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Carisoprodol

Pronunciation

Pronunciation

(kar eye soe PROE dole)

Index Terms

  • Carisoprodate
  • Isobamate

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Soma: 250 mg, 350 mg

Generic: 250 mg, 350 mg

Brand Names: U.S.

  • Soma

Pharmacologic Category

  • Skeletal Muscle Relaxant

Pharmacology

Precise mechanism is not yet clear, but many effects have been ascribed to its central depressant actions. In animals, carisoprodol blocks interneuronal activity and depresses polysynaptic neuron transmission in the spinal cord and reticular formation of the brain. It is also metabolized to meprobamate, which has anxiolytic and sedative effects.

Metabolism

Hepatic, via CYP2C19 to active metabolite (meprobamate)

Excretion

Urine, as metabolite

Onset of Action

Rapid

Time to Peak

Plasma: 1.5-2 hours

Duration of Action

4-6 hours

Half-Life Elimination

Carisoprodol: ~2 hours; Meprobamate: ~10 hours

Protein Binding

Carisoprodol: (<70%); Meprobamate: (<25%) (Olsen, 1994)

Special Populations: Gender

Carisoprodol exposure is 30% to 50% higher in women than men; however, meprobamate exposure is not affected by gender.

Special Populations: Race

Individuals with reduced CYP2C19 activity have a fourfold increase in carisoprodol exposure and a 50% reduced exposure to meprobamate compared with normal CYP2C19 metabolizers. Prevalence of poor metabolizers in white and black patients is ~3% to 5% and in Asian patients ~15% to 20%.

Use: Labeled Indications

Short-term (2-3 weeks) treatment of acute musculoskeletal pain

Contraindications

Hypersensitivity to carisoprodol, carbamates (eg, meprobamate), or any component of the formulation; history of acute intermittent porphyria

Dosing: Adult

Note: Carisoprodol should only be used for short periods (2-3 weeks) due to lack of evidence of effectiveness with prolonged use.

Acute musculoskeletal pain: Oral: 250-350 mg 3 times daily and at bedtime

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Adolescents ≥16 years: Refer to adult dosing.

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer’s labeling (has not been studied); carisoprodol undergoes renal excretion and should be used with caution.

Dialysis: Removed by hemo- and peritoneal dialysis

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer’s labeling (has not been studied); carisoprodol undergoes hepatic metabolism and should be used with caution.

Administration

Administer with or without food.

Dietary Considerations

May be taken with or without food.

Storage

Store at 20°C to 25°C (68°F to 77°F).

Drug Interactions

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy

Aspirin: May increase serum concentrations of the active metabolite(s) of Carisoprodol. Specifically, Meprobamate concentrations may be increased. Aspirin may decrease the serum concentration of Carisoprodol. Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy

CYP2C19 Inducers (Strong): May increase the metabolism of CYP2C19 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP2C19 Inhibitors (Moderate): May decrease the metabolism of CYP2C19 Substrates. Monitor therapy

CYP2C19 Inhibitors (Strong): May decrease the metabolism of CYP2C19 Substrates. Consider therapy modification

Dabrafenib: May decrease the serum concentration of CYP2C19 Substrates. Management: Seek alternatives to the CYP2C19 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification

Dimethindene: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification

Enzalutamide: May decrease the serum concentration of CYP2C19 Substrates. Conversely, concentrations of active metabolites may be increased for those drugs activated by CYP2C19. Management: Concurrent use of enzalutamide with CYP2C19 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP2C19 substrate should be performed with caution and close monitoring. Consider therapy modification

Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification

HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Consider starting with a 20% to 30% lower hydrocodone dose when using together with any other CNS depressant. Dose reductions in the other CNS depressant may also be warranted. Consider therapy modification

HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Luliconazole: May increase the serum concentration of CYP2C19 Substrates. Monitor therapy

