The effect of concentration on vasoactivity of bupivacaine and lignocaine

In a double-blind trial bupivacaine 0.125, 0.25 and 0.5% and lignocaine 0.5, 1 and 2% were given intradermally to 31 volunteers. Vasoconstriction was observed more frequently at low concentrations of each drug, and vasodilatation at high concentrations. These observations were highly significant (P less than 0.001). Duration of action was unaffected by concentration, except in the case of bupivacaine 0.5%, the effect of which was longer lasting than that of other solutions.