Pediatric & Geriatric Pharmacology

Question 1

Pediatric loading dose - considerations

Answer 1

Body proportions of fat and distribution have little effect on Vd; loading doses change little for children

Cp (mg/L) = Dose (mg) / Vd (L)

Question 2

Grey Baby Syndrome

Answer 2

Chloramphenicol toxicity in infants

Due to inadequacy of hepatic glucuronidation (Phase II conjugation)

Question 3

Hepatic vs. renal clearance in kids

Answer 3

Hepatically eliminated drugs have clearances that vary widely in children due to multiple enzyme systems that mature at independent rates; requires careful monitoring

Renal clearance of drugs is generally more predictable and occurs more rapidly in children than in adults

Question 4

Drugs that affect growth in children

Answer 4

Psychoactive agents - i.e. methylphenidate (due to appetite suppression / sleep disturbance)

Corticosteroids (including topical / inhalted) - via inhibition of pituitary GH release

Question 5

Use of salicylates in children

Answer 5

Increased risk of Reyes syndrome - fatty liver + acute encephalopathy; especially in use following viral infection

Question 6

Use of tetracyclines in children

Answer 6

Tetracyclines are incorporated into growing bone and deeth; contraindicated in children < 8 years old and during pregnancy

Question 7

Absorption consideration in geriatrics

Answer 7

Decreased gastric acid absorption; decreased absorption of weak acid drugs (warfarin, penicillin) vs. increased absorption of weak base drugs (TCADs, benzos, opioids)

Decreased gastric emptying / GI motility; exacerbated by anticholinergic drugs (TCADs, diphenhydramine)

Decreased splanchnic blood flow

Question 8

Distribution considerations in geriatrics

Answer 8

Decreased water / lean body mass and increased adipose

Vd is decreased for water-soluble drugs causing higher plasma concentrations with increased risk of toxicity

Vd is increased for lipid-soluble drugs causing drug accumulation and prolonged elimination

Question 9

Water-soluble drugs - require lower loading dose in geriatrics

Answer 9

Digoxin
Aminoglycosides
Lithium

May require lower loading dose

Question 10

Lipid soluble drugs - require lower maintenance dose in geriatrics

Answer 10

Chloriazepoxide

Diazepam

Question 11

Changes in hepatic metabolism with age

Answer 11

Hepatic mass / hepatic blood flow decreases 1%/year after age 40

Phase I hepatic metabolism decreases by ~30% with age; Phase II hepatic metabolism is less affected

Thus, drugs that are metabolized by phase II hepatic metabolism (oxazepam, lorazepam) are more reliably eliminated in geriatric patients than are phase I metabolized drugs (diazepam)

Question 12

Renal Dosing - Considerations

Answer 12

GFR decreases by ~ 10mL / decade along with decreased elimination of renally cleared drugs

Adjust dose based on CrCl but remember that serum Cr may be “normal” even in the setting of decreased renal function due to decreased muscle mass in elderly

Question 13

Drugs that exacerbate arthralgias, myopathies, osteoporosis

Answer 13

Corticosteroids
Phenytoin
Heparin / warfarin

Question 14

Drugs that exacerbate movement disorders

Answer 14

Dopamine receptor blockers - antipsychotic agents, metoclopramide

Question 15

Drugs that exacerbate tinnitus / vertigo

Answer 15

Aspirin
Aminoglycosides
Ethacrynic acid

Question 16

Drugs that exacerbate hypotension

Answer 16

Beta blockers 
Calcium channel blockers 
Diuretics 
Vasodilators 
Anti-depressants

Question 17

Drugs that exacerbate psychomotor slowing

Answer 17

Benzodiazepines
Antihistamines
Antipsychotic agents
Antidepressants

Question 18

Drugs that exacerbate overflow incontinence

Answer 18

Drugs with anticholinergic side effects (due to urinary retention):

TCADs
Antihistamines
Typical antipsychotic agents 
Smooth muscle relaxants 
alpha-adrenergic agonists

Question 19

Treatment of overflow incontinence

Answer 19

Tamsulosin (Flomax) [alpha-adrenergic antagonist]

Question 20

Drugs that exacerbate stress incontinence

Answer 20

Due to urethral sphincter insufficiency

Prazosin, Doxazosin [alpha-adrenergic antagonists]

Question 21

Drugs that exacerbate urge incontinence

Answer 21

From detrusor hyperreflexia with sphincter dysfunction

Cholinergic drugs for dementia [AChEIs]

Question 22

Treatment of urge incontinence

Answer 22

Anti-muscarinic agents [Tolterodine]