A multicentre, randomized, double-blind, placebo-controlled parallel design trial of the efficacy and safety of subcutaneous tetrodotoxin (TTX) for moderate to severe inadequately controlled cancer-related pain.

The study was designed to determine the safety and effectiveness of TTX in relieving pain and improving quality of life. In addition, the time to the start of the pain relief and its duration was studied and whether TTX helped to reduce the use of opioids. Physical and emotional functioning of patients was measured. This phase 3 trial showed a clinically important analgesic effect (NNT about 4-6) in a cohort of patients with advanced illness and otherwise poorly controlled cancer pain.