Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DELAXIN vs BACLOFEN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
DELAXIN (cyclobenzaprine) is a centrally acting muscle relaxant that is thought to relieve muscle spasms by inhibiting the descending serotonergic pathways in the spinal cord, specifically at the level of the brainstem. It acts as a serotonin 5-HT2 receptor antagonist, reducing excessive motor neuron activity.
GABA-B receptor agonist; inhibits monosynaptic and polysynaptic spinal reflexes by hyperpolarizing afferent terminals.
Adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions
Spasticity due to multiple sclerosis (FDA approved),Spinal cord injury (FDA approved),Intrathecal use for severe spasticity of cerebral origin (off-label),Hiccups (off-label),Alcohol withdrawal syndrome (off-label),Trigeminal neuralgia (off-label)
10 mg orally once daily, preferably at bedtime.
Initial: 5 mg orally 3 times daily; increase by 5 mg per dose every 3 days to max 80 mg/day (20 mg 4 times daily). Intrathecal: initial test dose 50-100 mcg; for continuous infusion, daily dose typically 300-800 mcg.
Terminal elimination half-life: 12-18 hours (prolonged in renal impairment; up to 30 hours in severe renal failure).
Terminal half-life: 2.5-4 hours (young adults), 4-8 hours (elderly); clinical context: requires frequent dosing for spasticity.
Primarily hepatic via cytochrome P450 enzymes, mainly CYP3A4, CYP1A2, and CYP2D6. Also undergoes N-demethylation and glucuronidation.
Metabolized via hepatic deamination by transaminase; primarily excreted unchanged in urine (approximately 70-80%), with minor hepatic metabolism.
Renal: 60-70% as unchanged drug; biliary/fecal: 20-30% as metabolites.
Renal: 70-80% unchanged; fecal: <5%; biliary: minimal.
92-95% bound to albumin.
30-35% bound to albumin.
Vd: 0.8-1.2 L/kg (indicates extensive tissue distribution).
Vd: 0.5-0.7 L/kg; indicates distribution into total body water.
Oral: 70-80% (first-pass metabolism); intramuscular: 100%.
Oral: 70-85% with high variability; intrathecal: 100%.
GFR 30-50 m L/min: 5 mg once daily; GFR <30 m L/min: not recommended.
Cr Cl 30-50 m L/min: reduce dose by 50%; Cr Cl <30 m L/min: avoid use or use with extreme caution, reduce dose by 75%.
Child-Pugh A: 5 mg once daily; Child-Pugh B: 2.5 mg once daily; Child-Pugh C: not recommended.
No specific guidelines; use with caution due to potential for increased sedation/neurotoxicity.
Not established in pediatric patients under 18 years.
Children 2-7 years: initial 2.5 mg orally 4 times daily, increase by 2.5 mg/dose every 3 days to max 40 mg/day; children ≥8 years: initial 5 mg orally 3 times daily, increase as in adults to max 60 mg/day.
Initiate at 5 mg once daily; may increase to 10 mg based on response and tolerability.
Start at low end of dosing range (5 mg twice daily), titrate slowly due to increased risk of sedation, weakness, and cognitive impairment.
None
Abrupt discontinuation may cause withdrawal symptoms including hallucinations, seizures, and life-threatening hyperpyrexia; taper dose gradually.
Serotonin syndrome (especially when used with other serotonergic drugs), sedation and impairment of mental/physical abilities, anticholinergic effects, cardiac arrhythmias (in patients with hyperthyroidism or cardiovascular disease), withdrawal symptoms after abrupt discontinuation, and hepatic impairment.
May cause CNS depression (drowsiness, sedation) and impair ability to drive or operate machinery.,Risk of withdrawal syndrome including fever, altered mental status, and autonomic instability upon abrupt cessation.,Use with caution in patients with renal impairment; dose adjustment required.,May exacerbate psychiatric disorders; monitor for hallucinations, confusion.,Risk of respiratory depression when combined with other CNS depressants.
Concomitant use with MAOIs or within 14 days of MAOI therapy, acute recovery phase of myocardial infarction, heart block, congestive heart failure, hyperthyroidism, and hypersensitivity to cyclobenzaprine.
Hypersensitivity to baclofen.,Intrathecal formulation is contraindicated in patients with active infection or bleeding disorders at lumbar puncture site.,Women who are breastfeeding (relative contraindication).
No significant food interactions. Delaxin (methocarbamol) may be taken with or without food. Grapefruit juice does not interact. Avoid alcohol due to additive CNS depression.
No specific food interactions. Avoid alcohol due to additive CNS depression.
DELAXIN (methocarbamol) is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, methocarbamol has demonstrated embryotoxic and fetotoxic effects at doses similar to or greater than human therapeutic doses. Risk to the fetus cannot be ruled out, especially during the first trimester. Use only if potential benefit justifies potential risk.
First trimester: Limited human data; animal studies show increased fetal malformations (omphalocele, exencephaly) at doses equivalent to human therapeutic range. Second and third trimesters: Risk of neonatal withdrawal (hypertonia, seizures) with chronic maternal use. Avoid unless benefit outweighs risk.
