Lithium Flashcards
(24 cards)
Mechanism of action (4)
Unknown
Reduces dopamine release
Increases serotonin release
Reduces secondary intracellular messengers
Indications (3)
Prevent manic/depressive episodes in bipolar
Treat acute mania
Schizoaffective disorder and chronic schizophrenia
Precautions with use (4)
Hyponatremia->+risk of toxicity Hypothyroidism Psoriasis- exacerbate/precipitate Drugs which risk serotonin toxicity Renal function- including with drugs that affect renal clearance (NSAIDS)
How does hyponatremia affect lithium use
Low water and salt= +reabsorption of lithium in proximal tubule of kidney->risk of toxicity
When patient has surgery, should they keep taking the lithium
Consider interrupting treatment briefly as fasting and changes in fluid intake can alter serum levels
Effects on pregnancy
Increased CHD
Neurotoxicity
Hypothyroidism
Should lithium be used in pregnancy
Avoid in first trimester, use following.
Need to check lithium levels more frequently
When should bloods be taken for lithium concentration
12 hours after last dose
After starting treatment when do you measure levels
5-7 days later, and after every dose change until stabilised
Once stabilised how frequently are levels checked
Every 3 months
When should levels be monitored more frequently
During illness Manic or depressive phases Changes in diet or temp Pregnancy Concomittant medication
Counselling a patient using lithium (using ALTHETICS model)
Mood stabiliser. Exact mechanism unknown. Thought to enter cells and interfere with neurotransmitter release and second messenger
Take once or twice daily in tablet/capsulesyrup form
Long term treatment
4-6 months before full effect.
Prior to starting need to test- FBC, LFTs, UEC, BUN/Cr, TSH, pregnancy, ECG. Test lithium level after 5-7 days, then retest every week until stabilised, then every 3 months
SE: Leukocytosis, Insipidus, Tremore/teratogenic, Hypothyroid, Increase weight, Vomiting, nausea, ECG changes
Toxicity: GI (severe NVD), Cerebellar- ataxia, slurred speech, lack of coordination, Cerebral- drowsy, myoclonus, choreiform, UMN, seizures, delirium, coma, death
Complications- renal toxicity, nephrogenic diabetes insipidus, hypothyroidism
Contraindications- 1st trimester, breast feeding, Cardiac/renal/addisons, low sodium diets, untreated hypothyroidism
Important complications
Renal toxicity
Nephrogenic diabetes insipidus
Hypothyroidism
Common causes of lithium toxicity
Overdose
Sodium or fluid loss
Concurrent medical illness
Clinical presentation in lithium toxicity
Severe NVD
Ataxia, poor coordination, slurred speech
Drowsiness, myoclonus, choreiform/parkinsonism, UMN, seizures, delirium, coma
ECG changes
Is acute or chronic lithium toxicity more common
Chronic more common, acute ingestion= large excretion from the kidney
Why is acute toxicity less common
Excreted from the kidneys, not a reflection of CNS concentration
When does chronic lithium toxicity occur
Change in dose
Addition of other medications interfering (NSAIDs)
Reduced elimination- kidney dysfunction
When chronic level is associated with severe toxicity
> 2mmol/L
How does the level in acute differ from chronic
Levels in acute can reach >5mmol/L without causing severe toxicity
What are the key factors in chronic lithium toxicity (6)
Age >50 Fluid status Impaired kidney function Hypothyroidism Diabetes insipidus Drug interactions
Key investigations in toxicity
UEC
ECG
Serum lithium
Management
Fluid resuscitation
Measure UEC, ECG, levels
Consider dialysis if indicated
Indications for dialysis in toxicity
Lithium >2.5mmol/L in chronic
Persistent clinical effects
Lithium concentration >1.5 and associated with persistent clinical effects, failure to respond to fluids, impaired kidney function
