Drug-Drug Interactions Involving Dexamethasone in Clinical Practice: Myth or Reality?

Concomitant administration of multiple drugs frequently causes severe pharmacokinetic or pharmacodynamic drug-drug interactions (DDIs) resulting in the possibility of enhanced toxicity and/or treatment failure. The activity of cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp), a drug efflux pump sharing localization and substrate affinities with CYP3A4, is a critical determinant of drug clearance, interindividual variability in drug disposition and clinical efficacy, and appears to be involved in the mechanism of numerous clinically relevant DDIs, including those involving dexamethasone. The recent increase in the use of high doses of dexamethasone during the COVID-19 pandemic have emphasized the need for better knowledge of the clinical significance of drug-drug interactions involving dexamethasone in the clinical setting. We therefore aimed to review the already published evidence for various DDIs involving dexamethasone in vitro in cell culture systems and in vivo in animal models and humans.

18-Fluorodeoxyglucose positron emission tomography/computed tomography for large vessel vasculitis in clinical practice.

Diagnosis, prognostic assessment, and monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. Early recognition of LVV and treatment adaptation is essential because vascular complications (aneurysm, dilatations, ischemic complications) or treatment related side effects can occur frequently in these patients. 18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) is increasingly used to diagnose, follow, and evaluate treatment response in LVV. In this review, we aimed to summarize the current evidence on the value of 2-[18F]FDG-PET/CT for diagnosis, follow, and treatment monitoring in LVV.

Characteristics of circulating KSHV-infected viroblasts during active KSHV+ multicentric Castleman disease.

Kaposi sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8-associated multicentric Castleman disease (MCD) is a polyclonal B-cell lymphoproliferative disorder that mainly occurs in immunocompromised hosts. The diagnosis relies on lymph node biopsy demonstrating KSHV-infected cells located in the mantle zone with a marked interfollicular plasma cell infiltration. Infected cells are large cells positive for immunoglobulin M (IgM), λ light chain, and CD38, described initially as infected plasmablasts. We show that IgM+λ+CD38high cells were also detectable in the peripheral blood of 14 out of 18 (78%) patients with active KSHV-MCD and absent in 40 controls. Using immunofluorescence and flow-fluorescence in situ hybridization, we demonstrate that these cells are KSHV infected and express both latent and lytic KSHV transcripts. These KSHV-infected viroblasts (KIVs) harbor a distinct phenotype compared with conventional plasmablasts. We also identified several putative mechanisms of immune escape used by KSHV, because KIVs displayed an overall decrease of costimulatory molecules, with a remarkable lack of CD40 expression and are interleukin-10-producing cells. The identification of this specific and easily accessible KSHV+ circulating population brings new elements to the understanding of KSHV-MCD but also raises new questions that need to be clarified.

Drug-induced meningitis: A review of the literature and comparison with an historical cohort of viral meningitis cases.

BACKGROUND: Drug-induced aseptic meningitis (DIAM) is potentially insufficiently considered by clinician, being of rare etiology, with there being no previously published exhaustive study describing its clinical and biological features. METHODS: Two independent academic clinicians searched all the case reports of DIAM from 1995 until 15th April, 2017. The search was limited to studies performed in humans, published in English or French. Clinical and biological data of subjects were compared with those of patients with documented viral meningitis. RESULTS: One hundred and fifty-one case reports fulfilled our inclusion criteria. Non-steroidal anti-inflammatory drugs were the commonest drug cause of AM n=49, followed by antibiotics n=46, biotherapy n=19 and finally immunomodulators n=15. The clinical and biological presentation of DIAM varies according to the causative etiological drug, especially with respect to the interval between exposure and presentation and cerebrospinal fluid (CSF) pleiocytosis. Clinical symptoms associated with meningitis were more prevalent in viral meningitis than in DIAM, except for fever and signs of encephalitis. Cerebrospinal fluid examination in DIAM reveals an increased CSF white cell count and an increased proportion of neutrophils and protein, compared with viral meningitis. DISCUSSION: We present an extensive review of the DIAM case reports, and highlight their clinical and biological characteristics according to the drugs involved. While comparing for the first time their characteristics with those of viral meningitis, this review hopes in facilitate earlier diagnosis and management of DIAM in clinical practice.