Pharmacokinetics and Drug Interactions in the Elderly and Special Issues in Elderly African-American Populations Workshop Summary (1997) / Chapter Skim
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2 WORKSHOP ON PHARMACOKINETICS AND DRUG INTERACTIONS IN THE ELDERLY AND SPECIAL ISSUES IN ELDERLY AFRICAN-AMERICAN POPULATIONS
2 WORKSHOP ON PHARMACOKINETICS AND DRUG INTERACTIONS IN THE ELDERLY AND SPECIAL ISSUES IN ELDERLY AFRICAN-AMERICAN POPULATIONS
Pages 7-34
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From page 7... ...
Although it is thought that drug absorption is not markedly altered by age, drug distribution, excretion, and metabolism can be affected by a number of the physiological changes associated with aging. For example, agerelated changes in body composition with loss of lean body mass and decreased total body water can lead to decreased volume for the distribution of some drugs.
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1` Bone mineral loss Eyes ~t Lens flexibility Time for papillary reflexes (constriction, dilation) 1~ Incidence of cataracts Gastrointestinal ~ Hepatic mass Hepatic blood flow 4, Splanchnic blood flow Transit time continues
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From page 9... ...
Research on the physiology of aging is complicated by difficulties in distinguishing the effects of normal aging from the consequences of coexisting diseases. There is significant variability among individuals (in physical and mental health status and a number of other parameters)
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From page 10... ...
The significance of distribution of body weight is of increasing research interest, and the implications of poor nutrition and weight loss are only beginning to be explored in elderly populations (Clarkston et al., 1997~. It has been noted that high waist-to-hip ratios are associated with a higher prevalence of diabetes, hypertension, and coronary artery disease.
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From page 11... ...
For example, blood concentrations of serum estrogens after estrogen replacement therapy at currently recommended doses are in the range of 153 pg/mL of estrone and 40 pg/mL of estradiol. This contrasts to physiological levels among postmenopausal women, not on hormone replacement therapy, in the range of 30 pg/mL of estrone and 8 pg/mL of estradiol.
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From page 12... ...
12 In ~ to o ~ ~ ~ _ Z I U)
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From page 13... ...
, a multicenter study of community-based ambulatory elderly patients, has shown that treatment of isolated systolic hypertension can significantly improve cardiovascular survival and decrease risk of stroke in elderly patients (SHEP Cooperative Research Group, 1991~. However, as in many studies, there was not significant representation from minority patients.
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From page 14... ...
When creatinine clearance falls below 30mL/minute,4 We excretion of drugs Mat are eliminated mainly by We kidneys decreases significantly and 3In general, frailty is the term used by health professionals to describe elderly persons who require assistance with mobility and activities of daily living, have abnormal laboratory findings, and suffer with co-occurring medical conditions including Alzheimer's disease, multi-infarct cerebrovascular disease, Parkinsonism, osteoporosis, or healed fractures (Scharf and Christophidis, 1993~. 4Normal creatinine clearance in a young adult is 10~120 mL/minute.
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From page 15... ...
Multiple confounding variables (e.g., gender, race, e~nicity, body weight, and exposure to caffeine, nicotine, and alcohol) and concomitant diseases, increase We difficulty of understanding We implications of age-related changes on clinical therapeutics in the elderly population.
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From page 16... ...
With regard to cardiac and arterial function, the following changes are also characteristic of aging: · decreased intrinsic heart rate, · impaired diastolic function (e.g., slowed cardiac diastolic relaxation) , · increased atrial and ventricular ectopy, · prolonged AV conduction times and increased depolarization times · decreased elasticity of the aorta and large vessels, · impaired baroflextunction,and · impaired vascular endothelium-mediated function (Stolarek et al., 1991; Lakatta, 1993; Lakatta et al., 1987, 1993; Craft and Schwartz, 1995~.
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From page 17... ...
win a prevalence as high as 47 percent in people over 85 years, and this disease is He leading cause of cognitive impairment in He elderly population. The pathological features of Alzheimer's disease include neuritic plaques, neurof~brillary tangles, and the death and disappearance of nerve cells in the cerebral cortex.
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From page 18... ...
