History of T-cain: a local anesthetic developed and manufactured in Japan.

In many anesthesia textbooks written in English, lidocaine, tetracaine, bupivacaine, ropivacaine, and chloroprocaine are listed as useful local anesthetics for spinal anesthesia. In contrast, T-cain is not included in these lists, even though it has been reported to be suitable for spinal anesthesia in Japan. T-cain was developed as a local anesthetic in the early 1940s by Teikoku Kagaku Sangyo Inc. in Itami, Japan, by replacing a methyl group on tetracaine (Pantocaine(®)) with an ethyl group. T-cain was clinically approved for topical use in Japan in November 1949, and a mixture of dibucaine and T-cain (Neo-Percamin S(®)) was approved for spinal use in May 1950. Simply because of a lack of foreign marketing strategy, T-cain has never attracted global attention as a local anesthetic. However, in Japan, T-cain has been used topically or intrathecally (as Neo-Percamin S(®)) for more than 60 years. Other than the side effects generally known for all local anesthetics, serious side effects have not been reported for T-cain. In fact, several articles have reported that T-cain decreases the neurotoxicity of dibucaine. In this historical review, the characteristics of T-cain and its rise to become a major spinal anesthetic in Japan are discussed.

A continuous flow method for estimation of drug release rates from emulsion formulations.

We present a continuous-flow method that allows the release of drugs from submicron colloidal carriers to be estimated on a millisecond timescale. The technique is applied to the study of release of a model drug (tetracaine) from lipid emulsions, and shows that the solute drug is released in this timescale, and thus is primarily controlled by the rapid diffusion of the drug within the oil droplet. This confirms our previous claims that existing methods, such as dialysis or centrifugation, are too slow to provide useful release data for drug-containing emulsions, and demonstrates that it is unlikely that a simple emulsion could be used as a circulating sustained-release formulation, as has been suggested by some workers.