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worse than the disease.
• Choose nondrug therapies when possible.
• Assess patient’s response frequently--observe for signs of accumulation.
• Monitor hydration.
• Consider drug holidays from time to time. 36 Absorption Altered GI absorption is not a major factor in drug
sensitivity. Percentage of an oral dose that is absorbed does not
change with age.
change Rate of absorption may slow. Delayed gastric emptying and reduced splanchnic blood
flow 37 Distribution Increased percentage of body fat • Storage depot for lipid-soluble drugs Decreased percentage of lean body mass Decreased total body water • Distributed in smaller volume; thus concentration is increased and
effects are more intense
effects Reduced concentration of serum albumin • May be significantly reduced in the malnourished
• Causes decreased protein binding of drugs and increase in levels
of free drugs
of 38 Metabolism
Hepatic metabolism declines with age.
Reduced hepatic blood flow, reduced liver mass, and
decreased activity of some hepatic enzymes occur.
decreased Half-life of some drugs may increase, and responses are
prolonged. Responses to oral drugs (those that undergo extensive
first-pass effect) may be enhanced.
first-pass 39 Excretion Renal function undergoes progressive decline beginning in
early • Reductions in renal blood flow, GFR, active tubular secretion,
and number of nephrons
and Drug accumulation secondary to reduced renal excretion
is the most important cause of adverse drug reactions in
the 40 Excretion Renal function should be assessed with drugs that are
eliminated primarily by the kidneys.
eliminated In elderly patients:
In • Use creatinine clearance, not serum creatinine, because
lean muscle mass (source of creatinine) declines in parallel
with kidney function.
• Creatinine levels m...
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This document was uploaded on 03/25/2014.
- Spring '14