A 32-year-old woman from Delhi presents with a 6-month history of progressive proximal muscle weakness, easy bruising, and amenorrhea. On examination, she has central obesity with supraclavicular fat pads, purple striae, and hypertension (160/100 mmHg). 24-hour urinary free cortisol is elevated at 250 µg/day (normal <50). High-dose dexamethasone suppression test (8 mg overnight) shows cortisol of 45 ng/mL (suppressed <50% from baseline). Which corticosteroid would be most appropriate for initial management of her underlying condition?