pharmacokinetics in the elderly
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Pharmacology
- increased 1/2life of lipid-soluble drugs
- increased peak concentration of hydrophilic drugs
- increased time for drug clearance
- increased sensitivity to:
- diminished sensitivity to:
- factors that alter drug levels in the elderly:
- absorption
- decreased gastric acidity ?
- decreased gastric emptying
- decreased absorptive surface
- decreased GI blood flow
- increased intestinal transit time
- decreased GI active transport
- decreased liver blood flow
- decreased liver size
- generally considered NOT greatly affected by age
- distribution
- decreased cardiac output
- decreased total body water
- decreased lean body mass
- increased body fat
- decreased total body size
- decreased serum albumin
- greater free drug for a given serum drug level
- potential complications with: phenytoin, benzodiazepines, warfarin, etc.
- increased alpha-1 acid glycoprotein (orosomucoid)
- major serum protein binding basic drugs
- diminished free drug for a given serum drug level
- reduced effectiveness of: quinidine, lidocaine, tricyclic antidepressants
- metabolism
- decreased hepatic blood flow (10-15% by age 80)
- decreased liver mass & volume (20-50% by age 80)
- decreased enzyme activity ?
- poor nutritional status
- concurrent drug use (interactions)
- renal excretions
- decreased filtration rate
- decreased tubular secretion
- decreased tubular reabsorption
- renal disease
- absorption
More general terms
References
- ↑ Ambrose P. In: Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
- ↑ Ambrose P. In: Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 25-28, 2002
- ↑ Taffet GE, Physiology of Aging, In: Geriatric Medicine: An Evidence-Based Approach, 4th ed, Cassel CK et al (eds), Springer-Verlag, New York, 2003