As a phenothiazine derivative, Promethazine may undergo structural modifications when it is exposed to light. This process consists in the degradation of the initial compound and in the generation of new photoproducts with possible anti-infectious qualities. Stability studies are necessary in order to establish the proper use of drug solutions in different applications. At the same time, these investigations are important in the context of the generation of side-products induced by environmental conditions that bring new benefits to the compound.
This study reports the stability of Promethazine aqueous solutions, based on their absorption spectra acquired before and after Nd:YAG laser irradiation sessions or under different temperature and illuminating storage conditions. Samples of Promethazine solutions in ultrapure water, at a concentration range between 10-6 M – 10-2 M, were kept in dark at 22°C, and 4°C as well as at 22°C in ambient light up to a time interval of three months. Absorption spectra were recorded periodically in order to determine any changes of the optical properties. Also, solutions of 20 mg/mL were exposed for different time intervals to laser radiation emitted at 266 nm by the Nd:YAG laser. The stability of the optical properties of irradiated Promethazine solutions for 4 h was investigated up to two months.
The laser irradiated samples show similar but more rapid and intense changes compared to solutions exposed to ambient light, suggesting molecular modifications that could be due to the production of more polar phenothiazine derivatives.
The study reports an investigation of the photoproducts obtained by exposure of chlorpromazine hydrochloride in ultrapure water (concentration 2 mg/mL) to a 266-nm laser beam obtained by fourth harmonic generation from a Nd:YAG laser (6-ns full time width at half maximum, 10-Hz pulse repetition rate). The photoproducts were analyzed by steady-state UV-Vis absorption, laser-induced fluorescence, Fourier transform infrared spectroscopy, and liquid chromatography–tandem time-of-flight mass spectroscopy. Two figures showing pathways that take place during irradiation for obtaining the final products are shown. The quantum yield of singlet oxygen generation by chlorpromazine (CPZ) was determined relative to standard Zn-phthalocyanine in dimethyl sulfoxide. To outline the role of fluorescence in photoproducts formation rates, fluorescence quantum yield of CPZ during exposure to 355-nm radiation (third harmonic of the fundamental beam of Nd:YAG laser) was investigated relative to standard Coumarin 1 in ethanol. The CPZ solutions exposed 60 and 240 min to 266-nm laser beam, respectively, were tested against Staphylococcus aureus ATCC 25923 strain. For 25 μL of CPZ samples irradiated 240 min, a higher diameter of inhibition has obtained against the tested strain than for the 60-min exposed ones.
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 species 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, Thin Layer Chromatography, and for antimicrobial activity of Chlorpromazine against different test organisms such as Staphylococcus aureus.
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.
The multiple resistances to treatment, developed by bacteria and malignant tumors require finding
alternatives to the existing medicines and treatment procedures. One of them is strengthening the effects of
cytostatics by improving the delivery method. Such a method is represented by the use of medicines as
micro/nano-droplets. This method can reduce the substance consumption by generating drug micro-droplets
incorporated in substances that can favour a faster localization, than the classical mode of medicine
administration, to the tumor tissues.
This paper contains the results concerning the generation and study of micro/nano-droplets and the
generation of micro-droplets with an inner core (medicine) and a thin layer covering it. We have measured the
surface tension at water/air interface and water/oil interface for a medicine (Vancomycin) and we have
generated and measured droplets of medicine containing a layer of Vitamin A by using a double capillary
system.
The micro/nano-droplets may be produced by mixing of two immiscible solutions in particular conditions (high
rotating speed and/or high pressure difference). For this we have studied the generation of emulsions of
vitamin A diluted in sunflower oil and a solution of a surfactant Tween 80 in distilled water. The concentration
of surfactant in water was typically 4*10-5M. We have studied in a batch stirred tank system the dependence
of the droplet dimensions in emulsion, function of the mixing rotation speed, agitation time and components
ratio.
The droplet diameters were measured using a Malvern light scattering instrument type Mastersizer Hydro
2000M. We have obtained droplets with diameters smaller than 100 nm; the diameters distribution exhibited a
peak at 65 nm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.