Methylmethacrylate sulfopropylmethacrylate copolymer nanoparticles for drug delivery

Development of dorzolamide loaded 6-o-carboxymethyl chitosan nanoparticles for open angle glaucoma

Chitosan (CS) is a biodegradable, biocompatible, and mucoadhesive natural polymer soluble in acidic pH only and can be irritating to the eye. Objective of the study was to synthesize water soluble 6-O-carboxymethyl (OCM-CS) derivative of CS, and to develop CS and OCM-CS nanoparticles (NPs) loaded with dorzolamide hydrochloride (DRZ). CS was reacted with monochloroacetic acid (MCA) for OCM-CS synthesis and was characterized by FT-IR, DSC, and ¹³C NMR. CS and OCM-CS NPs were prepared by ionic gelation method. Ocular irritation potential were evaluated and therapeutic efficacy was measured by reduction in intraocular pressure (IOP) in normotensive rabbits. Maximum yield was obtained when the ratio of water/isopropyl alcohol was 1/4 at 55°C. The FT-IR, DSC and ¹³C NMR confirmed the formation of an ether linkage between hydroxyl groups of CS and MCA. The particle size and zeta potential of optimised CSNPs was 250.3 ± 2.62 nm and +33.47 ± 0.723 mV, whereas those for OCM-CSNPs were 187.1 ± 2.72 nm and 30.87 ± 0.86 mV. The entrapment efficiency was significantly improved for OCM-CSNPs, compared to CSNPs. OCM-CSNPs had tailored drug release and improved bioavailability with reduction in pulse entry as compared to CSNPs. Hence, it can be concluded that DRZ loaded OCM-CSNPs would be better alternative option to available eye drops for glaucoma treatment.

Brimonidine tartrate-eudragit long-acting nanoparticles: formulation, optimization, in vitro and in vivo evaluation

In the present study, an effort was made to design prolonged release Eudragit nanoparticles of brimonidine tartrate by double emulsion-solvent evaporation technique for the treatment of open-angle glaucoma. The effect of various formulation variables like initial drug amount, lecithin proportion, phase volume and pH, secondary emulsifier and polymer proportion were studied. Various process variables like energy and duration of emulsification, lyophilization on the characteristics of nanoparticles and in vitro drug release profile were studied. The selected formulations were subjected to in vivo intraocular pressure-lowering efficacy studies by administering aqueous dispersion of nanoparticles into the lower cul de sac of glaucomatous rabbits. The prepared Eudragit-based nanoparticles were found to have narrow particle size range and improved drug loading. The investigated process and formulation variables found to have significant effect on the particle size, drug loading and entrapment efficiency, and in vitro drug release profile of nanoparticles. The selected formulations upon in vivo ocular irritability and tolerability tests were found to be well tolerated with no signs of irritation. In vivo pharmacodynamic efficacy studies revealed that the selected nanoparticle formulations significantly improved the therapy as area under the ∆IOP vs. time curve [AUC((∆IOP vs. t))] showed several fold increase in intensity and duration of intraocular pressure (IOP) decrease. All the selected nanoparticle formulations were found to prolong the drug release in vitro and prolong IOP reduction efficacy in vivo, thus rendering them as a potential carrier in developing improved drug delivery systems for the treatment of glaucoma.

Methylmethacrylate-sulfopropylmethacrylate nanoparticles with surface RMP-7 for targeting delivery of antiretroviral drugs across the blood-brain barrier

This study investigates the capability of methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) nanoparticles (NPs) with grafted RMP-7 (RMP-7/MMA-SPM NPs) to deliver stavudine (D4T), delavirdine (DLV), and saquinavir (SQV) across the blood-brain barrier (BBB). The permeability coefficients of the three drugs across the BBB were evaluated by a co-culture model containing human brain-microvascular endothelial cells and human astrocytes. An increase in the concentration of ammonium persulfate (APS), the polymerization initiator, enhanced the particle size of drug-loaded RMP-7/MMA-SPM NPs. When the concentration of APS was 0.6%, the average particle diameter was smaller than 50 nm. These spherical drug carriers were uniform in size and displayed a dominant topography of discrete hillocks and deep pits in deposited film. Smaller RMP-7/MMA-SPM NPs yielded a larger drug loading efficiency. The order of drug in the loading efficiency and in the particle uptake was, respectively, D4T>DLV>SQV and D4T>SQV>DLV. Endocytosis of RMP-7/MMA-SPM NPs and tight junction mediation can improve the permeability of D4T, DLV, and SQV across the BBB.

Ocular drug delivery - a look towards nanobioadhesives

IMPORTANCE OF THE FIELD

A major challenge emanating in the design of topical ophthalmic preparations is their short precorneal residence time. Retention of a drug delivery system in the front of the eye is thus desirable. One solution identified to address this concern is a retentive system that can preferably be delivered in a liquid drop form and ultimately remain attached to the corneal tissue owing to incorporation of a bioadhesive component. Forward-thinking approaches are required to achieve advancements in this approach for the attainment of an effective drug concentration at the site of action. Accordingly, several investigators have identified the benefits of nanotechnology-based drug delivery systems for ophthalmic drug delivery.

