Dexamethasone-induced perineal irritation

MRGPRX4 mediates phospho-drug-associated pruritus in a humanized mouse model

The phosphate modification of drugs is a common chemical strategy to increase solubility and allow for parenteral administration. Unfortunately, phosphate modifications often elicit treatment- or dose-limiting pruritus through an unknown mechanism. Using unbiased high-throughput drug screens, we identified the Mas-related G protein-coupled receptor X4 (MRGPRX4), a primate-specific, sensory neuron receptor previously implicated in itch, as a potential target for phosphate-modified compounds. Using both Gq-mediated calcium mobilization and G protein-independent GPCR assays, we found that phosphate-modified compounds potently activate MRGPRX4. Furthermore, a humanized mouse model expressing MRGPRX4 in sensory neurons exhibited robust phosphomonoester prodrug-evoked itch. To characterize and confirm this interaction, we further determined the structure of MRGPRX4 in complex with a phosphate-modified drug through single-particle cryo-electron microscopy (cryo-EM) and identified critical amino acid residues responsible for the binding of the phosphate group. Together, these findings explain how phosphorylated drugs can elicit treatment-limiting itch and identify MRGPRX4 as a potential therapeutic target to suppress itch and to guide future drug design.

Dexamethasone-Related Perineal Burning in the Prehospital Setting: A Case Series

Dexamethasone is frequently used in the treatment of allergic reactions and airway inflammation because of its potent anti-inflammatory effects and long duration of action. As prehospital use becomes more common, it is important for providers to be aware of unique and potentially distressing associated adverse effects. We report eight cases of intravenous dexamethasone administration associated with perineal or diffuse burning sensation in female patients.

Generalized pruritus as an unusual side effect after epidural injection with dexamethasone

A 51-year-old man with lumbar radiculopathy underwent a right L5 transforaminal epidural steroid injection with dexamethasone. One minute after the injection, the patient experienced severe pruritus and burning, which began in the groin and then spread throughout his body. The symptoms resolved completely after 1 minute, and the patient was discharged without any complications. Although there are a small number of publications reporting perineal pruritus after intravenous administration of dexamethasone, to our knowledge there is no report of a generalized reaction to an epidural dexamethasone injection such as the one described here.

Supportive Care of Brain Tumor Patients

The supportive care of patients who have brain tumors consists mainly of the treatment of brain edema, seizures, venous thromboembolism, and cognitive dysfunction. Each of these complications may occur in patients who have primary or metastatic brain tumors. The development of any of these complications significantly increases the morbidity and mortality associated with brain tumors. Effective treatment is usually possible, however, and can result in an improved quality of life for these patients.

Excruciating perineal pain after intravenous dexamethasone

We describe two cases of unexpected perineal pain immediately after intravenous injection of fentanyl and dexamethasone (100 microg and 8 mg respectively) during induction of general anaesthesia. In both cases the pain was immediate (onset within 30 seconds), severe, localized to the genital region and of shooting and burning character No other clinical signs or symptoms were observed in either case and both patients made an uneventful recovery without neurological sequelae. We review the existing literature on perineal pain as an adverse effect of intravenous corticosteroid esters and recommend their administration either in diluted form or after induction of general anaesthesia.