The biopharmaceutical evaluation of four commercial preparations of lidocain-epinephrine for use as local anaesthetic

Abstract

In vivo tests on humans, to establish the bioavailability and bioequivalence of a product, include those in which theappropriate physiological effect may be measured throughout a determined period of time. Such tests may be carried outproviding that statistically validated evaluation techniques are applied to ensure safety, sensitivity and reproducibility.The so-called local action products based on clinical effectiveness and toxicity are specifically indicated, as importantevaluation alternatives.In the present work, pharmacodynamic concepts have been applied, in order to establish the relative Bioequivalence offour commercial preparations of lidocaine hydrochloride and epinephrine, used as local anaesthetic in dentistry andother medical specialisations. Substantial differences in the retail price of the preparations were found to exist. Thedetermination of pharmacodynamic properties was based on their effects on sensitivity to pain and the time lapse required for them to produce an effect. The parameters evaluated were; maximum effect achieved (Emax) - conductionamplitude – Time required for maximum effect (Temax) and the area under time vs effect curve (AUCe).The products were codified as A, B, C, & D and were subjected to the required physicochemical analyses in accordancewith the official Colombian pharmacopoeia (USP), in order to establish the pharmaceutical equivalence between them.The statistical analyses, applied to the data on average conduction amplitude and to the areas under the curve, usingthe method of repeated measurements in the former and randomised blocks in the latter, did not show significantdifferences among the four products, shown as the level of significance, enabling the bioequivalence to be establishedamong them for their effect as local anaesthetic.