Fosphenytoin alleviates subacute herpetic neuralgia and postherpetic neuralgia in mice

Abstract

Abstract Objective This study aimed to explore the analgesic effects of fosphenytoin (fPHT) on pain-related behaviours in mouse models of subacute herpetic neuralgia (subAHN) and postherpetic neuralgia (PHN). SubAHN refers to pain experienced immediately after the disappearance of a skin rash, while PHN is characterized by persistent pain long after skin rash resolution. Methods Our experimental approach involved the induction of acute herpes zoster-like skin lesions and pain-related responses (mechanical allodynia and hyperalgesia) in the hind paws of mice through cutaneous inoculation with herpes simplex virus type 1 (HSV-1). Subsequently, subAHN and PHN developed in the mice. Key findings Intravenous administration of fPHT (30 mg/kg) effectively mitigated HSV-1-induced subAHN and PHN. The suppressive effect of fPHT on subAHN was comparable to that of pregabalin (3 mg/kg, oral), a commonly used positive control. However, fPHT exhibited a slightly more potent effect than pregabalin in alleviating PHN. Conclusions These findings suggest that intravenous fPHT could serve as a promising alternative for pain relief in both subAHN and PHN.