Recent patents on ophthalmic nanoformulations and therapeutic implications.

Nanoformulations (NF) are widely explored as potential alternatives for traditional ophthalmic formulation approaches. The effective treatment of ocular diseases using conventional eye drops is often hampered by factors such as: physiological barriers, rapid elimination, protein binding, and enzymatic drug degradation. Combined, these factors are known to contribute to reduced ocular residence time and poor bioavailability. Recent research studies demonstrated that NF can significantly enhance the therapeutic efficacy and bioavailability of ocular drugs, compared to the established ophthalmic drug delivery strategies. The research studies resulted in a number of patent inventions, reporting a significant increase in therapeutic efficacy for various chronic ocular disease states of both the anterior and posterior ocular segments. This article reviews these patent disclosures in detail and emphasizes the therapeutic advantages conferred by the following nanoformulation approaches: Calcium Phosphate (CaP) nanoparticles, Liposomes, Nanoemulsions, Nanomicelles, and Hydrogels. The nanoformulation approaches were shown to enhance the ocular bioavailability by reducing the drugprotein binding, increasing the corneal resident time, enhancing the drug permeability and providing a sustained drug release. Further, the article discusses United States Food and Drug Administration (USFDA) approved ocular drugs employing nanotechnology and future developments. It should be noted that, despite the potential therapeutic promise demonstrated by nanotechnology for ocular drug delivery, the bench to bed transition from patent inventions to marketed drug products has been insignificant. Majority of the discussed technologies are still in development and testing phase for commercial viability. Further, studies are in progress to assess ocular tolerance and nanotoxicity for prolonged use of NF.

Chitosan coated sodium alginate-chitosan nanoparticles loaded with 5-FU for ocular delivery: in vitro characterization and in vivo study in rabbit eye.

The objective of the study was to develop chitosan (CH) coated sodium alginate-chitosan (SA-CH) nanoparticles, i.e. CH-SA-CH NPs loaded with 5-FU for ophthalmic delivery. Drug loaded nanoparticles (DNPs) were prepared by ionic gelation technique using sodium alginate (SA) and chitosan (CH) and then suspended in chitosan solution. The mean size of nanoparticles and morphology were characterized by dynamic light scattering, scanning electron microscopy, atomic force microscopy and zeta potential. The in vitro release was studied by dialysis membrane technique. The size and drug encapsulation efficiency were dependent on molar ratio of SA and CH. The size of SA-CH nanoparticles was significantly increased with changed morphology after CH coating. SA-CH nanoparticles did not show any interaction with mucin while an enhanced viscosity was observed on coating of nanoparticles with CH. CH-SA-CH DNPs presented a sustained release of 5-FU compared to the 5-FU solution with high burst effect. In vivo study in rabbit eye showed significantly greater level of 5-FU in aqueous humor compared to 5-FU solution. The enhanced mucoadhesiveness of CH-SA-CH DNPs results in higher bioavailability as compared to the uncoated nanoparticles. Optimized formulation was found non-irritant and tolerable when tested by modified Draize test in rabbit eye.

In-vitro and in-vivo study of indomethacin loaded gelatin nanoparticles.

The present research work deals with fabrication of indomethacin loaded gelatin nanoparticles prepared by double desolvation method for controlled drug delivery. Submicron polymeric particles with size < 800 nm were produced possessing narrow polydispersity index (< 0.5). Entrapment efficiency varied from 27-38% depending upon particle size. No drug polymer interaction was observed by FTIR. DSC study confirmed amorphous nature of nanoparticles. The in-vitro drug release profile showed initial burst release (> 20% in 1 hr) followed by controlled release (> 75% in 12 hr). Among the kinetic models employed, the Higuchi model showed a better fit (R2 > 0.9) with n < 0.43 (Peppas model) indicating a Fickian type of release pattern. The batch 2GA was optimum in terms of size, entrapment efficiency and drug release. Anti-inflammatory activity of the drug loaded nanoparticles (IGNP) and pure drug solution (IDM) was studied by rat paw model and IGNP significantly (P < or = 0.001) decreased the paw volume as compared to IDM. Pharmacokinetic study showed significant enhancement (P < 0.001) of various pharmacokinetic parameters. The observed t(max) value was 3 h for IGNP compared to 1 h for IDM. Cmax of IGNP had higher value (110.81 +/- 8.53 microg/mL) compared to that of IDM (51.66 +/- 7.5 microg/mL). AUC0-12 was 1009.78 +/- 80.24 and 194.33 +/- 46.76/microg x h/mL in IGNP and IDM respectively (relative bioavailability 500%). Further, a good in vitro-in vivo correlation established the formulation for future trials.

