medication order, checks a medication administration record, or administers a medication, it is important to have a foundational understanding of how medications work within the human body.

Nurses should understand the key components of pharmacology:

• Pharmacotherapeutics: The clinical purpose or reason for the medication.
• Pharmacokinetics: The movement of the drug through the body.
• Pharmacodynamics: The physiological response of the body to the drug.

These next sections will introduce pharmacokinetics and pharmacodynamics. Future chapters of this textbook will focus on the pharmacotherapeutics of specific drug classifications.

References

Adams, M. P., Urban, C. Q., El-Hussein, M., Osuji, J. & King, S. (2018). Pharmacology for nurses. A pathophysiological approach (2^nd Canadian ed.). Pearson.

Aithal, A., & Aithal, P.S. (2018). The concept of ideal drug & its realization opportunity using present pharmaceutical sciences scenario. International Journal of Health Sciences and Pharmacy (IJHSP), 2(2), 11–26. https://doi.org/10.5281/zenodo.1469963

Burcham, J. R., & Rosenthal, L. D. (2019). Lehne’s pharmacology for nursing care (10^th ed.). Elsevier.

Chippewa Valley Technical College, Egert, A., Lee, K., & Gill, M. (2023). Fundamentals of nursing pharmacology (1^st Canadian ed.). BCcampus. https://opentextbc.ca/nursingpharmacology/chapter/1-9-examining-effect/

Government of Canada (2015). Drug product database: Access the database. https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html

Health Information Management. (n.d.). Glossary of terms. Retrieved October 16, 2025, from https://www.himconnect.ca/meet-him/faqs/glossary-of-terms

Media Attributions

• Figure 1.01 is by Sheila Odubote, Thompson Rivers University Open Press, and is subject to the CC BY-NC-SA license.