Butorphanol is a mixed opioid agonist-antagonist that acts as a potent analgesic by binding to μ and κ opioid receptors, with preferential activity at κ receptors. For cluster headache, it provides rapid pain relief by modulating central pain processing and reducing neurogenic inflammation through its unique receptor interactions. Its mixed agonist-antagonist profile allows for effective pain management with potentially lower abuse potential compared to pure μ-receptor agonists.