Background and Importance Cytomegalovirus (CMV) infection poses a significant threat to transplant recipients,¹ often necessitating antiviral treatment. Ganciclovir and valganciclovir have been mainstays, but CMV resistance in over 20% of cases requires alternatives like foscarnet or cidofovir.² Maribavir, a novel CMV UL97 protein kinase inhibitor, has emerged as an effective option.³ Here, we unveil a previously unreported adverse effect (AE) associated with maribavir.

Aim and Objectives Our aim is to report a case of toxic epidermal necrolysis (TEN) linked to maribavir intake.

Material and Methods In March 2021, a male liver-transplanted patient with CMV-related retinal necrosis developed severe pancytopenia during valganciclovir treatment, subsequently receiving foscarnet in multiple hospitalisations. In May 2023, maribavir was initiated, marking the first such case in our hospital. Within a month, the patient was readmitted with painful skin lesions and mucositis in oral and genital mucosa. TEN diagnose was assumed, evidenced by tense bullae, extensive epidermal detachment (60% of Body Surface Area), and a clearly positive Nikolsky sign. He was transferred to the ICU 3 days later and treated with a 5-day-course of 125 mg intravenous methylprednisolone and 2g/kg immunoglobulin.

Results The patient’s overall status improved, with reduced lesions and epidermal detachment. After 10 days, only scarring remained. This AE was classified as probable causality due to maribavir, with a score of 6 on the Naranjo Scale.⁴ The Spanish System for Pharmacovigilance of Human Drugs was informed of this event by the Pharmacy Service.

Conclusion and Relevance TEN, a life-threatening drug-associated AE, must be considered when prescribing. While antibiotics cause 25% of TEN cases, antivirals rarely induce it.⁵ This AE is especially noteworthy since maribavir, marketed in November 2022, has limited exposure to patients in Spain. Early-phase pharmacovigilance is crucial for detecting unreported AEs. Establishing multidisciplinary teams comprising physicians and pharmacists is essential to ensure drug safety, mitigating severe AEs.

References and/or Acknowledgements 1. Razonable RR. Clin Transplant. 2019;33:e13512. DOI: 10.1111/ctr.13512

2. Chemaly RF, et al. Clin Infect Dis. 2019;68(8):1420–1426. DOI: 10.1093/cid/ciy696

3. Livtencity technical data sheet. EMA. 2022.

4. Naranjo CA, et al. Clin Pharmacol Ther. 1981;30:239245. DOI: 10.1038/clpt.1981.154

5. Lee EY, et al. JAMA Dermatol. 2023;4:384–392. DOI:10.1001/jamadermatol.2022.6378

Conflict of Interest No conflict of interest.