Resumo

GERONIMO, M.; FUSTER, O.; VICENTE-GUTIERREZ, U.  e  VICENTE-GUTIERREZ, L.. Alkalinized 1.5% mepivacaine stability over time. Rev. Soc. Esp. Dolor [online]. 2008, vol.15, n.7, pp.440-443. ISSN 1134-8046.

Purpose: It is recommended to alkalinize mepivacaine Just before employing it. However, data regarding alkalinized mepivacaine stability over time are very scarce. The aim of this work was to investígate for pH stability and precipitation of alkalinized mepivacaine. Materials and Methods: Three syringes (A, B, C) containing 20mL of 1.5% mepivacaine each one were prepared. Syringe A served as pH control, and syringes B and C were alkalinized by adding 2mL of 8.4% sodium bicarbonate solution. pH was measured into each syringe before alkalinization and every ten minutes lasting for one hour after. Associated free base percentage was calculated, except for the last 30 minutes for syringe C, which remained closed to serve as C02 leakage control. Solutions were examinated by naked eyes looking for macroscopic precipitates, filtered after the procedure and the filters were weighed in order to looking for microscopic precipitates. After filtration pH was again measured. Results: Alkalinization resulted in immediate and significant increases in pH valúes and associated free base percentage of syringes B and C compared to syringe A. After that and for one hour pH valúes remained very stable. Besides, pH valúes between syringes B and C were very similar at 60 minutes, indicating no significative leakage of C02. The procedure was completed without evidence of precipitation by visual inspection, and differences between dry filters weights were minimal indicating no significative formation of microprecipitates. Conclusions: 1.5% mepivacaine solutions can be alkalinized and stored at room temperature in closed syringes for at least one hour before administration. In our opinión previous alkalinization is much more convenient to daily clinical practice that actual recommendation of alkalinization Just before use.

Palavras-chave : Research; Alkalinization; Mepivacaine; Sodium Bicarbonate; Drug Stability.

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