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Chlorzoxazone (Chlorzoxazone) - Summary



Chlorzoxazone USP is a centrally acting skeletal muscle relaxant.

Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.
See all Chlorzoxazone indications & dosage >>


Media Articles Related to Chlorzoxazone

Muscle Spasms
Source: MedicineNet Claudication Specialty [2014.07.14]
Title: Muscle Spasms
Category: Diseases and Conditions
Created: 6/16/2009 12:00:00 AM
Last Editorial Review: 7/14/2014 12:00:00 AM

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Published Studies Related to Chlorzoxazone

Effect of high-dose aspirin on CYP2E1 activity in healthy subjects measured using chlorzoxazone as a probe. [2006.01]
The authors evaluated the effect of high-dose aspirin at a therapeutic dose, using chlorzoxazone as a probe for CYP2E1 enzyme activity. In a randomized, open-label, 2-way crossover study, 10 healthy men were treated 3 times daily for 6 days with 1 g aspirin or placebo...

An interaction between the cytochrome P450 probe substrates chlorzoxazone (CYP2E1) and midazolam (CYP3A). [2001.11]
AIMS: The use of multiple probe substrates to evaluate the activity of drug metabolizing enzymes requires that there are no inter-substrate interactions. As part of a series of studies to develop a clinically useful collection of probe substrates that could be given alone or in any combination, we observed an interaction between midazolam (MDZ) and another component of the six-drug cocktail. Published data indicated that the interacting component was likely to be chlorzoxazone. This was investigated as part of a second study. The data relating to the interaction from both studies are reported here... CONCLUSIONS: Chlorzoxazone appears to significantly influence the pharmacokinetics of oral MDZ, probably through inhibition of first pass metabolism by CYP3A in the GI tract. Data from these studies and literature evidence showing a further interaction between chlorzoxazone and CYP1A2 substrates and questions concerning the specificity of chlorzoxazone as a probe substrate for CYP2E1, indicate that the use of chlorzoxazone in multisubstrate probe cocktails should be avoided.

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Clinical Trials Related to Chlorzoxazone

Placebo-Controlled Cross Over Trial of Chlorzoxazone Intake [Recruiting]
The overall goals of this study are to (1) expand knowledge about interactions of chlorzoxazone with alcohol by assessing the effects of chlorzoxazone compared to placebo in moderate and heavy social alcohol users and (2) to compare the effects of chlorzoxazone on visual cue induced alcohol craving to placebo in moderate to heavy social alcohol users.

Effect of Ethanol and Genetic Polymorphisms on Bupropion Metabolism [Completed]
The two purposes of this study are

1. to determine what effect the chronic and moderate/heavy drinking of alcoholic beverages has

1. on the blood level of bupropion and chlorzoxazone and their major breakdown products in the blood and

2. on the stimulant effect of bupropion and

2. to determine what effect a normal and common (25% frequency) genetic variation of a specific liver enzyme (that breaks down bupropion) has

1. on the blood levels of bupropion and its major breakdown products in the blood and

2. on the stimulant effect of bupropion.

Two groups of volunteers will be recruited for this study:

1. volunteers who drink moderate to heavy amounts of alcohol frequently and

2. volunteers who usually do not drink alcohol.

Volunteers will NOT be asked to change their drinking (or nondrinking) habits during the study.

Pharmacokinetic Study to Investigate Low-dose Combinations of a Cocktail of Seven Drugs for Simultaneous Phenotyping of Cytochromes [Recruiting]
The purpose of this study is to assess whether a cocktail of seven approved drugs (so-called "Basel cocktail") can be used for simultaneous phenotyping of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4.

Cytochrome P450 2E1 and Iron Overload [Completed]
The aim of the study is to determine, in patients presenting with insulin resistance and hepatic iron overload, the effects of venesection therapy on cytochrome P450 2E1 activity by comparing the rates of metabolization of chlorzoxazone before and after venesection.

Effect of Genetic Differences on Levels of Water Disinfection Byproducts in Blood After Showering [Active, not recruiting]
This study will examine whether genetic differences among individuals affect blood levels of certain chemicals called DBPs after showering. Chemicals such as chlorine and ozone are used to kill germs in water. These chemicals may react with organic matter in the water and form other chemicals called disinfection byproducts, or DBPs. Although people are usually exposed to DBPs by drinking tap water, these chemicals may also penetrate the body during showering. This study will see whether the levels of DBPs after showering vary among individuals depending on differences in genes that code for enzymes called GSTT1, CYP2D6, and CYP2E1, which break down DBPs. This study, sponsored by the Centers for Disease Control and Prevention and the National Institutes of Health, is conducted at the University of Pittsburgh's Center for Clinical Pharmacology.

Healthy adults between 18 and 45 years of age who do not smoke cigarettes and are not taking any medicines may be eligible for this study. Candidates are screened with a medical history and blood and urine tests. Participants are given a diary to record the foods they eat and how much water they drink during the 2 days before their study appointment. The following activities are scheduled on the appointment day:

- Measurements of blood pressure, height, and weight, and pregnancy test for women

- Questions about alcohol consumed and medications taken in the last 48 hours

- Review of food and water diary

- Interview for demographic information (name, address, date of birth, etc.) and other information, such as sex, height, weight. Subjects are also asked about anything, such as exercise, that might affect their breathing, since breathing problems are a rare side effect of chlorzoxazone, a drug used in this study.

- Urine sample collection

- Blood draw and insertion of a small catheter (plastic tube) to allow for additional blood draws during the test procedure without having repeated needle sticks

- 10-minute shower in a private bathroom

- Blood sample collection 10 minutes after the shower and again at 30 minutes after the shower

- Dose of chlorzoxazone (a drug used to treat muscle pain)

- Interview about subject's exposure to water

- Light breakfast

- Blood and urine collections 2 hours after the chlorzoxazone dose

- Lunch

- Observation for drug side effects for 2 hours, or longer if needed

Seven blood samples totaling 75 milliliters (about 5 tablespoonfuls) of blood are collected during this study. The blood is tested for chemicals called trihalomethanes to see how they are broken down. The urine samples are tested for chemicals called haloacetic acids, which are found in tap water after it has been treated with chlorine.

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Reports of Suspected Chlorzoxazone Side Effects

Completed Suicide (12)Poisoning (2)Toxicity TO Various Agents (2)Hepatic Enzyme Increased (2)Feeling Abnormal (2)Confusional State (1)Drug Ineffective (1)Pain (1)Somnolence (1)Abdominal Pain Upper (1)more >>

Page last updated: 2014-07-14

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