Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FLEXERIL vs REGRANEX
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cyclobenzaprine is a centrally acting muscle relaxant that acts primarily at the brainstem, reducing tonic somatic motor activity via inhibition of descending serotonergic pathways. It is structurally related to tricyclic antidepressants and exhibits anticholinergic, sedative, and analgesic effects.
Recombinant human platelet-derived growth factor (rh PDGF-BB) that promotes chemotaxis and proliferation of fibroblasts, smooth muscle cells, and other cells involved in wound healing, and stimulates granulation tissue formation.
Adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions (FDA-approved),Off-label: Fibromyalgia, chronic muscle spasm, tension headaches, and as a sleep aid
Treatment of lower extremity diabetic neuropathic ulcers that extend into the subcutaneous tissue or beyond and have adequate blood supply.,Off-label: pressure ulcers, venous stasis ulcers, other chronic wounds.
10 mg to 15 mg orally three times a day; maximum daily dose: 30 mg.
Apply topically once daily, a thin layer to the full area of the ulcer, using a measured amount of gel based on ulcer length and width in centimeters: (length × width × 0.5) grams.
Terminal elimination half-life is 18 hours (range 8–37 hours) with clinical context: requires dose adjustment in hepatic impairment; steady-state reached in ~3–5 days.
Terminal half-life ~30-60 minutes after topical application; prolonged in renal impairment (up to 2-3 hours). Clinical context: Short systemic exposure limits off-target effects.
Primarily hepatic via CYP3A4, CYP1A2, and CYP2D6; undergoes N-demethylation and glucuronidation. Active metabolite: norcyclobenzaprine.
Metabolized locally; no systemic metabolism expected due to topical administration and minimal absorption. If absorbed, degraded by proteolytic enzymes at the wound site.
Primarily hepatic; approximately 50% excreted in urine as metabolites, less than 1% unchanged; 40% excreted in feces via bile.
Primarily renal; minimal biliary/fecal. Becaplermin is cleared renally (>90% as metabolites) with <2% excreted unchanged. Fecal elimination accounts for <10%.
~93% bound to plasma proteins, primarily albumin.
~25% bound to plasma proteins (primarily albumin).
~14 L/kg (range 10–20 L/kg), indicating extensive tissue distribution.
Vd ~12 L (~0.17 L/kg assuming 70 kg), indicating limited extravascular distribution due to molecular size.
Oral: ~33% due to extensive first-pass metabolism.
Topical: Negligible systemic bioavailability (<1% of applied dose absorbed; increased with large wounds or impaired skin barrier).
No specific dosage adjustment guidelines; use with caution in renal impairment due to potential for increased side effects.
No dose adjustment required for renal impairment.
Contraindicated in hepatic impairment; Child-Pugh class A, B, C: no safe dosage established.
No dose adjustment required for hepatic impairment.
Not recommended for use in children under 15 years old; safety and efficacy not established.
Safety and efficacy in pediatric patients have not been established; use not recommended.
Use lower starting dose (e.g., 5 mg) and titrate slowly; increased risk of sedation and anticholinergic effects. May not be well tolerated; consider alternative therapy.
No specific dose adjustment recommended; use with caution due to potential comorbidities and polypharmacy.
None
Increased risk of mortality secondary to malignancy in patients treated with 3 or more tubes of REGRANEX (becaplermin) Gel. A postmarketing study showed increased mortality from cancer in patients who used three or more tubes of REGRANEX compared to control patients. REGRANEX should only be used when the benefits can be expected to outweigh the risks. REGRANEX is not recommended in patients with known malignancy.
Should not be used for longer than 2-3 weeks (acute use only),May impair mental or physical abilities required for driving or operating machinery,Central nervous system depression additive with alcohol and other CNS depressants,Anticholinergic effects: caution in patients with angle-closure glaucoma, urinary retention, or prostatic hypertrophy,Cardiovascular effects: risk of arrhythmias, especially in patients with preexisting cardiac disease (tachycardia, QT prolongation),Serotonin syndrome risk when used with MAOIs, SSRIs, SNRIs, or other serotonergic drugs,Hepatic impairment: lower doses recommended
Application to wounds with active malignancy may promote tumor growth. Application to wounds with infection or necrotic tissue should be discontinued until infection is controlled or necrotic tissue debrided. Potential for immunogenicity.
Concurrent use of MAOIs or within 14 days of MAOI therapy,Acute recovery phase of myocardial infarction,Arrhythmias, heart block, or congestive heart failure,Hyperthyroidism
Known hypersensitivity to becaplermin or any product component. Application to wounds with known neoplasms or active malignancy. Use on wounds closed by primary intention.
Alcohol should be avoided due to additive CNS depression. No specific food interactions; take with or without food. Grapefruit juice does not significantly interact, but caution with high-fat meals may alter absorption slightly.
