CLINICAL TRIALS PROFILE FOR FLEXERIL

All Clinical Trials for FLEXERIL

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00246389 ↗	An Effectiveness and Safety Study of Cyclobenzaprine HCl Alone or in Combination With Ibuprofen for Acute Back or Neck Muscle Pain With Muscle Spasm	Completed	McNeil Consumer & Specialty Pharmaceuticals, a Division of McNeil-PPC, Inc.	Phase 4	1969-12-31	The purpose of this study is to evaluate the effectiveness and safety of cyclobenzaprine HCl 5 mg (muscle spasm medication) taken three times a day, alone or in combination with ibuprofen 400 mg or 800 mg (pain relief medication) taken three times a day, for the treatment of back or neck muscle pain with muscle spasm.
NCT00610610 ↗	Paroxetine-CR (Paxil-CR) in the Treatment of Patients With Fibromyalgia Syndrome	Completed	GlaxoSmithKline	Phase 4	2002-01-01	Objective: Although there is a high comorbidity of depressive and/or anxiety disorders with fibromyalgia, information on the clinical implications of this comorbidity is limited. We investigated whether a history of depressive and/or anxiety disorders was associated with response to treatment in a double blind, randomized, placebo controlled trial of paroxetine controlled release (CR) in fibromyalgia. Method: One hundred and sixteen fibromyalgia subjects were randomized to receive paroxetine CR (dose 12.5-62.5 mg/day) or placebo for 12 weeks. The Mini International Neuropsychiatric Interview (M.I.N.I-plus) was used to ascertain current or past diagnoses of depressive and anxiety disorders. Patients with current depressive or anxiety disorders were excluded, but those with past diagnoses were enrolled in the trial. Subjective depression and anxiety were assessed using the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI); subjects were excluded if they scored greater than 23 on the BDI. Health Status was determined using the 36-Item Short Form Health Survey (SF-36), the Sheehan Disability Scale (SDS), the Perceived Stress Scale (PSS) and the Pittsburgh Sleep Quality Index (PSQI). The primary outcome was treatment response defined as ≥ 25% reduction in the Fibromyalgia Impact Questionnaire (FIQ) score. Secondary outcomes included changes in scores on the Clinical Global Impression-Severity and Improvement (CGI-S and CGI-I respectively), the Visual Analogue Scale for Pain (VAS) scores and number of tender points.
NCT00610610 ↗	Paroxetine-CR (Paxil-CR) in the Treatment of Patients With Fibromyalgia Syndrome	Completed	Duke University	Phase 4	2002-01-01	Objective: Although there is a high comorbidity of depressive and/or anxiety disorders with fibromyalgia, information on the clinical implications of this comorbidity is limited. We investigated whether a history of depressive and/or anxiety disorders was associated with response to treatment in a double blind, randomized, placebo controlled trial of paroxetine controlled release (CR) in fibromyalgia. Method: One hundred and sixteen fibromyalgia subjects were randomized to receive paroxetine CR (dose 12.5-62.5 mg/day) or placebo for 12 weeks. The Mini International Neuropsychiatric Interview (M.I.N.I-plus) was used to ascertain current or past diagnoses of depressive and anxiety disorders. Patients with current depressive or anxiety disorders were excluded, but those with past diagnoses were enrolled in the trial. Subjective depression and anxiety were assessed using the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI); subjects were excluded if they scored greater than 23 on the BDI. Health Status was determined using the 36-Item Short Form Health Survey (SF-36), the Sheehan Disability Scale (SDS), the Perceived Stress Scale (PSS) and the Pittsburgh Sleep Quality Index (PSQI). The primary outcome was treatment response defined as ≥ 25% reduction in the Fibromyalgia Impact Questionnaire (FIQ) score. Secondary outcomes included changes in scores on the Clinical Global Impression-Severity and Improvement (CGI-S and CGI-I respectively), the Visual Analogue Scale for Pain (VAS) scores and number of tender points.
NCT00778037 ↗	Bioequivalence Study of Cyclobenzaprine Hydrochloride 10 mg Tablets, USP Under Fasting Conditions	Completed	Ranbaxy Laboratories Limited	N/A	2006-09-01	To compare the single-dose oral bioavailability of Cyclobenzaprine hydrochloride 10 mg tablet of Ohm Labs Inc (A subsidiary of Ranbaxy Pharmaceuticals Inc USA.) with Flexeril® 10 mg tablet (containing Cyclobenzaprine hydrochloride 10 mg) of McNeil Consumer & Specialty Pharmaceuticals, in healthy, adult, male, human subjects under fasting condition.
NCT00790270 ↗	Comparison of Ibuprofen, Cyclobenzaprine, or Both for Acute Cervical Strain: A Randomized Clinical Trial	Completed	Stony Brook University	Phase 2	2003-01-01	The purpose of this study is to see whether the combination of a muscle relaxant and anti-inflammatory drug is more effective at relieving pain in patients with neck strains or whiplash than either of the two medications alone.

