Alkalinization of amide local anaesthetics by addition of 1% sodium bicarbonate solution

A number of methods exist by which the pH of local anaesthetic solutions ma y be increased. Most commonly, these require the addition of differing amou nts of sodium bicarbonate solution according to the local anaesthetic drugs . Sodium bicarbonate (1%) was titrated against pH in six commonly used loca l anaesthetic solutions. Titration curves of pH and volume of sodium bicarb onate solution added are shown for this group of local anaesthetics. This s tudy demonstrates that 1 mL of 1% sodium bicarbonate solution may be used t o alkalinize this range of local anaesthetics without the risk of precipita tion. We also conclude that Ropivacaine (at concentration 0.75% and 1.0%), is unsuitable for alkalinization since it precipitates at a pH of 6.0.