July 19, 2014
Senior Health and Medicines
Medicines enter the body in several ways. They enter through an inhaler, a skin patch, a pill, an IV, or a hypodermic needle. Oh, you say I forgot an insulin syringe. Sorry folks, the needle on the syringe is a hypodermic needle. The meaning of hypodermic is under the skin and those of us injecting insulin do inject it under the skin and hopefully into a layer of fat below the skin and not in the muscle.
Medicines are also termed drugs and the terms are used interchangeably. As the drugs make their way through the body, changes happen along the path they travel. In this blog, I will focus on drugs taken by mouth, since those are the most common and many people with type 2 diabetes use them.
When you take drugs by mouth, they move through the digestive tract and are taken up by internal organs like the stomach and small intestine. Often, they are then sent to the liver, where they might be chemically altered. Finally, they are released into the bloodstream. As the bloodstream carries medicines throughout the body, the drugs can interact with many tissues and organs. Side effects can occur if a drug has unintended effects anywhere in the body.
Drugs are treated just like food, as the body attempts chemically to break them down as soon as they enter the body. Most are broken down in the stomach or small intestine and sent to the liver. The liver in turn contains protein molecules called enzymes that chemically modify drugs and other non-food substances. The chemical change of a medicine by the body is termed drug metabolism.
Often, a drug is metabolized by the body; it is processed into products called metabolites. These metabolites are often weaker than the original drug, but sometimes they have effects that are stronger than the original drug. An example of this is the codeine in the prescription painkiller Tylenol#3, which becomes fully active only after the medicine is metabolized in the liver.
Since most drugs and other 'foreign' substances are broken down in the liver, scientists often refer to the liver as the 'detoxifying' organ. This means that the liver can be damaged by too much medicine in the body. Drug metabolites usually return to the liver and are chemically altered again before they exit the body.
After a drug's metabolites have circulated in the bloodstream and done their work as medicine, the body eliminates then the same way it eliminates other wastes, in the urine or feces. Age-related changes in the kidney function can have significant effects on how fast a drug is eliminated from the body.
The above discussion helps explain in a small way, how important the liver and kidneys are to the processes that take place in the body for our drugs we take, and why many researchers refuse to test drugs on the elderly. Not only are they concerned about comorbid conditions, but also they are unsure of the liver and kidney and how well the body can handle the medicines.
Yet, our doctors prescribe these drugs and think nothing about the liver and kidney functions or the factor of aging on our liver and kidneys. Think about this the next time your doctor insists on keeping you on oral diabetes medications instead of insulin.