Introduction
Aging is a natural phenomenon occurring globally. Individuals aged 60 and above have been increasing since 1980, and estimates suggest that the figure will double by 2050. Although this shift represents advances in medicine and technology, it poses significant challenges to clinicians. Pharmacotherapy is a vital intervention in geriatric medicine (the branch of medicine that deals with elderly patients). Furthermore, the appropriate prescription requires a thorough understanding of the unique pharmacologic properties of drugs in this population. The clinician must also know the clinical, epidemiologic, sociocultural, economic, and regulatory aspects of medication use in aged patients. Also, age-related systemic factors should be considered when prescribing for older adults.
What Are the Relevant Age-Related Factors in Geriatric Pharmacology?
Various age-associated changes in pharmacokinetics and pharmacodynamics occur in an aged individual.
1. Pharmacokinetics: It is the study of how the body deals with the administered medication for the duration of exposure. There are four components of pharmacokinetics, including absorption, distribution, metabolism, and excretion. However, distribution, metabolism, and excretion are affected by age.
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Drug Distribution: The volume of distribution of the drug varies with age. The volume of distribution is a theoretical space that a particular drug occupies in a given patient. The volume of distribution is greatly influenced by lean body mass versus fat. As fat increases in older patients, fat-soluble drugs (for example, Benzodiazepines) have a greater volume of distribution in older patients as compared to water-soluble drugs (such as lithium).
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Metabolism: Aging is associated with reduced metabolism. It may be due to a reduction in liver mass and blood flow. As a result, the drug bioavailability (the amount of available drug to the body) significantly increases. However, some drugs need activation in the liver. Therefore, their availability reduces with advancing age.
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Excretion: Several drugs are excreted mainly by the kidney (some antibiotics). Studies of renal function in aging suggest a constant decrease in renal function between adulthood and old age. Hence, the clearance of the drugs also decreases with age.
2. Pharmacodynamics: It is the branch of pharmacology that studies the action of a drug on the body. Pharmacodynamic changes with aging are more difficult to define than pharmacokinetics. It is because the effect of many drugs is magnified because of reduced drug clearance, resulting in higher available concentrations. Also, age-related changes can result in more therapeutic effects and increased toxicity.
What Are the Clinical Strategies for Prescribing Geriatric Patients?
Before considering drug therapy in an old patient, the clinician must note some aspects related to pharmacotherapy.
1. Polypharmacy: Polypharmacy means using multiple medications by a patient. Although polypharmacy refers to prescribed medications, one must consider the number of over-the-counter (OTC) drugs and supplements. It is of particular concern in older people who suffer from more conditions as compared to younger individuals. Multiple reasons why polypharmacy impacts older adults are:
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Older individuals are at greater risk for adverse drug events (ADEs, an untoward event after exposure to a particular drug) due to metabolic changes and reduced drug clearance. Moreover, the risk multiplies by increasing the number of drugs. Studies suggest that ADEs occur in 81 percent of patients on six or more medications.
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Polypharmacy increases drug-to-drug interaction chances and the prescription of unnecessary medications.
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Polypharmacy increases the "prescribing cascade” possibility. A prescribing cascade occurs when an ADE is considered a new medical condition. Hence, additional drugs are prescribed to treat this medical condition.
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The use of multiple drugs can lead to adherence problems in older patients.
2. Adverse Drug Events: The diagnosis of an ADE in elderly patients is complicated by the lack of awareness of the normal aging process. Further, patients, their families, and even physicians mislabel many symptoms as “just growing old.” As a result, drug-induced effects such as confusion, fatigue, and depression occur. Hence, these conditions need proper diagnosis and treatment.
3. Patient Compliance: No compliance is a failure of the patient to adhere to the prescribed medication schedule. Non-compliance includes dose alteration, wrong dose timing, and incorrect drug administration. Studies report that compliance rates in older patients range from 26 to 59 percent. There are numerous causes of non-compliance or barriers to good compliance in older patients. Attitudes about illness, aging, and medications can impair compliance. It may be because medications are a reminder of disease and aging. Hence, the patient may resist the medications. A solitary life and a lack of a support system to remind the patient about the medication may also lead to non-compliance.
What Are the Methods by Which Geriatric Patients Can Safely Manage Medications?
Medications need adjustments during old age. Some safety tips for older patients include:
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Following the Medication Regimen: The medication dosing is based on clinical trials. Hence, every medicine and its dose is different. Discussion with the clinician is helpful if a patient has trouble remembering the dose and timing. Various tools are available, such as prefilled pillboxes and reminders.
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Proper Storage of the Medication: Proper storage can ensure the adequate safety and efficacy of the medicines. Improperly stored medicines may not work appropriately. Most medicines are best stored in a dry place such as a drawer, box, or kitchen cabinet. One must note that keeping medicines in the bathroom can expose them to heat and humidity. Furthermore, it is pertinent to check the expiry date before using a particular medicine. Also, one must dispose of any medicine that is no longer needed.
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Awareness About Side Effects: An old patient must be aware of the potential side effects and drug-drug interactions between medications. One should carefully read drug labels on over-the-counter (OTC) medications and prescription medications. Further, one must follow instructions given by the clinician. For instance, some medications (antidepressants, antihistamines) should not be taken with alcohol. This is because the old patient can experience loss of coordination, memory issues, drowsiness, and collapse.
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Medication List: The medication list should be updated. Also, if the patient is consulting and seeing more than one clinician, the list must be shared with all of them. This is because clinicians should know all the prescription and OTC medications, herbal preparations, and supplements. Therefore, the clinician can also advise about potential interactions and side effects.
Conclusion
The aging process comprises structural and functional changes affecting all organ systems. A better understanding of the effects of aging on clinical pharmacology would enhance the prescribing quality. Some pertinent issues in older adults are regarding the proper use of medicines. Further, polypharmacy, non-compliance, and potentially inappropriate prescribing are challenges for clinicians. However, research must continue to focus on developing and evaluating novel interventions to address these challenges.
