Iatrogenic Cushing's Syndrome due to Coadministration of Ritonavir and Inhaled Budesonide in an Asthmatic Human Immunodeficiency Virus Infected Patient

Abstract

Corticosteroids are metabolized by cytochrome P450 3A4 (CYP3A4). Fluticasone has the longest glucocorticoid receptor-binding half-life and is 300 times more lipophilic than budesonide. Inhaled fluticasone possesses a high suppression rate of hypothalamic-pituitary-adrenal axis. Ritonavir, a potent CYP3A4 inhibitor, may inhibit corticosteroid degradation and increase its accumulation. Inhaled budesonide is less likely to cause adrenal suppression. Diagnosing Cushing's syndrome presents a clinical challenge due to similarities with clinical manifestations and side effects related to cART. In patients treated with inhaled or intranasal corticosteroids together with cART there may be a higher incidence of iatrogenic CS. CS should be looked for, and management considered carefully.