Ultrafast laser processing of drug particles in water for pharmaceutical discovery

The laser fragmentation technique has been extensively used to produce inorganic nanoparticles, but its practice on organic materials, especially on drugs, is less common. Here, we briefly review the recent advances in laser micro-/nanonization of organic materials and the rationale of using laser fragmentation for drug discovery. We present our case studies of two drug models: fenofibrate and naproxen. Both drugs were fragmented in water with femtosecond (fs) laser and characterized in terms of particle size distribution and physicochemical properties. Effects of fs laser fragmentation were also compared with nanosecond (ns) laser fragmentation and with conventional media milling technique. Fs laser was more suitable to produce sub-micron size drug particles than ns laser, but degradation of drugs after nanonization was also more pronounced than micronization. Physicochemical transformations such as oxidation, hydration and amorphisation might occur during the laser–material interactions. Laser nanonization showed improved dissolution kinetics, similar to media milling. Unlike the conventional milling techniques, laser fragmentation enabled the treatment of minute amount (as small as several milligrams) of drugs with high efficiency, thus is a useful tool for particle size reduction during the early phases of drug discovery.