Kaur Indu Pal, Chhabra Sonia, Aggarwal Deepika
University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh-160 014. India. indupalkaur@ yahoo.com
Curr Drug Deliv. 2004 Oct;1(4):351-60. doi: 10.2174/1567201043334623.
Cyclodextrins are oligosaccharides having outer hydrophilic surface and central hydrophobic cavity. These agents form inclusion complexes with poorly water-soluble drugs; hence they show an important implication for use in ophthalmics because of their applications in solubilising and stabilising the ocular drugs. Most of the drugs being used in ophthalmics were not tailor-made for the eye and considering the poor bioavailability of <1% from the corneal surface, presentation of the drug in a soluble form and at high concentration is important. Provision of a high drug concentration at the corneal surface increases the percent drug permeation indicating the usefulness of cyclodextrins as penetration enhancers. A decrease in irritation potential of some drugs upon incorporation of cyclodextrins is also reported. Polymer-cyclodextrin multicomponent systems further extend the role of cyclodextrins in improving the solubility and bioavilability of ocular drugs. Large hydrophilic cyclodextrins like hydroxypropyl-beta-cyclodextrin and sulphobutylether-beta-cyclodextrin are safe for the use in aqueous eye drop solutions especially since they do not cross the lipophilic cornea. Various aspects about the applications of cyclodextrins in ophthalmics, the formulation considerations and expected toxicity of cyclodextrins (especially if high concentration is used) is discussed in this review. Strategies like use of polymers to reduce the effective concentration of cyclodextrin required without compromising solubility are also included. Further the concept of incorporating the drug-cyclodextrin complexes into liposomes or niosomes for a better targeting of the drug at appropriate tissue destination is discussed as a possible future option.
环糊精是一类具有外部亲水性表面和中心疏水性空腔的寡糖。这些药剂能与水溶性差的药物形成包合物；因此，由于它们在增溶和稳定眼部药物方面的应用，在眼科领域具有重要意义。大多数眼科用药并非专门为眼部设计，考虑到药物从角膜表面的生物利用度低于1%，以可溶形式且高浓度呈现药物很重要。在角膜表面提供高药物浓度可提高药物渗透百分比，这表明环糊精作为渗透促进剂的有效性。也有报道称，一些药物加入环糊精后刺激性降低。聚合物 - 环糊精多组分体系进一步扩展了环糊精在提高眼部药物溶解度和生物利用度方面的作用。像羟丙基 - β - 环糊精和磺丁基醚 - β - 环糊精这样的大型亲水性环糊精在水性滴眼液中使用是安全的，特别是因为它们不会穿过亲脂性角膜。本文综述了环糊精在眼科应用的各个方面、制剂考虑因素以及环糊精的预期毒性（特别是如果使用高浓度时）。还包括了如使用聚合物在不影响溶解度的情况下降低所需环糊精有效浓度的策略。此外，还讨论了将药物 - 环糊精复合物包封到脂质体或非离子表面活性剂泡囊中，以便将药物更好地靶向到适当组织部位的概念，作为一种可能的未来选择。
