Lithium, valproate, carbamazepine and lamotrigine monitoring — Rapid

Synopsis

Plan drug-specific monitoring for four commonly used mood stabilisers, interpret abnormal results in their clinical context, and recognise toxicity, severe skin reactions and reproductive-safety requirements before harm develops.

Lithium samples for routine comparison should be taken twelve hours after the previous dose, with dose and sampling time documented.
Check lithium one week after starting or changing dose and weekly until stable; then every three months for the first year.
After year one, measure lithium every six months, or at least every three months in higher-risk groups.
Lithium renal function, calcium, thyroid function and weight need six-monthly monitoring, with earlier review for deterioration.
Valproate baseline monitoring includes weight, full blood count, platelets, liver function and clotting assessment; repeat liver tests periodically during the first six months, then at six months and annually.
Lamotrigine requires slow interaction-specific titration, urgent attention to rash and a restart assessment after interruption.
Carbamazepine sodium monitoring after initiation is particularly important in renal impairment or with sodium-lowering medicines.
All new valproate starts below age 55 need two independent specialists to document the regulatory criteria; established male treatment does not require a retrospective two-specialist review.

Key red flags

A new rash with mucosal lesions, blistering, fever or systemic illness on lamotrigine or carbamazepine needs immediate withdrawal assessment and urgent hospital review.

Abdominal pain with vomiting, jaundice, unusual bruising or marked lethargy during valproate treatment can indicate pancreatitis, hepatic injury or blood dyscrasia.

Pregnancy or pregnancy planning with a mood stabiliser requires prompt specialist review; unsupervised abrupt cessation can cause severe psychiatric or seizure relapse.

Investigation priorities

Lithium baseline assessmentFirst step

Identify renal, endocrine, cardiac and pregnancy factors that affect safe initiation.

Management branches

Starting safelyAgree medicine-specific surveillance

A mood stabiliser is being initiated or prescribing responsibility is transferring.

Confirm the psychiatric indication, product, contraindications, interactions and reproductive precautions before issuing the medicine.
Record baseline tests and an exact schedule for early and continuing monitoring with a named result reviewer.
Provide warning-symptom advice and a contact route for illness, missed doses, pregnancy concerns or unavailable blood testing.

Key medicines

Lamotrigine without valproate or enzyme inducersFor adult bipolar maintenance titration give 25 mg orally daily in weeks 1–2, 50 mg daily in weeks 3–4, 100 mg daily in week 5 and usually 200 mg daily from week 6.Use a different schedule with valproate or enzyme inducers; assess rash urgently. After an interruption exceeding five half-lives, generally restart the appropriate initial titration rather than the maintenance dose; half-life depends on interacting medicines.

Lamotrigine with concomitant valproateGive 25 mg orally on alternate days in weeks 1–2, 25 mg daily in weeks 3–4, 50 mg daily in week 5 and usually 100 mg daily from week 6.Do not accelerate to catch up missed doses; a new rash normally requires prompt discontinuation unless clearly unrelated, with urgent assessment for systemic or mucosal features.

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