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44 Geriatric analgesia
physiologic and pharmacologic changes have direct clinical implications for
the safe and effective provision of analgesia to older patients.
Opioid therapy provides an illustrative example of how altered elderly
pharmacology dictates a conservative approach to analgesia titration. Drug
administration regimens must allow for longer circulation times. Lower
opioid dosing is also necessitated by increased drug sensitivity, and by
decreased renal and hepatic drug clearance owing to diminished organ cell
mass and blood flow to the kidneys and liver. 11 In addition to hepatic and
renal clearance changes, pharmacokinetics are also altered by the increased
proportion of fatty tissue in older patients, and by decreases in lean body
mass and total body water.
Given the between-patient variability in physiology of aging and its pharmacologic
effects, there can be no “standard recommendation” that will
precisely adjust medication dosing as needed. Rather, it is recommended
that caution and awareness of the altered physiology inform decisions about
choice and dosing of analgesics. In approaching pain medication prescription
to older adults, the traditional dictum primum non nocere (“first do no
harm”) should be appended with an admonition to “start slow and go low.”
In geriatric patients in particular, the keys to safe and efficacious pain relief
are conservative dosing, vigilant reassessment, and judicious titration.
To avoid hypoanalgesia, it is prudent to start with a lower dose but repeat it
if the patient sustains inadequate relief. As repeated doses are given, it is
critical to monitor the patient closely, not only to observe if pain relief has
occurred but also to prevent a cumulative side effect of drug that might lead
to confusion or respiratory or circulatory failure.
n Polypharmacy and adverse drug events
Since 90% of elderly patients take at least one medication, with the average
geriatric patient taking four drugs, it is no great surprise that adverse drug
events are common in this population. 12,13
An example is provided by warfarin, one of the most often-implicated
drugs in adverse interactions in general. 14,15 One of warfarin’s more important
interactions entails potentiation of anticoagulation when the drug is