carisoprodol is a skeletal muscle relaxant that exerts its effect via sedation of the central nervous system rather than through direct muscle relaxation ( littrell et al 1993 ) . animal studies have demonstrated that carisoprodol blocks interneurons and depresses transmission of polysynaptic neurons in the spinal cord and descending reticular system of the brain . while its exact mechanism of action is unknown , it is pharmacologically similar to barbiturates and thought to have an indirect agonist effect on the same gaba - a receptor site to which barbiturates bind ( littrell et al 1993 ; rohatgi et al 2005 ) . a case study ( heacock and bauer 2004 ) found that an individual taking high doses of carisoprodol had the highest stage of barbiturate tolerance during a pentobarbital challenge test . furthermore , flumazenil , a competitive antagonist of the gaba - a receptor site for benzodiazepines and other drugs including pentobarbital , has been shown to be an effective antidote for carisoprodol intoxication ( del castillo and nelson 1960 ; hu and ticku 1994 ; roberge et al 2000 ) . with carisoprodol s cross tolerance to barbiturates , one would expect to see similar withdrawal symptoms . indeed , there have been many reports of anxiety , insomnia , tremors and hallucinations upon abrupt discontinuation of carisoprodol ( littrell et al 1993 ; reeves et al 2004 ) . in other cases , patients withdrawing from carisoprodol reported palpitations , diaphoresis , chills , stomach cramps , headache , backpain , myalgias , arthralgias , diarrhea , severe psychomotor agitation , feelings of depersonalization , anxiety with suicidal ideation , and disorientation ( luehr et al 1990 ; reeves and parker 2003 ; rohatgi et al 2005 ) . many of the above symptoms are considered to be characteristic of withdrawal from sedative- , hypnotic- , or anxiolytic- substances according to the dsm iv - tr . this class of substances include benzodiazepines , benzodiazepine - like drugs ( eg , zolpidem ) , carbamates , barbiturates , barbiturate - like hypnotics ( eg , methaqualone ) , and some prescription sleeping medications ( eg , chloral hydrate and paraldehyde ) . the dsm iv - tr identifies delirium as a possible symptom of withdrawal from sedative- , hypnotic- or anxiolytic- substances . despite the similarities between this class of drugs and carisoprodol , there has yet to be a case report of delirium during carisoprodol withdrawal . a 43-year - old woman with no previous psychiatric history or history of substance abuse was brought to the emergency room by her family after seven days of worsening insomnia , confusion , and hallucinations . one and a half years prior to presentation , the patient fell into a ditch . she experienced acute low back pain which developed into chronic back pain . during the six months following her accident , the patient tried several medications and therapies to alleviate her persistent back pain but found that only carisoprodol gave her relief . when her medical insurance was terminated six months after her accident , she began ordering carisoprodol from internet sites . over the following year , she ordered increasing quantities from the internet due to her tolerance . by the time the patient self - discontinued the medication at seven days prior to presentation , she had been taking approximately three hundred 350 mg tablets each week , at times up to fifty tablets per day . thus , she was consuming over ten times the indicated dosage of carisoprodol for acute musculoskeletal pain , which is one 350 mg tablet three to four times a day ( digregorio and barbieri 1996 ) . seven days prior to presentation , the patient stopped taking all carisoprodol because she was  sick of taking medication that [ she ] knew was bad for [ her . ] shortly thereafter , her family reports that she began to behave bizarrely and appeared increasingly confused . the patient was anxious and had pressured speech , psychomotor agitation and a fine bilateral hand tremor . she also experienced auditory and visual hallucinations such as seeing shadows and her fianc talking to her through the television . one night , the patient wandered over three miles from home and was returned by the police . during the middle of the night just prior to presentation , her fianc found her standing on the front porch , wet from rain , staring up into sky with outstretched arms . in the emergency room , she was disoriented to date , place and purpose with waxing and waning attention . she was tachycardic at 109 beats per minute . otherwise her vital signs were all within normal range . the only abnormal laboratory data were a leukocytosis of 13.1  10/ul white blood cells with 9.89  10/mm neutrophils , mildly low carbon dioxide of 19 meq / l and slightly elevated alanine aminotransferase of 68 u / l . she was placed on a clinical institute withdrawal assessment of alcohol scale ( ciwa ) protocol . the first ciwa score was fourteen triggering a second dose of oral lorazepam 2 mg . a computed tomography head scan did not show evidence of acute hemorrhage , swelling , white matter changes , or mass lesion . the ciwa assessments were discontinued after the patient fell asleep . by the morning after admission , the patient s sensorium largely cleared and she remembered some of her thoughts while she had been delirious . her vital signs were within normal limits and repeated ciwa scores were consistently less than three . she reported her back pain as better than it had been in a long while . she took two doses of 1 mg lorazepam in the afternoon and at bedtime for anxiety . on day three , the patient was discharged home , appearing to have fully recovered from her symptoms . the onset of delirium seen after abruptly stopping large daily doses of carisoprodol suggests that her symptoms were due to