Mood Stabilizers: Lithium, Valproate, Carbamazepine, and Lamotrigine

Mood stabilizers are first-line treatment for bipolar disorder and several seizure disorders. They have narrow therapeutic windows, significant black box warnings, and require careful lab monitoring — making them very high-yield for the NCLEX and nursing pharmacology exams.

Drug Classes at a Glance

• Lithium (lithium carbonate) — gold standard for bipolar disorder; narrow therapeutic index.
• Anticonvulsants used as mood stabilizers — valproate, carbamazepine, lamotrigine. Each has unique black box warnings.

Lithium (Most Tested)

Lithium is a salt that stabilizes mood by altering sodium transport and neurotransmitter activity in the brain. It is the gold standard for treating mania in bipolar disorder.

Therapeutic and Toxic Levels

• Therapeutic range (maintenance): 0.6–1.2 mEq/L.
• Toxic level: > 1.5–2.0 mEq/L.
• Monitor closely during the first few weeks of therapy, then every 6–12 months once stable, and with any dose change.

Signs of Lithium Toxicity

• Early: diarrhea, vomiting, drowsiness, muscular weakness, lack of coordination.
• Severe: coarse tremor, ataxia, blurred vision, tinnitus, large output of dilute urine, seizures, coma.

Factors That Affect Lithium Levels

• Low sodium intake → kidneys retain lithium → ↑ levels and toxicity risk.
• Dehydration → significantly ↑ lithium levels.
• Increased sodium or caffeine intake → ↓ lithium levels.
• Renal insufficiency → impaired excretion → accumulation.

Nursing Safety Rules

• Maintain adequate dietary salt intake, especially after sweating from heat or exercise.
• Drink about 1.5 L of water daily to maintain fluid balance.
• Monitor for kidney damage: decreased urine output, flank pain, sediment in urine.
• Watch for hypothyroidism with long-term use (fatigue, dry skin, edema); monitor thyroid function periodically — lithium may cause goiter.
• Give with food to prevent GI upset.

Valproate (Depakote)

Valproate enhances GABA activity and blocks sodium and calcium channels to stabilize neuronal membranes.

Black Box Warnings

• Hepatotoxicity — can cause fatal hepatic failure, especially in children under 2 on multiple anticonvulsants. May be preceded by malaise, weakness, and elevated liver enzymes.
• Teratogenicity — causes neural tube defects (e.g., spina bifida); absolutely contraindicated in pregnancy.
• Pancreatitis — life-threatening; can occur at any time. Presents with severe abdominal pain, nausea, vomiting, anorexia.

Common Side Effects

• Weight gain, tremor, alopecia, nausea, thrombocytopenia.

Nursing Safety Rules

• Monitor LFTs at baseline and frequently during the first 6 months.
• Check ammonia levels — hyperammonemia can occur even with normal LFTs.
• Teach patient to report abdominal pain, nausea, or vomiting immediately (possible pancreatitis).
• Obtain a pregnancy test before starting in women of childbearing age; avoid in pregnancy.
• Monitor platelet counts.
• When combined with lamotrigine, cut the lamotrigine dose in half (valproate inhibits lamotrigine metabolism).

Carbamazepine (Tegretol)

Carbamazepine blocks sodium channels to stabilize neuronal membranes and reduce excitability.

Black Box Warnings

• Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis — life-threatening skin reactions; stop the drug immediately.
• Aplastic anemia and agranulocytosis — severe bone marrow suppression; requires CBC monitoring.

Common Side Effects

• Dizziness, drowsiness, unsteadiness, nausea, vomiting (especially with initial therapy).
• Cardiovascular: dysrhythmias, AV block, thrombophlebitis.
• Hyponatremia from an SIADH-like effect.
• SJS often presents with flu-like symptoms followed by a blistering rash.

Nursing Safety Rules

• Monitor CBC regularly for bone marrow suppression.
• Teach patient to report fever, sore throat, or unusual bruising immediately.
• Monitor sodium levels.
• Avoid grapefruit juice — it increases carbamazepine levels.
• Decreases warfarin effectiveness — monitor INR.
• Never stop abruptly — withdrawal can trigger seizures or status epilepticus.

Lamotrigine (Lamictal)

Lamotrigine blocks sodium channels to stabilize neuronal membranes and reduce glutamate release.

Black Box Warning

• Serious rashes, including Stevens-Johnson syndrome — discontinue immediately.
• Risk is highest during initial titration and with concurrent valproate use.

Common Side Effects

• Somnolence, headache, dizziness.
• Rash may develop in up to 10% of patients during the first 1–2 months.

Nursing Safety Rules

• Titrate slowly, starting at 25 mg daily, to reduce rash risk.
• If the patient misses 3 or more doses, therapy must be restarted from the beginning.
• When combined with valproate: cut lamotrigine dose in half and start at 25 mg every other day.
• Teach the patient to report any rash immediately and stop the drug.
• Maximum dose: ~100–300 mg/day depending on indication.

Side Effects Summary

• Lithium: Common — nausea, vomiting, diarrhea, tremor, fatigue. Life-threatening — toxicity, hypothyroidism, nephrotoxicity.
• Valproate: Common — weight gain, tremor, alopecia, nausea. Life-threatening — hepatotoxicity, pancreatitis, thrombocytopenia.
• Carbamazepine: Common — dizziness, drowsiness, ataxia, nausea. Life-threatening — SJS, agranulocytosis, aplastic anemia.
• Lamotrigine: Common — headache, dizziness, somnolence. Life-threatening — Stevens-Johnson syndrome.

Labs and Monitoring Summary

• Lithium: serum lithium level, renal function, thyroid function — every 6–12 months once stable and with any dose change.
• Valproate: LFTs, ammonia, CBC — baseline, frequently during the first 6 months, then periodically.
• Carbamazepine: CBC, sodium, LFTs — baseline and periodically.
• Lamotrigine: clinical monitoring for rash — any rash requires immediate evaluation.

Pregnancy Safety

• Lithium: risk of Ebstein's anomaly; use only if benefits outweigh risks.
• Valproate: absolutely contraindicated — neural tube defects and cognitive impairment.
• Carbamazepine: neural tube defects; requires folate supplementation.
• Lamotrigine: relatively safer, but levels drop significantly in pregnancy — dose adjustment needed.
• Remember: uncontrolled bipolar disorder also poses risk to mother and fetus.

Common Exam Traps

• Forgetting that low sodium increases lithium levels, leading to toxicity.
• Missing early lithium toxicity signs such as vomiting and drowsiness.
• Giving valproate without a pregnancy test.
• Dismissing abdominal pain in a valproate patient (possible pancreatitis).
• Missing fever or sore throat as signs of agranulocytosis on carbamazepine.
• Failing to titrate lamotrigine slowly, or ignoring a rash that could be SJS.
• Abruptly stopping mood stabilizers — risks seizures and relapse.

Key Takeaways

• Lithium therapeutic range is 0.6–1.2 mEq/L; toxicity (>1.5) presents with vomiting, ataxia, tremor, and seizures — and is worsened by low sodium or dehydration.
• Valproate carries black box warnings for hepatotoxicity, pancreatitis, and teratogenicity — monitor LFTs and avoid in pregnancy.
• Carbamazepine can cause Stevens-Johnson syndrome and agranulocytosis — monitor CBC and teach patients to report fever or sore throat.
• Lamotrigine requires slow titration; any rash means stop the drug. Cut the dose in half if combined with valproate.
• Never stop mood stabilizers abruptly — risk of seizure, mania relapse, or status epilepticus.