Lithium

What is the therapeutic range for lithium?

0.8-1 mmol/L

What is Lithium?

Monitoring

Serum lithium concentration - weekly, then every 3 months once dose becomes stable.

• Renal function, cardiac function, thyroid function - 6 months

Which class of diuretics can cause a rapid increase in lithium levels?

Thiazides

Name a medication that can reduce lithium levels due to increased clearance

Dapagliflozin

What is the interaction between NSAIDs and lithium?

NSAIDs can increase lithium levels by 40-50%

Indications for Lithium

Treatment and prophylaxis for mania, bipolar disorder and recurrent depression

Therapeutic range

0.4-1.0 mmol/L

Range for acute episodes

0.8-1 mmol/L

Side effects

• Hypothyroidism

• Benign Intracranial Hypertension (signs: persistent headache, visual disturbances)

• Nephrotoxicity

• QT proplongation

• Teratogenic (in 1st Trimester)

• Rhabdomyolysis (breakdown of muscle tissue = causes release of muscle fibres into the blood)

What trimester in pregnancy is Lithium teratogenic in?

1st trimester

Signs of toxicity

Remember REVENGE

R - Renal impairment (incontinence = frequent urination)

E - Extrapyramidal side effects (tremors)

V - Visual disturbances

N - Nerve system disorder = confusion and restlessness

G - GI disorder = Diarrhoea and vomiting

How to differentiate Lithium toxicity from theophylline and digoxin toxicity?

Lithium - Sick & Tremour

• Theophylline - Sick & Fast

• Digoxin - Sick & Slow

Electrolyte imbalance that potentials Lithium toxicity

Hyponatraemia

• Patient counselling

• Maintain adequate fluid intake and avoid dietary changes which reduce or increase

  sodium intake.

• Warn patients to report to GP if they see any warning signs

• Advice on OTC interactions and 🚫avoid alcohol

• Stress important of not stopping lithium unless told by a doctor

Monitoring

• Lithium conc = measure 12 hours after a dose ➡weekly until stable ➡then 3 monthly for year 1 ➡ then 6 monthly

• Cardiac function

• Renal function

• Thyroid function

Interaction: Lithium & ACEi

Renal impairment (both cause nephrotoxicity) ➡excretion of lithium reduced ➡ risk of lithium toxicity

Interaction: Lithium & NSAIDs

Renal impairment (both cause nephrotoxicity) ➡excretion of lithium reduced ➡ risk of lithium toxicity

(NSAIDs can increase lithium levels by 40-50%)

Interaction: Lithium & Diuretics

Excretion of lithium reduced by Loop and thiazide - they cause Hyponatraemia ➡ risk of lithium toxicity

Interaction: Lithium & Amiodarone

Risk of ventricular arrhythmias

Interaction: Lithium & Antipsychotics

Risk of EPSEs - extrapyramidal side effects

(Examples of antipsychotics = Haloperidol & Metoclopramide)

Mnemonic for some of Lithium Interactions

RED HANDSS

R - Reduced Seizure threshold

E - EPSEs

D - Decreased thyroid function (HYPOthyroidism)

H - Hyponatremic drugs

A - ACEi & ARBs + Amiodarone

N - NSAIDs

D - Diuretics (loop & thiazide)

S - Serotonin syndrome

S - antipSychotics (EPSEs)

Mnemonic for some Lithium side effects

LITHIUM

L - Lethargy

I - Intracranial benign hypertension

T - Tremors, Teratogenic

H - HYPOthyroidism

I - increased urination

U - upset stomach e.g. N&V, diarrhoea

M - metallic taste, muscle weakness

S - skin effects e.g. acne, psoriasis

Name a medication that can reduce lithium levels due to increased clearance

Dapagliflozin