CONTENTS

Table of Contents
Introduction

1. Overview
2. Recognizing Alcohol Misuse and Abuse in Older Adults
3. Alcohol and Aging
4. Diagnosing Alcohol Problems in Older Adults
5. Recognizing Other Forms of Substance Abuse
6. Prevention and Early Intervention Strategies
7. Treatment
8. Outcomes and Cost Issues in Alcohol Treatment for Older Adults
9. Legal and Ethical Issues

Supplements
Resources

At Any Age, It Does Matter:
Substance Abuse and Older Adults (for Professionals)

Aging-Related Changes in How Medications Affect the Body

To use psychoactive prescription and over-the-counter drugs wisely, physicians and consumers need to understand how the aging process influences responses to medication. They also need to recognize how vulnerable older adults are to medication misuse and abuse.

Many of the hazards associated with use of medications in older adults relate to aging-related changes. For example, medication may remain active in the body longer and build to toxic levels. It can take three times longer for some drugs to be metabolized and cleared from an older person’s body.

Several age-related physical changes can affect the way drugs—both prescription and over-the-counter—act in the body and can cause problems. Normal aging changes the way drugs are absorbed, metabolized, distributed, and removed from the body. This is called pharmacokinetics. The other change is in the area known as pharmacodynamics—what the drug does to the body—e.g., increasing response to the same dose of drug.

Absorption

As a person ages, the percent of body weight composed of water decreases. Thus, certain medications that are water soluble, if given at the usual adult dose, are more concentrated and potent in an older adult. In addition, the amount of fatty tissue increases, even though the person’s total weight may remain the same.

Drugs distributed in fat have a wider distribution and a less intense, but more prolonged, effect. This is frequently seen in the “hangover” effect from sleeping medications and tranquilizers. Women, who have more fat to begin with, are at even greater risk for these adverse effects.

Other important changes occur in the digestive system related to drugs. The emptying of the stomach is delayed and intestinal activity slows. Therefore, drug action may be decreased or delayed. Risk of gastric lesions also increases.

Another change is a decrease in albumin and other serum proteins. When drugs are absorbed in the blood, they often bind with these proteins. However, the unbound portion of the drug is active. With fewer proteins to bind to, there is more active unbound drug in the system. Thus, what was once a normal therapeutic dose can become toxic in an older person.

Because of possible toxic effects, dosages for some medications might need to be reduced one-third to one-half. For example, usually 97 percent of the anticoagulant drug warfarin (Coumadin) is bound. Only 3 percent of the drug is active. In an older person, only 94 percent of the drug may be bound, leaving 6 percent of the drug active. Because the amount of active drug doubles, the dosage may need to be cut in half.

In addition, older people are more sensitive to the effects of psychiatric drugs. Therefore, it is wise to reduce the dosage of drugs such as benzodiazepines, analgesics, and sedative-hypnotics in older patients

Metabolism and Clearance

Perhaps the most significant change during aging is in liver function. Metabolism—the chemical detoxification of a drug—takes place in the liver. With aging, the liver decreases in size, blood flow decreases, and some enzyme activity that breaks down drugs decreases. Therefore, the liver takes longer to metabolize some drugs. These drugs may accumulate in the body because they metabolize too slowly. Thus, there is a higher concentration of the drug.

The kidneys also become smaller, blood flow decreases, and filtering capacity decreases. Medical conditions such as heart failure and anemia can further impair kidney function. Reduced kidney function causes certain drugs to be excreted more slowly, thus keeping them active longer.

Alcohol and smoking may compromise the action and metabolism of prescribed and over-the-counter drugs or cause harmful side effects. For more information on prescription and over-the-counter drugs, visit Intelihealth at www.intelihealth.com.

Information on the alcohol content of various products may be found at the San Diego State University Driving Under the Influence Program site, What Is the Alcohol Content of Some Nonprescription Medications?, and at the Medline Plus Drug Information page.