Geriatric Pharm

Question 1

Common Drug-Drug Interactions

Answer 1

ACE Inhibitor + Diuretic:

• -Hypotension
• -Hypokalemia

Anti-Arrhythmic + Diuretic:
–Arrhythmias

Benzodiazepine + Antidepressant:

• -Confusion
• -Sedation
• -Falls

ACE Inhibitor + Bladder Relaxant:
–Negate effects

Question 2

Drug-Disease Interactions

Answer 2

Obesity increases VD of Lipophilic drugs

Ascites Increases VD of Hydrophilic drugs

Dementia may increase sensitivity, and induce paradoxical reactions to drugs with CNS or Anti-Cholinergic activity.

Renal or Hepatic impairment may impair Detoxification and Excretion of Drugs.

Question 3

Impact of Aging on

Benzodiazepines

Morphine

Answer 3

Benzodiazepines:

• -Reduced Clearance
• -Higher Plasma Levels
• -Increased CNS effect (bad!)

Morphine:

• -Longer action
• -Greater pain relief at lower doses and infrequent doses (good!)

Question 4

Factors that Affect Absorption

Answer 4

Divalent Cations (Ca, Mg, Fe):

• -Affect absorption of some antibiotics
• -*Lots of elders take Antacids and Iron Supplements!

Enteral (tube) Feedings:

• -Interferes with absorption of some drugs (e.g. phenytoin/Dilantin for seizures)
• -*Artificial Nutrition is common in elders!

Drugs that affect GI motility:

• -*Anti-Cholinergic use is common in elders!
  (e. g. diphenhydramine/Benadryl)

Question 5

Volume of Distribution in Older People

Answer 5

Decreased Body Water:
–Lower VD for Hydrophilic drugs

Decreased Body Mass (Less Muscle):
–Lower VD for drugs that bind to muscle

Increased Fat Stores:
–Higher VD for Lipophilic drugs

Decreased Plasma Protein (Serum Albumin):
–Higher percentage of Drug that is Unbound (Active!)

Question 6

Aging Kidney

Answer 6

Decreased Kidney Size (about half the size of younger person)

Decreased Renal Perfusion

Decreased number of Functioning Nephrons

Decreased Tubular Secretion

= Lower GFR

Question 7

Serum Creatinine Trap!

Answer 7

Elders have Decreased Lean Body Mass:
–Less Muscle
–Thus, Produce Less Creatinine
(Creatinine is a byproduct of muscle breakdown)

Have Reduced Kidney Function:
–Thus, Excrete Less Creatinine

TRAP: Serum creatinine may, thus, appear “Normal”
–Use Cockroft-Gault Equation to determine Creatinine Clearance!!