Development and evaluation of rhubarb free anthraquinones loaded self-nanoemulsifying tablets

Abstract The paper aims to design and prepare rhubarb free anthraquinones (RhA) loaded solid self-nanoemulsifying drug delivery system (S-SNEDDS) to improve RhA's solubility and physical stability of RhA loaded nano emulsion. Suitable adsorbents of pre-concentrated RhA loaded nano emulsion were selected based on saturated adsorption capacity, flowability and reconsitution properties. The possible interactions among RhA, adsorbents and other excipients were investigated using powder X-ray diffraction and FTIR spectroscopy. RhA loaded SNEDDS tablets were designed and optimized using central composite design. In vitro dissolution, pharmacokinetics and stress stability were comparatively conducted to validate the advantages of RhA loaded SNEDDS tablets. No chemical interactions existed between the main materials. The optimal RhA loaded SNEDDS tablet formulation consisted of 1:1(w/w) Neusilin US2/pre-concentrated RhA loaded nanoemulsion, 5.0% (w/w) PVPP, 1% (w/w) Mg stearate. More than 90% RhA released from RhA loaded SNEDDS tablets while less than 10% were released from control tablets within 360 min. RhA in the SNEDDS tablets showed much improved absorption in comparison to control tablets. The percentage contents of RhA in the SNEDDS tablets were decreased more slowly than in RhA loaded nanoemlusion under stress conditions. The current study suggests that RhA loaded SNEDDS tablets could be an effective approach to improve RhA's solubility, bioavailability and physical stability of RhA loaded nanoemulsion.