Scholarly article on topic 'Comparison of Histologic Spinal Cord and Neurologic Changes in Guinea Pigs after Subarachnoid Block with Large Volumes of Racemic Bupivacaine, 50% Enantiomeric Excess Bupivacaine (S75-R25), and Levobupivacaine'

Comparison of Histologic Spinal Cord and Neurologic Changes in Guinea Pigs after Subarachnoid Block with Large Volumes of Racemic Bupivacaine, 50% Enantiomeric Excess Bupivacaine (S75-R25), and Levobupivacaine Academic research paper on "Educational sciences"

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Academic research paper on topic "Comparison of Histologic Spinal Cord and Neurologic Changes in Guinea Pigs after Subarachnoid Block with Large Volumes of Racemic Bupivacaine, 50% Enantiomeric Excess Bupivacaine (S75-R25), and Levobupivacaine"

Rev Bras Anestesio! 2009; 59: 1: 125-128

CARTAS AO EDITOR LETTERS TO THE EDITOR

Comparado das Alterares Histológicas da Medula Espinal e Neurológicas de Cobaias após Anestesia Subaracnóidea com Grandes Volumes de Bupivacaína Racémica, de Mistura com Excesso Enantiomérico de 50% de Bupivacaína (S75-R25) e de Levobupivacaína

(Rev Bras Anestesio!, 2008;58:234-245) Q. S. P. (quantum satis para...). Senhora Editora,

A mistura enantiomérica da bupivacaína (S75:R25) entra para sua primeira década de nascimento. Isso se deveu a sua fórmula na qua! o principio farmacotécnico do quantum satis para (Q.S.P) assegurou sua sobrevida devido ao binomio eficácia/seguranga.

Em 30 de outubro de 1998, data-limite (deadline) para o envio de papers ao Annual Meeting da ASRA, 1999, Filadélfia, EUA, esse novo anestésico local teve assegurado sua cer-tidao de nascimento 1; depois veio o batismo 2; e recente-mente acaba de receber a bengao da confirmagao (crisma) com esse trabalho de pesquisa básica 3. Nessa trajetória pode-se constatar que o composto foi bem-nascido, tendo recebido todos os sacramentos antes de atingir a sua adolescéncia. É a vitória da pesquisa básica que nos fez criar uma combinagao racional com base em evidéncias estereoisoméricas.

Vasconcelos Filho e col. 3 circunscrevem seu estudo na fi-nalidade precipua pela qual os anestésicos locais existem: o bloqueio do nervo, mais precisamente a estrutura maior, a medula. A parceria entre departamentos veio enriquecer a pesquisa básica brasileira pela colaboragao das Professoras Capelozzi que nos permitiram que nossa capacidade investigatória fosse conhecida lá fora através do respeitável Anesthesia & Analgesia, anos atrás 3 E poucos de nós tive-mos essa honra.

Nas trés apresentagoes isoméricas ensaiadas da bupivacaína da familia pipecolilxilidida (a racémica, a homoquiral e a mistura enantiomérica) foi possível constatar as diferen-gas toxicológicas em fungao da disposigao espacial dos seus isómeros, qualitativa e quantitativamente, (S(-) versus R(+) bupivacaína).

A estereoisomeria nos dá o roteiro: isómeros sao marcadamente diferentes... Resta balanceá-los na juste mesure, isto é quantum satis para nao lesar os tecidos, como soeu acontecer através do manuseio nao-equimolar da bupivacaína racémica na formulagao S75:R25 que nao diferiu estatisti-camente do composto homoquiral (levobupivacaína) 123. Á guisa de colaboragao a esse projeto estruturado sob um método tao fidedigno, sugiro a comparagao com outro ramo dessa família, o composto (p) ropivacaína, inerente e intrin-

Revista Brasileira de Anestesiologia Vol. 59, No 1, Janeiro-Fevereiro, 2009

sicamente vasoconstritor, mas passive! de injepäo intrateca! acidenta! quando da realizapäo da técnica epidural. Aguardemos, pois, o impacto da vasoconstripäo da ropivacaína sobre as estruturas medulares, talvez a razäo pela qua! a torna proibitiva na técnica subaracnoidéa.

