Pharmacotherapy in Older Adults Flashcards
In the aging population, how does absorption change?
Doesn’t change
How does the peak serum concentration change in the older population?
Peak serum conc. may be lower and delayed
Exception: Drugs with extensive first-pass effect may increase because less drug is extracted by the liver which is smaller with reduced blood flow
What are the three factors that affect absorption?
- Route of admin
- Concurrent drugs
- Comorbid illness
What are the effects of aging on volume of distribution?
- Decreased body water - Lower VD for hydrophilic drugs
- Decreased lead body mass - Lower VD for drugs that bind to muscle
- Increased fat stores - Higher VD for lipophilic drugs
- Decreased plasma protein - higher percentage of drug that is unbound
Factors causing decreased liver metabolism?
- Aging decreases liver bloodflow, size, mass
What drugs based on metabolism are preferred in older patients? Why?
Phase II (conversion drugs to inactive metabolites) because active metabolites can be dangerous
Why are benzos highly contraindicated in elderly patients?
Benzos have highly active metabolites!
What common drug metabolized through hepatic metabolism should be avoided if possible?
NSAIDs
What organ eliminates most drugs from the body?
Kidneys
Why can kidney failure be problematic when dosing drugs?
Reduced kidney fuction = reduced elimination = drug accumulation and toxicity
General effects of aging on the kidney
- Decreased kidney size
- Decreased renal blood flow
- Decreased number of functioning nephrons
- Decreased renal tubular secretion
And therefore decreased GFR
What changes in serum creatinine occur with aging?
Lean body mass decreases resulting in lower creatinine production, BUT, GFR decreases too resulting in Cr in normal range
What is the usual method to measure Cr clearance?
Estimate using the Cockroft and Gault equation
What are pharmacodynamics?
Time course and intensity of pharmacologic effect of a drug
What are the four goals of a successful drug diagnosis?
- Use the correct drug
- Prescribe correct dosage
- Target correct condition
- Drug is appropriate for patient