Monomolecular Films as a Model to Study Photosensitized Reactions

Synopsis--The effect of drugs on the permeability of cell membranes has been related to their surface activity and ability to interact with MONOMOLEGULAR FILMS. It was of interest, therefore, to determine the influence of ULTR•.V•OLET IRRADIATION on these properties of a series of potential PI•OTOSENS•TIZ•Ng DRWS. Chlorpromazine, promazine, triflupromazine, prochlorperazine, trifluoperazine, and fluphenazine were the drugs used. Monomolecular films of dipahnitoyl lecith,_'n (DPL) were spread onto an aqueous subphase into which one ot the drugs had been dissolved. The drug-film system was exposed to ultraviolet irradia-tion and resultant changes in the DRUG-F•LM INTERACTION were determined. Only chloropro-mazine and prochlorperazine exhibited an immediate, increased interaction with the film tollowing irradiation. Solutions of these same drugs also were irradiated in the absence of the film and changes in surface pressure were determined. Only chlorpromazine and pro-chlorperazine showed a steady increase in surface pressure during the period of irradiation. A relationship between irradiation-induced changes in surface pressure and reactivity toward a monomolecular film and in vivo photosensitizing properties was developed. A PUOTO-TOXIC INDEX was calculated and related to in vivo data