Exclusion Criteria: Diagnosed with or is suspected to have an acute, clinically severe infection, which may, in the opinion of the Investigator, may increase the subject's risk for participating in the study an/or may impair the ability of performing and/or interpreting study assessments; severe hyperthermia secondary to a condition other than a psychostimulant drug-induced toxicity; likelihood of head trauma in the past 3 months, or other systemic disease that might increase the subject's risk for participating in the study and/or may impair the ability of performing and/or interpreting study assessments; positive pregnancy test or evidence of active lactation; known history of allergy or hypersensitivity to dantrolene; known history of seizure disorders or epilepsy; current or prior use (within the past 2 weeks) of calcium channel blockers.