Lithium
Background
- Primarily used for uni / bipolar depression
- Narrow therapeutic range (0.4 - 1.0 mmol/). Toxicity at 2.0 mmol/l
- Acute toxicity
- Thirst, polyuria, tremor, dysarthria, ataxia, arrhythmia & coma
- Chronic toxicity
- Acne, hypothyroidism, alopecia & psoriasis
Toxicity
- Readily absorbed in GI tract over 4 - 6 hours post overdose.
- Widely distributed
- Not protein bound - circulates as simple cation
- Renal excretion
- Elimination t1/2 usually 24 hours but dependant upon renal function
- Acute toxicity usually occurs on background of chronic with altered metabolism eg dehydration
Management
- Admit all with symptoms of toxicity or levels > 2mmol/l
- Supportive management - A, B, C with correction fluid / electrolyte imbalance
- Avoid charcoal
- GI Tract decontamination unhelpful
- Whole bowel irrigation MAY be useful (no evidence either way) if sustained release preparation ingested
- Avoid forced diuresis
- Haemodialysis (repeated to treat rebound post treatment levels) very effective
- Haemodialysis indications (severe / life threatening overdose)
- Progressive clinical deterioration
- Life threatening arrhythmias
- Coma, seizures, respiratory failure
- Rising serum lithium concentration
- Impaired renal fxn
- Serum Li conc > 4 mmol/l in acute on chronic toxicity
- Serum Li conc > 8 mmol/l in acute toxicity
Links
- TOXBASE (Check resuscitation room PC for login details) (Toxbase email)
- Phone at The National Poisons Information Service
- The BNF is also available on line
