BACKGROUND AND OBJECTIVES: @entity34138 and its homologues are naturally occurring compounds that block the sodium channel with high potency. They have the potential for providing prolonged duration local anesthesia when coinjected with vasoconstrictors or conventional local anesthetics and are devoid of local @entity2359 . Here, we compare sciatic @entity616 with @entity34138 to those with neosaxitoxin, @entity68612 , and @entity1022 ( @entity4524 ), in a search for even safer compounds. METHODS: @entity35 received percutaneous sciatic @entity616 with toxins. The compounds were compared in terms of lethality, onset and duration of action for thermal analgesia (hot-plate testing), and @entity616 (weight-bearing). Data were expressed as medians with 25th and 75th percentiles, and median effective concentrations were determined. RESULTS: The median concentrations at which analgesia of 60 minutes duration was achieved were neosaxitoxin, 34+/-2 micromol/L; @entity34138 , 58+/-3 micromol/L; @entity4524 , 92+/-5 micromol/L; and @entity68612 , 268+/-8 micromol/L. Similar trends were observed for other measures of effectiveness (block duration of 90 minutes, maximal block), and for lethality so that the therapeutic indices were similar. No toxin had a marked predominance of sensory or @entity616 . The potency of @entity4524 was intermediate between those of the saxitoxins, and its therapeutic index was slightly better. No difference was observed in time to onset of nerve blockade among the toxins. CONCLUSIONS: Substitutions on the @entity34138 nucleus result in large differences in incidence and duration of block, and @entity137 . The therapeutic indices of the saxitoxins are similar; that of @entity4524 is slightly better.

The local anesthetic properties and @entity137 of XXXX homologues for @entity35 sciatic @entity616 in vivo.

@entity137 :: ('MESH:D064420', 'Disease') :: ['toxicity'] @entity68612 :: ('MESH:C034903', 'Chemical') :: ['decarbamoyl saxitoxin'] @entity1022 :: ('MESH:D013779', 'Chemical') :: ['tetrodotoxin'] @entity4524 :: ('CHEBI:9506', 'Chemical') :: ['TTX'] @entity2359 :: ('MESH:D020258', 'Disease') :: ['neurotoxicity'] @entity35 :: ('10116', 'Species') :: ['Rats'] @entity34138 :: ('MESH:D012530', 'Chemical') :: ['saxitoxin', 'Saxitoxin'] @entity616 :: ('MESH:D006327', 'Disease') :: ['motor block', 'nerve block']
@entity34138 :: (MESH:D012530,Chemical) :: ['saxitonin']
