3) Pharmacokinetics Applied

Question 1

What are the signs and symptoms of digoxin poisoning?

Answer 1

Nausea
Yellow vision (xanthopsia)
Bradycardia

Question 2

Describe the metabolism of paracetamol:

Answer 2

Metabolised to glucuronide (60%), sulfate (30%) and by P450 to NAPQI - which is conjugated with glutathione into inactive metabolites

Question 3

Why is paracetamol overdose dangerous?

Answer 3

Conjugation of NAPQI is saturated leading to increasing toxic levels of NAPQI which damages liver

Question 4

What is the treatment for paracetamol overdose?

Answer 4

N-acetylcysteine

Question 5

How do you calculate loading dose?

Answer 5

Vd = dose/drug conc at T0

Loading dose = Vd x [drug] target

Question 6

What drugs exhibit saturated kinetics?

Answer 6

High dose aspirin
Phenytoin
Verapamil
Fluoxetine
Alcohol

Question 7

How can a steady state be achieved?

Answer 7

Controlled continuous infusion or small repeated boluses

Question 8

Why doesn’t penicillin reach a steady state?

Answer 8

Short half life, so drug is eliminated between doses