Pulsed plasma surface modified omeprazole microparticles for delayed release application

Abstract In the present work, pulsed radio frequency (RF) plasma (PRFP) was used to functionalize omeprazole (OME) microparticles using precursor monomers methacrylic acid (MAA) and methyl methacrylate (MMA). This method had two significant factors involved – 1) ratio of monomer flow rate and 2) graded deposition by systematically varying the duty cycle of pulsed plasma. The MAA flow was set to 100 cc/min and MMA to 200 cc/min to rationalize the ratio (1:2) of monomers. Systematic variation in duty cycle (keeping ON time constant and increasing OFF time of the pulse) ensured graded deposition and functionalization of OME. The plasma functionalized OME microparticles were evaluated in-vitro via dissolution studies in pH 1.2 buffer showed a cumulative release of 3.6–9.1% within 120 min compared to complete release under 60 min in pH 6.8. Raman analysis exhibited the absence of peaks from 1800 to 1000 cm−1 and XPS studies showed an increase in oxygen-containing moieties on plasma functionalized OME surface. Thermal, NMR and HR-MS analysis confirmed successful deposition without alteration in original OME molecular structure. The decreased contact angle of post plasma treated OME resulted from hydrophilization of the OME surface. XRD data of plasma treated OME showed an improved degree of crystallinity with an increase in average crystallite size. Post plasma treated OME microparticles size through DLS corroborated well with SEM. Thus, the use of graded PRFP functionalization has proved it's potent to deliver a new, safe, and cheaper alternative to contemporary drug surface modification methods.