Lithosun SR Tablet contains lithium carbonate 400 mg, a mood stabilizer primarily indicated for the treatment and maintenance of bipolar disorder, including acute manic and depressive episodes. Lithium carbonate modulates neurotransmitter activity and stabilizes mood by influencing sodium transport in nerve and muscle cells, thereby reducing the frequency and severity of mood swings. It is effective in preventing relapse and recurrence of manic and depressive episodes in patients with bipolar disorder. Lithosun SR is formulated as a sustained-release tablet to ensure steady plasma concentrations, improving tolerability and adherence. Dosage should be individualized based on clinical response and serum lithium levels, with regular monitoring to avoid toxicity. Common adverse effects include tremor, polyuria, mild gastrointestinal discomfort, and weight gain; serious toxicity may present as confusion, ataxia, or severe gastrointestinal symptoms, necessitating immediate medical attention. Contraindications include significant renal impairment, severe cardiovascular disease, and hypersensitivity to lithium. Caution is advised during pregnancy and lactation. Regular monitoring of renal function, thyroid function, and serum lithium levels is essential to optimize therapeutic outcomes and minimize adverse effects. Lithosun SR should be prescribed and managed by healthcare professionals experienced in the treatment of mood disorders.