Drug delivery systems are essential components of drugs controlled release. In the last decades, several drug delivery technologies have emerged including capsules, liposomes, microparticles, nanoparticles, and polymers. These components must be biocompatible, biodegradable, and display a desired biodistribution providing a long-term availability of the therapeutic at specific target over time.

To achieve effective drug concentration at the intended site for a sufficient period of time is a requisite desired for many drug formulations. For drugs intended to ocular delivery, its poor bioavailability is due to pre-corneal factors. Most ocular diseases are treated by topical drug application in the form of solution, suspension and ointment. However, such dosage forms are no longer sufficient to combat some ocular diseases. Intravitreal drug injection is the current therapy for disorders in posterior segment. The procedure is associated with a high risk of complications, particularly when frequent, repeated injections are required. Thus, sustained-release technologies are being proposed, and the benefits of using colloidal carriers in intravitreal injections are currently under investigation for posterior drug delivery. This review will discuss recent progress and specific development issues relating to colloidal drug delivery systems, such as liposomes, niosomes, nanoparticles, and microemulsions in ocular drug delivery.

The use of the nasal route for drug delivery has attracted much interest in recent years in the pharmaceutical field. Local and principally systemic drug delivery can be achieved by this route of administration. But the nasal route of delivery is not applicable to all drugs. Polar drugs and some macromolecules are not absorbed in sufficient concentration due to poor membrane permeability, rapid clearance and enzymatic degradation into the nasal cavity. Thus, alternative means that help overcome these nasal barriers are currently in development. Absorption enhancers such as phospholipids and surfactants are constantly used, but care must be taken in relation to their concentration. Drug delivery systems including liposomes, cyclodextrins, micro- and nanoparticles are being investigated to increase the bioavailability of drugs delivered intranasally. This review article discusses recent progress and specific development issues relating to colloidal drug delivery systems in nasal drug delivery.

This paper describes the development and in vitro evaluation of poly(lactic-co-glycolic acid) (PLGA) nanoparticles coated with chitosan (CS) for oral delivery of ferulic acid (FA). Nanoparticles were obtained by an emulsion evaporation technique and characterized. Furthermore, we evaluated the scavenging activity over hypochlorous acid (HOCl), the cytotoxicity over tumour cells and the in vitro intestinal permeability. Nanoparticles were spherical with a mean diameter of 242 nm, positive zeta potential and 50% of encapsulation efficiency. The in vitro release in phosphate buffered saline (PBS) (pH 7.4) demonstrated a prolonged and biphasic profile diffusion-controlled. In simulated gastrointestinal fluids, about 15% of FA was released in gastric fluid and a negligible release was observed in the intestinal fluid. In the HOCl scavenging activity and cytotoxicity over B16-F10 and HeLa cells, FA-loaded nanoparticles presented the same efficacy of the free drug. Besides, in the antioxidant and cytotoxic assay, CS contributed to FA effects. In the intestinal permeability study, FA-loaded nanoparticles exhibited a permeation of 6% through the Caco-2 monolayer and 20% through the Caco-2/HT29-MTX/Raji B co-culture. CS-coated PLGA nanoparticles are promising carriers for oral delivery of FA.