(British Approved Name, US Adopted Name, rINN)
International Nonproprietary Names (INNs) in main languages (French, Latin, Russian, and Spanish):
Pharmacopoeias. In Europe and US.
European Pharmacopoeia, 6th ed., 2008 and Supplements 6.1 and 6.2 (Carisoprodol). A white or almost white fine powder. M.p. 92° to 95°. Very slightly soluble in water; freely soluble in alcohol, in acetone, and in dichloromethane.
The United States Pharmacopeia 31, 2008, and Supplements 1 and 2 (Carisoprodol). A white crystalline powder having a mild characteristic odour. M.p. 91° to 94°. Soluble 1 in 2083 of water, 1 in 2.5 of alcohol and of acetone, and 1 in 2.3 of chloroform. Store in airtight containers.
Dependence and Withdrawal, Adverse Effects, Treatment, and Precautions
As for Meprobamate.
The most common adverse effects reported with carisoprodol are drowsiness, dizziness, and headache. Sedation may affect the performance of skilled tasks and affected patients should not drive or operate machinery. Poor metabolisers, deficient in the cytochrome P450 isoenzyme CYP2C19, may be at greater risk of drowsiness.
Idiosyncratic reactions may occur within minutes of a dose in patients who have not previously received carisoprodol. Such reactions have been reported rarely and include anaphylactic shock, syncope, tachycardia, confusion, transient quadriplegia, and bronchospasm. Cross-reactivity can occur with its metabolite meprobamate.
Overdosage may result in seizures, stupor, coma, shock, respiratory depression, and rarely death.
Carisoprodol should be used with caution in patients with impaired hepatic or renal function.
Cases of dependence and abuse have been reported with the prolonged use of carisoprodol, particularly in patients with a history of addiction; withdrawal reactions have also occurred when treatment is suddenly stopped after prolonged use or the use of high doses. The increased risk of abuse and addiction with carisoprodol, as well as the risk of altered mental state and psycho-motor impairment, has led the EMEA and some other authorities to recommend that it is suspended from the market; in the United States of America, however, it is recommended that use is limited to 2 to 3 weeks.
Analysis of data from the Norwegian Prescription Database found that carisoprodol was used in higher doses than recommended indicating its potential as a drug of abuse. Subsequently, the Norwegian Medicines Agency and the EMEA have recommended for suspension (see above).
Carisoprodol is distributed into breast milk, achieving concentrations 2 to 4 times those in maternal plasma; United Kingdom (UK) licensed product information and the BNF recommend that it is best avoided in women who are breast feeding although US licensed product information states to use with caution.
There are reports of carisoprodol dependence, probably due to its metabolism to meprobamate. In one case the patient had symptoms of meprobamate withdrawal that resolved with a dose-reducing schedule of meprobamate. Dependence may occur more often when carisoprodol is given in high doses and for prolonged periods, especially in patients with a history of alcohol or drug dependence or in those with marked personality disorders. One group found that patients with a history of substance abuse were twice as likely to use carisoprodol in larger doses to those prescribed than those with no such historyThe risk of dependence with carisoprodol has led the EMEA and some other authorities to recommend its suspension from the market (see above).
Carisoprodol has been associated with acute attacks of porphyria and is considered unsafe in porphyric patients.
The CNS effects of carisoprodol may be potentiated by alcohol or other CNS depressants. Carisoprodol may cause hepatic enzyme induction and it may therefore affect the metabolism of a number of drugs. The metabolism of carisoprodol is mediated by the cytochrome P450 isoenzyme CYP2C19; use with other drugs that inhibit or induce this isoenzyme may result in changes in plasma concentration of carisoprodol, however, there is a lack of data.
Carisoprodol is absorbed from the gastrointestinal tract and peak plasma concentrations are reached after 1.5 to 2 hours. It is metabolised in the liver mainly by the cytochrome P450 isoenzyme CYP2C19, which shows genetic polymorphism, and excreted in urine as metabolites, including meprobamate. The terminal elimination half-life of carisoprodol is about 2 hours. It is distributed in substantial amounts into breast milk.
Uses and Administration
Carisoprodol is a centrally acting skeletal muscle relaxant whose mechanism of action is not completely understood but may be related to its sedative actions. After oral doses its effects begin within about 30 minutes and last for 4 to 6 hours. It is used as an adjunct in the short-term symptomatic treatment of painful muscle spasm associated with musculoskeletal conditions. A usual oral dose is 250 to 350 mg given three or four times daily for up to 2 to 3 weeks. Half the usual dose or less is recommended in elderly patients. It is also given with analgesics in compound preparations.
The EMEA and some other authorities have recommended for carisoprodol to be suspended from the market due to the increased risk of abuse and addiction, as well as the risk of altered mental state and psychomotor impairment.
The United States Pharmacopeia 31, 2008, and Supplements 1 and 2: Carisoprodol and Aspirin Tablets; Carisoprodol Tablets; Carisoprodol, Aspirin, and Codeine Phosphate Tablets.
Canada: Soma ;
Denmark: Somadril ;
Norway: Somadril ;
Spain: Mio Relax;
Sweden: Somadril ;
Thailand: Myolax ;
United Kingdom (UK): Carisoma ;
United States of America (US and USA): Soma.
Argentina: Algiseda; Flexicamin; Flexicamin A; Flexicamin BI2; Flogiatrin; Flogiatrin BI2; Ketazon Flex ; Mefenix Relax ; Naprontag Flex; Rumisedan Fuerte ; Solocalm Plus; Solocalm-Flex;
Brazil: Algi-Butazolon ; Algi-Tanderil ; Beserol; Cedrilax ; Diclofetamol; Dorilax; Flexalgin; Mio-Citalgan; Mioflex; Mioflex A; Mionevrix; Paceflex ; Sanilax; Sedilax; Tandene; Tanderalgin; Tandriflan; Tandrilax; Torsilax; Trilax ;
Czech Republic: Scutamil C ;
Finland: Somadril Comp ;
Greece: Relacton-C ;
Hungary: Scutamil C ;
India: Carisoma Compound; Somaflam;
Indonesia: New Skelan; Somadril Compound;
Italy: Soma Complex;
Mexico: Blocacid; Contraxen; Dolaren; Dorsal; Duoflex; Empatil; Naxodol; Profenlax; Somalgesic;
Spain: Flexagil ; Relaxibys ;
Sweden: Somadril Comp ;
Thailand: Alaxan; Asialax; Cariso-Co ; Carisoma Compound; Caritasone; Cenpadol; Muscelax; Myophen; Polixan;
United States of America (US and USA): Sodol Compound; Soma Compound with Codeine ; Soma Compound ;
Venezuela: Cotar; Flexidone ; Praxona.