Drug Safety and Side Effects

Question 1

Describe the differences between type A and type B adverse drug reactions (ADRs)?

Answer 1

Type A - pharmacological - common:

• Predictable consequence of drug action
• Often dose-dependent, rarely life-threatening

Type B - idiosyncratic or bizarre - rare:

• Unrelated to known pharmacology of drug
• Not dose related
• Often involves immune system and genetics
• Can be fatal

Question 2

What is Steven Johnson syndrome?

Answer 2

• Very rare, severe, hypersensitivity reaction
• Linked to genetics, infections, poor liver metabolism but very difficult to predict
• Flu-like symptoms, high fever
• Blistering of skin, mucous membranes - skin falls off
• Organ damage and blindness
• Mortality = 5%

Question 3

Outline the immune response that causes anaphylaxis.

Answer 3

Mast cells release histamine

Question 4

Outline the 3 main pharmacovigilance systems used to report ADRs in the UK.

Answer 4

• Yellow card - main method of post-marketing surveillance
• Black triangle - highlights possibility of ADRs with new medicines
• Green form - records any significant medical event that occurs whilst a patient is taking a drug - all patients taking drug are monitored

Question 5

Why does consuming grapefruit juice have the potential to increase risk of ADRs?

Answer 5

Grapefruit juice inhibits cytochrome P₄₅₀ enzymes in liver and P-glycoprotein transporters in intestine, so potentially increases drug bioavailability.

Question 6

What type of drugs reduce excretion of lithium?

Answer 6

Diuretics - cause increased reabsorption of lithium in kidney