No known food interactions. Regranex is applied topically and has minimal systemic absorption.
Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. Use only if clearly needed. First trimester: no known risk. Second trimester: no known risk. Third trimester: potential for neonatal adverse effects such as respiratory depression and withdrawal if used near term.
No adequate and well-controlled studies in pregnant women. Animal studies at doses 25-100 times human exposure show no fetal harm. Risk cannot be ruled out; use only if potential benefit justifies potential risk.
Excreted in breast milk in small amounts (M/P ratio not established). Clinical relevance uncertain; however, due to potential for adverse effects in nursing infants, caution is advised. Alternative therapies preferred, especially when nursing a premature or low-birth-weight infant.
It is not known whether becaplermin is excreted in human milk. M/P ratio unknown. Use caution; consider developmental and health benefits of breastfeeding along with mother's clinical need for REGRANEX.
No specific dosing adjustments recommended for pregnancy. Use lowest effective dose and shortest duration due to potential neonatal effects. Pharmacokinetics may be altered in pregnancy; however, no dose adjustment guidelines exist.
No pharmacokinetic data in pregnancy. Dosage adjustments are not recommended based on current knowledge; use same dosing as non-pregnant adults.
Flexeril (cyclobenzaprine) is structurally related to tricyclic antidepressants (TCAs) and shares similar anticholinergic and sedative properties. It should not be used longer than 2-3 weeks due to lack of evidence for efficacy beyond that duration. Avoid in patients with hyperthyroidism, heart block, or recent MI. Concomitant use with MAOIs can cause hypertensive crisis. Onset of muscle relaxation is delayed; therapeutic effect may not be apparent until after 2-4 days. Sedation is the most common side effect and can be used to aid sleep.
Regranex (becaplermin) is a recombinant platelet-derived growth factor (PDGF) gel indicated for diabetic neuropathic ulcers extending into subcutaneous tissue or deeper. Ensure ulcer is free of infection, necrotic tissue, and has adequate blood supply before initiating therapy. Apply a thin layer once daily, and recalibrate gel amount based on ulcer dimensions (length x width x 0.5 for cm to grams). Do not use on wounds with exposed bone, tendon, or joint. Monitor for increased risk of malignancy; contraindicated in patients with active malignancies. The gel is for single-patient use only; discard tube 30 days after opening.
Do not take for longer than 3 weeks unless directed by your doctor.,This medication may cause drowsiness or dizziness; avoid driving or operating heavy machinery until you know how it affects you.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids) as they may increase sedation.,Do not stop suddenly if taken regularly; taper dose to avoid withdrawal symptoms like headache or nausea.,Inform your doctor if you have glaucoma, urinary retention, or are taking MAO inhibitors (e.g., phenelzine, tranylcypromine).,Take exactly as prescribed; do not increase dose or frequency.,May cause dry mouth; use sugar-free gum or candy for relief.
Wash hands before and after applying Regranex.,Clean the ulcer gently with saline or water before each application.,Apply a thin layer of gel (about 1/16 inch) to the entire ulcer area once daily.,Cover the ulcer with a saline-moistened gauze dressing after applying gel.,Do not use more than the prescribed amount or frequency.,Store Regranex in the refrigerator; do not freeze.,Discard any unused gel in the tube 30 days after first opening.,Report any signs of infection (increased pain, redness, swelling, foul odor) or new skin changes around the wound.,You may need to have your wound measured weekly to adjust the gel amount.,Avoid applying other creams, ointments, or lotions to the same area.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about FLEXERIL vs REGRANEX, answered by our medical review team.
FLEXERIL is a Muscle Relaxant that works by Cyclobenzaprine is a centrally acting muscle relaxant that acts primarily at the brainstem, reducing tonic somatic motor activity via inhibition of descending serotonergic pathways. It is structurally related to tricyclic antidepressants and exhibits anticholinergic, sedative, and analgesic effects.. REGRANEX is a Topical Growth Factor (Platelet-Derived) that works by Recombinant human platelet-derived growth factor (rh PDGF-BB) that promotes chemotaxis and proliferation of fibroblasts, smooth muscle cells, and other cells involved in wound healing, and stimulates granulation tissue formation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FLEXERIL and REGRANEX depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of FLEXERIL is: 10 mg to 15 mg orally three times a day; maximum daily dose: 30 mg.. The standard adult dose of REGRANEX is: Apply topically once daily, a thin layer to the full area of the ulcer, using a measured amount of gel based on ulcer length and width in centimeters: (length × width × 0.5) grams.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between FLEXERIL and REGRANEX in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. FLEXERIL is classified as Category C. Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. Use only if clearly needed. First trimester: no known risk. . REGRANEX is classified as Category C. No adequate and well-controlled studies in pregnant women. Animal studies at doses 25-100 times human exposure show no fetal harm. Risk cannot be ruled out; use only if potential b. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.