CLINICAL TRIALS PROFILE FOR CHLORZOXAZONE

All Clinical Trials for chlorzoxazone

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00330434 ↗	Effect of Ethanol and Genetic Polymorphisms on Bupropion Metabolism	Completed	National Institute on Alcohol Abuse and Alcoholism (NIAAA)	N/A	2005-12-01	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.
NCT01187862 ↗	Pharmacokinetic Study to Investigate Low-dose Combinations of a Cocktail of Seven Drugs for Simultaneous Phenotyping of Cytochromes	Completed	University Hospital, Basel, Switzerland	Phase 1	2010-07-01	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.
NCT01342341 ↗	Placebo-Controlled Cross Over Trial of Chlorzoxazone Intake	Completed	University of California, San Francisco	Phase 4	2011-04-01	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.
NCT01933542 ↗	The Effect of Chlorzoxazone on Moderate to Severe Postoperative Pain After Spine Surgery	Completed	Glostrup University Hospital, Copenhagen	Phase 4	2013-08-01	Chlorzoxazone is a centrally acting muscle relaxant used to treat muscle spasm and the resulting pain or discomfort. It acts on the spinal cord by depressing reflexes. Our purpose is to investigate the effect of chlorzoxazone on moderate to severe postoperative pain after spine surgery. Our hypothesis is that chlorzoxazone can reduce postoperative pain and reduce opioidconsumption and side effects compared to placebo.
NCT01933542 ↗	The Effect of Chlorzoxazone on Moderate to Severe Postoperative Pain After Spine Surgery	Completed	Rigshospitalet, Denmark	Phase 4	2013-08-01	Chlorzoxazone is a centrally acting muscle relaxant used to treat muscle spasm and the resulting pain or discomfort. It acts on the spinal cord by depressing reflexes. Our purpose is to investigate the effect of chlorzoxazone on moderate to severe postoperative pain after spine surgery. Our hypothesis is that chlorzoxazone can reduce postoperative pain and reduce opioidconsumption and side effects compared to placebo.
NCT02291666 ↗	Evaluation of CYP450 Activities in Diabetic Patients vs. Non-diabetic Subjects	Completed	Canadian Institutes of Health Research (CIHR)	Phase 4	2015-04-01	Type 2 diabetes (T2D) could modulate CYP450 activities involved in drug-metabolism and cardiovascular homeostasis. We propose to carry out, for the first time, a comprehensive characterization of the effects of T2D on the expression and activity of major CYP450s. In our studies, patients with T2D will be studied since hyperglycaemia and/or hyperinsulinemia are believed to modulate CYP450s. This vicious cycle puts patients at risk of micro- and macro-vascular complications and inadequately controlled T2D due to high intersubject variability in drug disposition and action. Characterization of the effects of T2D on drug metabolism capacity will be performed using a cocktail of CYP450 probe drugs. CYP450 phenotype will be determined in 3 groups of patients (n=126 patients): 1) 42 T2D patients with good glycemic control; 2) 42 T2D patients with poor glycemic control; and 3) 42 non-T2D healthy subjects following a single oral administration of a cocktail of CYP450 probe drugs. Subjects will receive the CRCHUM-MT cocktail consisting of caffeine (CYP1A2), bupropion (CYP2B6), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A4/5) and chlorxozaxone (which will be administered separately) (CYP2E1). Serial blood samples will be drawn and urine collected. Metabolic ratios will be calculated and compared between three groups of subjects. Other co-variables to be studied include T2D biomarkers at baseline (glucose, insulin, HbA1c), medications, genetic polymorphisms and inflammatory markers. Our cocktail probe drug approach should allow us to demonstrate the effects of T2D on the activity of major CYP450s. Moreover, this project will indicate to us whether glycemic control should be considered as a covariate of intersubject variability in drug metabolism capacity.
NCT02291666 ↗	Evaluation of CYP450 Activities in Diabetic Patients vs. Non-diabetic Subjects	Completed	Centre hospitalier de l'Université de Montréal (CHUM)	Phase 4	2015-04-01	Type 2 diabetes (T2D) could modulate CYP450 activities involved in drug-metabolism and cardiovascular homeostasis. We propose to carry out, for the first time, a comprehensive characterization of the effects of T2D on the expression and activity of major CYP450s. In our studies, patients with T2D will be studied since hyperglycaemia and/or hyperinsulinemia are believed to modulate CYP450s. This vicious cycle puts patients at risk of micro- and macro-vascular complications and inadequately controlled T2D due to high intersubject variability in drug disposition and action. Characterization of the effects of T2D on drug metabolism capacity will be performed using a cocktail of CYP450 probe drugs. CYP450 phenotype will be determined in 3 groups of patients (n=126 patients): 1) 42 T2D patients with good glycemic control; 2) 42 T2D patients with poor glycemic control; and 3) 42 non-T2D healthy subjects following a single oral administration of a cocktail of CYP450 probe drugs. Subjects will receive the CRCHUM-MT cocktail consisting of caffeine (CYP1A2), bupropion (CYP2B6), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A4/5) and chlorxozaxone (which will be administered separately) (CYP2E1). Serial blood samples will be drawn and urine collected. Metabolic ratios will be calculated and compared between three groups of subjects. Other co-variables to be studied include T2D biomarkers at baseline (glucose, insulin, HbA1c), medications, genetic polymorphisms and inflammatory markers. Our cocktail probe drug approach should allow us to demonstrate the effects of T2D on the activity of major CYP450s. Moreover, this project will indicate to us whether glycemic control should be considered as a covariate of intersubject variability in drug metabolism capacity.

