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What changes in elderly, Pharmacodynamics, Pharmacokinetics, or both?
Pharmacokinetics will be altered in the elderly.
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What is pharmacodynamics?
What the drug does to the body. THE MOA (however age related changes can alter the EFFICACY of a medication)
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What is pharmacokinetics?
What the body does to the drug to metabolize it.
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What is the process of pharmacokinetics?
ADME. Absorption, Distribution, Metabolism, Excretion
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How can rate of absorption be changed in the elderly?
GI absorption can be altered due to increased pH, decreased GI motility. Rate of absorption will be altered, but not much of a clinical noted effect of amount absorbed.
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How can distribution of drug be changed in elderly?
Alterations in total body weight, body proteins, body fat amount and lean muscle mass can all alter distribution of drugs. Many fat soluble medication will hang around a lot longer in the elderly
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How can metabolism of drug be changed in elderly?
Liver is smaller, reduces rate of drug metabolism
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How can excretion of drug be changed in elderly?
GFR is reduced and tubular function changes. Slower excretion of drugs and drug metabolites, less renal reserve and increased susceptibility to effects of nephrotoxic drugs
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What is the amount of half-lives needed to reach steady state?
3 to 5 needed to reach stead state
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How long is needed for drug to be cleared from the body after discontinuation?
Need 3-5 half lives to be cleared from body
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What is the best Benzodiazepam to use in elderly, if you had to rx one? Serax has shortest half life, then followed by Xanax. AVOID Ativan or Valium, etc
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What happens to Beta 2 receptor sites in elderly?
Elderly lose Beta 2 receptors, therefore COPD have less bronchodilator effect. Add anticholinergic to the LABA in COPD elderly.
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What happens with RAS system in elderly?
Elderly people produce less Renin-angiotensin, therefore, less antihypertensive effect noted in elderly as same dose in younger person.
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What side effects can elderly have with anticholinergics?
Increased risk of confusion, hypotension, urinary retention, constipation, visual disturbance. As a guide, choose the drug that causes less dry mouth (as good indicator of systemic effect).
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Which is best in elderly? Oxybutynin (Ditropan) or Tolterodine (Detrol)
Detrol is best, less systemic anticholinergic effect
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Which is best in elderly? TCA- Amitriptyline or Nortriptyline?
Nortriptyline is better. Less systemic anticholinergic effect
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Best SSRI for elderly?
Citalopram or Escitalopram. Avoid Prozac- very long half life. Paxil avoid due to increased anticholinergic effect.
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SSRIs that interact with Warfarin (CYP 2C9)?
Fluoxetine, paroxetine, sertraline. Citalopram and Escitalopram is best.
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If see an elderly person in urgent care for URI who had no idea what meds they are on, but is on a lot and why do you choose this antibiotic?
Consider Azithromycin. (Clarithromycin is 3A4 inhibitors and many drugs including statins, are 3A4 substrates- rhabdo risk)
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What needs to be taken into consideration when prescribing an antibiotic or antifungal when someone is on simvastatin?
Ketoconazole, Itraconazole, erythromycin, or clarithromycin- should not be given. If unavoidable, hold Simvastatin during treatment.
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What is normative Renal function change in elderly?
Inability to conserve sodium and inability to off-load potassium. Loss of renal mass. Loss of functional nephrons. Diminished renal blood flow.
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When is dose adjustment needed in GFR rates?
If GFR less than 50, need to adjust dose. Will mean renal insufficiency. Many drugs will need dose adjustment, especially if person is sick.
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At what GFR is are many drugs contraindicated or used in small, infrequent doses?
GFR less than 25. 80% of nephrons are destroyed, kidneys unable to maintain normal fluid and electrolyte balance. Signs of renal failure.
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When is dialysis or transplant needed?
GFR <10.
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What is the best antibiotic for UTI in elderly?
Ciprofloxacin. Nitrofurantoin is not good if lower GFR as kidneys will not concentrate the drug enough to get into Urinary tract to treat infection. Avoid bactrim, as it will cause electrolyte imbalances.
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>20:1 BUN/Cr ratio means?
Pre renal failure. BUN reabsorption is increased. BUN is disproportionately elevated relative to creatinine in serum.
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10-20:1 BUN/Cr ratio means?
Normal or post renal failure. Normal range. Can also be postrenal disease. BUN reabsorption is within normal limits.
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<10:1 BUN/Cr ratio means?
Intrarenal damage. Renal damage causes reduced reabsorption of BUN, therefore lowering the BUN:Cr ratio.
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What antibiotics do not need dose adjustment in Elderly?
Ceftriaxone, moxifloxacin, Azithromycin, Nafcillin, Linezolid, minocycline, doxycycline, clindamycin,
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What is a good UTI drug if renal insufficiency?
Rocephin IM or IV
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What is the most common oral antibiotic implicated in C-diff?
Clindamycin
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Normal skin changes in elderly?
Loss of epidermis and dermis causes subcutaneous skin thinning.
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What blood pressure changes are noted in the elderly normally?
Normal widening of pulse pressure- increase in systolic B/P can be noted due to increased vascular resistance. Isolated systolic hypertension
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What is the Cockcroft-Gault equation?
Calculation for estimation of Cr. Clearance, in lieu of 24 hour urine
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What is the definition of postural hypotension?
Excessive drop in blood pressure with position change with signs and symptoms of dizziness, lightheadedness, vision changes.
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What is criteria of B/P change for postural hypotension diagnosis?
SBP drop of greater than 20 and DBP drop of greater than 10 and also a HR greater than 100 can also strongly suggest
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What is the class of medications best for elderly urinary urge incontinence?
Selective muscarinic receptor antagonists. They block bladder receptors nad limit bladder contraction.
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