Methocarbamol was administered to approximately 110 patients with various forms of neuromuscular disease marked by involuntary muscular activity. Given intravenously, the drug caused significant reduction of both involuntary tonic and clonic contractions in 30 patients whose symptoms were ascribed to lesions of the pyramidal tracts or to acute myalgic disorders. If relief was obtained, it appeared within 30 to 45 minutes. The results were sufficiently striking to warrant more thorough investigation.
Park HW. CLINICAL RESULTS WITH METHOCARBAMOL, A NEW INTERNEURONAL BLOCKING AGENT. JAMA. 1958;167(2):168-172. doi:10.1001/jama.1958.02990190022005