Action and Spectrum

Actions and Spectrum: 

carisoprodol is a centrally-acting muscle relaxant that modulates gamma-aminobutyric acid (GABA) activity in the brain and spinal cord. It produces muscle-relaxing effects by enhancing the inhibitory effects of GABA, an inhibitory neurotransmitter in the central nervous system.

By increasing the activity of GABA, carisoprodol reduces the activity of neurons in the spinal cord and brain that are involved in the perception of pain and muscle spasms 

carisoprodol has a broad spectrum of activity. It is indicated to relieve discomfort associated with acute, painful musculoskeletal conditions. It is primarily a short-term adjunct to rest, physical therapy, and other measures to relieve acute musculoskeletal pain 

Drug Interaction

Adverse Reaction

Frequency defined 

>10% 

Drowsiness (13-17%) 

1-10% 

Headache (3-5%) 

Dizziness (7-8%) 

<1% 

Orthostatic hypotension 

Tachycardia 

Irritability 

Allergic/idiosyncratic reactions (pruritus, rash, dizziness, etc.) 

N/V 

Weakness 

Syncope 

Agitation 

Depression 

Epigastric distress 

Facial flushing 

Black Box Warning

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

• carisoprodol is contraindicated in patients with a history of hypersensitivity to the drug or its components.  
• It is also contraindicated in patients with a history of acute intermittent porphyria, a rare metabolic disorder that affects heme production, a haemoglobin component. 
• carisoprodol is not recommended in patients with a history of drug abuse or addiction, as it has the potential for abuse and dependence. 
• It should also be used cautiously in patients with a history of liver or kidney disease, as the drug is metabolized in the liver and excreted by the kidneys 

Caution: 

• History of drug abuse or addiction: carisoprodol has the potential for abuse and dependence, particularly in individuals with a history of drug abuse or addiction 
• Impaired hepatic function: carisoprodol is primarily metabolized by the liver, and impaired hepatic function may result in decreased metabolism and elimination of the drug. Dosing adjustments may be necessary for patients with hepatic impairment. 
• Impaired renal function: carisoprodol and its metabolites are primarily excreted in the urine, and impaired renal function may result in decreased drug elimination. Dosing adjustments may be necessary for patients with renal impairment. 
• Pregnancy and lactation: The safety of carisoprodol use during pregnancy and lactation has not been established. carisoprodol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. carisoprodol is excreted in breast milk and may cause sedation in nursing infants. 
• Geriatric population: Geriatric patients may be more sensitive to carisoprodol’s soothing and muscle-relaxant effects. Dosing adjustments may be necessary for elderly patients. 
• Concomitant use of other CNS depressants: carisoprodol may potentiate the effects of other CNS depressants, such as alcohol, benzodiazepines, and opioids. Concomitant use of carisoprodol with these agents should be avoided or closely monitored 
• Risk of withdrawal: Abrupt discontinuation of carisoprodol may result in withdrawal symptoms, such as anxiety, insomnia, and muscle tremors. Tapering of the drug may be necessary to minimize the risk of withdrawal. 

Pregnancy / Lactation

Pregnancy consideration: Insufficient data available 

Lactation: Excretion of the drug in human breast milk is unknown 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.   

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacology: 

carisoprodol is a centrally-acting muscle relaxant that modulates gamma-aminobutyric acid (GABA) activity in the brain and spinal cord. It is a prodrug metabolized in the liver to form its active metabolite, meprobamate. 

Pharmacodynamics: 

The pharmacodynamics of carisoprodol involves its effects on the central nervous system (CNS). carisoprodol is a centrally-acting muscle relaxant that produces its effects by modulating the activity of gamma-aminobutyric acid (GABA) in the brain and spinal cord 

• carisoprodol enhances the inhibitory effects of GABA, an inhibitory neurotransmitter in the CNS, by binding to GABA-A receptors. By increasing the activity of GABA, carisoprodol reduces the activity of neurons in the spinal cord and brain that are involved in the perception of pain and muscle spasms. 
• carisoprodol has both muscle-relaxing and sedative effects, which may contribute to its therapeutic effects in treating musculoskeletal pain. The drug also has anxiolytic properties due to its metabolite, meprobamate, which has sedative and anxiolytic effects similar to benzodiazepines. 

Pharmacokinetics: 

Absorption 

carisoprodol is rapidly and well absorbed after oral administration, with an onset of action of approximately 30 minutes. The drug is metabolized to meprobamate, contributing to its pharmacological effects. 

Distribution 

carisoprodol is widely distributed throughout the body, with a volume of distribution of approximately 1.5-2.0 L/kg. The drug is extensively bound to plasma proteins, with a protein binding of approximately 60%. 

Metabolism 

carisoprodol is primarily metabolized by the liver microsomal enzyme CYP2C19 to form meprobamate, which has soothing and anxiolytic properties. Meprobamate is further metabolized by the liver to form glucuronide conjugates and is eliminated primarily by renal excretion. 

Elimination and Excretion 

The elimination half-life of carisoprodol is approximately 2 hours, while the half-life of meprobamate is approximately 8 hours. carisoprodol and its metabolites are excreted primarily in the urine, with approximately 10-20% of the dose excreted unchanged. The drug is dialyzable, with approximately 20-30% of the dose removed by hemodialysis. Peritoneal dialysis is also effective in removing carisoprodol and its metabolites 

Adminstartion

Administration: 

• carisoprodol is a prescription medication used as a muscle relaxant to treat acute musculoskeletal pain. It is usually administered orally in the form of tablets or capsules. 
• The recommended dose of carisoprodol is 250-350mg three times a day and at bedtime. The maximum recommended duration of treatment is two to three weeks. 
• carisoprodol should be taken with food or milk to minimize the risk of gastrointestinal adverse effects. It is essential to follow the dosage and duration of treatment as prescribed by the healthcare provider to avoid the risk of dependence, withdrawal, and other adverse effects. 
• carisoprodol is a controlled substance and can lead to dependence and addiction. Therefore, it should be used cautiously in patients with a history of drug abuse or addiction. Patients should also be advised not to share the medication with others and to store it in a safe and secure place. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: carisoprodol 

Pronounced: [ kar-eye-soe-PROE-dole ] 

Why do we use carisoprodol? 

carisoprodol is a muscle relaxant that blocks pain signals between the nerves and the brain. 

• It is used to treat skeletal muscle disorders such as pain or damage together with rest and physical therapy. 
• It should only be used for brief intervals (up to two or three weeks), as there is little evidence to support its continued usage, and most skeletal muscle injuries heal quickly. In the US, carisoprodol is regarded as a restricted drug.