title: Pharmacological studies of the new centrally acting muscle relaxant 4'-ethyl-2-methyl-3-pyrrolidinopropiophenone hydrochloride.
abstract: The pharmacological properties of 4'-ethyl-2-methyl-3-pyrrolidinopropiophenone hydrochloride (HSR-770), a new centrally acting muscle relaxant, were investigated in experimental animals. HSR-770, within a dose range of 1-10 mg/kg i.v., relaxed alpha- and gamma-rigidities in rats, the dose required to relax gamma-rigidity being lower than the dose required to relax alpha-rigidity. When HSR-770 was intraduodenally (i.d.) administered within a dose range of 25-50 mg/kg, the relaxant activity on alpha-rigidity was potent and long-lasting in comparison with eperisone or tolperisone. HSR-770 inhibited flexor reflex more strongly than patellar reflex in a dose-dependent manner within a dose range of 2.5-10 mg/kg i.v. or 25 and 50 mg/kg i.d. in anesthetized cats. In spinal cts, HSR-770 (5 and 10 mg/kg i.v.) inhibited flexor reflex but this potency was weaker than that in anesthetized cats. HSR-770 (12.5-50 mg/kg i.d.) inhibited he crossed extensor reflex in anesthetized rats. In spinal cats, HSR-770 inhibited mono- and polysynaptic reflex potentials to the same extent and also depressed dorsal root reflex potential at 5 and 10 mg/kg i.v. HSR-770 at a dose (50 mg/kg p.o.) which exerted muscle relaxant activity on both rigidity and flexor reflex, had little effect on spontaneous motor activity (mice), hexobarbital-induced sleeping time (mice) and conditioned avoidance response (rats). These results indicate that HSR-770 is a potent centrally acting muscle relaxant and that its central nervous system depressant activity is relatively weak.
mesh_terms: D000740:Anemia / Q000503:physiopathology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D002415:Cats; D003655:Decerebrate State; D005260:Female; D006591:Hexobarbital / Q000494:pharmacology; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009125:Muscle Relaxants, Central / Q000494:pharmacology*; D011427:Propiophenones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects; D012890:Sleep / Q000187:drug effects; D013045:Species Specificity
chemical_list: D009125:Muscle Relaxants, Central; D011427:Propiophenones; C052425:inaperisone; D006591:Hexobarbital