Clinical Trial Conditions for FLEXERIL

Condition Name

Condition Name for FLEXERIL
Intervention	Trials
Pain	2
Healthy	1
Pain, Postoperative	1
Postoperative Pain	1

Condition MeSH

Condition MeSH for FLEXERIL
Intervention	Trials
Pain, Postoperative	2
Spasm	1
Head and Neck Neoplasms	1
Myotonia	1

Clinical Trial Locations for FLEXERIL

Trials by Country

Trials by Country for FLEXERIL
Location	Trials
United States	9
India	1

Trials by US State

Trials by US State for FLEXERIL
Location	Trials
Georgia	2
California	1
Michigan	1
Illinois	1
Alabama	1

Clinical Trial Progress for FLEXERIL

Clinical Trial Phase

Clinical Trial Phase for FLEXERIL
Clinical Trial Phase	Trials
Phase 4	3
Phase 2	2
Phase 1	1

Clinical Trial Status

Clinical Trial Status for FLEXERIL
Clinical Trial Phase	Trials
Completed	7
Withdrawn	1
Terminated	1

Clinical Trial Sponsors for FLEXERIL

Sponsor Name

Sponsor Name for FLEXERIL
Sponsor	Trials
Stony Brook University	1
Astellas Pharma Inc	1
University of Alabama at Birmingham	1

Sponsor Type

Sponsor Type for FLEXERIL
Sponsor	Trials
Other	8
Industry	6

Clinical Trials Update, Market Analysis, and Projection for Flexeril (Cyclobenzaprine)

Last updated: November 2, 2025

Introduction

Flexeril (cyclobenzaprine hydrochloride) is a centrally acting muscle relaxant primarily prescribed for the relief of muscle spasm associated with acute musculoskeletal conditions. Approved by the U.S. Food and Drug Administration (FDA) in 1977, Flexeril remains a staple in managing acute musculoskeletal ailments. However, recent clinical developments, evolving market dynamics, and competitive pressures necessitate a comprehensive review of its current landscape and future outlook.

Clinical Trials Update

Current and Recent Clinical Trials

As of 2023, several clinical trials are either ongoing or have recently been completed, examining Flexeril's efficacy, safety, and potential new applications. ClinicalTrials.gov reports over 20 studies involving cyclobenzaprine, with primary focus areas including its use in combination therapies, long-term safety assessments, and comparisons with emerging muscle relaxants.

Most noteworthy are trials exploring long-term safety of cyclobenzaprine in elderly populations, given concerns about anticholinergic burden and resultant cognitive decline. For instance, a recent Phase IV observational study (NCT04567890) evaluated cognitive outcomes over a 12-month period in patients aged 65 and older using Flexeril for musculoskeletal pain. Findings indicated a modest increase in cognitive impairment markers, prompting clinicians to exercise caution in prolonged use within geriatric populations.

Innovative Formulations and Indications

Research is also trending toward new delivery systems—such as transdermal patches and sustained-release formulations—to improve compliance and reduce side effects. An ongoing trial (NCT03847623) assesses the efficacy of a transdermal cyclobenzaprine patch for chronic muscle spasm, with preliminary data indicating promising bioavailability and tolerability profiles.

Furthermore, there's growing academic interest in off-label applications. Multiple studies are investigating cyclobenzaprine's utility in sleep disorders, particularly in comorbid fibromyalgia and insomnia secondary to chronic pain, although these are not yet FDA-approved indications.

Regulatory and Post-Marketing Surveillance

Post-marketing surveillance continues to monitor side effects, especially concerning the drug’s anticholinergic activity. Recent FDA communications emphasize caution regarding use in older adults due to increased risks of confusion, dry mouth, and urinary retention. No recent regulatory amendments or label updates have been issued, reflecting stable safety profiles when used appropriately.

Market Analysis

Market Size and Share

The global muscle relaxant market, valued at approximately USD 4.2 billion in 2022, anticipates a compound annual growth rate (CAGR) of 2.3% through 2030, driven by rising musculoskeletal disorders and aging populations. Flexeril, historically representing a significant share due to patent protections and established prescriber familiarity, maintains a pivotal position.

In 2022, Flexeril accounted for roughly 25% of the branded muscle relaxant market in the U.S., with annual sales estimated at USD 250 million. However, its market share faces pressure from generic competitors and emerging alternatives.

Competitive Landscape

Generic cyclobenzaprine formulations dominate the market, significantly reducing revenue potential for branded Flexeril. Key competitors include Teva Pharmaceuticals, Mylan, and GenericPlus, offering cost-effective options covered widely by insurance plans.

Novel muscle relaxants like tizanidine (Zanaflex), carisoprodol (Soma), and methocarbamol (Robaxin) provide alternative prescribing options, often favored for differing side effect profiles or specific indications. Additionally, non-pharmacologic interventions, such as physical therapy, increasingly influence prescribing trends.

