The basics of geriatric pharmacology
Challenges in medication management
Strategies for effective medication management
Patient and caregiver education
The future of geriatric pharmacology
References
Further reading
Geriatric pharmacology is a challenging field of medical practice. This is because aging causes changes in body structure, function, composition, and metabolic pathways. In addition, older adults have multiple medical conditions and may be on many different medications, both prescription and over-the-counter, such as analgesics, nutraceuticals, and herbal medications. This boosts the risk of drug-drug or drug-disease interactions.
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Most clinical trials do not include older people, so there is a lack of data on these drugs in this group. The lack of clinical trial data also means that the use of most drugs in this group relies on data extrapolated from younger people.
As a result, medications may become more toxic or create new adverse effects in the aging population.
This article will help understand how medications cause altered effects with age, what healthcare providers need to understand to counter these risks, and the role of education and personalized medicine in averting or minimizing these challenges.
The basics of geriatric pharmacology
Geriatric pharmacology refers to the area of study dealing with the use of medications in older people. The aging population is peculiarly susceptible to drug-related adverse effects, as described above. Moreover, rising medication costs may prompt low adherence and nutritional deficits.
As the body ages, the proportion of body water falls with an increase in that fat. This means water-soluble drugs now have a smaller volume of distribution. On the other hand, these are more readily cleared by the kidneys.
Fat-soluble drugs, in contrast, tend to move into a larger volume and thus continue to produce pharmacological and adverse effects long after they are stopped in older people. Drug clearance by the liver may decrease because of liver shrinkage in old age, but this has not been found clinically relevant. More important is the decrease in renal clearance of several drugs.
The top medications among the elderly include antibiotics, diuretics, digoxin, beta-blockers, anticoagulants, and nonsteroidal anti-inflammatory drugs (NSAIDs). Some of them have narrow therapeutic margins and may, therefore, accumulate in the blood to toxic levels with failing kidney function falls, even before creatinine concentrations rise beyond normal limits.
Among long-term care home residents, antipsychotics are the most common type of prescription drug, followed by sedatives, diuretics, antihypertensives, analgesics, and drugs to stimulate or regulate cardiac function, besides antibiotics. The most used OTC medications are acetaminophen and NSAIDs, antihistamines, H2 receptor blockers, and proton pump inhibitors.
Sedative use among the elderly sets them up for a higher risk of falls, especially with compromised liver and kidney function and a larger volume of distribution, even at lower doses. The use of NSAIDs is linked to bleeding from a peptic ulcer in over 80% of patients, mostly following an OTC purchase of these drugs. Proton pump inhibitors may lead to brittle bones via vitamin B12 deficiency, while many of these agents induce zinc deficiency.
Many drugs acting on the central nervous system have more potent effects on older people compared to younger people. Antipsychotics like haloperidol are known to trigger extrapyramidal symptoms, including involuntary movements, loss of balance, and postural hypotension. Anticholinergics may cause reduced cognition and disorientation in patients with Alzheimer's disease.
Benzodiazepines like diazepam have strong sedative effects and increase the chances of falls. Opioids, antipsychotics, certain anti-diabetic drugs, and digoxin also increase falling risk. Vitamin K antagonists such as warfarin, the commonly used anticoagulant, inhibit vitamin K-dependent clotting factor synthesis to a greater extent in older adults. In contrast, newer ones like rivaroxaban lack proper real-world data to predict adverse effects in this group of patients.
Challenges in medication management
In developed countries, the elderly population may be on up to 5 prescriptions and 2 OTC drugs. The use of 5 or more drugs is defined as polypharmacy.
Drug interactions with other drugs and adverse reactions are both more common with polypharmacy. Combined with the age-related decline in body functioning and the probable presence of chronic illness, this leads to an increase in the risk of adverse reactions by about 9% per additional drug.
Double dosage by the patient, out of forgetfulness, or a healthcare provider who is unaware of the patient's medication history is quite possible since only 5% of OTC medicines are recorded as part of the drug charts for older people.
