Pharmacology is the study or science of drugs. What is a drug? A drug is any chemical that affects the
physiologic processes of a living organism. Commonly, the term drug refers to any medication that is used for
diagnosing, curing, or treating disease.
Drug Effects
Drugs have many different effects on the body including the following: (1) therapeutic effects, (2) side effects, (3)
adverse effects, and (4) toxic effects.
Therapeutic effect is the desired drug effect to alleviate some condition or symptom.
Side effects are the drug effect other than the therapeutic effect that are usually undesirable but not harmful.
Adverse effect is a general term for undesirable and potentially harmful drug effects.
Toxic effects are undesirable drug effects that implies the drug is poisoning the body and can be harmful or even
life- threatening.
Clinically, it is important to recognize the difference between these different ways drugs can affect the body. A
simple side effect could be something as harmless as mild nausea after taking a medication that can be
managed by taking it with food. The drug therapy can continue without a problem. However, adverse effects
need to be assessed to determine whether there is any risk of harm. Drug therapy is often a risk vs. benefit
assessment. The patient’s provider should weigh the risk of taking the medication vs. the benefit. It often
comes down to the severity of the disease being treated to decide the number of adverse events that will be
tolerated. A good example of this is chemotherapy treatments for cancer. There are often adverse events
associated with these treatment regimens, yet the treatment is continued because the benefit of treating the
A+
, NURS 251 Pharmacology Module 1- Portage Learning
cancer is greater than the adverse events the patient experiences. However, there are certainly times when a
treatment becomes too toxic, and the patient is unable to tolerate the regimen. This is often a large part of
managing a cancer patient’s treatment, to assess how they are handling the adverse effects associated with
the treatment regimen and determine whether it is becoming too toxic and needs to be suspended.
Basic Concepts
There are some basic concepts that are important to understand and that can be applied to any drug. Most
important is the drug’s mechanism of action—how a drug produces its effects. This course will cover the
accepted mechanism of action of known drugs. When a drug enters the body, it has a targeted site of action—
the location within the body where a drug exerts its therapeutic effect, often a specific drug receptor.
Generally, these sites of action or receptors are on the surface or inside a cell. Receptors are specific cellular
structures that a drug binds to in order to produce a physiologic effect. When a drug binds to a receptor, it can
act either as an agonist, works to activate a physiologic response or drug effect, or an antagonist, works to
interfere with other drugs or substances from producing a drug-effect.
The dose-dependent relationship is a basic principle of pharmacology which states that the response to any
drug depends on the amount of drug given. This is referred to as the dose dependent relationship. A dose is
the exact amount of drug that is given. As shown in Figure 1.1, the onset of action is the time from the drug
administration to the first observable effect. The duration of action is the length of time that the drug
continues to produce its effect. All drugs have a therapeutic range defined as when the drug concentration is
above the minimum effective concentration and below the maximum tolerate concentration.
A+
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ASolution. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $12.99. You're not tied to anything after your purchase.