HCQS 400 Tablet contains Hydroxychloroquine 400 mg, an antimalarial and immunomodulatory agent primarily used in the treatment of malaria, rheumatoid arthritis, and systemic lupus erythematosus. Hydroxychloroquine exerts its therapeutic effects by interfering with lysosomal activity and autophagy, modulating the immune response, and inhibiting the growth of certain parasites. It is indicated for the prevention and treatment of acute attacks of malaria caused by Plasmodium species, as well as for managing autoimmune conditions characterized by inflammation and abnormal immune activity. HCQS 400 Tablet is administered orally, with dosage tailored according to the specific condition being treated, patient weight, and clinical response. Common adverse effects may include gastrointestinal disturbances, headache, dizziness, and skin rash, while rare but serious side effects include retinopathy, cardiomyopathy, and hematological abnormalities, necessitating regular monitoring during prolonged therapy. Caution is advised in patients with pre-existing retinal or cardiac conditions, and it is contraindicated in individuals with hypersensitivity to hydroxychloroquine or related compounds. HCQS 400 should be used under medical supervision, with periodic ophthalmologic examinations recommended to detect early signs of retinal toxicity. This medication should be stored at room temperature, away from moisture and direct light.