Cushing's syndrome induced by enhanced systemic absorption of topical corticosteroids when co‐administered with hand sanitiser in a patient with COVID‐19‐induced chronic plaque psoriasis

Field: Medicine (Health Sciences)

Factors that influence topical, and subsequent systemic, absorption of topical corticosteroids (TCS) include the potency and concentration of the TCS, the delivery vehicle and the characteristics of the skin to which the TCS is applied.1 A 36-year-old female of Russian background developed a scaly, macular eruption on her torso 2 months (May 2022) after contracting coronavirus disease 2019 (COVID-19). She was otherwise well and had a family history of chronic plaque psoriasis (CPP). The patient had been inappropriately treated for atopic dermatitis, using up to 120 g of betamethasone dipropionate 0.05% ointment a week. With the hope of improving her response to treatment, the patient found a lay reference on the Internet (Reddit) and mixed her TCS (60 g) with hand sanitiser (70% ethanol, 1 tablespoon) to increase its efficacy (September 2022). Two months after utilising this self-compounded product, the patient started developing a Cushingoid appearance (Figure 1). Consultation with an endocrinologist revealed insulin resistance (random insulin 12.4 mU/L; normal < 10 mU/L), for which she was started on oral metformin. The patient was diagnosed with Cushing's syndrome secondary to the use of TCS. The patient's symptoms have slowly resolved since weaning off TCS. A second dermatologic opinion was sought, and the patient's diagnosis was revised to CPP. She was ultimately commenced on subcutaneous guselkumab. Binding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein to the human angiotensin converting enzyme (ACE) 2 receptor leads to increased ACE enzyme in the serum with consequent raised levels of interleukin 6 and 8.2 Through this mechanism, COVID-19 is thought to induce or flare psoriasis.3 The stratum corneum is the main barrier to the transepidermal absorption of topical drugs.1 Ethanol enhances drug absorption by disrupting corneocyte soft keratin, denaturing proteins and pooling in the intercellular lipid matrix creating channels for molecular transit.4 By mixing 70% ethanol hand sanitiser with TCS, our patient may have increased the cutaneous permeability and thus systemic absorption of TCS, leading to Cushing's syndrome. Systemic adverse effects of TCS include hypothalamic–pituitary–adrenal (HPA) axis suppression, a cushingoid appearance (moon face, buffalo hump, weight gain, central adiposity), headaches, psychosis, propensity for bruising and hyperglycaemia.5 Although more common with super-potent TCS, systemic adverse effects may also occur in weak TCS.5 Management of these adverse effects is individualised and typically involves the weaning of TCS. The recovery of the HPA axis after discontinuation of topical steroids ranges from 1 to 12 months.5 The above report is an unusual case of Cushing's syndrome induced by TCS, where systemic absorption and potency were enhanced by mixing and co-administration with an ethanol-based hand sanitiser. As far as the authors are aware, this is the first report of such a case (Supporting Informations 1 and 2). Paradoxically, it illustrated that TCS are quite safe in normal use, where the pharmacokinetics of absorption required significant perturbation for adverse effects to occur. It should also remind clinicians of the need to take a careful history; otherwise, patients can create unintended consequences when they follow ill-advised treatment from their Internet searches. Open access publishing facilitated by The University of Sydney, as part of the Wiley - The University of Sydney agreement via the Council of Australian University Librarians. The authors have no conflicts of interest to declare. No funding was sought or granted in preparing this manuscript Data sharing is not applicable to this article, as no datasets were generated or analysed during the current study. We confirm that this manuscript contains original unpublished work that is not being considered for publication elsewhere at the same time. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.