Drugs Acting on the Central Nervous System (CNS)

Mood Stabilizers (Anti-manic Drugs): Lithium and Other Agents

Mood stabilizers are a crucial class of medications used primarily in the management of bipolar disorder and related conditions characterized by mood fluctuations. Among them, lithium remains the gold standard due to its proven efficacy.

Pharmacological Effects of Mood Stabilizers

These agents function by modulating neurotransmitter activity and intracellular signaling pathways. Lithium, for example, stabilizes mood by influencing synaptic transmission, particularly affecting dopamine, serotonin, and glutamate pathways.

Therapeutic Monitoring

• Serum Lithium Levels: Regular monitoring is essential to prevent toxicity. Therapeutic levels typically range between 0.6–1.2 mEq/L.
• Renal and Thyroid Function: Lithium can affect kidney and thyroid function, necessitating periodic tests.
• Adverse Effects: Tremors, weight gain, and cognitive dulling are common, while severe toxicity can lead to seizures or coma.

Toxicity and Side Effects

Lithium toxicity can occur with excessive intake or inadequate renal clearance. Symptoms include nausea, diarrhea, tremors, confusion, and in severe cases, cardiac arrhythmias.

Alternative Mood Stabilizers

• Valproic Acid: A broad-spectrum antiepileptic also used for bipolar disorder.
• Carbamazepine: Effective for manic episodes but requires close monitoring due to potential hematologic effects.
• Lamotrigine: Primarily used for bipolar depression, with fewer side effects compared to lithium.