School of Pharmacy, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.
Int J Pharm. 2012 Aug 20;433(1-2):142-8. doi: 10.1016/j.ijpharm.2012.05.011. Epub 2012 May 14.
Naltrexone hydrochloride (NTX) is a promising treatment for corneal disorders linked to diabetes mellitus (diabetic keratopathy). However, NTX has a major stability problem due to autoxidation, which is likely to hinder its formulation as eye drops for treatment of diabetic keratopathy. In this study, in-house developed NTX non-ionic surfactant vesicles (niosomes and discomes) were evaluated for their spreading, rheological properties and their ability to impede the inevitable autoxidation of NTX in aqueous solutions. The measured contact angles and spreading coefficients for niosomes reflected significantly (P<0.05) better wetting and spreading abilities than the aqueous vehicle. The prepared niosomes were significantly more viscous (P<0.05) than the aqueous solution. The lipid content, size and composition of niosomes are the main factors affecting the viscosity of niosomal dispersions. Exposure of NTX solution to artificial daylight illumination (10,000 lux) can produce extensive degradation of NTX due to oxidation. The prepared formulations were able to significantly (P<0.05) protect the encapsulated NTX from the photo-induced oxidation compared with free NTX solutions. The investigated niosomes lend themselves as a potential ocular delivery modality for NTX.
盐酸纳曲酮（NTX）是一种有前途的治疗与糖尿病相关的角膜疾病（糖尿病性角膜病变）的方法。然而，由于自氧化，NTX 存在严重的稳定性问题，这可能会阻碍其作为治疗糖尿病性角膜病变的滴眼剂的配方。在这项研究中，我们评估了内部开发的 NTX 非离子表面活性剂囊泡（niosomes 和 discomes）在水基溶液中的铺展、流变性能以及抑制 NTX 不可避免的自氧化的能力。niosomes 的测量接触角和铺展系数明显（P<0.05）反映出比水性载体更好的润湿性和铺展能力。制备的 niosomes 的粘度明显（P<0.05）高于水溶液。niosomes 的脂质含量、大小和组成是影响其分散体粘度的主要因素。将 NTX 溶液暴露于人工日光照射（10,000 lux）下会因氧化而导致 NTX 广泛降解。与游离 NTX 溶液相比，所制备的制剂能够显著（P<0.05）保护包封的 NTX 免受光诱导氧化。所研究的 niosomes 可作为 NTX 的潜在眼部递药方式。
