Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
REGRANEX vs CHLORZOXAZONE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
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.
Chlorzoxazone acts centrally on the spinal cord and subcortical areas of the brain to inhibit multisynaptic reflex arcs involved in producing and maintaining muscle spasm. It may also have some sedative effects.
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.
Adjunct for relief of acute painful musculoskeletal conditions associated with muscle spasm
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.
250-500 mg orally 3-4 times daily, maximum 750 mg 4 times daily.
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.
Terminal elimination half-life approximately 1–2 hours; clinically relevant for muscle relaxant effect duration.
Metabolized locally; no systemic metabolism expected due to topical administration and minimal absorption. If absorbed, degraded by proteolytic enzymes at the wound site.
Hepatic, primarily via CYP2E1, also CYP1A2 and CYP3A4
Primarily renal; minimal biliary/fecal. Becaplermin is cleared renally (>90% as metabolites) with <2% excreted unchanged. Fecal elimination accounts for <10%.
Primarily hepatic metabolism followed by renal excretion of metabolites; <1% excreted unchanged in urine; minor biliary/fecal elimination.
~25% bound to plasma proteins (primarily albumin).
Approximately 90–95% bound, primarily to albumin.
Vd ~12 L (~0.17 L/kg assuming 70 kg), indicating limited extravascular distribution due to molecular size.
0.46–0.64 L/kg; indicates distribution into total body water.
Topical: Negligible systemic bioavailability (<1% of applied dose absorbed; increased with large wounds or impaired skin barrier).
Oral: nearly complete; rapidly absorbed with extensive first-pass metabolism; systemic bioavailability approximately 30–50% due to first-pass effect.
No dose adjustment required for renal impairment.
No specific guidelines; use with caution in severe renal impairment (GFR <30 m L/min) due to potential accumulation of active metabolite.
No dose adjustment required for hepatic impairment.
Contraindicated in hepatic impairment; avoid use in Child-Pugh class B or C due to risk of hepatotoxicity.
Safety and efficacy in pediatric patients have not been established; use not recommended.
Not established; safety and efficacy not studied in pediatric patients.
No specific dose adjustment recommended; use with caution due to potential comorbidities and polypharmacy.
Initiate at lower end of dosing range (250 mg 3-4 times daily); monitor for CNS effects (dizziness, drowsiness) and liver function.
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.
None
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.
May cause drowsiness, dizziness, or impaired coordination. Caution in patients with hepatic impairment. Discontinue if hypersensitivity reactions occur. Avoid concurrent use with alcohol or other CNS depressants.
Known hypersensitivity to becaplermin or any product component. Application to wounds with known neoplasms or active malignancy. Use on wounds closed by primary intention.
Hypersensitivity to chlorzoxazone or any component of the formulation; impaired hepatic function
No known food interactions. Regranex is applied topically and has minimal systemic absorption.
No significant food interactions. Take with or without food. Grapefruit juice may increase drug levels; avoid large quantities.
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.
Teratogenic risk in humans is not well-studied. No major teratogenic effects have been reported in animal studies. However, as with all medications, use during pregnancy only if clearly needed and after weighing risks vs. benefits. Avoid during first trimester unless necessary.
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.
Not recommended during breastfeeding due to potential for sedation in the infant. No M/P ratio data available.
No pharmacokinetic data in pregnancy. Dosage adjustments are not recommended based on current knowledge; use same dosing as non-pregnant adults.
No dosage adjustment specific to pregnancy is required based on pharmacokinetic data; however, clinical response should be monitored.
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.
Chlorzoxazone is a centrally acting muscle relaxant used for acute musculoskeletal pain. Onset of action is within 1 hour; peak effect at 1-2 hours. Monitor for hepatotoxicity, especially with prolonged use or high doses. Can cause drowsiness and impair motor skills; avoid concurrent use with alcohol or other CNS depressants. Tablets may be crushed for patients with swallowing difficulties.
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.
Take exactly as prescribed; do not increase dose or frequency.,May cause drowsiness or dizziness; avoid driving or operating machinery until you know how it affects you.,Avoid alcohol and other CNS depressants while taking this medication.,Report signs of liver problems: dark urine, yellowing of eyes/skin, persistent nausea, abdominal pain.,Do not suddenly stop taking if used long-term; taper under medical supervision to avoid withdrawal.
No interactions on record
"Lumacaftor is a strong inducer of cytochrome P450 (CYP) 3A4 and other drug-metabolizing enzymes, including CYP2E1. Chlorzoxazone is primarily metabolized by CYP2E1 to its inactive metabolite. Concomitant use increases CYP2E1 activity, leading to accelerated chlorzoxazone clearance and reduced systemic exposure, potentially diminishing its therapeutic effect as a muscle relaxant."
"Chlorzoxazone, a centrally acting muscle relaxant, inhibits the metabolism of diltiazem, a calcium channel blocker, via competitive inhibition of CYP3A4. This leads to increased plasma concentrations of diltiazem, potentially causing enhanced negative chronotropic and vasodilatory effects, resulting in bradycardia, hypotension, or atrioventricular block. Patients may experience dizziness, syncope, or exacerbate heart failure symptoms."
"Butalbital, a barbiturate, induces hepatic cytochrome P450 enzymes (particularly CYP2E1), accelerating the metabolism of chlorzoxazone, a centrally acting muscle relaxant primarily metabolized by CYP2E1. This results in reduced plasma concentrations of chlorzoxazone, leading to diminished therapeutic efficacy and potential loss of symptom control. Clinically, patients may experience inadequate muscle relaxation, requiring dose adjustments or alternative therapy."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about REGRANEX vs CHLORZOXAZONE, answered by our medical review team.
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.. CHLORZOXAZONE is a Skeletal Muscle Relaxant that works by Chlorzoxazone acts centrally on the spinal cord and subcortical areas of the brain to inhibit multisynaptic reflex arcs involved in producing and maintaining muscle spasm. It may also have some sedative effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between REGRANEX and CHLORZOXAZONE 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 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.. The standard adult dose of CHLORZOXAZONE is: 250-500 mg orally 3-4 times daily, maximum 750 mg 4 times daily.. 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 REGRANEX and CHLORZOXAZONE 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. 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. CHLORZOXAZONE is classified as Category C. Teratogenic risk in humans is not well-studied. No major teratogenic effects have been reported in animal studies. However, as with all medications, use during pregnancy only if cl. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.