PHOTODEGRADATION OF ANTIMYCOTIC DRUGS .2. PHOTODEGRADATION OF POLYENEANTIBIOTICS

The polyene antibiotics amphotericin B, natamycin and nystatin are rap idly degraded under the influence of light, Amphotericin B as a heptae ne has a markedly higher photostability than the tetraenes natamycin a nd nystatin. With a new HPLC method for the separation of the differen t polyene components we could perform a quantitative analysis of the p hotodegradation process, Initially degradation products with unchanged spectrophotometric absorption spectra are formed from each of the thr ee polyene antibiotics. Longer light exposure leads to the subsequent degradation of the polyene structures. This photochemical instability was also detected in various drug products with polyene antibiotics as active ingredient. On direct sun exposure of topically applied polyen e antibiotics a pronounced photodeactivation of the drug substances is expected.