Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
REGRANEX vs AMRIX
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.
Centrally acting muscle relaxant; it is the R-enantiomer of baclofen. Agonist at GABA-B receptors in the spinal cord, leading to inhibition of monosynaptic and polysynaptic spinal reflexes, thereby reducing muscle spasticity.
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.
Treatment of spasticity due to multiple sclerosis, spinal cord injury, or other spinal cord disorders
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.
15 mg orally once daily. May increase to 30 mg once daily if needed, after at least 1 week. Maximum 30 mg/day.
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 32 hours (range 28–40 hours); clinically relevant for once-daily dosing in chronic muscle spasm
Metabolized locally; no systemic metabolism expected due to topical administration and minimal absorption. If absorbed, degraded by proteolytic enzymes at the wound site.
Hepatic via deamination; primarily metabolized by monoamine oxidase B (MAO-B) to inactive metabolites.
Primarily renal; minimal biliary/fecal. Becaplermin is cleared renally (>90% as metabolites) with <2% excreted unchanged. Fecal elimination accounts for <10%.
Renal: approximately 40% as unchanged drug and metabolites; biliary/fecal: minimal; total clearance: 2.5 L/min
~25% bound to plasma proteins (primarily albumin).
40–45% bound to serum proteins, primarily albumin
Vd ~12 L (~0.17 L/kg assuming 70 kg), indicating limited extravascular distribution due to molecular size.
5–8 L/kg; suggests extensive tissue distribution, including skeletal muscle
Topical: Negligible systemic bioavailability (<1% of applied dose absorbed; increased with large wounds or impaired skin barrier).
Oral: 85–95% (extended-release formulation)
No dose adjustment required for renal impairment.
No specific dose adjustment recommended; use with caution in severe renal impairment (Cr Cl < 30 m L/min).
No dose adjustment required for hepatic impairment.
Contraindicated in Child-Pugh class C. For Child-Pugh class A or B: initiate at 15 mg once daily; do not increase dose. Use with caution.
Safety and efficacy in pediatric patients have not been established; use not recommended.
Safety and efficacy not established in pediatric patients under 12 years. For ages 12 and older, same as adult dosing.
No specific dose adjustment recommended; use with caution due to potential comorbidities and polypharmacy.
Initiate at 15 mg once daily. Due to higher incidence of anticholinergic effects and falls, monitor closely; consider lower doses in frail elderly.
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.
Abrupt discontinuation may precipitate withdrawal syndrome including hallucinations, seizures, autonomic instability.,May cause sedation, dizziness, and muscle weakness; caution with activities requiring alertness.,Use with caution in patients with impaired renal function due to reduced clearance.,May exacerbate seizures in patients with epilepsy.,Avoid concomitant use with 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 amrix or baclofen.,Abrupt withdrawal is contraindicated; must be tapered.,Concomitant use with MAO inhibitors is contraindicated due to risk of hypertensive crisis.
No known food interactions. Regranex is applied topically and has minimal systemic absorption.
Avoid grapefruit and grapefruit juice during treatment as they may increase cyclobenzaprine levels. Taking AMRIX with or without food does not significantly affect absorption. Alcohol should be strictly avoided as it potentiates CNS depression.
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.
Cyclobenzaprine (AMRIX) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but adequate well-controlled studies in pregnant women are lacking. Use only if clearly needed. First trimester: no specific teratogenic effects documented; second and third trimesters: avoid near term due to potential neonatal effects (e.g., sedation, withdrawal).
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.
Cyclobenzaprine is excreted into human milk in small amounts. M/P ratio: not established. Use with caution in nursing mothers; monitor infant for sedation, poor feeding, or hypotonia.
No pharmacokinetic data in pregnancy. Dosage adjustments are not recommended based on current knowledge; use same dosing as non-pregnant adults.
No specific dose adjustments are recommended based on pharmacokinetic changes in pregnancy; however, due to potential for increased clearance, lowest effective dose should be used. Avoid use during labor and delivery due to potential neonatal depression.
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.
AMRIX (cyclobenzaprine extended-release) should not be used longer than 2-3 weeks due to lack of evidence for efficacy in muscle spasm beyond that period. It has significant anticholinergic effects; avoid in patients with glaucoma, urinary retention, or those taking MAOIs. Do not crush or chew capsules; administer once daily at same time. Onset of action is delayed compared to immediate-release cyclobenzaprine.
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 AMRIX exactly once daily at the same time each day; do not crush, chew, or open the capsule.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids) as they increase the risk of severe drowsiness and dizziness.,Do not drive or operate heavy machinery until you know how AMRIX affects you; it may cause drowsiness, dizziness, or blurred vision.,Contact your healthcare provider if you experience symptoms of serotonin syndrome (e.g., agitation, hallucinations, rapid heart rate, fever, muscle stiffness, nausea, diarrhea).,Do not use AMRIX for longer than 2-3 weeks unless specifically directed by your doctor; prolonged use is not recommended.,Inform your doctor if you have a history of urinary retention, glaucoma, thyroid disorders, heart problems, or liver disease.,If you miss a dose, take it as soon as you remember unless it is almost time for your next dose; do not double the dose.
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 REGRANEX vs AMRIX, 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.. AMRIX is a Muscle Relaxant that works by Centrally acting muscle relaxant; it is the R-enantiomer of baclofen. Agonist at GABA-B receptors in the spinal cord, leading to inhibition of monosynaptic and polysynaptic spinal reflexes, thereby reducing muscle spasticity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between REGRANEX and AMRIX 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 AMRIX is: 15 mg orally once daily. May increase to 30 mg once daily if needed, after at least 1 week. Maximum 30 mg/day.. 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 AMRIX 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. AMRIX is classified as Category C. Cyclobenzaprine (AMRIX) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but adequate well-controlled studies in pregnant women are lacki. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.