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.
NCT01028014 ↗	Medication Effects on Periurethral Sensation,Urethral Sphincter Activity and Pressure Flow Parameters	Completed	Astellas Pharma Inc	N/A	2010-04-01	Lower urinary tract symptoms such as urinary leakage and overactive bladder affect millions of American women. Women may develop these problems because the innervation of the muscles of the bladder and urethra are injured. Most research on treating these problems has focused on the abnormalities of the bladder muscle, but newer studies have shown abnormalities in the innervation and muscle function of the urethra. Women with these symptoms may benefit from treatment with medications to improve their urethral function. However, to truly understand what types of medications will help women with these symptoms, the investigators wish to study how these medications affect innervation and muscle function in healthy women who do not have lower urinary tract symptoms.
NCT01028014 ↗	Medication Effects on Periurethral Sensation,Urethral Sphincter Activity and Pressure Flow Parameters	Completed	University of Alabama at Birmingham	N/A	2010-04-01	Lower urinary tract symptoms such as urinary leakage and overactive bladder affect millions of American women. Women may develop these problems because the innervation of the muscles of the bladder and urethra are injured. Most research on treating these problems has focused on the abnormalities of the bladder muscle, but newer studies have shown abnormalities in the innervation and muscle function of the urethra. Women with these symptoms may benefit from treatment with medications to improve their urethral function. However, to truly understand what types of medications will help women with these symptoms, the investigators wish to study how these medications affect innervation and muscle function in healthy women who do not have lower urinary tract symptoms.

Clinical Trial Conditions for Flexeril

Condition Name

Condition Name for Flexeril
Intervention	Trials
Pain	2
Spasm	1
Urethral Sphincter Activity	1
Cervical Strain	1

Condition MeSH

Condition MeSH for Flexeril
Intervention	Trials
Pain, Postoperative	2
Disease	1
Sleep Initiation and Maintenance Disorders	1
Muscle Cramp	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
Terminated	1
Withdrawn	1

Clinical Trial Sponsors for Flexeril

Sponsor Name

Sponsor Name for Flexeril
Sponsor	Trials
NorthShore University HealthSystem Research Institute	1
Damon Runyon Cancer Research Foundation	1
Lynn Henry	1

Sponsor Type

Sponsor Type for Flexeril
Sponsor	Trials
Other	8
Industry	6

FLEXERIL (cyclobenzaprine) Clinical Trials Update, Market Analysis, and 2026–2036 Forecast

Last updated: May 12, 2026

What is Flexeril’s clinical trial status and what do the latest results show?

Answer: Flexeril (cyclobenzaprine) is an established, off-patent small-molecule muscle relaxant with a clinical record dominated by older randomized trials for acute musculoskeletal pain and post-injury muscle spasm. There are no ongoing late-stage pivotal development programs publicly tied to a new Flexeril active ingredient or a new branded formulation that would materially change its label in the 2024–2026 window.

Which clinical trial endpoints have historically defined Flexeril’s efficacy?

Published Flexeril trials have largely centered on:

• Symptom reduction in acute skeletal muscle spasm (pain and tenderness).
• Global assessment by investigators and patients.
• Short-term duration of effect measured over days rather than weeks.

What is the most current evidence base used for clinical practice?

The evidence base is primarily consolidated into:

• FDA-approved labeling for cyclobenzaprine in acute musculoskeletal conditions.
• Guideline integration for short-course use.
• Safety risk management around sedation, anticholinergic effects, and contraindications (notably in arrhythmia risk contexts).

Are there new studies changing dosing or safety guidance?

No new, label-altering late-stage dataset is identifiable as a current development driver. Recent clinical activity for cyclobenzaprine in general has largely been re-evaluation work (real-world use patterns, safety monitoring, and comparative effectiveness in combination settings), not new registration-grade efficacy endpoints.

How large is the Flexeril market and what drives demand for cyclobenzaprine?

Answer: Cyclobenzaprine’s market is a mature, generic-heavy category tied to acute musculoskeletal episode incidence, prescribing behavior in primary care and urgent care, and formulary access. Branded Flexeril pricing power is limited by widespread generic substitution.

Demand drivers

• High volume of outpatient acute back pain and musculoskeletal injury visits.
• Use patterns for short-duration therapy (days).
• Competitive substitution within oral muscle relaxants.

Key supply-side features

• Generic cyclobenzaprine tablets are widely available.
• Brand economics depend on payer contracting and adherence to short-course prescriber habits.

Who competes with Flexeril and how does cyclobenzaprine compare vs alternatives?

Answer: Flexeril competes with other oral skeletal muscle relaxants and analgesic strategies, including:

• Other muscle relaxant classes (e.g., agents with different CNS targets).
• Non-pharmacologic management and NSAID or acetaminophen pathways.
• In some indications, off-label use patterns can shift between agents depending on sedation risk and patient profile.

Competitive differentiation in practice

Cyclobenzaprine’s practical competitive positioning is shaped by:

• Sedation and anticholinergic tolerability tradeoffs.
• Patient selection (age, comorbidities, concomitant QT-prolongation risk).
• Short course prescribing habits and switching behavior when adverse effects occur.

What does the regulatory landscape look like for Flexeril (Orange Book and FDA status)?

Answer: Cyclobenzaprine is FDA-approved and has a mature regulatory footprint with broad generic availability. The branded Flexeril product’s exclusivity is not expected to materially constrain generic market share.

What is the Orange Book dynamic for cyclobenzaprine?

• The Orange Book typically reflects multiple generic approvals for cyclobenzaprine dosage forms.
• The category exhibits low barriers to entry compared with newer NMEs because the active ingredient is well established.

What FDA changes matter for Flexeril?

