Drugs in health and disease 2: Elderly

Question 1

Drug absorption in the elderly

Answer 1

Decreased rate of absorption and increased time to steady state due to:

• Reduced saliva
• Reduced gastric acid
• Decreased GI motility
• Reduced surface area
• Reduced splanchnic blood flow

Question 2

Volume of distribution

Answer 2

Amount of drug in body/ concentration in plasma

- Volume obtained if all the drug is in blood

Question 3

Drug distribution in the elderly

Answer 3

Decreased Vd for drug distribution into muscle
- Due to decreased lean body mass
= Plasma concentration of drug

Increased Vd for fat soluble drugs

• Due to increase in body fat
• Increases half life of drugs
• example= diazepam

Decreased Vd of water soluble drugs
- Due to decreased body water
= Increases plasma concentration of drugs
- Example: gentamicin

Decreased albumin

• Less drug binding= more free drugs
• Examples: phenytoin, warfarin, propranolol,, diazepam levothyroxine, digoxin, furosemide.

Question 4

Digoxin toxicity

• Cardiac
• Psychiatric
• Visual
• Gastro

Answer 4

Cardiac

• Heart block
• Bradycardia
• Junctional tachy

Psychiatric

• Delirium
• Fatigue
• Malaise
• Confusion
• Dizziness

Visual

• Blurred/ yellow-green vision
• Halos
• Double vision
• Photophobia

Gastro

• Nausea
• Vomitting
• Anorexia
• Diarrhoea
• Abdominal pain

Question 5

Treating digoxin toxicity

Answer 5

Withdrawing drug

Correcting any electrolyte disturbance
- Treats cardiotoxicity

Severe toxicity
- Digoxin specific antibody fragments (digibind)

Question 6

Benzodiazepine toxicity

Answer 6

Symptoms

• Drowsiness
• Confusion
• Ataxia
• Dependence

Treatment
- IV flumazenil 200 mag

Question 7

Phenytoin toxicity

Answer 7

Symptoms

• Nausea
• Vomiting
• Tremor
• Ataxia
• Nystagmus
• Coarse facies
• Hepatitis