Medications In Older Adults

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Pharmacokinetic alterations in metabolism

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Age Related Changes in Metabolism
• Liver mass is reduced by 20-30%; hepatic blood flow is decreased by as much as 40%. Metabolic clearance of some drugs is decreased by 20 to 40% while other drugs may not be affected at all. Remember, that a reduction in 1st pass metabolism will result in higher than expected oral bioavailability. There may be a history of hepatitis or alcohol abuse also affecting drug metabolism. Due to the higher overall number of medications prescribed in older adults, there is an increased risk of liver metabolism drug interactions (Cyp p450).

Front 2

Pharmacokinetic alterations in renal excretion

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Age Related Changes in Renal Excretion
• The most important PK change with aging is the reduction in kidney function & renal drug elimination. As people age, renal blood flow, renal mass, glomerular filtration rate, filtration fraction, and tubular secretion decrease. Special attention should be given to renally cleared medications. Histories of diabetes, poorly controlled HTN, or heart failure may contribute to reduced renal clearance.

Front 3

Pharmacodynamics alterations

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• There are natural declines and changes in organ function as people age. This is partially due to the effect of multiple disease states that are more prevalent in older adults such as renal failure & liver failure, heart failure, diabetes, COPD, vascular disease, and hypertension
• There are alterations in receptor properties, numbers of available receptors, and alterations in receptor affinity that may affect physiological and medication responses
• Older adults are more sensitive to cardiovascular side effects. They have slowed orthostatic homeostasis, resulting in an increased risk of orthostatic hypotension and a slowed baroreceptor reflex response. The cardiac tissue may, in general, be more sensitive to the effects of medications including dysrhythmias
• Older adults are more sensitive to CNS side effects.

Front 4

Long-acting benzo's reasons for increase fall/fracture

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• ADRs: These drugs cause daytime sedation, confusion, dizziness, movement awkwardness, and slowed physical and mental responses. The long-half life increases the risk of accumulation and accumulation can mimic dementia & depression. All benzodiazepines have been associated with an increased risk of falls & hip fractures. Long-acting benzos have been associated with an increased risk of motor vehicle accidents.

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Tricyclic Antidepressants reasons for increased fall/fracture

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• ADRs: The TCAs have heavy anticholinergic side effects and can cause orthostatic hypotension, sedation, and dysrhythmias. TCAs have been associated with falls

Front 6

Diphenhydramine (Benadryl) ADRs

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Diphenhydramine (Benadryl)
• Exception: Acceptable for short-term treatment of allergic reactions, rash, & itching
• ADRs: diphenhydramine has heavy anticholinergic side effects and has been associated with disturbances in balance & gait.

Front 7

Antipyschotics ADRS

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• ADRs: Associated with falls, anticholinergic side effects, T2DM, weight gain, & EPSEs. Black box warning: antipsychotics increase mortality in older adults with dementia. Antipsychotics are sometimes prescribed prn to treat aberrant behaviors in non-psychotic older adults (e.g. pacing, wandering, restlessness, crying out, yelling, insomnia, nervousness, agitation, or uncooperative behavior). Antipsychotics are considered “chemical restraints” and, therefore, inappropriate and unethical.

Front 8

List medications associated with an increased risk of falls and/or fractures in older adults.

Back 8

Long acting benzodiazepine, TCAs, Antipsychotics

Front 9

List medications associated with impaired cognition in older adults.

Back 9

Anticholinergic drugs