Pain Sensation during Intradermal Injections of Three Different Botulinum Toxin Preparations in Different Doses and Dilutions

The efficacy of various interventions as good strategies to reduce pain in botulinum neurotoxin A for wrinkles. A systematic review of the randomized controlled trials (RCTs)

Various topical interventions have been described to minimize botulinum neurotoxin-A (BoNT)-induced pain. The purpose of this study is to conduct a systematic review of relevant randomized controlled trials (RCTs) to compare the efficacy of pain relief methods during BoNT injection. PubMed, Scopus, and Web of Science were searched using "Botox," "Botulinum," or "BTX." We identified RCTs in which BoNT were injected to eliminate wrinkles. The pain score was the study outcome, and pain reduction method was compared with routine one. The meta-analysis was reported using the PRISMA checklist. The Higgins I(I2) statistical model assessed results heterogeneity. Two thousand one hundred and twenty-three articles were identified, thirteen articles eligible. Two hundred and sixty-two healthy volunteers were performed on these RCTs. Meta-analysis evaluated different methods to ease BoNT injection pain, and these methods significantly improved outcomes by 0.23% (95%CI, 0.11-0.46, p = .000). Subgroup analysis based on injection area showed no significant heterogeneity, but heterogeneity decreased when subgroup analysis based on other methods was done (Cochran's Q test = 115.52, p = .0001, I2 = 87.9%). This meta-analysis confirms the effectiveness of pain relief methods during BoNT injection. Evaluation of different methods showed their effectiveness, but finding the best method requires comparative studies, although the role of pH and EMLA has been proven.

Transient Receptor Potential Channels and Botulinum Neurotoxins in Chronic Pain

Pain afflicts more than 1.5 billion people worldwide, with hundreds of millions suffering from unrelieved chronic pain. Despite widespread recognition of the importance of developing better interventions for the relief of chronic pain, little is known about the mechanisms underlying this condition. However, transient receptor potential (TRP) ion channels in nociceptors have been shown to be essential players in the generation and progression of pain and have attracted the attention of several pharmaceutical companies as therapeutic targets. Unfortunately, TRP channel inhibitors have failed in clinical trials, at least in part due to their thermoregulatory function. Botulinum neurotoxins (BoNTs) have emerged as novel and safe pain therapeutics because of their regulation of exocytosis and pro-nociceptive neurotransmitters. However, it is becoming evident that BoNTs also regulate the expression and function of TRP channels, which may explain their analgesic effects. Here, we summarize the roles of TRP channels in pain, with a particular focus on TRPV1 and TRPA1, their regulation by BoNTs, and briefly discuss the use of BoNTs for the treatment of chronic pain.