Market impact tends to come from:

• Labeling updates related to safety warnings.
• Changes in utilization management (prior authorization, step therapy) at payers.
• Updates in muscle relaxant prescribing recommendations.

When does Flexeril lose exclusivity and what are the generic entry risks?

Answer: Flexeril’s branded exclusivity constraints are effectively obsolete given the long market history and extensive generic penetration. Generic entry risk is therefore not a “future” issue; the risk is ongoing competitive price pressure.

What generic scenarios are realistic?

• Continued substitution in oral tablet formats.
• Ongoing erosion of branded share if payer contracts tighten against legacy brands.
• Competition remains primarily pricing and formulary access, not legal entry timing.

What patent estate protects Flexeril today and how strong is it?

Answer: Flexeril’s active ingredient is old. Any remaining enforceable value typically comes from late-expiring patents on specific formulations, processes, or device-like delivery (if any), not the base molecule. For cyclobenzaprine, the commercially meaningful protections are generally limited in scope and duration compared with newer brand drugs.

How does this affect market structure?

• Brand value is capped by generic substitution.
• Investment and litigation attention typically centers on product-specific improvements (if any exist) rather than broad molecule monopoly.

What litigation has affected Flexeril or cyclobenzaprine generics (Paragraph IV and settlements)?

Answer: No current, high-impact Flexeril-specific Paragraph IV litigation is identifiable as driving an ongoing market exclusivity dispute in the 2024–2026 period. Historically, the active ingredient’s age implies that any branded exclusivity-related litigation is already resolved.

What has mattered historically

• Standard generic entry pathways and routine settlement structures have had limited bearing on aggregate cyclobenzaprine demand because generics are already widely entrenched.
• Where disputes occurred, they were typically between brand holders and generic applicants for specific dosage/formulation patents with finite remaining term.

What is the current clinical use pattern and how does safety shape prescribing?

Answer: Cyclobenzaprine is used short-term for acute musculoskeletal conditions. Safety constraints govern adoption and switching, especially in older adults and patients with risk factors for CNS depression or anticholinergic burden.

Primary safety factors affecting utilization

• Sedation and impairment risk.
• Anticholinergic effects.
• Cardiac risk considerations (including arrhythmia/QT-related warnings per label).
• Drug-drug interactions.

How safety affects market projections

Safety-related discontinuations and dose adjustments can cap the number of patients who sustain therapy, supporting limited incremental growth even if incidence of acute back pain remains stable.

Clinical trials update: Is there any new evidence of comparative effectiveness or combination therapy that matters commercially?

Answer: Evidence growth for cyclobenzaprine in recent years is more likely to be:

• Comparative effectiveness research in real-world practice.
• Studies of combination regimens (with NSAIDs or acetaminophen) and patient selection. These do not typically reset brand economics through label expansion.

Market projection: What will the Flexeril category and branded Flexeril likely do from 2026 to 2036?

Answer: The underlying cyclobenzaprine category should track baseline growth from patient incidence and population aging, but branded Flexeril should face persistent share and price pressure. Net outcomes depend on payer contracting and the speed of further generic price compression rather than on brand-specific clinical development.

Base-case projection logic (category vs brand)

• Category volume: modest growth driven by higher care utilization and aging demographics.
• Category value: limited by generic price competition.
• Branded Flexeril: declines in share unless it holds a defensible payer position; revenue is more likely to be flat-to-down than to re-accelerate.

Scenario framework for forecasting

Base case (most likely):

• Continued generic dominance.
• Branded Flexeril revenue declines at a low-to-moderate single-digit annual rate due to pricing and contracting.

Downside:

• Faster payer tightening and additional competitive price pressure.
• Greater channel shift away from brand toward lowest-cost generics.

Upside:

• Payer or PBM formulary positioning that retains branded share in specific networks.
• Minor rebound in utilization from guideline alignment or formulary preference.

What outcomes matter most for investors and BD

• Branded revenue trajectory is likely driven by contracting, not clinical pipeline events.
• Clinical evidence is unlikely to create a step-change in utilization without label expansion or a new delivery platform.

Where are the commercial pockets for cyclobenzaprine (geography and channel)?

Answer: Demand is strongest where prescribing for acute musculoskeletal pain is high and where oral generics are broadly available through large PBMs. Market behavior differs by:

• PBM formularies and tier placement.
• Wholesale price compression and pharmacy contracting.
• State-level Medicaid reimbursement patterns.

Channel considerations

• Retail pharmacy drives most volume.
• Mail order can influence share if PBMs adopt standardized lowest-cost lists.

Key takeaways

• Flexeril is clinically mature with no identifiable late-stage, label-changing development program driving a new approval cycle in the 2024–2026 period.
• Cyclobenzaprine demand is sustained by acute musculoskeletal incidence, but branded economics are capped by generic substitution.
• Market growth is more likely to be value-constrained and share-fragmented than to show meaningful branded reacceleration.
• From 2026–2036, the most probable outcome is stable-to-slow category volume growth with continued branded revenue pressure driven by pricing and formulary access rather than clinical breakthroughs.

FAQs

1. Is Flexeril still prescribed for acute back pain and muscle spasm in 2026?
2. Do generics of cyclobenzaprine have interchangeable effectiveness to Flexeril per real-world studies?
3. What patient populations are most likely to discontinue cyclobenzaprine due to sedation or anticholinergic effects?
4. How do payer formulary tiers typically affect branded Flexeril versus generic cyclobenzaprine?
5. What safety warnings on cyclobenzaprine most influence prescribing restrictions in primary care?

References

1. FDA. Drug Label: FLEXERIL (cyclobenzaprine HCl). U.S. Food and Drug Administration.
2. U.S. FDA. Drugs@FDA: FLEXERIL (cyclobenzaprine HCl).
3. U.S. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations for cyclobenzaprine.