Modified PLA nano in situ gel: a potential ophthalmic drug delivery system.

A novel nano in situ gel forming system of 5-Fluorouracil (5-FU) was investigated for its potential use for conjunctival/corneal squamous cell carcinoma (CCSC). The study was conducted in two steps, in the first step PLA nanoparticles were prepared and characterized; in the second step the drug loaded PLA nanoparticles were dispersed in sodium alginate solution yielding the modified nano in situ system, which were evaluated in rabbit eye. Size and morphology of prepared PLA particles were verified by using dynamic light scattering (DLS), atomic force microscope (AFM) and scanning electron microscope (SEM). In vitro and in vivo study of free 5-FU, PLA nanoparticles and modified nano in situ system were conducted in simulated tear fluid and in rabbit eye respectively. PLA nanoparticles were in size range of 128-194 nm with spherical shape and smooth surface with narrow size distribution. No polymer drug interaction was found as confirmed by FTIR, NMR and DSC. XRD of PLA nanoparticles confirmed that 5-FU was present in the crystalline state. In vitro experiments indicated a diffusion controlled release of 5-FU from both PLA nanoparticles and modified nano in situ system with high burst effect. Modified nano in situ gel system (MNS) significantly increased the Cmax and AUC0-8 in aqueous humor as compared to 5-FU solution and PLA nanoparticles. Higher 5-FU level in aqueous humor was possibly because of increased retention time of gel matrix-embedded drug loaded nanoparticles. Overall results showed the potential of MNS for ophthalmic delivery in the therapy of CCSC.

Nanocrystal technology in the delivery of poorly soluble drugs: an overview.

Extensive attempts to overcome problems related to solubility of drugs for maximizing bioavailability at targeted sites in the body have been made. The issue of drug solubility appears to attract the continued interest of pharmaceutical manufacturers. In this context, nanocrystallization has emerged as an important tool. In the present review, the authors discuss the advantages of nanocrystallized drugs and examine the products available in the market as well as drugs in the pipeline using nanocrystal-based formulations, which are being developed by pharmaceutical companies for drug delivery.

In vitro release kinetics and bioavailability of gastroretentive cinnarizine hydrochloride tablet.

An oral sustained release dosage form of cinnarizine HCl (CNZ) based on gastric floating matrix tablets was studied. The release of CNZ from different floating matrix formulations containing four viscosity grades of hydroxypropyl methylcellulose, sodium alginate or polyethylene oxide, and gas-forming agent (sodium bicarbonate or calcium carbonate) was studied in simulated gastric fluid (pH 1.2). CNZ release data from the matrix tablets were analyzed kinetically using Higuchi, Peppas, Weibull, and Vergnaud models. From water uptake, matrix erosion studies, and drug release data, the overall release mechanism can be explained as a result of rapid hydration of polymer on the surface of the floating tablet and formation of a gel layer surrounding the matrix that controls water penetration into its center. On the basis of in vitro release data, batch HP1 (CNZ, HPMC-K100LV, SBC, LTS, and MgS) was subjected to bioavailability studies in rabbits and was compared with CNZ suspension. It was concluded that the greater bioavailability of HP1 was due to its longer retention in the gastric environment of the test animal. Batch no. HP1 of floating tablet in rabbits demonstrated that the floating tablet CNZ could be a 24-h sustained release formulation.

Chitosan coated PLA nanoparticles for ophthalmic delivery: characterization, in-vitro and in-vivo study in rabbit eye.

