Every year, an estimated 32,000 older people suffer hip fractures during drug-induced slips and falls. Some problems come about simply because we are older. Our bodies are changing, and don't react the same way to medications as they once did. For one thing, aging reduces the amount of water and lean tissue in the body, and replaces it with fat. This affects the length of time a drug stays in the body, how it's absorbed, and how long it acts.
Metabolism also slows.
The kidneys and liver are less efficient, so many medicines stay in the body longer still. Health problems also play a part. Ulcers, diabetes, and chronic heart, liver, or kidney disease can also affect how quickly and how well a drug works in the body. On the other hand, side effects can make existing problems worse. Another frequent source of trouble is the use of more than one drug for more than one problem.