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Objective To prepare everolimus self-microemulsifying drug delivery systems (Everolimus-SMEDDS) and evaluate its physicochemical properties.Methods Everolimus-SMEDDS were developed by using rational blends of components with good solubilizing ability for everolimus which were selected based on solubility investigation.Then, pseudo-ternary phase diagram was constructed to determine the self-emulsifying region.The appearance, morphology, particle size distribution, Zeta potential and in vitro drug release behavior of Everolimus-SMEDDS were investigated after being diluted by water.Results An optimal Everolimus-SMEDDS consisting of ethylis oleas, Solutol HS 15 and propylene glycol were identified, and the optimum proportion was 8∶1∶1.Upon mixing with water, Everolimus-SMEDDS formed a clear and transparent microemulsion solution with homogeneous small spherical as seen in transmission electron microscopy.Particle size and Zeta potential of Everolimus-SMEDDS were found to be (48.7±25.1) nm and (-14.2±2.5) mV, respectively.The in vitro release profile indicated that the accumulated release of everolimus in SMEDDS reached up to nearly 100% within 30 min.Conclusion The in vitro dissolution of everolimus was remarkably improved by SMEDDS.It can provide reference for the new dosage form of everolimus.
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OBJECTIVE:To investigate the effects of hydrophilic polymers on the stability of self-microemulsifying drug deliv-ery systems (SMEDDS). METHODS:Taking felodipine (FDP) as model drug,the content of FDP was determined by HPLC method. The effects of pure water,0.5% Kollidon VA64,HPMC E5,HPMC K100LV,HPMC K4M,PVP K30 solution,while 0.1%,0.5% and 1.0% HPMC E5 and Kollidon VA64 on residual content of dissolved FDP were determined in SMEDDS. RE-SULTS:The residual contents of dissolved FDP in SMEDDS placed in Kollidon VA64,HPMC E5,HPMC K100LV,PVP K30, HPMC K4M and pure water for 1 h were 92.7%,63.6%,50.2%,46.2%,36.0%and 24.0%,respectively. The order of maintain-ing the supersaturation state was Kollidon VA64>HPMC E5>HPMC K100LV>PVP K30>HPMC K4M>pure water. The residu-al contents of dissolved FDP in SMEDDS placed in 0.1%,0.5%,1% Kollidon VA64 and HPMC E5 and pure water for 1 h were 93.2%,95.1%,96.0% and 48.4%,62.1%,75.1%. CONCLUSIONS:Kollidon VA64 and HPMC E5 can significantly inhibit drug release in SMEDDS and be used as stabilizer of SMEDDS,wherein Kollidon VA64 was better.
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This study examined the effect of self-microemulsiflying drug delivery system (SMEDDS) containing Cremophor RH40 or Tween 80 at various dilutions on cytochrome P450 3A (CYP3A) enzymes in rat hepatocytes, with midazolam serving as a CYP3A substrate. The particle size and zeta potential of microemulsions were evaluated upon dilution with aqueous medium. In vitro release was detected by a dialysis method in reverse. The effects of SMEDDS at different dilutions and surfactants at different concentrations on the metabolism of MDZ were investigated in murine hepatocytes. The cytotoxicity of SMEDDS at different dilutions was measured by LDH release and MTT technique. The effects of SMEDDS on the CYP3A enzymes activity were determined by Western blotting. Our results showed that dilution had less effect on the particle size and zeta potential in the range from 1:25 to 1:500. The MDZ was completely released in 10 h. A significant decrease in the formation of 1'-OH-MDZ in rat hepatocytes was observed after treatment with both SMEDDS at dilutions ranging from 1:50 to 1:250 and Cremophor RH 40 or Tween 80 at concentrations ranging from 0.1% to 1% (w/v), with no cytotoxicity observed. A significant decrease in CYP3A protein expression was observed in cells by Western blotting in the presence of either Cremophor RH40 or Tween 80-based SMEDDS at the dilutions ranging from 1:50 to 1:250. This study suggested that the excipient inhibitor-based formulation is a potential protective platform for decreasing metabolism of sensitive drugs that are CYP3A substrates.