ZY-Q 400 Tablet contains Hydroxychloroquine 400 mg, an antimalarial and immunomodulatory agent primarily indicated for the treatment and prophylaxis of malaria caused by Plasmodium species. Additionally, it is widely used in the management of autoimmune disorders such as rheumatoid arthritis and systemic lupus erythematosus due to its ability to modulate immune responses and reduce inflammation. Hydroxychloroquine exerts its therapeutic effects by increasing the pH within intracellular vacuoles, thereby interfering with lysosomal activity and antigen presentation, which ultimately diminishes the activation of immune cells. The tablet is administered orally, with dosage and duration tailored according to the specific condition and patient response. Common adverse effects include gastrointestinal disturbances, headache, and skin reactions, while more serious but rare effects involve retinopathy and cardiomyopathy, necessitating regular monitoring during prolonged therapy. Contraindications include hypersensitivity to hydroxychloroquine or related compounds, and caution is advised in patients with pre-existing retinal or cardiac conditions. ZY-Q 400 Tablet should be used under strict medical supervision to ensure optimal therapeutic outcomes and minimize potential risks. It is essential to adhere to prescribed dosing regimens and report any unusual symptoms promptly to healthcare providers.