What is the drug class of Lithium?

mood stabiliser

What is the method of action of Lithium?

Not fully understood

• interferes with inositol triphosphate formation
• interferes with cAMP formation

What is the main clinical use of Lithium?

• bipolar disorder
• refractory depression

What are the main adverse effects of Lithium?

• 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
• leucocytosis
• hyperparathyroidism and resultant hypercalcaemia

How is Lithium excreted?

renally

Why do Lithium levels need to be monitored?

very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life

How regularly should Lithium levels be checked?

• weekly on starting or dose change until stable
• when stable every 3 months

What other bloods need to be monitored in patients on lithium?

thyroid and renal function should be checked every 6 months

What can precipitate lithium toxicity?

• dehydration
• renal failure
• drugs: diuretics (especially thiazides), ACEi/ARB, NSAIDs and metronidazole.

What are the features of*** Lithium*** toxicity?

• coarse tremor (a fine tremor is seen in therapeutic levels)
• hyperreflexia
• acute confusion
• polyuria
• seizure
• coma

What is the menagement of*** Lithium*** toxicity?

• mild-moderate toxicity may respond to volume resuscitation with normal saline
• haemodialysis may be needed in severe toxicity
• sodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion