These posts, tagged “Primer,” are posted for two reasons: 1). to help me get better at teaching non-scientists about science-related topics; and 2). to help non-scientists learn more about things they otherwise would not. So, while I realize most people won’t read these, I’m going to write them anyway, partially for my own benefit, but mostly for yours.
Whenever my parents had to try and explain what I was getting my Ph.D. in to their friends or my extended family, the common response would be: “he’s going to be a Pharmacist?” Whenever I’d be asked the question, I’d typically respond with a “sigh” and then continue to say: “The difference is that a Pharmacist sells drugs, and a Pharmacologist makes drugs.” Of course, that’s a simplified definition, but was typically good enough for my purposes.
In actuality, that isn’t completely accurate. The Dictionary.com definition reads as follows
the science dealing with the preparation, uses, and especially the effects of drugs.
The Wikipedia article on Pharmacology is also pretty useful, and goes into much greater depth than I prefer to here. To summarize more broadly, Pharmacology is the study of how drugs work in an organism. This definition encompasses how a drug gets produced, how it gets into your body, where it goes once it’s in your body, what effect it has once it reaches its destination, and how it ultimately gets out of your body.
According to Goodman & Gilman’s The Pharmacological Basis of Therapeutics (11 ed), the study of Pharmacology can be subdivided into a few different categories, both dependent upon one another.
When a drug enters the body, the body begins immediately to work on the drug: absorption, distribution, metabolism (biotransformation), and elimination. These are the processes of pharmacokinetics. The drug also acts on the body, an interaction to which the concept of a drug receptor is key, since the receptor is responsible for the selectivity of drug action and for the quantitative relationship between drug and effect. The mechanisms of drug action are the processes of pharmacodynamics. The time course of therapeutic drug action in the body can be understood in terms of pharmacokinetics and pharmacodynamics.
So, the study of pharmacokinetics looks at how a drug moves through your body (“pharma” for drug; “kinetic” for movement). It is important to understand these principles when developing or prescribing a drug. For example, in the case of sleeping medication, you want the drug to act rapidly in your body so that you fall asleep, however you also want the drug’s effects to last for enough time to keep you asleep…but wear off in time for you to get up the next day. The study of a drug’s pharmacokinetic properties will help develop treatment regimens that those other doctors (read: M.D.s) can use to prescribe medications accordingly, for whatever the situation calls for.
Pharmacodynamics, on the other hand, looks at how a drug works once it reaches its destination in the body. Some drugs work primarily in the brain, some in the heart, some in the lungs, and so on. Many drugs have their function by binding to a receptor on the outside of a cell (example: diazepam [Valium]), perhaps a receptor that is responsible for “exciting” the cell or “depressing” the cell (i.e. increasing a cell’s function or decreasing a cell’s function). Perhaps Drug A will bind more effectively to that receptor, giving you a more efficient response. However, maybe Drug B isn’t quite as efficient in eliciting a response. Along that paradigm, while Drug A may be more efficient, perhaps the desired function by you and your doctor is a more delayed, longer lasting effect, and Drug B could fit that bill (typically, you want anti-anxiety medications to last throughout the day, for example…not just for a few hours).
Knowing principles of pharmacokinetics can help you maximize how much drug gets to the site of action. Knowing principles of pharmacodynamics can help maximize how much of an effect the drug has once it’s there. Both of these concepts are essential to effective drug design and usage.
As a brief (yet related) aside, I first became interested in the subject when taking a class on Psychopharmacology in the Psychology department at Truman State. It was very interesting to learn about how different drugs affect your brain to result in different effects. For example, a drug like diazepam (Valium) is a drug that’s intended to function as an anxiolytic and sedative. The basis of its function, however, is that it works on specific receptors that effectively “depress” neurons, limiting their firing ability. It turns out that function is also quite useful to help prevent seizures, a disorder where neurons fire more often than they should. So, some drugs that are intended for one purpose can be useful in another, but you need some understanding of how that drug works before you can begin to apply it to another situation.
So, in short, pharmacology refers to the study of how drugs work and, therefore, a pharmacologist works on such things. I should point out that pharmacists do play an important role in the development of drugs, as well. Merck and Pfizer employ both Pharmacologists (Ph.D.) and Pharmacists (Pharm.D.), amongst a wide variety of others.
But, they’re quite different in their training.