Abstract
BackgroundDrugs photostability plays two different opposite roles; a real advantage arises considering the longer expiration time of the drugs while the consequent persistence in the environment involves an obvious negative effect bound to their harmfulness.On this basis we tested the photostability and toxicity of three pharmaceutical active principles: Finasteride, Diclofenac and Naproxen. The pure active principles, as well as commercial drugs containing them, were considered; for the last, the protective effect of the packaging was also evaluated. Samples were irradiated according to the ICH Guidelines for photostability testing (The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use); a simulating sunlight source (a mercury-vapor lamp coupled to a tungsten filament one) was used to cover the wavelength range 300–2000 nm; Temperature, Relative Humidity, Irradiance and Illuminance were maintained constant during the photodegradation. The concentrations of the pharmaceutical active principles during the photodegradation were monitored by HPLC with UV/Vis detector. Toxicity tests were performed by means of an amperometric biosensor based on suspended yeast cells. Since the products obtained by the photodegradation process can result as toxic or more toxic than the original molecules, tests were performed first and after the photodegadation.ResultsAfter 90 hours of exposure the concentration resulted lowered by 42.9%, 88.4% and 91% for Finasteride, Naproxen and Diclofenac respectively. Toxicity of the pure active principles follows the same order of the photostability. After photodegradation a contribute of the reaction products was evidenced.ConclusionsThe simple and cheap analytical procedure here proposed, allowed to obtain not only data on photostability and toxicity of the pure active principles but, even if roughly, also useful information on the reactions kinetic and toxicity of the photodegradation products.
Highlights
Drugs photostability plays two different opposite roles; a real advantage arises considering the longer expiration time of the drugs while the consequent persistence in the environment involves an obvious negative effect bound to their harmfulness
Even if simple and cheap, the proposed procedure can be a starting point to obtain useful information about the fate of drugs entering the environment as a consequence of the normal metabolic processes or bad wasting and so on; a more complex procedure is needed to take into account the very low concentration up today found there [10]
The proposed procedure can be of help in optimizing the process conditions adopted in water treatment plants of pharmaceutical industries; in such case, the concentration is enough high and its decrease need to be speeded up using, as an example, heterogeneous photocatalysis through UV irradiation catalyzed by TiO2 that can be combined with visible and/or microwaves irradiation [24,25]. In these cases the coupling of the two analytical techniques, HPLC and toxicity tests, allows us to achieve the goal of obtaining data on the photostability and on non-specific toxicity of the active ingredients and, though roughly, of the photodegradation products
Summary
Drugs photostability plays two different opposite roles; a real advantage arises considering the longer expiration time of the drugs while the consequent persistence in the environment involves an obvious negative effect bound to their harmfulness. On this basis we tested the photostability and toxicity of three pharmaceutical active principles: Finasteride, Diclofenac and Naproxen. The topic received scarce attention due to the incorrect belief that the packaging could protect the active principle so avoiding its photodegradation [2] This led to a limited knowledge of the phenomenon until relatively recent time. Degradation products could be more toxic than the starting reagents causing side effects on humans and producing unknown biological effects and new risks for ecosystems
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