Transcript Includes adults >65 years old

Geriatric Pharmacology:
Relevance
Clarissa Zaoirov (2009)
Includes adults >65 years old
Fastest growing population in US and in the majority of
developed nations.
20% of hospitalizations for those >65 are due to
medications they’re taking = Adverse Drug
Events/Interactions are very common in the elderly.
What is different about geriatric
pharmacotherapy?
• Absorption – Not usually significantly altered with age.
Reduced motility and gastric emptying = constipation
• Distribution – Change in total body composition, vascular
changes, lower albumin production (not always)
• Metabolism – Reduced hepatic blood flow & mass, low
CYP-450, slow biotransformation (Phase I metabolic
pathways)
• Excretion = Renal blood flow by age 80, can be reduced
by as much as ½. Reduction in tubular function & size.
Pharmacodynamic Changes:
• Disturbed homeostatic mechanisms:
•
•
•
•
•
•
- Reduced compensatory tachycardia, baroreceptor and
vasomotor response.
- Poor thermoregulatory mechanisms
- Cardiac Beta receptor sensitivity reduced
- Hepatic Beta receptor sensitivity increased
- Greater sensitivity to medications affecting the CNS
(benzodiazepines and opioids)
- Pre-existing depletion of dopamine = Parkinsonism
when using anti-psychotic medications.
Total Result:
• These age-related changes result in greater
therapeutic effect and increased risk of
accumulation & toxicity. (Longer ½ life)
• Complicated by alterations in metabolism,
distribution and clearance.
– Example: Benzodiazepines may cause more sedation and
poorer psychomotor performance in older adults. Likely
cause: reduced clearance of the drug and resultant higher
plasma levels, wider volume of distribution of lipophylic
drug and active metabolites.
Other factors that complicate
pharmacotherapy:
•
•
•
Polypharmacy including naturaceuticals. (Ginko biloba)
Non-Compliance Issues
Drug-Disease Interactions
•
-
–
–
–
–
–
–
–
–
–
–
–
–
Anticholinergics
Benign. Prostatic Hypertrophy (BPH),
constipation, dementia
Antiarrhythmics (Type 1A)
CHF (systolic dysfunction)
Amphetamines
Hypertension (HTN), insomnia
Aspirin
Peptic Ulcer disease (PUD)
Atypical antipsychotics
DM (Diabetes Mellitus)
Barbiturates
Depression
Benzodiazepines
COPD,dementia, falls
Beta-blockers
COPD, DM, syncope
CCB 1st generation
CHF (systolic dysfunction)
Chlorpromazine
Postural hypotension, seizures
Clozapine
Seizures
Corticosteroids
DM, PUD, COPD
Decongestants
Insomnia
Recommendations:
• Start low and advance dosage slowly. Avoid the prescription
cascade!
• Cockcroft-Gualt Formula (Creatinine Clearance) :
• Beers Criteria or MAI *
• ANY new symptom or disease in an elderly patient should be
treated as Adverse Drug Event unless proven otherwise. (i.e..
Dementia) Constantly review medications for
appropriateness.