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Phenothiazine exposed to white light or UV radiation undergoes a variety of reactions that result in the degradation of the parental compound and the formation of new species. Chlorpromazine exposed to the 266 nm laser beam of given energy levels yielded s pecies derived from it, whose number increased with the exposure duration. At distinct time intervals the irradiation products were evaluated by spectrophotometry between 200 -1500 nm, T hin L ayer C hromatography, and for antimicrobial act ivity of Chlorpromaz ine against different test organisms such as Staphylococcus aureus . Keywords: Ch lorpromazine, CPZ, Promazine, PZ, TLC , absorption spectroscopy, photo -degradation . 1. INTRODUCTION Ph enothiazine s are labeled as pharmaceutical s since 1950s and their derivatives are powerful antihistamines used as neuroleptics [1] . Chlorpromazine (CPZ) , a phenothiazine derivative, is used for its sedative and antipsychotic properties for over 40 years [2]. A significant number of drugs used curre ntly in medicine have their bas es in the chemical manipulation of phenothiazine s [3]. Creating new derivatives t hrough a chemical pathway is limited by the existing organic chemistry and it is also time consuming . N ew derivatives of current drugs with a be tter activity against bacteria which acquired multidrug resistan ce (MDR) at treatments with antibiotics may be obtained by exposure of the existing medicines to UV light. E xperiments dating from 1963 to 1667 [4 , 5] were made using an incoherent UV source , but the exposure time of the medicines was too long and time consuming : C PZ was expose d up to 5 -7 days to the UV lamp. A s a consequence, a better solution seems to be the use of a coherent source of light, such as a laser. The difference between using an UV instead of an incoherent UV light source is that a laser has a specific wavelength that may be as narrow as 10

One of the alternatives to the existing medicines and treatment procedures in fighting multi drug resistance (MDR) is strengthening the effects of medicines by modifying their molecular structures through exposure to laser radiation. A method associated with this, is the generation of micro-droplets which contain medicines solutions; the droplets are utilized/produced as vectors to transport the medicines to targets. In our studies we try to combine these two methods in order to obtain a new technique to deliver the efficient medicines to targets that can be applied for a relative large number of chemicals. For this purpose we have developed an experimental set-up containing a liquid droplets generator, a tunable laser source used to irradiate droplets, a subunit to measure the laser induced fluorescence (LIF) signals and a real time recording system for droplet image analysis. Measurements on different probes, like ultrapure water, commercial grade medicines, newly developed medicines and laser dyes were performed.. All these measurements were performed on waterbased solutions. We present in this paper the laser induced fluorescence measurements results on medicine solutions (in bulk or in a micro-droplet form) that exhibit important modifications after the exposure at laser radiation. It was evidenced that the exposures to laser beams/coherent optical radiation of some medicines solutions in ultrapure water may produce molecular modifications in solutions. These slight modifications of the molecules made them more efficient against bacteria strains.