ZY-Q 300 Tablet contains Hydroxychloroquine 300 mg, an antimalarial and immunomodulatory agent used primarily in the treatment and prevention of malaria, as well as in autoimmune conditions such as rheumatoid arthritis and systemic lupus erythematosus. Hydroxychloroquine exerts its therapeutic effects by increasing the pH within intracellular vacuoles, thereby interfering with lysosomal activity and antigen presentation, which modulates immune responses. It is indicated for the prophylaxis and treatment of acute attacks of malaria caused by Plasmodium species sensitive to the drug. Additionally, it is employed as a disease-modifying agent in autoimmune disorders to reduce inflammation, pain, and tissue damage. Dosage should be individualized based on the indication, patient weight, and clinical response, with careful monitoring for potential adverse effects such as retinopathy, cardiotoxicity, and gastrointestinal disturbances. Regular ophthalmologic examinations are recommended during prolonged therapy. Contraindications include hypersensitivity to Hydroxychloroquine or related compounds, pre-existing retinopathy, and certain cardiac conditions. Caution is advised in patients with hepatic or renal impairment. ZY-Q 300 Tablet should be administered under medical supervision, and patients should be advised to report any visual changes, muscle weakness, or cardiac symptoms promptly. This medication is not recommended for use in pediatric patients without specialist guidance.