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Lithium

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Lithium

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Lithium-Is an alkali metal- available as Li carbonate or Li citrate Mode of action not fully known Modifies the production and turnover of certain neurotransmitters , particularly serotonin May also block dopamine receptors Primarily excreted by kidneys

Usage-Acute mania or hypomania episodes Prophylaxis of bipolar ( manic-depressive disorder ) Unipolar affective disorder Recurrent depressive disorders where treatment with other antidepressants has been unsuccessful and / or as an adjunct with other antidepressants Mood stabilizer Control of aggressive behaviour, mutilating behaviour or intentional self harm often in the context of personality disorder

Long term side effects-Nephrogenic diabetes insipidus Hypothyroidism ( risk greatest in 1st 2 yrs of treatment ) Hyperthyroidism ( rare ) Hyperparathyroidism Cardiotoxicity Decreased renal function 
( a small benign fall in eGFR seen in in 20 % of people ) Oedema Weight gain Hyperglycaemia Tardive dyskinesia ( and other movement disorders )

Why bother-Narrow therapeutic index Recommended range is 0.4 to 1.0 mmol/L Level 0.6-0.8 if being prescribed 1st time 0.8 to 1.0 → who have relapsed previously while taking Li or who still have sub-threshold symptoms with functional impairment while on treatment with Li

Toxicity-Toxicity happens at approx level of > 1.5 mmol / L and above (but may occur despite an apparent normal level ) Mild symptoms may occur at lower levels than 
full toxicity ( still need rapid assessment ) Risk of toxicity is higher in people with hypertension , diabetes , CCF , CKD , schizophrenia or Addison’s disease

More than 1 mmol/L-Nausea Diarrhoea Blurred vision Polyuria Light headedness Fine resting tremor Muscular weakness Drowsiness-Contact the patient that day Check on timing of dose Instruct to stop Lithium till further advice Contact the mental health team OOH → Contact patient , instruct to stop Lithium and contact Consultant -On-Call

More than 1.5 Increasing confusion Blackouts Fasciculations and ↑ deep tendon reflexes Myoclonic jerks Choreaoatheetoid movements Urinary or faecal incontinence ↑ restlessness followed by stupor Hypernatraemia.Contact patient immediately Stop Lithium Check serum Lithium , 
Creatinine, U/Es Contact a Dr in Mental Health Team for advice Out of Hrs →same as above

More than 2 mmol/L-Coma Convulsions Cerebellar signs Cardiac dysrhythmias Sinus and junctional bradycardia 1st° heart block Hypotension or rarely hypertension Circulatory collapse Renal failure-Emergency-admit No specific antidote Treatment is supportive Osmotic or forced alkaline diuresis

Only issue on repeat once safe to do so satisfied by serum Li conc and results of biochemical monitoring Monitor Li levels every 3 months ( guidance range 0.6 to 1 mmol/L) Older patients can experience toxicity even at upper end of the guidance range- monitor carefully Monitor renal function more often ( ie less than 6 monthly interval ) if impaired – seek adv from nephrology/ psych if urea and creatinine conc rises Monitor carefully for clinical and biochemical evidence of hypothyroidism
Women age 40-59 are at higher risk of developing hypothyroidism than men and symptoms overlap with those of depression Explain the importance of record books Take into account interaction of Lithium with other medications which can reduce renal excretion and precipitate toxicity eg ACEi , thiazide diuretics and NSAIDs

References ; Further reading
 Monitoring patients on lithium- a good practice guideline Joy Nicholson , Brian Fitzmaurice DOI : 10.1192/pb.26.9.348 Sept 2002 Monitoring of patients prescribed lithium : Key messages for primary care POMH-UK 2002 Medicine compendium accessed via http://www.medicines.org.uk/emc/medicine/
25500#PHARMACOLOGICAL_PROPS Evidence-based guidelines for treating bipolar disorders : Revised third edition recommendations from the British Association for Psychopharmacology GM Goodwin et al Journal of Psychopharmacology 1-59 CKS NHS accessed via https://cks.nice.org.uk/bipolar-disorder#!prescribinginfosub:8 Lithium in General Practice accessed via http://www.bpac.org.nz/magazine/2007/february/
pdfs/bpj3_lithium_pages16-27.pdf Prescribing and monitoring lithium therapy: summary of a safety report from the National Patient Safety Agency BMJ 2010 ; 341 : c6258

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