7. Medicine Flashcards
The body percentage of extracellular water (increases/decreases) with aging… intracellular water?
stays same… decreases
Age alters what two aspects of drug effects
- Pharmacokinetics
- Pharmacodynamics
Define pharmacodynamics and pharmacokinetics
Pharacokinetics
-How the body processes the drug after administration (how the body affects the drug)
Pharmacodynamics
- How the body reacts to the drug at receptor sites
- How drug affects the body
What are the five elements of pharmacokinetics
L= liberation A= Absorption D= Distribution M=MEtabolism E=Excretion
What factors influence pharmacodynamics
- Receptor status
- Genetic factors
- Drug interactions
- Drug tolerance
Factors that influence absorption are
- Alterations in GI function
- Reduced motility
- Increased pH
- reduced first-pass effect
- Use of concomitant meds
- pH changes
- reducing absorption
Aspect of PK least affected by aging
Absorption
Describe distribution
Where the drug goes after it enters the blood
Factors that influence distribution
- Reductions in protein binding
- Increased % body fat
- Decreased muscle
- Decreased total body water
Two main organs of drug metabolism are
liver
kidney
First pass metabolism (increases/decreases) with age
decreases due to reduced liver function
How can you measure kidney function
GFR
-Creatinine clearance (Cockcroft-Gault equation)
Factors that influence PD
- Distribution to biopahse (site of action reached?)
- Receptor affinity
- Receptor number
- Post-receptor events
- Homeostatic control mechanisms
- NO generalizations
Examples of antiplatelet agents
- Clopidogrel (plavix)
- Aspirin
- Ticagrelor
- Prasugrel
Examples of anticoagulant drugs
- Warfarin
- Pradaxa
- Eliquis
- Xarelto
Patients most likely on anti-coagulants are
atrial fibrilation
Other brugs of caution for bleeding
- NSAIDs
- SSRI/SNRI
- Omega 3 fatty acid
- Herbals (garlic, cordyceps, saw palmetto)
Effect of NSAIDs on bleeding
reversible inhibition of platelet aggregation
Effect of SSRI/SNRI on bleeding
may impair platelet agg.
Effect of Omega 3 FA on bleeding
Prolong bleeding time (potentially
What drug results in irreversible inhibition of platelet agg.
aspirin
Aging results in changes to
- CNS clearance
- BBB permeability
decrease…increase
Commonly used classes of drugs for sedation are
- Induction agents
- Muscle relaxants
- Anesthetic gases
Considerations for sedation are
- Postop delirium (POD)
- POstop cognitive dysfunction (POCD)
POD and POCD lasts how long
POD= 24-72 hrs POCD= weeks to months
How to reduce risks of sedation
- Choice of sedative (short duration action)
- Slow titration
- Shortest duration possible
Rule of thumb for sedation
reduce intiial dose by 50% in geriatic patients over 70 yrs old
Strategies for healthy perscribing
- Treat indications not symptoms
- Weigh risks and benefits
- Know patients health history and meds they are taking
- Simplify regimen avoid PRN and monotherapy
- Educate patients about effects both therapeutic and toxic
- Consider new symptoms may be drug induced
Sympathetic nervous system stimulates (thick/thin) saliva production. Patients on anti-cholinergic meds will have (thick/thin) saliva
Sympathetic= thick PSNS= thin
-Anti-cholinergics –> thick saliva
Common xerogenic drug classes
- Anti-histamines
- Anti-hypertensives(alpha agonists and blockers and beta blockers)
- Anti-psychotics
- Bronchodilators (anti-muscarinics, and beta agonists)
- Decongestants
- Opioid
Which will have worse xerostomia (1st/2nd) gen antihistmaines and why
1st becasue they penetrate the BBB
Pilocarpine and cevimeline are what kinds of drugs
cholinergic agonist (muscarinic agonist)
Uses for pilocarpine and cevimeline are
- Uncontrolled asthma
- Glaucoma
- Iritis
Caution should be taken when using pilocarpine and cevimeline in what patients
- Active cardiac disease
- Biliary tract disease
- hepatic disease
Side effects of pilocarpine and cevimeline
- Sweating
- Flushing
- Dizziness
- Rhinitis
- Increased urinary freq
Use of amifostine is
xerostomia prophylaxis (acute and chronic)
Does amifostine negativelt affect cancer treatment
no
Indications for amiforstine
- Patients undergoing radiation (xerostomia prophy) for head/neck cancer
- Radiation includes substantial portion of the parotid glands
Amifostine is administered how
IV
Adverse effects of Amifostine
hypotension
neusea and vomitting