AREAS COVERED IN THIS REVIEW

A concerted effort was made to review critically all 'nanobioadhesives', that is, nanosystems designed for ocular drug delivery with the goal of attaining prolonged ocular retention, in a systematic, chronological manner, from their reported point of inception to the present.

WHAT THE READER WILL GAIN

A perspective on possible future trends in this growing field of ocular drug delivery is formulated.

TAKE HOME MESSAGE

The importance of and need for new developments in the field of ocular nanobioadhesives is emphasized.

Hyaluronan: pharmaceutical characterization and drug delivery

Hyaluronic acid (HA), is a polyanionic polysaccharide that consists of N-acetyl-D-glucosamine and beta-glucoronic acid. It is most frequently referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates and presents as a component of the cell coat of many strains of bacteria. Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, wound healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, and dermal routes. The purpose of our review is to describe the physical, chemical, and biological properties of native HA together with how it can be produced and assayed along with a detailed analysis of its medical and pharmaceutical applications.

Effect of nanoparticulate polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate on the permeability of zidovudine and lamivudine across the in vitro blood-brain barrier

Effect of size of nanoscaled polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) on the permeability of zidovudine (AZT) and lamivudine (3TC) across the blood-brain barrier (BBB) was investigated. Also, influence of alcohol on the permeability of AZT and 3TC incorporated with the two polymeric nanoparticles (NPs) was examined. The loading efficiency and the permeability of AZT and 3TC decreased with an increase in the particle size of the two carriers. By employing PBCA NPs, the BBB permeability of AZT and that of 3TC became, respectively, 8-20 and 10-18 folds. Application of MMA-SPM NPs leaded to about 100% increase in the BBB permeability of the two drugs. In the presence of 0.5% ethanol, 4-12% enhancement in the BBB permeability of the two drugs was obtained in the current carrier-mediated system.

Hyaluronic acid: a unique topical vehicle for the localized delivery of drugs to the skin

Hyaluronic acid (HA) is a naturally occurring polyanionic, polysaccharide that consists of N-acetyl-D-glucosamine and beta-glucoronic acid. It is present in the intercellular matrix of most vertebrate connective tissues especially skin where it has a protective, structure stabilizing and shock-absorbing role. The unique viscoelastic nature of HA along with its biocompatibility and non-immunogenicity has led to its use in a number of clinical applications, which include: the supplementation of joint fluid in arthritis; as a surgical aid in eye surgery; and to facilitate the healing and regeneration of surgical wounds. More recently, HA has been investigated as a drug delivery agent for various routes of administration, including ophthalmic, nasal, pulmonary, parenteral and topical. In fact, regulatory approval in the USA, Canada and Europe was granted recently for 3% diclofenac in 2.5% HA gel, Solaraze, for the topical treatment of actinic keratoses, which is the third most common skin complaint in the USA. The gel is well tolerated, safe and efficacious and provides an attractive, cost-effective alternative to cryoablation, curettage or dermabrasion, or treatment with 5-fluorouracil. The purpose of this review is to describe briefly the physical, chemical and biological properties of HA together with some details of its medical and pharmaceutical uses with emphasis on this more recent topical application.

Polysaccharide-decorated nanoparticles

Surface modified colloidal carriers such as nanoparticles are able to modulate the biodistribution of the loaded drug when given intravenously, but also to control the absorption of drugs administered by other routes. This review presents the different strategies to coat the surface of polymeric as well as inorganic nanoparticles with polysaccharides. Various physicochemical and biological methods have been described to demonstrate such surface modification. The medical applications, mainly in imaging cancer, of polysaccharide-coated nanoparticles are presented, including their abilities to increase the blood circulation time and to target specific tumoral tissues. It has been shown that these coatings allow also to improve drug absorption via nasal or ocular pathways, due the mucoadhesive and/or permeability enhancer properties of the polysaccharides. Finally, the ability of polysaccharide-coated nanoparticles to deliver DNA or oligonucleotides will be discussed.

Loading efficiency of stavudine on polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate copolymer nanoparticles

Loading efficiency (LE) of stavudine (D4T), a human immunodeficiency antiretroviral agent, on the external surfaces of polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) was investigated. The experimental results indicate that the larger the polymeric nanoparticles (NPs), the smaller LE of D4T on the two kinds of biomaterials. Freeze drying of the two NPs, however, yields an increase in particle size and an increase in LE of D4T, in general. Preservation of the two D4T-loaded NPs through cold storage at 4 degrees C over 6 weeks leads to an increase in particle size and a decrease in LE of D4T. LE of D4T on both of the two NPs decreases with a variation in pH value from pH 7.2 of loading medium. LE of D4T on MMA-SPM NPs is larger than that on PBCA NPs at pH 7.4; and for the case of variation in pH value of loading medium from pH 7.2, the extent of decrease in LE of D4T for MMA-SPM NPs is higher than that on PBCA NPs. These outcomes imply that for oral administration, D4T-loaded MMA-SPM NPs may be more advantageous than D4T-loaded PBCA NPs, and D4T-loaded PBCA NPs may be more favorable than D4T-loaded MMA-SPM NPs for intravenous injection.