Date of report 02 Sep 2021

Reported case interaction between
Cobicistat and Triamcinolone

A 76-year-old HIV-infected women with type 2 diabetes presented with complaints of fatigue, weight loss (2.7 kg) and uncontrolled hyperglycemia. The patient reported being treated with 4 sequential 80 mg epidural triamcinolone injections (6 months apart) for chronic back pain. Physical examination revealed moon facies and muscle weakness. The patient presented episodes of hypotension and uncontrolled hyperglycemia during her hospitalization. Endocrine evaluation revealed biochemical evidence of hypothalamic-pituitary-adrenal axis suppression with a low morning serum cortisol level (4.5 mcg/dl; normal value 5-25 mcg/dL). Response to cosyntropin stimulation testing was adequate thus excluding primary adrenal insufficiency. An elevated triamcinolone level was found (0.69 mcg/dL, reference value 0.10 mcg/dL). An interaction between elvitegravir/cobicistat and triamcinolone was suspected given that cobicistat is a strong inhibitor of CYP3A4, the metabolizing enzyme of triamcinolone. Elevated concentrations of corticosteroids can result in negative feeback on the endogenous HPA axis leading to adrenal atrophy and reduced cortisol secretory capacity. Elvitegravir/cobicistat was replaced by dolutegravir and the patient was started on maintenance hydrocortisone to prevent an adrenal crisis. Her fatigue and muscle weakness improved and a marked decrease in triamcinolone level to 0.32 mcg/dL was observed. Three months later, the patient's hyperglycemia had improved and after 8 months, morning cortisol and ACTH levels were in the normal range (11 mcg/dL and 13 pg/ml, respectively). This case has been published by Mathias PM et al. in AACE Clinical Case Rep 2020; 6(5), e217-220.