UniORV, a New Multi-Unit Dosage Form, Improved Biopharmaceutical Properties of Tacrolimus in Rats and Humans.

PURPOSE: The aim of the present study was to develop a new multi-unit dosage formulation, Universal ORbicular Vehicle (UniORV), to improve the biopharmaceutical properties of tacrolimus (TAC). METHODS: TAC-loaded UniORV (UO/TAC) was produced by the dripping and gelling of a solution comprising TAC, gelatin, starch syrup, and triethyl citrate at 0.5 w/w% drug loading. Its microstructure was elucidated by polarized light microscopy and the Raman mapping technique. The pharmacokinetic profiles of TAC after the oral administration of UO/TAC were evaluated in rats and healthy humans. RESULTS: The dissolution behavior of UO/TAC was similar to that of commercial capsules, and the formation of nanoparticles was detected by TEM in dissolved media. In a stability study on UO/TAC, only 2.6 and 4.7% decreases in TAC concentrations were observed at 40± 2°C/75 ± 5% relative humidity for 4 months and at 50± 2°C for 2 months, respectively. A pharmacokinetic study on rats revealed a 30-fold higher AUC than that with crystalline TAC. A randomized double-blind crossover study on 8 healthy males showed that UniORV achieved a 1.4-fold increase in AUC and 34% decrease in inter-individual variation from the reference formulation. CONCLUSION: The new dosage form UniORV is a promising approach to improve the dissolution, amorphous stability, and biopharmaceutical properties of TAC, which is a poorly water-soluble drug.

Cyclosporine a-loaded UniORV®: Pharmacokinetic and safety characterization.

This study aimed to improve pharmacokinetic behavior and reduce safety concern of cyclosporine A (CsA) by UniORV® approach, a new platform for solid dispersion formulation. CsA-loaded UniORV® (UO/CsA) was prepared, and its physicochemical properties were evaluated in terms of droplet size distribution and dissolution. The pharmacokinetic behavior and nephrotoxic potential of orally-dosed CsA samples (10 mg-CsA/kg) were assessed in rats. After re-dispersion of UO/CsA in water, fine droplets were observed, and the mean diameter of droplets was calculated to be 45 nm. The UniORV® approach markedly improved the dissolution behavior compared with amorphous CsA in water. After oral administration of amorphous CsA, Neoral®, and UO/CsA in rats, UO/CsA exhibited a 32% lower maximum concentration and 5.1 h longer mean residence time than those of Neoral®. The oral absorption of CsA formulations was higher compared with amorphous CsA; in particular, the oral bioavailability of UO/CsA was 71-fold higher than that of amorphous CsA. Neoral® elicited nephrotoxicity with plasma creatinine level of 1.29 mg/dL; however, Neoral®-induced nephrotoxicity was attenuated in UO/CsA, as evidenced by a 15% lower plasma creatinine level of UO/CsA than that of Neoral®. From these findings, UO/CsA might be a promising dosage form with improved biopharmaceutical properties of CsA.

A novel protein phosphorylation pathway involved in osmotic-stress response in tobacco plants.

Osmotic stress is one of the severest environmental pressures for plants, commonly occurring under natural growing condition due to drought, salinity, cold and wounding. Plants sensitively respond to these stresses by activating a set of genes, which encode proteins necessary to overcome the crises. We screened such genes from tobacco plants, and identified a particular clone, which encoded a 45 kDa protein kinase belonging to the plant receptor-like cytoplasmic protein kinase class-VII, NAK (novel Arabidopsis protein kinase) group. The clone was consequently designated as NtNAK (Nicotiana tabacum NAK, accession number: DQ447159). GFP-NtNAK fusion protein was localized in both cytoplasm and nucleus, and bacterially expressed NtNAK exhibited in vitro kinase activity. Its transcripts were clearly induced upon treatments of leaves with salt, mannitol, low temperature and also with abscisic and jasmonic acids and ethylene. These properties indicated NtNAK to be a typical osmo-stress-responsive protein kinase. Its target protein(s) were then screened by the yeast two-hybrid system, and one clone encoding a 32 kDa protein was identified. The protein resembled a potato stress-responsive protein CK251806, and designated as NtCK25 (accession number: DQ448851). Bacterially expressed NtCK25 was phosphorylated by NtNAK, and NtCK25-GFP fusion protein was exclusively localized in nucleus. The structure of NtCK25 was found to be similar to a human nuclear body protein, SP110, which is involved in DNA/protein binding regulation. This suggested that, perceiving osmo-stress signal, NtNAK phosphorylates and activates NtCK25, which might function in regulation of nucleus function. The present study thus suggests that NtNAK/NtCK25 constitutes a novel phosphorylation pathway for osmotic-stress response in plants.