Loading efficiency of stavudine on polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate copolymer nanoparticles.

Loading efficiency (LE) of stavudine (D4T), a human immunodeficiency antiretroviral agent, on the external surfaces of polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) was investigated. The experimental results indicate that the larger the polymeric nanoparticles (NPs), the smaller LE of D4T on the two kinds of biomaterials. Freeze drying of the two NPs, however, yields an increase in particle size and an increase in LE of D4T, in general. Preservation of the two D4T-loaded NPs through cold storage at 4 degrees C over 6 weeks leads to an increase in particle size and a decrease in LE of D4T. LE of D4T on both of the two NPs decreases with a variation in pH value from pH 7.2 of loading medium. LE of D4T on MMA-SPM NPs is larger than that on PBCA NPs at pH 7.4; and for the case of variation in pH value of loading medium from pH 7.2, the extent of decrease in LE of D4T for MMA-SPM NPs is higher than that on PBCA NPs. These outcomes imply that for oral administration, D4T-loaded MMA-SPM NPs may be more advantageous than D4T-loaded PBCA NPs, and D4T-loaded PBCA NPs may be more favorable than D4T-loaded MMA-SPM NPs for intravenous injection.