PERCUTANEOUS ABSORPTIOMETRY BY A LASER PH OTOACOUSTIC METHOD AND ITS APPLICATIONS

Skin plays not only a physical role as the shelter for the living body but also many important biological roles. Observing the out- or insid e of skin by the photoacoustic (PA) method, new information that is di fficult to measure can be detected. We have attempted to measure the p ercutaneous absorption of chemical substances in order to investigate the effect and the toxicity of medicinal compounds. To do this, we had to develop a PA cell that could detect a chemical substance on skin w ith high sensitivity and accuracy. Several such investigations have be en reported; however the conventional open-ended PA cells had unfavora ble signal to noise ratio (SIN) and sensitivity. We have reported the development of percutaneous absorptiometry using the laser PA method. A series of in vitro and in vivo percutaneous absorptiometries was per formed. As a result, if was concluded that this PA method is applicabl e to percutaneous absorption in situ.