Lumacaftor: May decrease the serum concentration of CYP2C19 Substrates. Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Ombitasvir, Paritaprevir, and Ritonavir: May decrease the serum concentration of Carisoprodol. Monitor therapy

Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir: May decrease the serum concentration of Carisoprodol. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: When oxycodone is combined with another CNS depressant, a dose reduction of one or both agents should be considered. The extended release oxycodone starting dose should be reduced 50% to 67% when initiated in patients already receiving CNS depressants. Consider therapy modification

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

St John's Wort: May increase serum concentrations of the active metabolite(s) of Carisoprodol. Specifically, Meprobamate concentrations may be increased. St John's Wort may decrease the serum concentration of Carisoprodol. Monitor therapy

Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification

Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Start tapentadol at a dose of one-third to one-half of the normal dose if being initiated in a patient who is taking another drug with CNS depressant effects. Monitor closely for evidence of excessive CNS depression. Consider therapy modification

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification

Adverse Reactions

>10%: Central nervous system: Drowsiness (13% to 17%)

1% to 10%: Central nervous system: Dizziness (7% to 8%), headache (3% to 5%)

Postmarketing and/or case reports (Limited to important or life-threatening): Abdominal cramps, agitation, allergic dermatitis, anaphylaxis, angioedema, ataxia, burning sensation of eyes, depression, drug dependence, dyspnea, epigastric pain, eosinophilia, erythema multiforme, exacerbation of asthma, fixed drug eruption, hallucination, headache, hiccups, hypersensitivity reaction, idiosyncratic reaction (symptoms may include agitation, ataxia, confusion, diplopia, disorientation, dysarthria, euphoria, extreme weakness, muscle twitching, mydriasis, temporary vision loss, and/or transient quadriplegia); insomnia, irritability, leukopenia, nausea, orthostatic hypotension, pancytopenia, paradoxical central nervous system stimulation, pruritus, psychosis, seizure, skin rash, syncope, tachycardia, transient flushing of face, tremor, urticaria, vertigo, vomiting, weakness, withdrawal syndrome (abdominal cramps, headache, insomnia, nausea, seizure)

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; concomitant use of other CNS depressants may enhance these effects. Patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving); in postmarketing reports, motor vehicle accidents have been associated with use.

• Seizures: Has been associated (rarely) with seizures in patients with and without seizure history.

Disease-related concerns:

• Drug abuse: Use with caution in patients with a history of drug abuse or acute alcoholism; potential for drug dependency exists. Tolerance, psychological and physical dependence to carisoprodol (or its metabolite meprobamate) may occur with prolonged use. Limit use to 2-3 weeks.

• Hepatic impairment: Safety has not been established in patients with hepatic impairment; use caution.

• Renal impairment: Safety has not been established in patients with renal impairment; use caution.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

• Sedatives: Effects with other sedative drugs or ethanol may be potentiated.

Special populations:

• Poor CYP2C19 metabolizers: Use with caution in patients with reduced CYP2C19 activity; poor metabolizers have been shown to have a fourfold increase in carisoprodol exposure and a 50% reduced exposure to meprobamate (active metabolite) compared to normal metabolizers. Prevalence of poor metabolizers in the Asian population is ~15% to 20% while that of Caucasians and African-Americans is ~3% to 5%.

Other warnings/precautions:

• Abrupt discontinuation: May precipitate withdrawal after abrupt cessation of prolonged use. Reported withdrawal symptoms have included insomnia, vomiting, abdominal pain, headache, tremors/twitching, ataxia, hallucinations, and psychosis.

Monitoring Parameters

CNS effects (eg, mental status, excessive drowsiness); relief of pain and/or muscle spasm; signs of misuse, abuse, and addiction

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have been observed in animal reproduction studies. Limited postmarketing data with meprobamate (the active metabolite) do not show a consistent association between maternal use and an increased risk for congenital malformations.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience headache, dizziness, or fatigue. Have patient report immediately to prescriber seizures or severe loss of strength and energy (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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