Spring and parachute approach for piroxicam dissolution; its phenomenological model on the thermodynamics of irreversible processes.

Even though the spring and parachute approach for poorly water-soluble drug candidates effectively improves their dissolution curves with eutectic mixtures, deep eutectic solvents, solid dispersion polymers, and solid solutions, we cannot consider that its enabling factor in these pharmaceutical modifications was enough to be clarified. Based on our previous study that oxybuprocaine acts as a role of parachute generator for piroxicam, the present study explored a small-molecule parachute generator and found that propranolol, a β-adrenergic-blocking drug, has a parachute effect on the supersaturated state of piroxicam. In addition, changing the concentration of tetracaine and dibucaine to 10 mM and 2.5 mM also showed a parachute effect. These parachute generators control piroxicam's dissolved state kinetically by making the supersaturated state of piroxicam a steady state. However, as the piroxicam anhydrous crystals diminished and the piroxicam monohydrate crystals grew due to Ostwald ripening, it led to attenuating the supersaturated state. This finding advances the elucidation of the mechanism of the parachute effect of polymers.