Analgesic Efficacy of a Novel Traditional Chinese Medicine Ointment Against Mechanical Allodynia in Rat Models

Huan Liu,1,* Juan Deng,2,* Jiao Wei,3 Juan Wu,1 Yi Gan,1 Yongqun Hu,1,* HongMei Mo1,* 1Department of Pediatric, Maternal and Child Health Hospital of Hubei Province, Wuhan, People’s Republic of China; 2College of Pharmacy, Hubei University of Chinese Medicine, Wuhan, People’s Republic of China; 3Nursing Department, Shanxi Provincial People’s Hospital, Taiyuan, Shanxi, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yongqun Hu, Department of Pediatric, Maternal and Child Health Hospital of Hubei Province, Wuhan, People’s Republic of China, Tel +86-27-87169053, Email [email protected] HongMei Mo, Department of Pediatric, Maternal and Child Health Hospital of Hubei Province, Wuhan, People’s Republic of China, Tel +86-27-87169053, Email [email protected]: Effective management of procedure-related pain, such as venipuncture, is a critical clinical need. The Eutectic Mixture of Local Anesthetics (EMLA) cream is a standard topical analgesic but has limitations including contraindications and potential adverse effects. The Cortex Erythrinae formula recorded in the Golden Mirror of Medicine is traditionally used to dispel wind-dampness, unblock collaterals, and relieve arthralgia.Objective: This study aimed to develop a novel Traditional Chinese Medicine (TCM) ointment based on classical prescriptions and to evaluate its efficacy against mechanical allodynia, using EMLA cream as a positive control.Methods: Fifty male Sprague-Dawley rats were randomly allocated to five groups (n=10). Mechanical allodynia was induced; the mechanical withdrawal threshold (MWT), pain-related behaviors, skin irritation, and systemic toxicity were assessed following topical application of low-, medium-, or high-concentration TCM ointment, EMLA cream, or blank vehicle.Results: High-concentration TCM ointment significantly elevated MWT (P < 0.001 vs EMLA) and reduced paw-licking and writhing responses, without inducing skin irritation or systemic toxicity.Conclusion: The high-concentration TCM ointment provided rapid (within 20 min), superior, and cost-effective analgesia with an excellent safety profile, suggesting its promise as an alternative to EMLA for managing mechanical allodynia.Plain Language Summary: This study developed a new Traditional Chinese Medicine (TCM) ointment inspired by a classical formula. Tested in a rat model of pain, this high-concentration ointment provided faster and stronger pain relief compared to the commonly used EMLA cream, without causing skin irritation or other safety concerns. The results suggest this TCM ointment could be a promising, safe, and cost-effective alternative topical analgesic.Keywords: EMLA, herbal medicine, mechanical allodynia, topical analgesia, traditional chinese medicine, von Frey test