Maria P.B. Simonetti, TSA

E-mail: simonet@usp.br

REFERENCIAS — REFERENCES

01. Simonetti MPBS, Ferreira FM — Does the D-isomer of bupivacaine contribute to improvement of efficacy in neural block. Reg Anesth, 1999;24(Supp ASRA):43.

02. Trachez MM, Zapata-Sudo G, Moreira OR et a!. — Motor nerve blockade potency and toxicity of non-racemic bupivacaine in rats. Acta Anaesthesiol Scand, 2005;49:66-71.

03. Vasconcelos Filho PO, Posso IP, Capelozzi M et a!. — Compara-päo das alterapöes histológicas da medula espinal e neurológicas de cobaias após anestesia subaracnóidea com grandes volumes de bupivacaína racémica, de mistura com excesso enantiomérico de 50% de bupivacaína (S75-R25) e de levobupivacaína. Rev Bras Anestesiol, 2008;58:234-245.

RÉPLICA

Prezada Dra. Simonetti,

Agradepo o comentário e informapöes pertinentes. Estamos com um experimento em andamento avaliando a apäo da ropivacaina. Atenciosamente,

Dr. Paulo Vasconcelos.

Comparison of Histologic Spinal Cord and Neurologic Changes in Guinea Pigs after Subarachnoid Block with Large Volumes of Racemic Bupivacaine, 50% Enantiomeric Excess Bupivacaine (S75-R25), and Levobupivacaine

(Rev Bras Anestesiol, 2008;58:234-245) Q. S. P. (quantum satis para...). To the Editor,

The enantiomeric mixture of bupivacaine (S75-R25) has completed its first decade since it was created. This was possible due to the formula in which the pharmacotechnical principle "quantum satis para" (Q. S. P) ensured its survival due to the efficacy/safety binomium.

CARTAS AO EDITOR / LETTERS TO THE EDITOR

On October 30, 1988, the deadline for papers for the ASRA Annual Meeting, Philadelphia, USA, this new local anesthetic guaranteed its birth certificate 1; its baptism came soon after 2; and it recently received its confirmation with this basic research 3.

In this trajectory, it is possible to confirm that this compound was well-born, having received all sacraments before reaching adolescence. It represents the triumph of basic research, which created a rational combination based on stereoisomeric evidence.

Vasconcelos Filho et al. circumscribed his work on the main finality by which local anesthetics exist: nerve block, more precisely, the larger structure, the spinal cord. The partnership among departments enriched Brazilian basic research through the collaboration of the Capelozzi Professors, who allowed our investigative capacity to be known abroad through the respectable journal Anesthesia & Analgesia several years ago3. And very few among us had this honor. On the three rehearsed presentations of bupivacaine, of the pipecoloxylidides family (the racemic, the homochiral, and the enantiomeric mixture) it was possible to demonstrate, qualitatively and quantitatively, the toxicological differences due to the spatial disposition of its isomers (S(-) versus R(+) bupivacaine).

Stereoisomerism provides us the script: isomers are markedly different... One only has to balance them "juste mesure", i.e., "quantum satis para" without causing tissue damage, which happened through the non-equimolar handling of

racemic bupivacaine in the S75-R25 formulation, which did not differ statistically from the homochiral compound (levobu-pivacaine) 1,2,3

To collaborate with this project, structured under such a reliable method, I suggest the comparison with another branch of this family, the compound (p) ropivacaine - intrinsically vasoconstrictor -susceptible to accidental intrathecal administration when the epidural technique is used. Therefore, we will wait for the impact of the vasoconstriction of ropivacaine on spinal structures, maybe the reason for its contraindication in the subarachnoid technique.

Maria P.B. Simonetti, TSA E-mail: simonet@usp.br

Dear Dr. Simonetti,

We thank you for your comments and pertinent information. We are currently conducting a study evaluating the actions of ropivacaine. Sincerely,

Dr. Paulo Vasconcelos.

Revista Brasileira de Anestesiologia Vol. 59, No 1, Janeiro-Fevereiro, 2009