Clinical Trial Conditions for chlorzoxazone

Condition Name

Condition Name for chlorzoxazone
Intervention	Trials
Pharmacokinetics	2
Alcohol Drinking	1
Orofacial Pain	1
Attention Deficit Disorder	1

Condition MeSH

Condition MeSH for chlorzoxazone
Intervention	Trials
Alcoholism	1
Breast Neoplasms	1
Depression	1
Osteoarthritis, Knee	1

Clinical Trial Locations for chlorzoxazone

Trials by Country

Trials by Country for chlorzoxazone
Location	Trials
United States	3
Denmark	2
Switzerland	1
Germany	1
Iraq	1

Trials by US State

Trials by US State for chlorzoxazone
Location	Trials
Texas	1
California	1
Massachusetts	1

Clinical Trial Progress for chlorzoxazone

Clinical Trial Phase

Clinical Trial Phase for chlorzoxazone
Clinical Trial Phase	Trials
PHASE4	1
Phase 4	4
Phase 2	1

Clinical Trial Status

Clinical Trial Status for chlorzoxazone
Clinical Trial Phase	Trials
Completed	8
Recruiting	2
Not yet recruiting	1

Clinical Trial Sponsors for chlorzoxazone

Sponsor Name

Sponsor Name for chlorzoxazone
Sponsor	Trials
Canadian Institutes of Health Research (CIHR)	1
Kuopio University Hospital	1
Centre hospitalier de l'Université de Montréal (CHUM)	1

Sponsor Type

Sponsor Type for chlorzoxazone
Sponsor	Trials
Other	18
Industry	2
NIH	1

Chlorzoxazone: Clinical Trials Update, Market Analysis, and Projection

Last updated: April 24, 2026

What is chlorzoxazone’s current clinical development status?

Chlorzoxazone is an established oral muscle relaxant with long market history and does not show an active, late-stage clinical trial pipeline in public registries that would materially change near-term product competition or regulatory status. Public records focus on older studies and supportive or non-core work rather than new Phase 3 readouts that would extend IP or materially shift the commercial curve.

Public clinical trial activity pattern (high level)

• Core therapeutic use: muscle spasm and musculoskeletal pain syndromes (commonly in combination or supportive regimens in older literature).
• Recent focus in public sources: small studies and/or operational research rather than pivotal Phase 3 development.
• Investment implication: near-term demand is primarily driven by generic market dynamics, reimbursement, and formulary access rather than new clinical evidence likely to expand indications.

Are there any material new clinical trials that could extend exclusivity or expand labeling?

No public evidence indicates new, late-stage trials (commonly Phase 3 with registration intent) for expanded indications or meaningful label extension that would create a clear exclusivity runway.

Interpretation for business planning

• If a company is underwriting growth based on “new data,” the realistic path is incremental (formulation, line extensions, and lifecycle management), not label expansion from new pivotal trials.
• Absent a visible pivotal readout, pricing power is constrained by generic substitution.

What does the market look like today?

Chlorzoxazone is a largely generic-dominated product class, with pricing and volume sensitive to:

• PBM formulary status for muscle relaxants
• Ingredient-level substitution (generic vs brand equivalents)
• Competition from adjacent agents (other skeletal muscle relaxants) and shifting prescribing patterns
• Setting of short-term use (acute musculoskeletal complaints) that limits chronic pull-through

Commercial structure

• Supply: multiple generic manufacturers in common US distribution channels.
• Demand drivers: primary care, urgent care, orthopedics, and pain-focused prescribing for acute muscle spasm.
• Seasonality: typical musculoskeletal complaint seasonality patterns; however, the dominating factor remains plan coverage and copays.

How large is the market and what is the demand basis for projection?

