Mood Stabilisers: the clinical idea
Mood stabilisers are medicines used to treat bipolar disorder by reducing acute mood episodes and preventing relapse. They are not simply “calming drugs”: each has a different role in acute mania, bipolar depression and long-term maintenance. Good prescribing combines a clear diagnosis, safety monitoring, psychosocial care, and a relapse plan.
Learning outcomes: classify the principal agents; select treatment according to the phase of illness; recognise dangerous toxicity and interactions; and counsel a patient safely.
1. Start with the phase of bipolar disorder
| Clinical phase | Typical features | Drug principle |
|---|---|---|
| Acute mania or hypomania | Elevated/irritable mood, reduced sleep, grandiosity, risky behaviour, psychosis or severe agitation | Rapid control commonly needs an antipsychotic; lithium or valproate may be used where appropriate. |
| Bipolar depression | Low mood, anhedonia, biological symptoms, impaired function and possible suicidal thinking | Use a bipolar-depression strategy; avoid casually starting antidepressant monotherapy because it can precipitate mood elevation in susceptible people. |
| Maintenance | Recovery between episodes; relapse risk remains | Choose the agent with best evidence for the patient’s previous episode pattern and tolerability, then support adherence and early detection of relapse. |
Before prescribing, confirm that symptoms are not due to alcohol, stimulants, corticosteroids, thyroid disease, delirium or another medical condition. Ask about pregnancy potential, renal and liver disease, epilepsy, current medicines, substance use, self-harm risk and the availability of family support.
2. The main medicines at a glance
Lithium
A classic maintenance medicine with anti-manic and relapse-prevention benefit. It has a narrow therapeutic index, so monitoring is essential.
Valproate
An anticonvulsant used particularly for acute mania and maintenance in selected patients. It has major fetal risk and requires liver and blood-count monitoring.
Lamotrigine
Useful especially in prevention of depressive episodes. It must be titrated slowly because a serious rash can occur.
Carbamazepine
An alternative anticonvulsant in selected cases. It causes important interactions and can affect blood counts and sodium.
Atypical antipsychotics
Several agents are used for mania, bipolar depression or maintenance. Match the agent to the episode and monitor metabolic effects.
3. Lithium: high-yield pharmacology and safe use
Lithium is a small ion that influences intracellular second-messenger signalling and neuronal plasticity. In practice, its key lesson is not a single receptor: lithium effectiveness depends on keeping the blood concentration in a safe therapeutic range. It is used in acute mania in some settings and is an important maintenance option, particularly when relapse prevention and suicide-risk reduction are priorities.
| Before and during treatment | Why it matters |
|---|---|
| Check renal function, electrolytes, thyroid function and calcium; assess pregnancy potential. | Lithium is cleared by the kidney and can impair renal and thyroid function over time. |
| Measure lithium concentrations at the local protocol interval, including after dose changes. | There is a small gap between therapeutic and toxic concentrations. |
| Ask about fluid intake, vomiting, diarrhoea, fever and heavy sweating. | Dehydration and sodium loss can increase lithium concentration. |
| Review all medicines. | NSAIDs, ACE inhibitors, ARBs and thiazide diuretics can raise lithium concentrations. |
Recognise lithium toxicity early
New worsening tremor, nausea, vomiting, diarrhoea, slurred speech, ataxia, confusion, coarse tremor, seizures or reduced consciousness should be treated as possible toxicity. Withhold further doses, assess urgently, check level/renal function/electrolytes, correct dehydration and seek senior or specialist advice. Severe toxicity may need haemodialysis.
Counselling: take it regularly; do not double a missed dose; keep salt and fluid intake reasonably consistent; avoid self-starting NSAIDs; and seek advice promptly during significant illness with fluid loss.
4. Anticonvulsant mood stabilisers
| Medicine | Useful place in treatment | Key safety points |
|---|---|---|
| Valproate | Acute mania and maintenance in selected patients. | Check baseline/ongoing liver function and blood count. Warn about weight gain, tremor, gastrointestinal effects, thrombocytopenia, pancreatitis and hepatotoxicity. Avoid in pregnancy where possible: fetal harm risk is substantial; use a pregnancy-prevention and specialist pathway where relevant. |
| Lamotrigine | Maintenance, especially where depressive relapse predominates; not a rapid solution for severe acute mania. | Titrate slowly. Stop and assess urgently if rash, mucosal lesions, fever or systemic illness occurs because Stevens–Johnson syndrome/toxic epidermal necrolysis is rare but serious. |
| Carbamazepine | Alternative for mania or maintenance when first-line approaches are unsuitable. | Check full blood count, liver function and sodium. Watch for rash, dizziness, hyponatraemia and blood dyscrasias. It induces hepatic enzymes and can reduce the effectiveness of many medicines, including hormonal contraception. |
5. Antipsychotics in bipolar disorder
Second-generation antipsychotics are frequently used as mood-stabilising agents, particularly when mania has psychotic symptoms, severe agitation or a need for rapid symptom control. Some also have evidence in bipolar depression or maintenance. Their use must include baseline and follow-up weight, waist circumference where possible, blood pressure, glucose and lipids. Ask actively about sedation, extrapyramidal symptoms, sexual adverse effects and adherence.
For a severely agitated or psychotic manic patient, first ensure safety: assess risk to self/others, capacity, medical causes and substance intoxication. Urgent mental-health input and a safe environment are part of treatment; medication alone is not the whole management plan.
6. A practical prescribing and monitoring checklist
- Define the episode: mania, depression, mixed state, psychosis, emergency or maintenance?
- Assess immediate risk: suicide, neglect, violence, exploitation, inability to care for self, intoxication and pregnancy.
- Choose an agent deliberately: previous response, dominant episode pattern, medical disease, interactions, reproductive safety and monitoring capacity all matter.
- Record baseline tests: targeted to the medicine—renal/thyroid/calcium for lithium; FBC/LFT for valproate or carbamazepine; metabolic measures for antipsychotics.
- Give a clear safety-net: toxicity symptoms, rash warning, pregnancy advice, missed-dose advice and contact route.
- Make a relapse plan: regular review, adherence support, sleep routine, substance-use care and early warning signs agreed with the patient and family where appropriate.
7. OSCE station: counselling a patient starting lithium
Open: explain the indication and that regular monitoring makes treatment safer. Check: renal/thyroid history, pregnancy possibility, diarrhoea/vomiting, current pain medicines and diuretics. Advise: consistent fluids and salt; no unsupervised NSAIDs; avoid dehydration; attend blood tests. Safety net: urgent review for worsening tremor, vomiting/diarrhoea, unsteadiness, confusion or seizures. Close: check understanding and provide a follow-up plan.
8. Knowledge check
- Why can dehydration cause lithium toxicity?
- Which mood stabiliser needs slow titration because of a potentially life-threatening rash?
- Name four medicine groups that require careful review before or during lithium therapy.
- Why is valproate a major reproductive-safety concern?
- What baseline and follow-up measures are important for an atypical antipsychotic?
9. Further study and references
- Mood stabilizer lecture slides
- World Health Organization. Mental health guidance on bipolar disorder medicines and safety monitoring.
- National and local clinical guidelines should determine the exact dose, target concentration and monitoring interval used in your setting.
