Fluid properties of solvents and oils used in in situ forming microparticles

Abstract

In situ forming microparticle (ISM) has been recently used as the injectable drug delivery system prepared from polymeric non-aqueous phase in oil emulsion. Solvents and oils used in ISM including N-methyl pyrrolidone (NMP), 2-pyrrolidone (PYR), dimethyl sulfoxide (DMSO), glycofurol, triacetin, olive oil, camellia oil and isopropyl myristate (IPM) were evaluated for pH, density, viscosity, flow time, surface tension, contact angle, color distribution, injectability, antimicrobial activities and cytotoxicity. The most viscous camellia oil and olive oil showed the highest flow time with lowest color diffusion and lower injectability; thus, they were suitable for performing as external phase of ISM to prolong drug release. Lower viscosity of NMP with low contact angle promoted its rapid wetting and faster color diffusion rate. All the solvents inhibited C. albicans more effective than bacteria. DMSO showed the lowest cytotoxicity against HCT116 human colorectal carcinoma cell among tested solvents which was followed by PYR, NMP, triacetin and glycofurol, respectively. These obtained fluid properties of solvents provide the useful information for preparation of ISM for drug delivery. Camellia oil and olive oil demonstrated their potency for using as external phase while NMP with its good injectability/ antimicrobial activities exhibited the most suitable solvent of internal phase of ISM.