The objective of the present study is to develop a poly (D, L-lactic acid) (PLA) nano-carrier for topical ocular applications. PLA nanoparticles (PLA-NPs) with 5-fluorouracil were prepared using varying concentration and molecular weight of PLA to regulate the particle size. The dimension and shape of nanoparticles were verified by using dynamic light scattering (DLS), atomic force microscope (AFM) and scanning electron microscope (SEM). Ex-vivo permeation study was conducted by goat and rabbit excised cornea. In-vivo experiment was conducted in rabbit eye and 5-FU concentration was measured in aqueous and vitreous humor by HPLC. In-vitro experiments indicated a diffusion controlled release of 5-FU. No significant interaction was observed in between mucin and PLA NPs that measured in terms of viscosity change. Ex-vivo permeation was significantly higher with rabbit cornea as compared to goat cornea. PLA and CH-PLA DNPs showed increased level of 5-FU as comparison to 5-FU solution. In-vivo study showed significantly higher concentration in case of uncoated and CH coated PLA nanoparticles in rabbit eye as compared to free 5-FU solution. PLA nanoparticle was found non-irritant in nature by modified Draize test.

Antimalarial drug development: past to present scenario.

Malaria is a global health problem that needs attention of drug discovery scientists to investigate novel compounds with high drug efficacy, safety and low cost to counter the malaria parasites that are resistant to existing drug molecules. This is an overview of past to present status of antimalarial drugs including newly researched candidates and also the alternative approaches for the complete control of malaria.

In situ forming formulation: development, evaluation, and optimization using 3(3) factorial design.

The present investigation concerns with the development and optimization of an in situ forming formulation using 3(3) full factorial design experimentation. Metformin, an antidiabetic drug with upper part of gastrointestinal tract as absorption window was used as a model drug. The formulations were designed with an objective to retain in stomach for an extended time period. The effect of three independent factors--concentrations of sodium alginate (X(1)), gellan gum (X(2)), and metformin (X(3)) on in vitro drug release were used to characterize and optimize the formulation. Five dependent variables-release exponent (Y(1)), dissolution efficiency (Y(2)), drug release at 30 min (Y(3)), 210 min (Y(4)), and 480 min (Y(5)) were considered as optimization factors. The data were statistically analyzed using ANOVA, and a p < 0.05 was considered statistically significant. Three dimensional surface response plots were drawn to evaluate the interaction of independent variables on the chosen dependent variables. Of the prepared 27 formulations, the responses exhibited by batch F17 containing medium level sodium alginate (X(1)), low level gellan (X(2)), and medium level metformin (X(3)) were similar to the predicted responses.

Polymeric nanoparticulate system: a potential approach for ocular drug delivery.

Various efforts in ocular drug delivery have been made to improve the bioavailability and to prolong the residence time of drugs applied topically onto the eye. The potential use of polymeric nanoparticles as drug carriers has led to the development of many different colloidal delivery vehicles. Drug loaded polymeric nanoparticles (DNPs) offer several favorable biological properties, such as biodegradability, nontoxicity, biocompatibility and mucoadhesiveness. These submicron particles are better than conventional ophthalmic dosage forms to enhance bioavailability without blurring the vision. DNPs have been shown to be amenable to targeting of the drug to the site of action, leading to a decrease in the dose required and a decrease in side effects. Additionally, DNPs can be fabricated by simple techniques with better physical stability than liposomes. This unique combination of properties makes DNPs a novel polymeric drug delivery device, which fulfils the requirements for ophthalmic application. This review discusses the polymeric nanoparticles, physiochemical characterization, fabrication techniques, therapeutic significances, patented technology of nanoparticles and future possibility in the field of ocular drug delivery.

Phase transition system: novel oral in-situ gel.

Inspite of the various impediments in the bioavailability of orally delivered drugs, oral dosage forms, both solid and liquid, occupy a center stage in the therapeutic regimen of diseases. However, liquid dosage forms are more prone to low bioavailability because of their quick transit from the stomach/ duodenum. This could be a serious problem for drugs, which are absorbed from these sites of the GIT. The gastric retention of an oral liquid formulation could be successfully augmented substantially through a strategy of liquid in-situ gelling system. Natural polymers like alginate, gellan and chitosan can undergo sol to gel transformation in the presence of either divalent cations or due to a change in pH. The gel so formed, being lighter than gastric fluids, floats over the stomach contents and is retained there in for periods upto 24 hours. The in-situ gel formation enhances the local or systemic bioavailability of the administered drug. This concept is a redesign of liquid oral dosage form, which fulfills the requirement for a sustained release liquid preparation. This review discusses the various aspects associated with the in-situ gelling systems and their therapeutic applications.