Tidsskr Nor Laegeforen. 2000 Jun 30;120(17):1966-9.
[Centrally acting muscle relaxants and traffic hazards]

[Article in Norwegian]

Bramness JG, Skurtveit S, Grung M, Morland J.

Statens rettstoksikologiske institutt, Oslo.

BACKGROUND: An increasing number of the centrally acting muscle relaxants were withdrawn from the Norwegian market during the 1988-98 period. The only drug in this group now marketed in Norway is carisoprodol. The National Institute of Forensic Toxicology in Norway analyses all blood samples from suspected drugged drivers. In later years there has been a marked increase in the number of blood samples testing positive for carisoprodol or meprobamate (the major metabolite). MATERIAL AND METHODS: 480 cases testing positive for central muscle relaxants in the years 1984-1998 were further studied. RESULTS: Compared with blood samples positive primarily for benzodiazepines, there were more women in the group (39% vs. 15%), and fewer drugs and less alcohol were detected. INTERPRETATION: The positive samples may indicate misuse or abuse due to the fact that high drug concentrations and concomitant use of benzodiazepines were frequent. This knowledge should have implications for doctors prescribing centrally acting muscle relaxants.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11008526&dopt=Abstract soma carisoprodol




J Anal Toxicol. 2003 Jul-Aug;27(5):275-83.
Direct and rapid determination of baclofen (Lioresal) and carisoprodol (Soma) in bovine serum by liquid chromatography-mass spectrometry.

Miksa IR, Poppenga RH.

University of Pennsylvania, School of Veterinary Medicine, Department of Pathobiology, New Bolton Center, Toxicology, 382 West Street Road, Kennett Square, PA 19348, USA. irudiet.upenn.edu

Baclofen (Lioresal), a lipophilic analogue of c-aminobutyric acid (GABA), and carisoprodol (Soma), a central nervous system depressant with an unknown mechanism of pharmacologic action, are categorized as muscle relaxants. Baclofen is used clinically in the management of spasticity and its sequelae secondary to severe chronic disorders such as multiple sclerosis and other types of spinal cord lesions. Carisoprodol is used for discomfort associated with acute and painful musculoskeletal conditions. Intoxication from these drugs occurs in both humans and animals necessitating a need for their detection in plasma/serum, tissue, and gastrointestinal contents samples. A sensitive and specific analytical method for detection and quantitation of these compounds using liquid chromatography with positive atmospheric pressure chemical ionization-mass spectrometry was developed. A rapid extraction procedure for both analytes from fortified bovine sera is described. Chromatographic separation was carried out on a C(18) reverse-phase column with a gradient elution of acetonitrile and 0.25% acetic acid. The effluent was directed to the mass spectrometer with fragmentation information for baclofen and carisoprodol obtained in a scan monitoring mode. Linear standard curves for baclofen and carisoprodol were constructed based on at least two corresponding extracted ions over a concentration range of 0.1-50 micro g/mL. The analysis of fortified sera samples demonstrates good accuracy and precision for the method with a limit of detection of 0.5 micro g/mL for carisoprodol (n = 3) and 1 micro g/mL for baclofen (n = 4) and a




Clin Ther. 2004 Sep;26(9):1355-67. Related Articles, Links

Commonly used muscle relaxant therapies for acute low back pain: a review of carisoprodol, cyclobenzaprine hydrochloride, and metaxalone.

Toth PP, Urtis J.
Department of Family and Community Medicine, University of Illinois School of Medicine, Peoria, USA.

BACKGROUND: Low back pain is a leading reason for primary care visits. Many treatment options are available, but some lack scientific support. OBJECTIVE: The aim of this review was to discuss the etiology of low back pain and the relative risks and benefits of muscle relaxants commonly prescribed for the management of back pain. METHODS: We searched Intercontinental Marketing Services data for January 2003 through January 2004 to determine the most commonly prescribed agents for the management of musculoskeletal pain. Carisoprodol, cyclobenzaprine hydrochloride, and metaxalone represented >45% of all such prescriptions. Cochrane Library, MEDLINE, and EMBASE databases were searched (time frame: 1960 through January 2004; search terms: back pain, carisoprodol, cyclobenzaprine, metaxalone, muscle relaxants, and pharmacotherapy) and reference lists of identified articles were hand-searched. RESULTS: Three trials of carisoprodol (N = 197) were located in the Cochrane Library database. Two double-blind, randomized, placebo-controlled trials evaluating the safety and efficacy of cyclobenzaprine hydrochloride (N = 1405) were identified in the literature. Three double-blind, placebo-controlled trials were identified for metaxalone (N = 428) in 2 reports. The types of adverse events seen with these agents involved the central nervous system, including drowsiness/sedation, fatigue, and dizziness. However, the efficacy of cyclobenzaprine hydrochloride was shown to be independent of its sedative effects, which were dose related. The potential for abuse with carisoprodol is of growing concern. CONCLUSIONS: Analgesic pain management for low back pain due to muscle spasm may be combined with a muscle relaxant. Cyclobenzaprine hydrochloride has the most recent and largest clinical trials demonstrating its benefit, but carisoprodol and metaxalone also appear to be effective. However, carisoprodol's usefulness is mitigated by its potential for abuse.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract soma carisoprodol &list_uids=15530999




J Forensic Sci. 2000 May;45(3):619-23.
Carisoprodol, meprobamate, and driving impairment.

Logan BK, Case GA, Gordon AM.

Washington State Toxicology Laboratory, Washington State Patrol, Seattle 98134, USA. blogasp.wa.gov

This paper considers the pharmacology of the centrally acting muscle relaxant carisoprodol, and its metabolite meprobamate, which is also administered as an anxiolytic in its own right. Literature implicating these drugs in impaired driving is also reviewed. A series of 104 incidents in which these drugs were detected in the blood of drivers involved in accidents or arrested for impaired driving was considered, with respect to the analytical toxicology results, patterns of drug use in these subjects, the driving behaviors exhibited, and the symptoms observed in the drivers. Symptomatology and driving impairment were consistent with other CNS depressants, most notably alcohol. Reported driving behaviors included erratic lane travel, weaving, driving slowly, swerving, stopping in traffic, and hitting parked cars and other stationary objects. Drivers on contact by the police displayed poor balance and coordination, horizontal gaze nystagmus, bloodshot eyes, unsteadiness, slurred speech, slow responses, tendency to doze off or fall asleep, difficulty standing, walking or exiting their vehicles, and disorientation. Many of these cases had alcohol or other centrally acting drugs present also, making difficult the attribution of the documented impairment specifically to carisoprodol and meprobamate. In 21 cases, however, no other drugs were detected, and similar symptoms were present. Impairment appeared to be possible at any concentration of these two drugs; however, the most severe driving impairment and most overt symptoms of intoxication were noted when the combined concentration exceeded 10 mg/L, a level still within the normal therapeutic range.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10855968&dopt=Abstract soma carisoprodol