Pharm elderly pharm

Question 1

what are pharmacokinetics based on?

Answer 1

absorption
distribution
metabolism
elimination

Question 2

what does aging affect absorption?

Answer 2

• amount absorbed (bioavailability) is not changed

- but peak serum concentration may be lower and delayed

Question 3

what is the exception to aging and absorption?

Answer 3

drugs with extensive first pass effect - bioavailability may increase because less drug is extracted by the liver which is smaller with reduced blood flow

Question 4

what are the factors that affect absorption?

Answer 4

• route of administration (enteral feedings interfere with absorption of some drugs)
• what is taken with the drug (divalent cations - ca, mg, fe - can affect absorption of many fluoroquinolones; drugs)
• comorbid illnesses (increased gastric pH may increase/decrease absorption)

Question 5

what are the effects of aging on volume of distribution

Answer 5

• lower body water (lower VD for hydrophilic drug)
• lower lean body mass (lower VD for drugs that bind muscle)
• higher fat stores (higher VD for lipophilic drugs)
• lower plasma protein (albumin) - higher percentage of drug that is unbound (active)

Question 6

what are the effects of aging on metabolism

Answer 6

metabolic clearance of a drug by the liver may be reduced because aging decreases liver blood flow, size and mass

Question 7

phase I metabolic pathways

Answer 7

hydroxylation, oxidation, dealkylation and reduction

-convert drugs to metabolites with greater, less or the same effect as the parent compound

Question 8

phase II metabolic pathways

Answer 8

convert drugs to inactive metabolites that do not accumulate

Question 9

which metabolic pathway is preferred for older patients?

Answer 9

phase II (convert drugs to inactive metabolites that do not accumulate)

Question 10

example of phase 1 pathway metabolism drug

Answer 10

benzodiazepine (causes old people to fall down)

Question 11

examples of protein bound drugs

Answer 11

warfarin, barbiturates, phenytoin, carbamezapine

Question 12

examples of water soluble drugs

Answer 12

digoxin and lithium

Question 13

example of lipid-soluble drug

Answer 13

diazepam

Question 14

list some drugs that require dose reduction with decreased creatinine clearance

Answer 14

aminoglycosides, fluoroquinolones, penicillins, procainamide, lithium, digoxin, metformin, biphosphonates, thiazides, atenolol, clofibrate, fluconazole, ACEi

Question 15

what are some other factors other than aging that affect drug metabolism?

Answer 15

gender, hepatic congestion from heart failure, smoking (increases clearance of theophylline)

Question 16

list some drugs that require hepatic metabolism

Answer 16

NSAIDs, aspirin, Ca channel blockers, acetaminophen, statins, cimetidine, ranitidine, proton pump inhibitors, beta blockers, ketoconazole, tricylic antidepressants, serotonin reuptake inhibitors, valproic acid, lidocaine, erythromycin, phenytoin

Question 17

why is kidney function critical for elimination of a drug?

Answer 17

• most drugs exit via kidney

- reduced elimination causes drug accumulation and toxicity

Question 18

what are the effects of aging on the kidney?

Answer 18

• reduced kidney size
• reduced renal blood flow
• reduced number of functioning nephrons
• reduced renal tubular secretion
• -> lower GFR

Question 19

why does serum creatinine not reflect creatinine clearance?

Answer 19

lower lean body mass causes lower creatinine production AND there is a lower GFR causing serum creatinine to stay in normal range while masking change in creatinine clearance

Question 20

what is the equation to calculate creatinine clearance?

Answer 20

cockroft and gault:

ideal weight in kg)(140-age) / (72)(serum creatinine in mg/dL) X (.85 if female

Question 21

pharmacodynamics definition

Answer 21

time course and intensity of pharmacologic effect of a drug

Question 22

impact of aging on pharmacodynamics

Answer 22

may change with aging:

• benzos cause more sedation and poorer psychomotor performance in older adults (d/t reduced clearance of drug)
• older patients may experience higher levels of morphine with longer pain relief

Question 23

which medications are most commonly involved in adverse drug events?

Answer 23

cardiovascular, CNS (esp anticholinergics), musculoskeletal medications, diphenhydramine (PM meds)

Question 24

what are the risk factors for adverse drug events?

Answer 24

1. 6 or more concurrent chronic conditions
2. 12+ doses of drugs/day
3. 9+ meds
4. prior adverse drug reaction
5. low body weight or BMI
6. age 85+
7. estimated CrCl less than 50

Question 25

most common adverse effects of drug-drug interactions

Answer 25

1. confusion
2. cognitive impairment
3. arterial hypotension (esp when standing)
4. acute renal failure

Question 26

risk with combination of ACE inhibitor + diuretic

Answer 26

hypotension, hyperkalemia

Question 27

risk with combination of antiarrhythmic + diuretic

Answer 27

electrolyte imbalance, arrhythmias

Question 28

risk with combination of calcium channel blocker + diuretic or nitrate

Answer 28

hypotension

Question 29

principles of prescribing for older patients

Answer 29

start low and go slow!

titrate upward slowly and avoid starting 2 drugs at teh same time

Question 30

what are the most important things to check before starting a drug/receiving a new elderly patient?

Answer 30

1. creatinine clearance
2. BP standing and sitting
3. digoxin should be a lower dose
4. PM drugs have a fall risk
5. iron is constipating