The purpose of this study is to evaluate the local anesthetic properties of neosaxitoxin in humans

Neosaxitoxin is a phycotoxins that reversible block the voltage-gated sodium channels at neuronal level. Its activity is express as blocking the axonal conduction, stopping the propagation of the nerve impulse. The objective of the present work is to evaluate the neosaxitoxin efficacy and safety as local anesthetic in a human trial

Methods: Randomized, double-blind, placebo-controlled trial, with 10 healthy volunteers. The anesthetic effect will be evaluated using a standardized human sensory and pain model. TSA Neurosensory analyser and Von Frey Technique will be used to evaluate five parameters: sensory threshold for warm and cold, pain thresholds for heat and cold and mechanical touch perception threshold.

Inclusion Criteria:

• Healthy males with the abilities to understand and respond the tests to perform

Exclusion Criteria:

• Use of any oral analgesics at least ten days before the study
• Drugs abuse history
• Showing at the clinical examination any signal of psychiatric disorder