Medicines and How They Work

How Medicine Works

shutterstock_209281729Over-the-counter and prescription medicines are ubiquitous in our society, and are used for almost every ailment. Most afflictions have a medicine to heal the problem or treat the symptom. It may be helpful to understand how medicines work in our body. All medications are chemicals that, after being ingested, travel to a target or “receptor” in the body where they perform their action.

Medicines taken by mouth as pills, tablets, capsules, caplets, powders, or liquids are first swallowed, then travel through the esophagus to the stomach. Occasionally pills get hung up at the stomach junction, forming a “pill ulcer” in the lower esophagus. Once in the stomach a medicine is dissolved in acid then flushed into the small intestine. Medicine taken for diarrhea or constipation seek out their target receptor right there in the hollow gut, but other medicines travel across the gut and into the bloodstream before seeking out their target receptors. Some drugs, such as iron, get pumped through the gut wall, but most drugs just casually cross the gut wall into the bloodstream.

Some drugs such as blood thinners have their target receptor in the blood itself. Most others ride a carrier molecule to another part of the body such as brain or liver. Once there the drug jumps off the carrier and moves into the target organ. Once inside the drug seeks out it’s target receptor, which may be on the cell surface, in the liquid outside, or even in the cell center (nucleus). When the drug molecule finally reaches the target receptor, it attaches, and only then becomes able to perform the desired function. For pain medicine, the pain signal gets shut off in the nerve. For reflux medicine, the acid secretion is halted in the stomach. For antidepressants, the chemistry in the brain gets adjusted and the depression improves. For antibiotics, the bacteria gets killed. There are many ways a drug can produce an effect, but it first needs to latch onto the target receptor.

Drugs can also surreptitiously bind to other receptors, leading to unwanted side effects. This is more likely to happen if the dose is too high. In contrast, if the dose is too low, the drug fails to bind the good, target receptor and is not effective. This explains why the dose is so important when a medication is being administered.

After drugs finish their work, they leave the target receptor and wash out of the body. They may go back into blood, get transported to the liver or kidney, and get chemically changed and excreted in stool or urine. By taking medication on a regular basis, the drug is replenished in the body and maintained at an adequate level to perform the desired function. The science of drug action, called pharmacology, is a fascinating and complicated subject of study.

Generic drugs should be equally safe and effective as their name-brand equivalents, because they contain the identical molecule that seeks out the same target receptor. Many good medicines for depression, heart disease, high cholesterol, and other conditions are now available in generic form, sometimes at a fraction of the cost. Patients on expensive medication should ask their doctor if there is a less costly generic equivalent.

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