title: Postmortem carisoprodol and meprobamate concentrations in blood and liver: lack of significant redistribution.
abstract: Carisoprodol is a therapeutic and occasionally abused centrally acting muscle relaxant. We compare central blood and liver concentrations of carisoprodol and the metabolite meprobamate to concentrations in peripheral blood in 11 medical examiner cases. Specimens were initially screened for alcohol and simple volatiles by gas chromatography (GC)-flame ionization detection headspace analysis, enzyme-linked immunosorbent array for drugs of abuse, and therapeutic drugs by GC-mass spectrometry (MS). Carisoprodol, when detected by the therapeutic drug screen, was confirmed and quantified by a specific GC-MS procedure. The results suggest that when ingested with other medications, carisoprodol may be a contributing factor in death, even when present at therapeutic concentrations. Considering the cases studied, together with previously published therapeutic and fatal concentrations, blood carisoprodol concentrations greater than 15 mg/L and liver concentrations greater than 50 mg/kg may be considered excessive and potentially fatal. Carisoprodol central blood to peripheral blood ratios averaged 1.31 + 0.33 (mean ± standard deviation), and liver to peripheral blood, 2.83 ± 1.51. Meprobamate central blood to peripheral blood ratios averaged 0.92 ± 0.22, and liver to peripheral blood, 1.25 ± 0.69. The low liver to peripheral blood ratio (less than 5), taken together with the low central blood to peripheral blood ratio, is an indicator that both carisoprodol and meprobamate lack the potential to exhibit postmortem redistribution.
authors.affiliation: Forensic Toxicology, County of San Diego Medical Examiner's Office, 5570 Overland Ave., Suite 101, San Diego, CA 92123, USA. Iain.McIntyre@sdcounty.ca.gov
authors.forename: Iain M
authors.initials: IM
authors.lastname: McIntyre
authors.forename: James
authors.initials: J
authors.lastname: Sherrard
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lucas
mesh_terms: D002328:Carisoprodol / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D003933:Diagnosis; D053593:Forensic Toxicology / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008099:Liver / Q000378:metabolism; D008620:Meprobamate / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D009125:Muscle Relaxants, Central / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D011180:Postmortem Changes; D015813:Substance Abuse Detection / Q000379:methods*; D019966:Substance-Related Disorders / Q000097:blood / Q000175:diagnosis*; D013405:Suicide; D014018:Tissue Distribution
chemical_list: D009125:Muscle Relaxants, Central; D002328:Carisoprodol; D008620:Meprobamate