Geriatric Pharmacology Flashcards
How can we avoid the drug AA cascade?
- Avoid prescribing until test results confirm suspected diagnosis
- Start with low dose then titrate
- Avoid starting multiple meds at the same time
- Reach theraputic dose b4 switching or ading agents
What is the drug AA cascade?
Drug 1 => AA 1 confused as new disease =>Drug 2 = AA 2 confused as new disease
What are the causes of drug related problems?
Drug interactions Inadequate monitoring Innapropriate drug selection Innapropriate Tx Lack of Pt adherence Overdosage Under Prescribing unTx medical Problem
What are the tools for medication decisions in older adults?
Beers Criteria
STOPP
START
What are the physiological changes that come with aging?
Inc. Waist Circum then plateau or decline
Increase Fat Mass
Dec. weight
Dec. LBM
What are the physiologic changes in the liver associated with age?
Dec. Hepatic size
Dec. Hepatic BF
What are the physiologic changes in the Lungs associated with age?
Dec. Respiratory Muscle Strength Dec. Chest wall compliance Dec Total alveolar surface Dec. Vital Capacity Dec. Maximal breathing capacity
What are the physiologic changes in the kidneys associated with age?
Dec GFR Dec Renal Blood Flow Dec Filtration fraction Dec. Tubular secretory function Dec Renal Mass
What are the physiologic changes in the skeleton associated with age?
Loss of skeletal bone mass
What are the physiologic changes in the body composition associated with age?
Dec. Total body water
Dec Lean body mass
Inc Body Fat
What are the physiologic changes in the cardiovascular system associated with age?
Dec Myocardial Sensitivity to B adrenergic stim
Dec. Baroreceptor Activity
Dec. Cardiac output
Increased Total Peripheral resistance
What are the parameters involved in pharmacokinetics?
Absorption
Distribution
Metabolism
Clearance/Elimination
What paramenter is least effected by aging?
Absorption
What is first pass inactivation?
Before entering systemic circulation a drug can be metabolized(inact) in the gut wall or liver, more commonly.
What hapens to first pass metabolism in the elderly?
Decreased therefore,
they will need less drug to have the same theraputic effect
May need more of a drug that requires hepatic activation
What is the equation for volume of distribution?
Vd= amt of drug in body/plasma drug conc.
What happens to the Vd of a muscle bound drug in elderly pop?
It will decrease
What happens to the kinetics of Lipid sol. drugs in elderly?
Longer HL
What is the clearance of a drug?
Rate of elimination of a drug from the body in relation of drug conc.
CL = Q x E
Q=flow rate to organ
E = Extraction ratio
What is the size of the maitenence dose?
Maint rate is equal to rate of clearance at steady state
Requires less frequent and lower maint dose
What is the chemical of choice to measure Renal clearance?
Creatinine is filtered and not reabsorbed
Creatinine clearance is an index of GFR
How is the Creatinine Clearance measured?
Compare 24 hr urine collection concentration to serum conc.
Blood conc increases and Urine conc decreases as renal function decreases
What is the purpose of the Cockroft and Gault equation
Accounts for decreased muscle mass in elderly Pts
What most significantly changes the T1/2 of drugs in the elderly?
Hepatic and renal clearance
What happens to the clearance of FLOW LIMITED drugs in the elderly?
Dec Clearance and inc T 1/2
What is the effect of aging on the B adrenergic system?
Decreases responsiveness to cardiac and vascular receptors
Dec response to Hypotensve effects of B Blockers
What is the effect of Anesthetic sensitivity in the aging population?
Incresed sensitivity!
What are considerations for NSAIDS in the elderly?
More succeptible to toxicity of NSAIDS
Renal damage
(cleared mostly by the kidneys)
Prostaglandins naturally increase in the elderly to retain perfusion to the kidneys
What are the risks of Anticholinergic drugs in the elderly?
Orthostatic hypotension and blurry vision =>Fall risk increases