Aging patients are also likely to be unaware that their confusion, for instance, could be caused by H2 receptor antagonists or muscle breakdown by statins. This could lead to a prescribing cascade, with more drugs being added to deal with other drug-induced symptoms.
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Adverse reactions increase exponentially with the number of medications in use, but most are linked to inappropriately high dosages, are predictable, and could have been avoided in many situations. The drugs responsible are mainly antibiotics, anticoagulants, diuretics, NSAIDs, and anti-diabetic drugs.
About 12% of elderly patients are admitted because of medication adverse effects, which could have been prevented in half the cases. To prevent such outcomes, pharmacists and geriatricians need to be involved in the care of older adults.
Strategies for effective medication management
The two steps in medication management in the aging population are comprehensive evaluation followed by medication review. This ensures they are neither undertreated nor prescribed unnecessary or toxic medications,
Medication reviews comprise a verification of all the medications the patient is currently using. Newly prescribed medications are compared to the older ones on the list, and changes are properly recorded. This is called reconciliation and reduces adverse effects due to prescribing errors at admission. Finally, the updated list is shared with other care providers.
Both implicit and explicit methods are used for medication review. The former relies on patient data elicited systematically, for instance, with the structured history taking of medication use (SHIM) method. Using SHIM, about 1 in 10 patients was found to suffer complications because of discrepancies in the medication history due to the use of OTC drugs.
The latter is based on expert consensus or recommendations that specifically lay down combinations that should not be prescribed. Explicit methods can easily be automated and converted to clinical rules such as the Beers drug list, START (screening tool to alert doctors to the Right Treatment), and STOPP (screening tool for older persons' prescriptions).
While implicit methods are more flexible and patient-tailored, explicit tools provide consistency but cannot detect undertreatment.
To improve geriatric pharmacology, adherence should be explored in a non-judging manner. Only about half of elderly patients typically adhere well to treatment for elderly patients. For instance, statins continue to be properly used by 60% of patients after three months but by only one in four at five years.
High adherence, even to placebo, is reported to be linked to a 3.5-fold increase in mortality reduction vs active treatment, indicating that its effect may be mediated by accompanying consistent lifestyle changes.
Reasons for poor adherence in the aging population should be kept in mind and rectified, such as lack of information about their disease, health literacy, reduced cognitive function, unwillingness or inability to tolerate the adverse effects, and polypharmacy, besides the rapport with their healthcare providers, and difficulties in obtaining medication.
Personalized medicine is vital in improving medication management in the aging population. Not only is lecturing patients about taking their medications counterproductive, but it ignores many reasons why they fail to do so. Reducing dose frequency is an important method of improving compliance, which is best with once-daily frequency.
Patient and caregiver education
Clinical practice guidelines are not always the best tools for elderly care. Life expectancy, the goals of care, and the risk-benefit ratio must be consulted when treating patients with multiple illnesses. Wherever possible, patient preferences must be consulted, and the final plan must be framed on a collaborative basis.
Monitoring and changing the plan are essential steps to improving patient care. Tools like STRIP (structured tool to reduce inappropriate polypharmacy) are useful in integrating the various steps of polypharmacy optimization.
Both students and practitioners need to be familiarized with these tools and their potential to optimize geriatric pharmacology. Special focus should be put on factors that increase the risk of medication errors, chiefly polypharmacy, lack of dose adjustments for organ dysfunction, and the use of psychotropic drugs.
The future of geriatric pharmacology
Many countries have set up special groups to provide evidence-based guidelines on optimal geriatric prescribing. More studies, including older individuals, are required, as well as a re-evaluation of clinical practice from multiple new viewpoints. Educating caregivers and healthcare providers is also essential in addition to patients, especially as studies show a lack of such education.
Automated systems are in the future, with enormous potential to recognize adverse drug interactions. This could be incorporated into computerized healthcare systems online on mobile apps or as part of a medical information network. The challenge is to ensure adequate specificity so that alerts will be heeded, enhancing safety in elderly care.
References
Further Reading
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