CHRONIC USE OF MEDICATIONS~ Treating the health problems of older patients presents a number of challenges, as these patients frequently have multiple health problems. For example, elderly patients who survive a myocardial infarction may have chronic ischemic heart disease, hypertension, and other related chronic conditions such as diabetes.
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From page 19... ...
. The three techniques most commonly used to measure drug exposure are biologic measurement, interviews, and the use of pharmacy or other medical records.
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Although the prevalence of depression has not been found to differ by race, there are some indications that depression is an undertreated problem among African Americans (Brown et al., 1995~. Pharmacotherapeutic treatments for depression must be carefully monitored in elderly patients because the consequences of treatment failure due to undermedication and the risk of drug toxicity resulting from overmedication may be more severe in older patients than in younger adults (Salzman, 1993; Pollock, 1996~.
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From page 21... ...
This situation, coupled with the often-held belief that the American diet is nutritionally adequate and a lack of knowledge regarding nutritional factors and malnourishment in the elderly, result in confusion regarding the status of nutraceuticals in the diet of elderly persons. What is known, however, is that the potential risks and benefits to the elderly resulting from the use of various nutraceuticals beyond current recommended doses are controversial.
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From page 22... ...
The cost of medications is of concern to older persons, many of whom live on fixed incomes. Approximately 45 percent of the elderly population do not have insurance coverage for prescription drugs (Long, 1994)
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Fillenbaum and coworkers (1993) found a lower utilization of prescription and nonprescription drugs among African-American elderly populations than among Caucasian elderly populations.
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However, the systematic exclusion of elderly populations from clinical trials leaves many questions unanswered with regard to age-disease interactions, diseasedisease interactions, disease-drug interactions, and age~rug interactions. These questions remain unanswered for elderly minority populations as well.
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The barriers include · the complexity of the elderly population, which can confound the study interpretation because of multiple diseases and therapies and coexisting psychological and social problems; · differing physiology and pathophysiology in the elderly as compared to younger populations; · problems with obtaining proper informed consent in those elderly patients who are confused,who are demented or become so during the study, or who have declining or fluctuating cognition; and · the costs associated with recruitment and surveillance of the elderly, and the need for a larger sample size. There are methodological issues, however, that can be utilized to overcome some of the barriers.
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From page 26... ...
The recruitment of elderly minority populations into clinical trials, especially African Americans, has proved to be difficult. A variety of factors have contributed to this situation:
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From page 27... ...
; · frustration over an inability to have access to costly pharmacotherapeutic interventions once medications are chosen as the therapy of choice; · a poor understanding of the need for clinical trials; · a poor understanding of the safeguards in place in human subject research; and · difficulty in getting to the site of a trial. Yet it is important to include minorities in drug trials, as there may be significant differences in drug metabolism and therapeutic outcomes between ethnic groups.
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Patients The elderly population varies with regard to their knowledge and understanding of drug-related information. At one end of the spectrum are elderly patients who are extremely knowledgeable about their health and their medica i2This section is based on the workshop presentations by Dr.
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From page 29... ...
Cultural differences and disparate ethnic backgrounds between health care providers and elderly patients from minority populations may interfere with the effective transfer of information about drug use and potential side effects. Further, health care providers may not be aware of the community groups and service resources that are available to provide information to patients of different ethnic backgrounds regarding their medication use.
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From page 30... ...
New approaches suggested by the workshop speakers included a 1- or 2-year postbaccalaureate program that would provide research assistant positions in geriatric medicine programs linked to pharmacology and clinical therapeutics. Such a postbaccalaureate program offered by schools of medicine or pharmacy could provide exposure to research and clinical activities and to a series of role models including geriatric physicians, clinical pharmacists, and investigators evaluating drugs used with the elderly.
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From page 31... ...
As discussed throughout the workshop, there are a number of innovative methods that could be implemented to increase recruitment of minority elderly populations in clinical trials. In addition, the maintenance of professional career paths will require new and expanded approaches and funding mechanisms.
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From page 32... ...
1995. Estrogen replacement therapy and fractures in older women.
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1993. Prevalence of complications and response to different treatments of hypertension in African Americans and white Americans in the U.S.
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From page 34... ...
1991. Prevention of stroke by antihypertensive drug treatment in older persons with isolated systolic hypertension.
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