Lithium


  • Patients should maintain adequate water intake and not reduce Na in their diet

Indications

  • prophylaxis in recurrent affective disorder
  • acute treatment of mania
  • augmentation of antidepressants in refractory depression
    • ~50% patients show useful response at 1-3 weeks
  • schizoaffective disorder
  • control of aggression

Use

Prior to therapy
  • thyroid function tests
  • renal function / U&Es
  • contraception for women / pregnancy test
    • teratogen in 1st trimester
  • serum lithium levels need monitoring (0.4-1mmol/L) - initially weekly until stable

Monitoring

  • Level every 6 months, 8-12 hours after last dose
  • aim 0.4 -1.0 mmol/l
  • TFT, U&E and Ca once a year

Mechanism of action

  • Acts as a 5HT1A agonist so increasing 5HT action in the CNS
  • Also acts as 5HT2 antagonist
  • PI pathway blockage??
  • affects sodium, potassium, calcium and magnesium
  • 5HT, noradrenaline, dopamine, acetylcholine systems
  • cAMP linked receptors may explain effects on thyroid and kidney

Side effects

  • nausea
  • fine tremor
  • weight gain
  • oedema
  • polydipsia, polyuria
  • exacerbation of psoriasis and acne
  • loose bowels
  • long term
    • hypothyroidism
    • impaired renal function
    • hypercalcaemia
    • tardive dyskinesia

Overdose

>1.5 mmol/l,  indicated by

  • vomiting
  • diarrhoea
  • coarse tremor
  • slurred speech / dysarthria
  • ataxia
  • drowsiness
  • confusion
  • convulsions
  • coma
  • death (>2mmol/L)

Treatment

  • cessation of lithium
  • forced diuresis (IV mannitol)
  • haemodialysis / peritoneal dialysis

Contra-indications

  • renal, cardiac, thyroid, 
  • Na losing states
    • Addison's disease
    • dehydration / diuretics
  • pregnancy, breastfeeding
  • Myasthenia gravis
  • Operations

Interactions

  • Levels increased by diuretics and NSAIDS
  • Toxicity (5-HT) increased by 
    • haloperidol
    • SSRIs / venlafaxine 
    • anticonvulsants
  • Calcium channel blockers
  • antibiotics