Bipolar Drugs

Question 1

Lithium

Answer 1

Mechanism:

1) Permeate the voltage gated Na+ channels but are not pumped out by the Na+/K+ ATPase
2) Prevent agonist stimulated cAMP/ IP3 formation
3) Suppress glycogen synthase kinase 3

Side effects:
Hypothyroidism
Weight gain
Acute toxicity

Narrow therapeutic window. Need to monitor plasma concentration

Question 2

Antiepileptics

Answer 2

Mechanism:
Block Na+ channel

Examples: valproate, carbamazepine, lamotrigine

Fewer side effects than lithium

Question 3

Atypical antipsychotics

Answer 3

Mechanism: 5 HT2A (higher preference) , D2 receptor antagonist

Example: olanzapine, risperidone

High 5HT2A /D2 ratio may explain low incidence of EPS