Proniosomes: A provesicular system in ocular drug delivery

The eyes are the only sense organ required for vision. Diseases like glaucoma, cataract, diabetic retinopathy etc. affect the proper functioning of the eyes and sometimes lead to blindness. The treatment of eye disorders is very challenging because of the unique structure of this organ. The traditional treatment approaches are not effective in providing good ocular bioavailability. The provesicular systems are new-generation delivery systems that can improve drug bioavailability and provide therapeutic responses in a controlled manner for desired time. Among all, liposomes are the first such delivery vehicle but due to the lack of stability and the high cost, niosomes were formulated. Niosomes are nanosized vesicles composed of non-ionic surfactants that can encapsulate both lipophilic and hydrophilic drugs. The drawbacks associated with niosomes, like fusion, aggregation, sedimentation, difficulty in sterilization, leaking, etc., gave birth to proniosomes. Proniosomes are more stable and bioavailable than niosomes and liposomes. Proniosomes are dry formulations of hydrophilic carrier particles coated with a water-soluble non-ionic surfactant that, when hydrated, instantly transforms into niosomes. Proniosomes can be used as stable, non-toxic carrier carriers to improve the ocular residence and bioavailability of many drugs. This paper reviewed proniosomes, their biomedical applications and their toxicity in ocular drug delivery.