Public sources do not provide a single authoritative, up-to-the-minute revenue estimate by ingredient that is consistent across payers and geographies. The correct projection method in practice is to model units and net price using:

• Generic market price erosion (annual declines driven by competition)
• Utilization (scripts or treated patient counts)
• Mix shift toward higher-quantity packs and/or combination products where present

A practical approach is to anchor projections to:

• historical US prescription demand for skeletal muscle relaxants (ingredient class) and
• expected net price compression consistent with generic penetration patterns.

What is the near-term outlook (2025–2027)?

The near-term commercial expectation is:

• continued net price pressure from generic competition and supply normalization
• stable-to-slightly declining unit growth driven by prescribing variability and therapeutic substitution within the muscle relaxant class
• continued payer preference for low-cost options where clinical equivalence is accepted

Key scenario drivers

1. Formulary dynamics: preferred tier placement can preserve volume; loss of tier can cause quick declines.
2. Acquisition of share by adjacent muscle relaxants: prescribers often switch within the class based on tolerability and formulary preference.
3. Cost pressure: reimbursement trends continue to pressure gross-to-net.

What is the medium-term outlook (2028–2032)?

Without a visible late-stage clinical catalyst, the medium-term baseline is:

• further price compression
• gradual stabilization of volume at a lower net price floor
• potential market share reshuffling versus newer muscle relaxants with better payer positioning

Most likely commercial end state

• a mature, stable generic market with modest volume changes and persistent net price erosion

How should R&D teams and investors frame “growth” for chlorzoxazone?

Growth is more likely to come from lifecycle and access levers rather than clinical expansion:

• product format optimization (dose form, pack engineering, taste masking if relevant, manufacturing cost improvements)
• portfolio positioning in formulary strategies for muscle relaxant categories
• payer contracting to maintain preferred status where feasible

What are the competitive implications across the muscle relaxant category?

Chlorzoxazone competes with a range of skeletal muscle relaxants, and formulary behavior tends to reward:

• lower net cost
• established safety and clinical substitutability
• dosing convenience for prescribers and patients

Practical competitive implications

• chlorzoxazone’s competitiveness hinges on net price and formulary tiering more than differentiation
• substitutes with favorable PBM contracting can displace volume quickly even if clinical outcomes remain comparable

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Market Projection Summary (Scenario Framework)

Base case (most likely)

• Units: flat to low-single-digit annual growth early in the period, then stabilization
• Net price: persistent decline as generic competition remains active
• Revenue: modest decline or near-flat depending on whether volume offsets net price erosion

Downside case

• formulary tier loss and substitution accelerates
• net price declines faster than utilization offsets
• revenue declines in low double digits cumulatively over the period

Upside case

• preferred status maintained or regained
• pack/mix improvements reduce effective net erosion
• volume holds better than expected, limiting revenue decline

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Key Takeaways

• Chlorzoxazone has no visible public pathway of late-stage clinical trial activity that would drive near-term label expansion or exclusivity renewal.
• The market is mature and generic-dominated, with revenue sensitivity dominated by net price compression and formulary access rather than clinical differentiation.
• Projections should be modeled through units plus net price with scenario outcomes driven by PBM tiering and class substitution within skeletal muscle relaxants.
• Near-term (2025–2027) outlook is stable utilization with continued pricing pressure; medium-term (2028–2032) is a low-growth mature end state.

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FAQs

1) Is chlorzoxazone facing any major clinical trial-driven risk of label change in the near term?

No. Public records do not show late-stage registration-intent trials that would likely force label revisions or enable major new indications on a near-term timeline.

2) What is the primary commercial risk for chlorzoxazone?

Net price erosion and formulary substitution within skeletal muscle relaxants.

3) What is the most realistic source of growth for chlorzoxazone products?

Lifecycle and contracting levers such as pack optimization and preferred formulary positioning, not new pivotal clinical outcomes.

4) How should revenue projections be modeled for chlorzoxazone?

Use a scenario model of scripts (units) multiplied by expected net price, accounting for generic competition and gross-to-net trends.

5) Does chlorzoxazone’s clinical evidence history support differentiation versus other muscle relaxants?

Evidence supports established use, but payer behavior and ingredient substitutability limit differentiation-based pricing power.

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References

[1] ClinicalTrials.gov. “Chlorzoxazone” (search results and study listings). U.S. National Library of Medicine. https://clinicaltrials.gov/
[2] DailyMed. “Chlorzoxazone” labeling (current and archived product information). National Library of Medicine. https://dailymed.nlm.nih.gov/
[3] World Health Organization. WHO Model Lists of Essential Medicines (class context for muscle relaxants and analgesics). https://www.who.int/teams/health-product-and-policy-standards/essential-medicines/essential-medicines-selection
[4] FDA. Drug safety and labeling resources relevant to skeletal muscle relaxants (class regulatory context). https://www.fda.gov/drugs/drug-safety-and-availability