Prabhakar Reddy

The present study involves the formulation and evaluation of o/w nanoemulsions with two simple edible oils in micro-liter quantities, avoiding large quantities of surfactants and co-surfactants. The nanoemulsions were prepared by high energy emulsification technique. The process optimization was based on the particle size, size distribution and entrapment efficiency in relation with the quantity of oil and concentration of surfactant. The percent drug content was determined by HPLC with UV detector. The particle size, polydispersity index (PDI), and zeta potential of nanoemulsions were determined by using particle sizer. Stability studies at 4°C for two months, centrifugation and freeze-thaw cycling were carried out.  Pharmacokinetic studies of nanoemulsion and marketed dosage form were performed in male SD rats and blood plasma samples were analyzed by LC-MS/MS. The particle size, polydispersity index (PDI), and zeta potential of nanoemulsions were found to be in the range of 26.8±0.72 to 154.6±11.4 nm, 0.09±0.01 to 0.28±0.06 and 0.07±0.01 to -28±0.65 mv respectively. Transmission electron microscopy (TEM) and stability studies revealed the physical stability of the nanoemulsions. The percent drug content was found to be in the range of 73.74±3.79 to 101.16±1.35. The oral bio-availability was significantly increased in nanoemulsion compared with the marketed dosage form. These results showed a successful incorporation of felodipine into nanoemulsion with high drug loading efficiency and good stability. Key words: Sesame oil, olive oil, felodipine, sonication, Oral bioavailability.

  The aim of the present study was to prepare and characterize twice-daily sustained-release matrix tablets of Timolol maleate (TM) using different concentrations of hydrophilic Hydroxypropylmethylcellulose (HPMC K100M CR) alone and its combination with hydrophobic ethyl cellulose (EC). Formulations prepared by the wet granulation technique and were evaluated for the release of TM over a period of 12 hours using United States Pharmacopoeia (USP) type-II dissolution apparatus. Along with physical properties, the dynamics of water uptake and erosion degree of tablets were also studied. The in-vitro drug release study revealed that formulation F3 (40% wt/wt HPMC K100M) could extend the drug release up to 8 hours. The most successful formulation of the study, F5 (HPMC to EC, 1:1), extended the drug release up to 12 hours, exhibited satisfactory drug release in the initial hours, and the total release pattern was close to the theoretical release profile. The drug release from optimized formulation (F5) followed first-order kinetics via Non-Fickian (anomalous) diffusion. FTIR studies revealed that there was no interaction between the drug and excipients. In conclusion, the results indicated that the prepared sustained-release tablets of TM could perform therapeutically better than conventional tablets with improved efficacy and better patient compliance.   Key words: Timolol maleate; Matrix tablets; Sustained-release; Ethyl cellulose; Hydroxypropylmethylcellulose; In-vitro drug release.