Supercritical antisolvent coprecipitation in the pharmaceutical field: Different polymeric carriers for different drug releases

The supercritical antisolvent process (SAS) was employed to obtain polymer/drug coprecipitated powders. Indeed, processes based on the use of supercritical fluids allow us to obtain polymer/active drug coprecipitated microparticles with tunable bioavailability. In this work, two different biocompatible polymers were selected to be used as carriers for obtaining drug microparticles with different releases for different applications: polyvinylpyrrolidone (PVP) was coprecipitated with ketoprofen to obtain a rapid drug release and zein was coprecipitated with ampicillin to obtain a controlled drug release. The experiments were performed both on a bench-scale and a pilot-scale plant. Ketoprofen is one of the most prescribed non-steroidal anti-inflammatory drugs. It is poorly soluble in water and, to overcome this inconvenience, in this work, it was coprecipitated with PVP. In correspondence with the optimized polymer/drug ratio, the dissolution rate of the active principle in the coprecipitated particles was about three times higher than the one of the unprocessed ketoprofen. The second model drug under study in this paper is ampicillin, a semi-synthetic penicillin that is one of the most commonly prescribed broad-spectrum antibiotics. Prolonging the release of the drug would imply a reduction in the number of administrations and, therefore, of the side effects associated with too high dosages. For this purpose, in this work, ampicillin was coprecipitated with zein. Zein/ampicillin microparticles were produced up to a polymer/drug ratio of 5/1 w/w; in this case, the antibiotic coprecipitated with zein reaches 90% of its dissolution in about 14 hours, while the unprocessed antibiotic takes about 3 hours to dissolve.