Flashcards in Lithium Deck (24):
1
Mechanism of action (4)
Unknown
Reduces dopamine release
Increases serotonin release
Reduces secondary intracellular messengers
2
Indications (3)
Prevent manic/depressive episodes in bipolar
Treat acute mania
Schizoaffective disorder and chronic schizophrenia
3
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)
4
How does hyponatremia affect lithium use
Low water and salt= +reabsorption of lithium in proximal tubule of kidney->risk of toxicity
5
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
6
Effects on pregnancy
Increased CHD
Neurotoxicity
Hypothyroidism
7
Should lithium be used in pregnancy
Avoid in first trimester, use following.
Need to check lithium levels more frequently
8
When should bloods be taken for lithium concentration
12 hours after last dose
9
After starting treatment when do you measure levels
5-7 days later, and after every dose change until stabilised
10
Once stabilised how frequently are levels checked
Every 3 months
11
When should levels be monitored more frequently
During illness
Manic or depressive phases
Changes in diet or temp
Pregnancy
Concomittant medication
12
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
13
Important complications
Renal toxicity
Nephrogenic diabetes insipidus
Hypothyroidism
14
Common causes of lithium toxicity
Overdose
Sodium or fluid loss
Concurrent medical illness
15
Clinical presentation in lithium toxicity
Severe NVD
Ataxia, poor coordination, slurred speech
Drowsiness, myoclonus, choreiform/parkinsonism, UMN, seizures, delirium, coma
ECG changes
16
Is acute or chronic lithium toxicity more common
Chronic more common, acute ingestion= large excretion from the kidney
17
Why is acute toxicity less common
Excreted from the kidneys, not a reflection of CNS concentration
18
When does chronic lithium toxicity occur
Change in dose
Addition of other medications interfering (NSAIDs)
Reduced elimination- kidney dysfunction
19
When chronic level is associated with severe toxicity
>2mmol/L
20
How does the level in acute differ from chronic
Levels in acute can reach >5mmol/L without causing severe toxicity
21
What are the key factors in chronic lithium toxicity (6)
Age >50
Fluid status
Impaired kidney function
Hypothyroidism
Diabetes insipidus
Drug interactions
22
Key investigations in toxicity
UEC
ECG
Serum lithium
23
Management
Fluid resuscitation
Measure UEC, ECG, levels
Consider dialysis if indicated
24