withdrawal from carisoprodol . previous case studies have highlighted the role of meprobamate , a metabolite of carisoprodol , in the production of withdrawal symptoms ( reeves and parker 2003 ) . meprobamate is a carbamate derivative and belongs to the class of sedative- , hypnotic- , or anxiolytic- medication . while carisoprodol has a half life of only 2.5 hours , meprobamate has a half life of 11.3 hours or up to 48 hours with chronic use ( meyer and straughn 1977 ) . according to meprobamate s product circular , the onset of withdrawal occurs usually within 1248 hours after discontinuation of meprobamate ; symptoms usually cease within the next 1248 hours . the patient of this case experienced the onset of symptoms within the time frame suggested by the product circular , but symptoms persisted much longer than the indicated 48 hours , lasting 7 days and into the second day of admission . although withdrawal delirium is a known consequence of the abrupt discontinuation of sedative- , hypnotic- , or anxiolytic- substances , this case is the first to report symptoms of delirium as component of withdrawal from carisoprodol . the case highlights carisoprodol s potential for dependence . while the dea is still debating whether to classify carisoprodol as a schedule iv drug , at least fourteen states have made it a schedule iv drug , including alabama ( 1998 ) , nevada ( 2005 ) , arizona ( 2003 ) , georgia , hawaii , kentucky , massachusetts , new mexico and oklahoma . carisoprodol s metabolite , meprobamate is considered to have greater abuse potential than the benzodiazepines . this case also illustrates the ease with which carisoprodol can be obtained on the internet . since 1999 , internet companies have provided a stable supply of prescription medications to us customers  many of which do not require a visit to a physician in order to obtain a prescription but rather an online consultation which consists of an anonymous questionnaire ( forman , woody , et al 2006 ) . most foreign web sites do not require prescriptions or an online consultation ( bloom and iannacone 1999 ) . these no - prescription websites ( npws ) generally focus on selling opioids ( forman , marlowe et al 2006 ) although many drugs of abuse are available including sedatives and stimulants . prior to 1990 , a person may have had to travel to a foreign country to obtain medications illegally or today , a patient would only need access to the internet and monetary resources to pay for the medication . with the search engines google or yahoo , several web sites that sell carisoprodol without a prescription carisoprodol no prescription  in the yahoo search engine reveals nine links to suppliers claiming they will sell carisoprodol without a prescription . one on - line seller site explains that their online questionnaire provides them with the information needed to grant a prescription  the questionnaire being a tool used by a licensed us doctor who writes the prescription . one study looked at 46 sites all of which failed to reveal the associated physician s name or location ( bloom and iannacone 1999 ) . the conflict of interest is apparent with a doctor providing both the prescription and reaping profits from the sale of the medication he or she prescribed . a danger to receiving drugs via the internet is the possibility of obtaining counterfeit or substandard medications . a customs lab analysis by the general accountability office and fda showed that out of 180 drug samples seized , 67% were either never approved by the fda or had been withdrawn from the u.s . market for safety reasons , 5% contained no active ingredients and 28% contained controlled substances prohibited from importation ( spake 2004 ) . counterfeit and substandard drugs are a huge industry with over $ 32 billion annual sales globally . with the internet the fda estimates that up to 25% of the medicines in developing countries are poor or substandard . in an fda blitz  where they examined 1,153 imported drugs , 99% contained unapproved drugs  many of which could pose safety problems ( fda 2003 ) . the who database showed in 1999 that 77% of substandard medicines coming into the united states were from developing countries and that 60% of these medicines were missing the active ingredient ( who 2003 ) . in general , the availability of npws increases the risks of drug abuse and diversion . were it not for npws , the patient in our case study may not have had access to such a large quantity of carisoprodol and thus could have avoided her subsequent hospitalization . these authors believe that carisoprodol , a drug with abuse potential that can be acquired relatively easily , should be considered a scheduled drug to restrict its potential for harm .
a 43-year - old woman with chronic back pain found relief by taking carisoprodol , a centrally acting skeletal muscle relaxant . 
 she had acquired large amounts of the prescription medication through the internet and was taking approximately three hundred 350 mg tablets each week , at times up to fifty tablets per day . 
 she then abruptly stopped the medication and presented to the emergency room one week later with waxing and waning attention , confusion , disorientation and visual hallucinations . 
 oral lorazepam was dosed according to a protocol employing the clinical institute withdrawal assessment of alcohol scale ( ciwa ) . 
 her symptoms of delirium resolved rapidly and she was discharged home on day three . 
 a review of the literature did not show any other reports of carisoprodol withdrawal induced delirium . 
 such withdrawal symptoms could be expected as the mechanism of action of carisoprodol is similar to that of hypnotic sedatives . 
 its availability and ease with which it can be acquired through the internet puts it at great risk for a drug of abuse .