Lithium

Question 1

Therapeutic Range:

Answer 1

Therapeutic Range: 0.4 to 1 mmol/L (lower end for maintenance therapy and elderly patients) and
0.8 to 1mmol/L for acute episodes of mania and for patients who have previously relapsed or have
sub-syndromal symptoms

Question 2

Monitoring

Answer 2

Serum lithium concentration, renal function, cardiac function, thyroid function

Question 3

Major Route of Elimination

Answer 3

Renal; freely fltered at glomerulus with 80% reabsorbed

Question 4

Warning Signs

Answer 4

• Increasing gastrointestinal disturbances e.g. vomiting, diarrhoea
• Visual disturbances e.g. blurred vision
• CNS disturbances e.g. drowsiness, unsteadiness, confusion
• Fine tremor increasing to coarse tremor, muscle weakness
• Incontinence, polyuria
• Serum concentration over 2 mmol/L (severe overdosage) – seizures, coma, renal failure,
arrhythmias, blood pressure changes, circulatory failure, sudden death
• Signs and symptoms of hypothyroidism (e.g. unexplained fatigue)
• Signs and symptoms of renal dysfunction (e.g. polyuria and polydipsia)
• Signs and symptoms of benign intracranial hypertension (e.g. persistent headache and visual
disturbance)

Question 5

Actions required

Answer 5

• Advise patient to report immediately to a doctor if any warning signs occur
• Check that the patient knows the importance of staying on the same brand of lithium, and has
a lithium treatment pack
• Inform the patient to keep a constant and adequate salt and water intake (especially if they
have an infection or during hot spells)
• Advise the patient on OTC interactions and to avoid alcohol
• Counsel the patient on the risks of driving or operating machinery if they feel sleepy
• Stress importance of not stopping lithium suddenly unless told to by a doctor

Question 6

Interactions

Answer 6

• Increased risk of toxicity with ACE inhibitors, angiotensin-II receptor antagonists, loop
diuretics, thiazides and related diuretics, NSAIDs, potassium-sparing diuretics, aldosterone
antagonists, metronidazole, SSRIs (and CNS effects), tricyclics
• Increased risk of ventricular arrhythmias with amiodarone
• Risk of neurotoxicity with methyldopa, phenytoin, carbamazepine, diltiazem, verapamil
• Increased risk of extrapyramidal side effects with clozapine, haloperidol, sulpiride,
phenothiazines, risperidone, fupentixol, zuclopenthixol