CLINICS 2010;65(5):531-7 BASIC RESEARCH MINIMUM ALVEOLAR CONCENTRATIONS AND HEMODYNAMIC EFFECTS OF TWO DIFFERENT PREPARATIONS OF SEVOFLURANE IN PIGS Denise A. Otsuki,I Denise T. Fantoni,II Carla Holms,I Jose Otavio C. Auler Jr.III doi: 10.1590/S1807-59322010000500011 Otsuki DA, Fantoni DT, Holms C, Auler-Junior JOC. Minimum alveolar concentrations and hemodynamic effects of two different preparations of sevoflurane in pigs. Clinics. 2010(65)5:531-7. BACKGROUND: Original sevoflurane (Sevo A) is made with water, while a generic sevoflurane (Sevocris) is produced with propylene glycol as a stabilizing additive. We investigated whether the original and generic sevoflurane preparations differed in terms of their minimum alveolar concentration (MAC) values and hemodynamic effects. METHODS: Sixteen pigs weighing 31.6±1.8 kg were randomly assigned to the Sevo A or Sevocris groups. After anesthesia in- duction via mask with the appropriate sevoflurane preparation (6% in 100% oxygen), the MAC was determined for each animal. Hemodynamic and oxygenation parameters were measured at 0.5 MAC, 1 MAC and 1.5 MAC. Histopathological analyses of lung parenchyma were performed. RESULTS: The MAC in the Sevo A group was 4.4±0.5%, and the MAC in the Sevocris group was 4.1±0.7%. Hemodynamic and metabolic parameters presented significant differences in a dose-dependent pattern as expected, but they did not differ between groups. Cardiac indices and arterial pressures decreased in both groups when the sevoflurane concentration increased from 0.5 to 1 and 1.5 MAC. The oxygen delivery index (DO I) decreased significantly at 1.5 MAC. 2 CONCLUSION: Propylene glycol as an additive for sevoflurane seems to be as safe as a water additive, at least in terms of he- modynamic and pulmonary effects. KEYWORDS: Inhalant anesthetics; Sevoflurane; Minimum alveolar concentration; Pigs. INTRODUCTION Sevoflurane is a fluorinated hydrocarbon that stands out among today’s inhaled anesthetics due to its low solubility (blood: gas partition coefficient of 0.68), non-irritating effects on the respiratory tract and pleasant smell. These properties allow for rapid and smooth anesthesia induction even without pre-medication and offer good control over the depth of anesthesia, a factor that is important in patients with I Laboratory of Medical Investigation, LIM/08 (Anesthesiology), Faculdade de Medicina da Universidade de São Paulo - São Paulo/SP, Brazil. II Department of Surgery, Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo - São Paulo/SP, Brazil. III Department of Anesthesia and Surgical Intensive Care, Heart Institute of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - São Paulo/SP, Brazil. Email: lim08@usp.br Tel: 55 11 3061-7293 Received for publication on December 09, 2009 First review completed on December 28, 2009 Accepted for publication on February 03, 2010 compromised hemodynamic status.1 Depending on storage and usage conditions, sevoflurane can be degraded into different compounds, including the highly pungent hydrofluoric acid, a substance known to be nephrotoxic and irritating to the respiratory tract mucous membrane. This sevoflurane decomposition reaction involves a metallic impurity, an acid (a Lewis acid) and a substance capable of receiving an electron pair to trigger the decomposition reaction. A number of compounds, both organic and inorganic, including H2O, butylated hydroxytoluene, methylparaben, propylparaben, propofol and thymol, can inhibit the Lewis acid reaction. A liquid additive (water) was developed as a stabilizer to the original sevoflurane (Sevorane®, Abbott) to prevent the production of the inorganic fluorides. Cristália Laboratories developed a new sevoflurane formula (Sevocris® , Cristalia, São Paulo) containing 0.026% p/p of propylene glycol as a stabilizer.2 This new product was introduced into the Brazilian market in September 2004, after being granted Copyright © 2010 CLINICS – This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons. org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.