7 DRUG INTERACTIONS

7.1 CNS Depressants

The sedative effects of carisoprodol and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may be additive. Therefore, caution should be exercised with patients who take more than one of these CNS depressants simultaneously. Concomitant use of carisoprodol and meprobamate, a metabolite of carisoprodol, is not recommended [ see Warnings and Precautions ( 5.1) ].

7.2 CYP2C19 Inhibitors and Inducers

Carisoprodol is metabolized in the liver by CYP2C19 to form meprobamate [ see Clinical Pharmacology ( 12.3) ]. Co-administration of CYP2C19 inhibitors, such as omeprazole or fluvoxamine, with carisoprodol could result in increased exposure of carisoprodol and decreased exposure of meprobamate. Co- administration of CYP2C19 inducers, such as rifampin or St. John’s Wort, with carisoprodol could result in decreased exposure of carisoprodol and increased exposure of meprobamate. Low dose aspirin also showed an induction effect on CYP2C19. The full pharmacological impact of these potential alterations of exposures in terms of either efficacy or safety of carisoprodol is unknown.

9 DRUG ABUSE AND DEPENDENCE

9.1 Controlled Substance

Carisoprodol is a Schedule IV controlled substance. Carisoprodol has been subject to abuse, misuse, and criminal diversion for nontherapeutic use [see Warnings and Precautions ( 5.2)] .

9.2 Abuse

Abuse of carisoprodol poses a risk of overdosage which may lead to death, CNS and respiratory depression, hypotension, seizures and other disorders [see Warnings and Precautions ( 5.2) and Overdosage ( 10)] . Patients at high risk of carisoprodol abuse may include those with prolonged use of carisoprodol, with a history of drug abuse, or those who use carisoprodol in combination with other abused drugs.

Prescription drug abuse is the intentional non-therapeutic use of a drug, even once, for its rewarding psychological effects. Drug addiction, which develops after repeated drug abuse, is characterized by a strong desire to take a drug despite harmful consequences, difficulty in controlling its use, giving a higher priority to drug use than to obligations, increased tolerance, and sometimes physical withdrawal. Drug abuse and drug addiction are separate and distinct from physical dependence and tolerance (for example, abuse or addiction may not be accompanied by tolerance or physical dependence) [see Drug Abuse and Dependence ( 9.3)] .

9.3 Dependence

Tolerance is when a patient’s reaction to a specific dosage and concentration is progressively reduced in the absence of disease progression, requiring an increase in the dosage to maintain the same. Physical dependence is characterized by withdrawal symptoms after abrupt discontinuation or a significant dose reduction of a drug. Both tolerance and physical dependence have been reported with the prolonged use of carisoprodol. Reported withdrawal symptoms with carisoprodol include insomnia, vomiting, abdominal cramps, headache, tremors, muscle twitching, anxiety, ataxia, hallucinations, and psychosis. Instruct patients taking large doses of carisoprodol or those taking the drug for a prolonged time to not abruptly stop carisoprodol [see Warnings and Precautions ( 5.2)] .

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Long term studies in animals have not been performed to evaluate the carcinogenic potential of carisoprodol.

Carisoprodol was not formally evaluated for genotoxicity. In published studies, carisoprodol was mutagenic in the in vitro mouse lymphoma cell assay in the absence of metabolizing enzymes, but was not mutagenic in the presence of metabolizing enzymes. Carisoprodol was clastogenic in the in vitro chromosomal aberration assay using Chinese hamster ovary cells with or without the presence of metabolizing enzymes. Other types of genotoxic tests resulted in negative findings. Carisoprodol was not mutagenic in the Ames reverse mutation assay using S. typhimurium strains with or without metabolizing enzymes, and was not clastogenic in an in vivo mouse micronucleus assay of circulating blood cells.

Carisoprodol was not formally evaluated for effects on fertility. Published reproductive studies of carisoprodol in mice found no alteration in fertility although an alteration in reproductive cycles characterized by a greater time spent in estrus was observed at a carisoprodol dose of 1200 mg/kg/day. In a 13-week toxicology study that did not determine fertility, mouse testes weight and sperm motility were reduced at a dose of 1200 mg/kg/day. In both studies, the no effect level was 750 mg/kg/day, corresponding to approximately 2.6 times the human equivalent dosage of 350 mg four times a day, based on a body surface area comparison. The significance of these findings for human fertility is not known.

17 PATIENT COUNSELING INFORMATION

Patients should be advised to contact their physician if they experience any adverse reactions to carisoprodol tablets.

17.1 Sedation

Patients should be advised that carisoprodol tablets may cause drowsiness and/or dizziness, and has been associated with motor vehicle accidents. Patients should be advised to avoid taking carisoprodol before engaging in potentially hazardous activities such as driving a motor vehicle or operating machinery [ see Warnings and Precautions ( 5.1) ].

17.2 Avoidance of Alcohol and Other CNS Depressants

Patients should be advised to avoid alcoholic beverages while taking carisoprodol tablets and to check with their doctor before taking other CNS depressants such as benzodiazepines, opioids, tricyclic antidepressants, sedating antihistamines, or other sedatives [ see Warnings and Precautions ( 5.1) ].

17.3 Carisoprodol Tablets Should Only Be Used for Short-Term Treatment

Patients should be advised that treatment with carisoprodol tablets should be limited to acute use (up to two or three weeks) for the relief of acute, musculoskeletal discomfort. In the post-marketing experience with carisoprodol tabletcarisoprodol tablets, cases of dependence, withdrawal, and abuse have been reported with prolonged use. If the musculoskeletal symptoms still persist, patients should contact their healthcare provider for further evaluation.

To report SUSPECTED ADVERSE REACTIONS, contact Chartwell RX, LLC. at 1-845-232-1683 or FDA at 1-800-FDA-1088 or [www.fda.gov/medwatch](https://www.fda.gov/safety/medwatch-fda-safety- information-and-adverse-event-reporting-program).

Manufactured for:
Chartwell RX, LLC.

L71137

Rev. 01/2023