Microencapsulation of Ketoprofen in Blends of Acrylic Resins by Spray Drying

Abstract

Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1:1 and 1:3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100°C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80°C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1:3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R ², and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.

Keywords:

• Acrylic resins
• Drug release
• Microparticles
• Spray drying
• Weibull model

ACKNOWLEDGMENT

The authors thank the Foundation of Research Support of São Paulo State (FAPESP) and the National Council of Technological and Scientific Development (CNPq) for financial support.

Notes

^a Eudragit RS/RL: aqueous dispersion of ammonium methacrylate copolymer at 30% w/w (dry basis).

^b q.s. ad: A sufficient quantity calculated to make 100%.

MC = ketoprofen microparticles; MW = microparticles without ketoprofen (empty microparticles, control); T _gi  = inlet drying gas temperature; W _susp = feed flow rate of microencapsulating composition.

^a Standard deviation of the particle distribution.

MC = ketoprofen microparticles; MW = microparticles without ketoprofen (empty microparticles, control); T_go = outlet gas temperature.

T _gi  = inlet air temperature (°C); W _susp = feed flow rate (g/min).

MC = ketoprofen microparticles; MW = microparticles without ketoprofen (control); FD = free drug.