It is not known whether methocarbamol is excreted in human breast milk. The M/P ratio has not been determined. Due to potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Baclofen excreted into breast milk in low concentrations (M/P ratio approximately 0.43). Relative infant dose estimated 0.9% of maternal weight-adjusted dose. Considered compatible with breastfeeding, but monitor infant for sedation and hypotonia.
No specific dosing adjustments are recommended in pregnancy due to lack of pharmacokinetic data. Use lowest effective dose for shortest duration. Methocarbamol has a short half-life (1-2 hours) and minimal protein binding, but pregnancy-induced changes in volume of distribution and renal clearance are not well studied.
No specific dose adjustments recommended. Increased renal blood flow and GFR in pregnancy may reduce baclofen levels; monitor clinical effect and adjust dose as needed. Avoid abrupt discontinuation due to risk of maternal withdrawal and rebound spasticity.
DELAXIN is a skeletal muscle relaxant containing methocarbamol. Administer intravenously at a rate not exceeding 3 m L/min to avoid hypotension, bradycardia, and syncope. Extravasation can cause thrombophlebitis. Contraindicated in myasthenia gravis. Onset of action is rapid (30 minutes) for IV route; peak effects at 2 hours. Monitor for CNS depression, especially with concurrent alcohol or sedatives.
Abrupt withdrawal can cause severe rebound spasticity, fever, and rhabdomyolysis; taper by 5-10 mg/week. Intrathecal baclofen pumps require careful monitoring for overdose (respiratory depression) or withdrawal. Use with caution in renal impairment (dose adjust for Cr Cl <30 m L/min).
May cause drowsiness, dizziness, or blurred vision; avoid driving or operating heavy machinery until effects are known.,Do not consume alcohol or take other CNS depressants while using DELAXIN.,Report any signs of allergic reaction, including hives, difficulty breathing, or swelling of the face, lips, or tongue.,If using the oral tablet, take with food to reduce stomach upset.,Do not stop suddenly; taper under medical supervision if used long-term.
Do not stop taking baclofen suddenly; sudden discontinuation can cause serious withdrawal symptoms including hallucinations, seizures, and high fever.,Avoid alcohol and CNS depressants as they increase sedation and risk of falls.,May cause dizziness or drowsiness; avoid driving or operating machinery until you know how it affects you.,Take exactly as prescribed; missed doses can lead to muscle spasms or withdrawal.,Report any unusual muscle stiffness, rapid heart rate, or dark urine immediately.
No interactions on record
"Sevoflurane enhances the inhibitory effects of baclofen on the central nervous system by potentiating GABA-B receptor activity, leading to an increased risk of profound sedation, respiratory depression, and hypotension. This synergistic interaction can result in prolonged recovery from anesthesia and the need for ventilatory support. Clinically, patients may exhibit exaggerated muscle relaxation and a delayed emergence from anesthesia, particularly at higher doses of either agent."
"Concomitant use of etidocaine, an amide-type local anesthetic that blocks voltage-gated sodium channels, and baclofen, a GABAB receptor agonist used for muscle spasticity, may lead to additive central nervous system (CNS) depression and respiratory depression. This interaction results from synergistic depressant effects on the brainstem and spinal cord, increasing the risk of sedation, dizziness, ataxia, and impaired consciousness. Clinically, patients may experience excessive drowsiness, respiratory compromise, and impaired motor coordination, particularly in the elderly or those with pre-existing renal impairment where baclofen accumulation is more likely."
"The coadministration of Baclofen and Metaxalone results in additive central nervous system (CNS) depression due to their shared pharmacodynamic effects on GABAergic and sedative pathways. This combination can potentiate sedation, dizziness, ataxia, and respiratory depression, particularly in elderly patients or those with renal impairment. Clinical outcomes may include increased risk of falls, cognitive impairment, and impaired motor coordination, necessitating cautious dose titration."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about DELAXIN vs BACLOFEN, answered by our medical review team.
DELAXIN is a Skeletal muscle relaxant that works by DELAXIN (cyclobenzaprine) is a centrally acting muscle relaxant that is thought to relieve muscle spasms by inhibiting the descending serotonergic pathways in the spinal cord, specifically at the level of the brainstem. It acts as a serotonin 5-HT2 receptor antagonist, reducing excessive motor neuron activity.. BACLOFEN is a Skeletal Muscle Relaxant that works by GABA-B receptor agonist; inhibits monosynaptic and polysynaptic spinal reflexes by hyperpolarizing afferent terminals.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DELAXIN and BACLOFEN 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 DELAXIN is: 10 mg orally once daily, preferably at bedtime.. The standard adult dose of BACLOFEN is: Initial: 5 mg orally 3 times daily; increase by 5 mg per dose every 3 days to max 80 mg/day (20 mg 4 times daily). Intrathecal: initial test dose 50-100 mcg; for continuous infusion, daily dose typically 300-800 mcg.. 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 DELAXIN and BACLOFEN 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. DELAXIN is classified as Category C. DELAXIN (methocarbamol) is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, methocarbamol has demonst. BACLOFEN is classified as Category C. First trimester: Limited human data; animal studies show increased fetal malformations (omphalocele, exencephaly) at doses equivalent to human therapeutic range. Second and third t. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.