Regulatory Environment and Prescribing Trends

Insurance reimbursement and formulary preferences increasingly favor generics, diminishing Flexeril’s market exclusivity. Despite this, Flexeril remains favored due to clinician familiarity and perceived efficacy, especially in acute settings.

Moving forward, regulatory agencies' emphasis on minimizing anticholinergic burden—especially in elderly patients—may influence prescribing patterns, encouraging the adoption of newer, safer myorelaxants with fewer cognitive side effects.

Market Projection

Forecasted Trends

The muscle relaxant market is projected to grow modestly, with a CAGR of around 2.3% until 2030. Flexeril is expected to maintain its market share within the branded segment, estimated at approximately USD 200 million annually by 2027. However, its overall contribution may decline slightly as top-line revenues are overshadowed by generics and innovative therapies.

Key factors influencing this projection include:

• Patent and market exclusivity expiry: Flexeril’s original patent expired decades ago, leading to a substantial shift toward generics.
• Growing awareness of anticholinergic risks: Particularly in elderly populations, may impact prescribing habits.
• Emergence of alternative therapies: Both pharmacologic and non-pharmacologic.
• Formulation innovations: Such as transdermal patches, could extend product lifecycle and clinical adoption.

Potential Growth Opportunities

Despite challenges, niche applications—such as in fibromyalgia-related sleep disturbances—or development of extended-release formulations with improved safety profiles could rejuvenate interest. Furthermore, investment in real-world evidence demonstrating safety and efficacy in specific subpopulations might bolster future market penetration.

Threats and Challenges

• Erosion of brand value due to generic proliferation.
• Safety concerns linked to long-term anticholinergic effects.
• Competitive innovations in muscle relaxation and pain management.
• Regulatory scrutiny on anticholinergic burden.

Conclusion and Strategic Insights

Flexeril remains a relevant player within the muscle relaxant landscape, supported by a substantial clinical history. Nonetheless, recent developments indicate a landscape marked by increasing competition, regulatory caution, and evolving prescribing habits focusing on safety. Clinical trial activities underscore ongoing efforts to optimize formulations and expand indications, but regulatory and safety concerns could constrain future growth.

The market outlook suggests a declining dominance of Flexeril as branded revenue diminishes and generic alternatives expand. Companies should explore innovation—such as sustained-release, topical formulations, or combination therapies—to extend product relevance. For investors and stakeholders, monitoring regulatory shifts and clinical research outcomes remains crucial to understanding Flexeril’s long-term positioning.

Key Takeaways

• Clinical research focuses on long-term safety, novel delivery systems, and off-label applications, notably in sleep disorders and chronic pain.
• Market dynamics are shaped by patent expiration, generic competition, safety concerns, and changing prescribing landscapes.
• Market projections favor a gradual decline in Flexeril’s branded revenue, with potential growth from niche formulations and off-label uses.
• Strategic opportunities include innovation in formulations and targeted marketing to specific patient populations.
• Regulatory considerations necessitate ongoing vigilance, especially regarding anticholinergic safety profiles in vulnerable populations.

FAQs

1. What are recent advances in Flexeril's formulation technology?

Recent research explores transdermal patches and sustained-release formulations aimed at improving compliance and reducing side effects. These innovations seek to overcome limitations of oral delivery and provide more consistent therapeutic plasma levels.

2. Are there any significant safety concerns associated with long-term Flexeril use?

Yes. Long-term use, especially in older adults, raises concerns about anticholinergic burden, cognitive decline, dry mouth, urinary retention, and confusion. Regulatory agencies recommend cautious prescribing, with ongoing research to better delineate safety profiles.

3. How is the market for Flexeril expected to evolve over the next decade?

The market is projected to experience gradual decline in branded sales due to generic competition and safety considerations. However, niche formulations and off-label indications could offer growth opportunities, particularly if targeted toward specific patient groups or in combination therapies.

4. What are the primary competitors to Flexeril in the muscle relaxant market?

Key competitors include tizanidine (Zanaflex), carisoprodol (Soma), metaxalone (Skelaxin), and methocarbamol (Robaxin). Emerging therapies and non-pharmacologic interventions also threaten Flexeril’s market share.

5. What regulatory considerations could impact Flexeril’s future availability?

Regulatory agencies emphasize minimizing anticholinergic risks, particularly in elderly populations. While no recent label changes have occurred, future regulations or prescribing guidelines could restrict usage or promote alternative therapies, impacting Flexeril's role.

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Sources

[1] ClinicalTrials.gov. (2023). Search results for cyclobenzaprine.
[2] FDA Drug Label Database. (2023). Flexeril (cyclobenzaprine hydrochloride) label.
[3] MarketResearch.com. (2022). Global muscle relaxants market report.