Feb 222013

Do you know how the medications you are taking work?

Knowing the mechanism of action of your medications is an important part in maintaining a healthy lifestyle. When you know how your medicine works, you are more cognizant of potential side effects. Read this article to learn how commonly utilized OTC medications work and what the potential side effects of those processes are.

Non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are two of the most commonly over-the-counter medications used for pain. Although many people think the two are the same, there are some key differences between the two types of drugs. Some common brand names for NSAIDs are Bayer, Celebrex, Advil, Motrin, and Aleve. NSAIDs help to decrease pain and inflammation by blocking a certain set of chemicals in the body called cyclooxygenases, or COX, from working. There are two types of COX enzymes, COX-1 and COX-2. The function of COX-2 is to help convert a certain protein in the body, arachidonic acid, into prostaglandins and thromboxane. Prostaglandins are one of the messenger molecules in the inflammation pathway, so when NSAIDs are taken and the body is not able to convert arachadonic acid into prostaglandins, a portion of the inflammation pathway is blocked and pain is diminished. The role of thromboxane is to dilate, or widen, the blood vessels and block platelets from clumping. Blood platelets are the chemicals in the body that help clot, or harden, your blood when you get a cut. NSAIDs are also frequently used to bring down a fever. They do this by changing the set point of your body’s internal thermostat, the hypothalamus.

If NSAIDs were able to selectively target only the COX-2 enzyme, they would not pose as great of a risk to people; however, most NSAIDs are non-selective, meaning they decrease the activity of both COX-1 and COX-2. The COX-1 enzyme plays a much more important role in the body in comparison to COX-2. COX-1 is responsible for regulating many physiological processes in the body, most notably the protective lining of the stomach. Because the stomach is always exposed to the very acidic gastric juices, it must have a protective layer of mucus so that it is not injured. With progressive NSAIDs use, this stomach lining wears down, resulting in ulcers and/or internal bleeding in the gastrointestinal tract. Some NSAIDs, specifically Celebrex, targets only the COX-2 enzyme, but Celebrex is associated with an increased risk of heart attacks and cardiovascular problems.

Acetaminophen, more commonly marketed as Tylenol, falls into a different category of drugs called analgesics, or pain killers, because it does not decrease inflammation. The exact mechanism by which acetaminophen decreases pain is not well understood, but it is believed that it increases the body’s threshold for pain, meaning a higher level of pain stimulus must be reached before one experiences pain. Acetaminophen is also an anti-pyretic, meaning it brings down fevers. It also decreases fevers by changing the set point of the body’s internal thermostat, the hypothalamus. Although acetaminophen is generally considered safer than NSAIDs because it does not have as great of an effect on the stomach lining, chronic acetaminophen use is also associated with an increased risk of stomach bleeding and liver damage. In fact, acetaminophen use is the number one cause of acute liver failure in the United States, and it is the number one cause of drug overdose.

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