Geriatric Pharmacy Practice

Geriatric pharmacy is a critical, patient-centered specialty focused on optimizing medication use for older adults. As the global population ages and individuals live longer with multiple chronic conditions, the risk of medication-related harm increases dramatically. This field requires a deep understanding of how aging alters the body's response to drugs and a systematic approach to navigating the complexities of polypharmacy—the concurrent use of multiple medications—to ensure therapy is both appropriate and beneficial.

Foundational Pharmacokinetic and Pharmacodynamic Changes

Aging induces predictable physiological changes that fundamentally alter how medications are processed and how they affect the body, known as pharmacokinetics and pharmacodynamics, respectively. You cannot safely dose for an older adult without considering these shifts. Pharmacokinetically, four key processes are affected: absorption, distribution, metabolism, and excretion.

While gastrointestinal changes rarely impact absorption significantly, alterations in distribution are profound. An increase in body fat and a decrease in lean body mass and total body water mean that water-soluble drugs (like lithium or digoxin) reach higher concentrations, while fat-soluble drugs (like diazepam) have a larger storage depot and prolonged effect. More critically, decreased production of albumin—a protein that binds many drugs in the bloodstream—can lead to a higher fraction of "free" or active drug, increasing the risk of toxicity even at standard doses.

The liver's capacity for metabolism (biotransformation) generally declines with age due to reduced blood flow and enzyme activity. This slows the breakdown of many commonly prescribed medications, such as certain benzodiazepines (diazepam) and antipsychotics (haloperidol). Most importantly, renal excretion consistently declines. Glomerular filtration rate (GFR) falls with age, but this is not accurately reflected by a normal serum creatinine level, as muscle mass—the source of creatinine—also decreases. This makes estimating creatinine clearance (using formulas like Cockcroft-Gault) essential for proper renal dosing adjustments to prevent the accumulation of renally eliminated drugs like antibiotics, gabapentin, and direct oral anticoagulants.

Pharmacodynamically, older adults often have increased sensitivity to medications. For example, they experience greater central nervous system (CNS) depression from sedatives and a more pronounced drop in blood pressure from antihypertensives. This heightened sensitivity underpins many adverse drug events (ADEs).

Systematic Approaches to Polypharmacy: Beers and STOPP/START

Managing polypharmacy is not simply about reducing pill counts; it's about ensuring each medication has a clear, appropriate indication. Two primary evidence-based tools guide this process: the American Geriatrics Society Beers Criteria® and the STOPP/START criteria.

The Beers Criteria is a list of medications that are potentially inappropriate for use in most older adults. It highlights drugs that should generally be avoided due to an unfavorable risk-benefit profile, those that should be avoided in specific diseases or syndromes (like heart failure or dementia), and medications that require dose adjustment based on renal function. For instance, it strongly advises against using first-generation antihistamines (e.g., diphenhydramine) due to their potent anticholinergic effects, which can cause confusion, dry mouth, constipation, and urinary retention.

The STOPP/START criteria (Screening Tool of Older Persons' Potentially Inappropriate Prescriptions/Screening Tool to Alert to Right Treatment) provides a more comprehensive, two-pronged framework. The STOPP section identifies medications that are potentially inappropriate, similar to Beers, but is often organized by physiological systems. The complementary START section identifies commonly missed evidence-based therapies. For example, STOPP might flag a proton pump inhibitor for indefinite use without indication, while START might recommend initiating a vitamin D supplement for an osteoporotic patient. Using these tools together facilitates a balanced medication review, targeting both inappropriate deprescribing and appropriate prescribing.

Managing Specific Medication-Related Risks: Falls and Cognition

Certain drug classes pose heightened risks for catastrophic events in the elderly. Medication review must proactively target these.

Fall risk from medications is a major concern. Drugs that cause postural hypotension (e.g., alpha-blockers, tricyclic antidepressants), sedation (e.g., benzodiazepines, opioids), or dizziness/ataxia (e.g., anticonvulsants) significantly increase fall and fracture risk. A systematic approach involves identifying all such agents, assessing the patient's personal fall history and gait stability, and determining if the indication for the high-risk medication still outweighs its danger. Often, safer alternatives exist or doses can be minimized.

Cognitive effects of medications are equally critical. Beyond the obvious sedatives, drugs with anticholinergic properties are prime culprits in causing or worsening delirium, confusion, and memory impairment. This includes many over-the-counter sleep aids (diphenhydramine), medications for urinary incontinence (oxybutynin), and some antidepressants (amitriptyline). The cumulative anticholinergic burden from multiple medications with milder effects can be just as damaging as one strong anticholinergic. Assessing this cumulative burden is a key step in evaluating an older adult with cognitive changes.

The Practical Art of Deprescribing

Deprescribing is the planned and supervised process of dose reduction or discontinuation of medications that are no longer beneficial or may be causing harm. It is a core competency in geriatric pharmacy. Effective deprescribing is not abrupt cessation but a collaborative, patient-centered process.

A practical framework involves five steps: First, compile a complete and accurate medication list, including non-prescription products. Second, identify medications that are potentially inappropriate or lack a current indication. Third, assess the overall risk of harm versus benefit for each drug, considering life expectancy and care goals. Fourth, prioritize which drug(s) to taper or stop, often beginning with those associated with immediate risks (like fall-causing agents). Finally, create and execute a monitored withdrawal plan. For some medications (like benzodiazepines or gabapentin), a very slow taper is necessary to avoid withdrawal symptoms. The goal is to simplify the regimen while maintaining control of symptoms and chronic conditions.

Common Pitfalls

1. Relying Solely on Serum Creatinine for Renal Function: A "normal" serum creatinine (e.g., 1.0 mg/dL) in a frail, 85-year-old woman likely indicates severely impaired renal function due to her low muscle mass. Failing to estimate creatinine clearance will lead to overdosing of renally excreted drugs.
2. Overlooking Anticholinergic Burden: Focusing only on one strong anticholinergic medication while missing the combined effect of several drugs with mild anticholinergic properties (e.g., furosemide, ranitidine, trazodone) can leave a reversible cause of cognitive decline unaddressed.
3. Inertia in Deprescribing: The mindset of "if it isn't broken, don't fix it" is dangerous in geriatrics. A medication started a decade ago for a transient issue may no longer be indicated but continues due to clinical inertia. Regular, systematic review is mandatory.
4. Neglecting Non-Prescription Medications: Patients may not consider over-the-counter sleep aids, NSAIDs (like ibuprofen), or herbal supplements as "medications." These can contribute significantly to risks like bleeding, kidney injury, and drug interactions, and must be included in every comprehensive review.

Summary

• Aging alters pharmacology: Systematic changes in pharmacokinetics (absorption, distribution, metabolism, excretion) and pharmacodynamics require tailored dosing and heightened vigilance for adverse effects.
• Use structured tools to tackle polypharmacy: The Beers Criteria and STOPP/START criteria provide evidence-based frameworks to identify potentially inappropriate medications and omissions in therapy, moving beyond subjective judgment.
• Proactively assess high-risk domains: Routinely screen for medications that increase fall risk (sedatives, antihypertensives) and negatively impact cognition (drugs with anticholinergic properties), evaluating their continued necessity.
• Master renal dosing: Always estimate creatinine clearance; do not rely on serum creatinine alone to guide renal dosing adjustments for eliminated medications.
• Deprescribing is active, necessary care: Deprescribing is a systematic, patient-centered process to reduce medication burden and harm, and is a fundamental responsibility in managing the health of older adults.