Buprenorphine Added to the Local Anesthetic for Axillary Brachial Plexus Block Prolongs Postoperative Analgesia:

Beta-phenylethylamines and the isoquinoline alkaloids

This review covers beta-phenylethylamines and isoquinoline alkaloids and compounds derived from them, including further products of oxidation, condensation with formaldehyde and rearrangement, some of which do not contain an isoquinoline system, together with naphthylisoquinoline alkaloids, which have a different biogenetic origin. The occurrence of the alkaloids, with the structures of new bases, together with their reactions, syntheses and biological activities are reported. The literature from July 2001 to June 2002 is reviewed, with 581 references cited.

Simultaneous determination of mepivacaine, tetracaine, and p-butylaminobenzoic acid by high-performance liquid chromatography

INTRODUCTION

The purpose of the present study was to develop a simple method for the simultaneous determination of mepivacaine, tetracaine, and p-butylaminobenzoic acid (BABA) in human plasma using high-performance liquid chromatography (HPLC) with a multiwavelength detector.

METHODS

Human blood samples containing heparin, as an anticoagulant, and physostigmine (100 microg/ml), as an anticholinesterase, or human plasma containing physostigmine were spiked with various concentrations of mepivacaine, tetracaine and, in some cases, BABA. Blood samples were centrifuged and plasma was deproteinized with trifluoroacetic acid (TFA; 7%). After centrifugation, the pH was adjusted to 4.5 and an aliquot of 20, 50 or 100 microl was injected into the HPLC apparatus. The detection was done simultaneously at wavelengths of 214 and 300 nm. Analytical chromatography was done on a Waters microBondapak C(18) reverse-phase column (3.9 x 300 mm; particle size 10 microm) with a 30-min increasing linear gradient of 20-40% acetonitrile+0.05% TFA in H(2)O+0.05% TFA at a flow rate of 1 ml/min. The Waters HPLC system included two pumps, an automatic injector, a column oven, and a M490 multiwavelength detector. Quantification was done using integration of peak areas with peaks of authentic mepivacaine, tetracaine, and BABA standards.

RESULTS

Calibration curves for standards of mepivacaine, tetracaine, and BABA were linear in the concentration ranges from 0.1 to 100 microg/ml, and the correlation coefficients exceeded.99 for all compounds. The lower limits of detection were 100 ng/ml for mepivacaine and 50 ng/ml for tetracaine and BABA. The yields for mepivacaine, tetracaine, and BABA were 91+/-2.1%, 82+/-3.3%, and 88+/-2.0% (mean+/-S.E.M., n=6), respectively. Degradation of tetracaine by human plasma at 37 degrees C was inhibited by physostigmine.

DISCUSSION

The method is sensitive enough to allow blood concentration determinations of mepivacaine and tetracaine or its metabolite, BABA, following local anesthesia induced by these two drugs, especially when their toxic effect may be present. This method also may be useful in forensic medicine for determination of the cause of death after local anesthesia with mepivacaine and/or tetracaine.