Top 10 Pharmacology Terms You Need to Know!

What is Pharmacology?

Pharmacology is about how drugs work in the body. As part of the PTCB test, candidates are expected to have a rounded knowledge of basic pharmacology as well as a solid understanding of the most common drug classes.

Here, we talk about the fundamentals of pharmacology – the most basic pharmacology terms that pharmacy technicians are expected to know. At first, pharmacology may seem difficult. That’s because it is. But with time, the subject becomes more and more manageable and interesting to study.

The 10 definitions we cover today include:

• Indication
• Mechanism of action
• Side effect
• Adverse effect
• Pharmacokinetics
• Pharmacodynamics
• Drug agonist
• Drug antagonist
• Drug interactions
• Generic versus branded drug

Let’s get started with the first of our pharmacology terms – indications!

Indication

The indication of a drug is what the drug is licensed to treat.

For example – ampicillin is licensed to treat bacterial infections. These bacterial infections are referred to as one of the drug’s indications. The indication of metformin is type 2 diabetes. The indication of Viagra (sildenafil) is erectile dysfunction. All drugs have indications. Some drugs have more than 1 indication.

For example, methotrexate is used to treat inflammatory disorders as well as types of cancer.

Mechanism of action

The mechanism of action of a drug is how the drug works.

For example, statins are drugs used to treat high blood cholesterol, or hypercholesterolemia. This is the indication of the drug class.

Statins work by inhibiting the enzyme HMG-CoA reductase; an essential enzyme in the production of cholesterol in the body. By inhibiting this enzyme, statins work to reduce blood cholesterol levels.

This mechanism of how the drug works is the mechanism of action – how the drug achieves its therapeutic effects.

Side Effect

All drugs have side effects. Side effects are expected reactions that often happen when a patient takes a drug.

Some side effects are more common than others.

Here is a list of side effects of the type 2 diabetes drug, metformin:

• Taste disturbances
• Diarrhea
• Weight loss
• Lactic acidosis
• Vitamin B₁₂ deficiency

Side effects are not the same thing as adverse effects.

Side effects are expected and sometimes intended effects of a drug. However, unintended pharmacological effects are referred to as adverse effects.

Patients may be told to expect side effects, and physicians are aware of these effects when they occur. However, in cases where an unexpected and harmful pharmacological effect occurs (for example: due to dose, or perhaps unexpected genetic reactions), this is referred to as an adverse effect.

Pharmacokinetics

Pharmacokinetics and pharmacodynamics are must-know pharmacology terms. Pharmacokinetics (PK) is a discipline of pharmacology that studies how an organism, such as humans, affects a drug.

The study of pharmacokinetics is often summarized in the acronym, ADME:

• Absorption
• Distribution
• Metabolism
• Excretion

In other words, how the body absorbs the drug, distributes it around the body, metabolizes it (for example – via the liver or gastrointestinal tract), and eliminates the drug from the body. For the PTCB exam, it’s important to know the difference between pharmacokinetics and its sister discipline, pharmacodynamics.

Pharmacodynamics

In contrast, pharmacodynamics (PD) talks about what the drug does to the body. In other words, the biochemical and physiological effects of the drug on the body.

Pharmacodynamics, then, is an important discipline that helps to learn what the optimum dose should be.

After all, some doses are more toxic than others, even though both doses may achieve a desired clinical outcome (defeating an infection, for example). Studying pharmacodynamics and the effect of the drug on the body helps to establish the most optimum dose-response relationship that limits side effects whilst maximizing the clinical effects of the drug.

Agonism and Antagonism

Many drugs work by targeting receptors. Receptors are chemical structures in the body composed of proteins. Once a receptor is activated, a physiological response takes place.

For example – when epinephrine binds to beta-1 receptors in the heart, it causes the heart to beat faster. When epinephrine is blocked from binding to this receptor, this effect does not occur.

There are hundreds of different receptor types – all of which have different effects on the body. Some drugs are used to activate receptors, to promote a physiological response, whereas other drugs are used to block the effects of receptors, thereby preventing a physiological response.

Drugs that bind to receptors and promote its natural physiological outcome are called agonists. In contrast, drugs that block receptors are called antagonists.

For example:

Albuterol targets beta-2 receptors found on the surface of the lung. When albuterol binds to these receptors, it produces an agonist effect that promotes bronchodilation – making it easier for people with asthma/COPD to breathe. Albuterol is, therefore, an agonist at beta-2 receptors.

Drug Interactions

Drugs can interact with many things.

Drugs can interact with other drugs, with food, and with disease.

Drug-drug interactions can be positive or negative. For example – many drugs negatively interact with one another. One drug can prevent the metabolism of another drug, increasing the risk of side effects and toxic reactions. Some drugs prevent the mechanism of action of other drugs. There are too many drug interactions to list here and, for the PTCB test, you are not expected to know these interactions. However, it is important you are aware of how drugs can interact with one another.

Similarly, drugs can interact with food. The antibacterial drug class, tetracyclines, for example, interacts with calcium ions. This means that, if the patient takes milk along with their tetracycline drug, it interacts with and prevents the antibacterial drug from working. For this reason, milk must be avoided before/after the patient takes the drug. There are hundreds of other food-drug interactions.

Generic versus Branded Drug

When a drug first comes on the market, it has a patent. This means that they have legal control over the ingredient production of that medicine. No competitor exists during this period where the founding company owns the patient.

After this patent expires, competitor pharmaceutical companies can now come flooding in to produce the medicine – often at a significantly cheaper cost. That’s because these competing companies do not have the significant drug manufacturing costs that the founding company had.

In other words, generic drugs are copies of brand-name drugs with the same dose, use, side effects, route of administration and almost every other clinical factor. The pharmacological effects are the same.

Take Home Message

For the PTCB examination, candidates are expected to have a thorough knowledge of pharmacology terms – the basics of the discipline as well as the most common drug classes, how they work, what side effects are most common, and what drug interactions can be expected to happen.

As part of this process, you will be asked questions about pharmacology terms. Above, we have covered the most fundamental definitions that you need to know. If you are already a registered member of PTCB Test Prep, please go to the relevant section now to test your knowledge of these definitions with our practice PTCB questions.

PTCB Test Prep is the leading online platform that trains pharmacy technicians throughout the United States. Check back to our blog soon for more neat articles on the detail you need to know to ace the PTCB exam!