Duration of the local anesthetic effect of tetracaine hydrochloride solutions and tetracaine in microspheres.

Abstract
The local anesthetic effect of tetracaine in polylactic acid micropheres was compared with that of tetracaine hydrochloride solutions. The local anesthetic effect of 0.1 ml tetracaine hydrochloride solutions was examined at 4 concentrations in vivo [on guinea-pig skin]. The local anesthetic effect of 0.2 ml tetracaine hydrochloride solutions was compared with that of 0.1 ml tetracaine hydrocholoride solutions. The greater the amount of tetracaine, the stronger and longer was the local anesthetic effect. The local anesthetic effect of tetracaine in microspheres was much longer and lasted over 100 h.