Sobre o emprego da 4-aminopiridina, 3.4-diaminopiridina e da neostigmina como antagonista de curare : estudo comparativo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1981

RESUMO

The effects ot 4-aminopyridine (1; 5 e 25 ug/ml), 3.4-diaminopyridine (1; 5 and 25 ug/ml) as well as the association of the drugs with neostigmine, were investigated using the noncurarized rat s phrenic nerve-hemidiaphragm preparations and d-tubocurarine-blocked preparations. The preparations were treated by two different procedures; indirect estimulation by low frequency (0.1 Hz) and stimulation at higher frequencies (2.5; 5; 10; 50 Hz). In the noncurarized preparations submitted to stimuli of low frequency it was found that: 1) the aminopyricines and neostigmine produced an augmentation of maximal twitch height which depends on concentration and time; 2) the association of both pyridines with neostigmine produce increases in the diaphragm twitch tension which were larger than those ob tained when the drugs were used without neostigmine demonstrating a potetiation of effects The aminopyridines reversed a 80 % d-tubocurarine block of twitches elicited by indirect stimulation,but they were not found to be effective when stimuli above 5 Hz of frequency were used. Association with neostigmine enhanced antagonism baminopyridines in a dose-dependent manner. Studies of the effects on arterial pressure, cardiac frequency, central nervous system and also the antagonist effect of pancuronium-induced neuromuscular blockade of difterent drugs and associations were carried out in halothane anesthetized dogs. Using the responses of the anterior tibial muscle tp low frequency stimuli, the capacity to mantain the tetanus obtained with stímuli of 50 Hz during 5 seconds and posttetanic facilitation, the evaluation of neuromuscular functions, was done at 10 and 20 minutes after the injection of anticurare drug. It was observed that for the doses studied: 1) only 4-aminopyridine caused stímulation of the central nervous systemi 21 the aminopyridines do not efficiently antagonize the blockade to the influxes created by 50 Hz although large doses have totally antagonized the blockade of low frequeney influxeSi 3) the association of 3.4-diaminopy;ridine (0,1 mg/Kg ) -with neostigmine ( 0.025 mg/Kg) efficiently antagonized the neuromuscular block to influxes caused by elevated frequency siímulation demostrating a potentiation of effects on neuromuscular junctions; 4) there were not observed alterations in arterial pressure, in cardiac frequency or with the use of this association. The results of this research suggest that the use of the 3.4-díaminopyridine - neostigmine association as an antaqonist of curare, can be advantageous in those clinical conditions where the effects of neostigmine and/or atropine on the heart must be avoided .

ASSUNTO(S)

piridina - derivados aminopiridinas

ACESSO AO ARTIGO

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