Lithium is mood stabilising drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys.

Mechanism of action

Not fully understood, two theories:
  • interferes with inositol triphosphate formation
  • interferes with cAMP formation

Adverse effects

Adverse effects
  • nausea/vomiting, diarrhoea
  • fine tremor
  • nephrotoxicity: polyuria, secondary to nephrogenic diabetes insipidus
  • thyroid enlargement, may lead to hypothyroidism
  • ECG: T wave flattening/inversion
  • weight gain
  • idiopathic intracranial hypertension