A few weeks ago I described how often adverse events occur when a doctor's or pharmacist's mistake causes people to leave the drugstore with the wrong medication or the wrong dose of the right medication. Older people are more likely to encounter these mistakes simply because, on average, they take more medications.
But older people are more likely to have drug side effects for other reasons, too. Their body tissues can be more sensitive to the effects of certain drugs, their blood levels of a drug may rise higher and last longer, and interactions may occur among multiple prescribed drugs.
The effects of many medications persist until they are inactivated (metabolized), usually in the liver. This process of drug metabolism slows down as people grow older. As a result, side effects can occur because a given dose of a drug may reach a higher and more persistent blood level in an older person than in a younger one.
Unwary physicians may prescribe the same starting dose of a medication for a 75-year-old as they do for a 40-year-old, even when the manufacturer's instructions may warn doctors to start treatment in older patients at a smaller dose.
Older people face the even more common and dangerous problem of interactions among drugs because they often take lots of them for different chronic ailments prescribed by different doctors.
The frequency of errors and side effects increases with both the number of medications and the number of doctors writing prescriptions for that patient. One analysis found that nearly one in four older people get prescriptions from five or more doctors and that the drug error rate is seven times greater among those over the age of 65 than in those under 65.
You can't change your body's rate of metabolism, but you can do something to minimize adverse interactions among drugs. Most of the doctors writing your prescriptions won't know what other medications you are taking unless you tell them.
Bring along a list of all of your prescription drugs; if that's difficult for you, bring all your prescriptions in their labeled containers to your appointments. Pharmacists check for dangerous drug interactions when they fill a new prescription, but they are probably unaware of prescriptions you get filled at other pharmacies. That's a good reason to try to use the same pharmacy for all of your prescriptions.
Your most important safeguard is having one doctor who serves as the quarterback for all of your medical care. This doctor, most likely your primary care provider, should know about all of your medical problems and all of the drugs you are taking, even if the care and prescriptions for those conditions are provided by other doctors.
