Mood Stabilizers

Overview

Mood stabilizers are drugs that are used to stabilise manic, mixed, and depressive episodes. They do not induce alternate mood symptoms AND prevent future relapse into manic, mixed, or depressive episodes.

Selected mood stabilizers

• 4 phase process in the treatment of Bipolar Disorder
  1. Evaluation and diagnosis
  2. Acute care and crisis stabilization
  3. Full recovery from depression/mania
  4. Maintenance of euthymia

Lithium

Lithium is the treatment of choice for Bipolar Disorder and Schizoaffective Disorder (alongside antipsychotic). The mechanism is not fully understood but is theorized to interfere with the formation of inositol triphosphate and cAMP. Lithium is not metabolized by the liver and is excreted unchanged by the kidney. Serum lithium levels should be monitored and kept below 1.5 mEq/L (therapeutic window is 0.8-1.2 mEq/L). Ensure the patient is hydrated and consider dialysis if the patient has very high lithium levels. Despite its narrow therapuetic range, lithium is actually the safest mood stabilizer in case of overdose (provided renal function is preserved). Lithium is HIGHLY TERATOGENIC and should be avoided in pregnancy since it causes Ebstein’s anomaly.

Lithium toxicity

• Investigations before prescribing Lithium
  • Electrocardiogram
  • Thyroid function tests
  • Complete blood count
  • Pregnancy test
  • Fasting blood glucose
  • Lipid profile
  • Renal function test
• Investigations after prescribing lithium
  • Lithium blood levels: every 3 months after a stable dose is reached. Blood should be drawn 12 hours post-dose
  • Thyroid and renal function test: every 6 months
• EKG changes seen in lithium toxicity (similar to hypokalemia)
  • ST depression
  • T wave flattening or inversion
  • QT prolongation
• Adverse effects of Lithium (LITHIUMS)
  • Leukocystosis
  • Increased irritation
  • Thirsty (polydypsia ,polyuria) and Tremors
  • Hair thinning (alopecia) and Hypothyrodism (and thyroid enlargment)
  • Interactions with other drugs
  • stomach Upset (and weight gain)
  • Muscle weakness
  • Skin lesions and psoriasis
    • Idiopathic intracranial hypertension
• Contraindications of lithium
  • Pregnancy
• What is the best way to keep lithium levels low (but therapeutic)?
  • Adequate hydration
• Treatment of Lithium toxicity
  • Dialysis
  • Diuresis

Valproic acid

Valproic acid is the treatment of choice for acute mania, rapid cycling, mixed state OR if Lithium is ineffective. Valproate is ineffective in the depressive phase.

Valproate is ALSO TERATOGENIC (Causes neural tube defects e.g. spina bifida)

• Adverse effects
  • Cognitive dulling
  • CNS symptoms: sedation, tremor, dizziness, ataxia, headache
  • GI symptoms: abdominal pain, nausea, vomiting, diarrhea, constipation, weight gain

Carbamazepine

Carbamazepine is a second-line treatment for mood disorders due to its complications – severe agranulocytosis and hepatotoxicity. Therefore, draw blood for CBC and LFTs when prescribing. Most effective for mixed state and rapid cycling (> 4 mood episodes per year). Caution when prescribed with OCPs (lower efficacy of contraceptives)

• Which group of patients with mood disorders do we avoid using Carbamazepine?
  • Patients with pre-existing liver disease
• Adverse effects
  • Significant sedation
  • Hepatotoxicity
  • Agranulocytosis

Lamotrigine

Lamotrigine is best used for the depressive phase and in women of childbearing age.

• Adverse effects
  • Sedation
  • Dizziness
  • Nausea or emesis
  • Diplopia