A 35-year-old farmer from rural Maharashtra presents with a 3-month history of progressive dyspnea, cough, and constitutional symptoms. Chest X-ray shows bilateral hilar lymphadenopathy with fine reticular opacities. Transbronchial biopsy reveals non-caseating granulomas. Serum ACE level is elevated, and serum calcium is 11.2 mg/dL. What is the drug of choice for initial management of this condition?