Comparative Pharmacology
Head-to-head clinical analysis: CYCLOBENZAPRINE HYDROCHLORIDE versus ROBAXIN 750.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLOBENZAPRINE HYDROCHLORIDE versus ROBAXIN 750.
CYCLOBENZAPRINE HYDROCHLORIDE vs ROBAXIN-750
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Cyclobenzaprine is a centrally acting muscle relaxant that reduces tonic somatic motor activity at the supraspinal level, primarily at the brainstem reticular formation and descending pathways. It is structurally related to tricyclic antidepressants and inhibits reuptake of norepinephrine and serotonin, but the direct relationship to its muscle relaxant effects is not fully established.
Methocarbamol, the active ingredient in Robaxin-750, is a centrally acting muscle relaxant. Its precise mechanism is not fully understood, but it is believed to cause general central nervous system depression, possibly through inhibition of polysynaptic reflexes at the spinal cord level.
Adults: 5 mg orally three times daily; may increase to 10 mg three times daily based on response. Maximum 30 mg per day.
750 mg orally four times daily (total daily dose 3000 mg).
None Documented
None Documented
Terminal half-life: 18–24 hours (range 8–37 hours). Clinical context: requires multiple doses to achieve steady state (5–6 days); active metabolite norcyclobenzaprine has half-life ~30 hours.
Terminal elimination half-life: 1-2 hours (methocarbamol); clinical context: short half-life necessitates frequent dosing (q6h) and may lead to fluctuating plasma levels.
Renal: ~50% as unchanged drug and metabolites; Fecal: ~40% primarily as metabolites; Biliary: minimal.
Renal: 90-95% as metabolites (mainly conjugated), <1% unchanged; biliary/fecal: minor; <2% eliminated in feces.
Category A/B
Category C
Skeletal Muscle Relaxant
Skeletal Muscle Relaxant