Engineered liposomes bearing camptothecin analogue for tumour targeting: in vitro and ex-vivo studies.

Topotecan (TPT) is a semi-synthetic, water-soluble derivative of camptothecin, which inhibits the action of topoisomerase I in the S-phase of the cell cycle leading to cell death. For the effective delivery of TPT to cancer cells, pH-sensitive sialic acid modified liposomes were developed. These liposomes were prepared by the thin-film hydration method using the active loading technique. Vesicle size, polydispersity index (PDI), zeta potential, and percentage entrapment efficiency were determined to be 167 ± 3.78 nm, 0.243, -8.39 mV, and 79.88 ± 1.67%, respectively. The pH-sensitive sialic acid (SA) conjugated liposomes enhanced the drug release at acidic pH 4 (92.33 ± 4.21%) as compared to physiological pH 7.4 (63.11 ± 4.51%). A Sulforhodamine B (SRB) cytotoxicity assay was performed in Murine sarcoma S180 cell lines and the GI50 value of free TPT, Lipo, P-Lipo, SA-P-Lipo, and Adriamycin (ADR) were determined to be 10.07 ± 0.15, 27.33 ± 1.01, 28.76 ± 0.87, 15.7 ± 0.45, and 11.5 ± 0.21 µg/mL, respectively. Results obtained from the apoptosis study revealed that cell death by a combination of early apoptosis and apoptosis caused by SA-P-Lipo was ∼24 fold higher than the control. These results demonstrated that pH-sensitive sialic acid conjugated liposomes will be a potential formulation for improving the antitumor efficacy of TPT. However, further research is necessitated to expedite its applicability in clinical regimen in order to ascertain its safety and efficacy.

Mucoadhesive gastroretentive microparticulate system for programmed delivery of famotidine and clarithromycin.

AIM: The present research was aimed to develop thiolated polyacrylic acid (TPA) based microspheres (MSPs) containing famotidine (FX) and clarithromycin (CLX). METHODS: TPA was synthesised from polyacrylic acid and l-cysteine in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC). The prepared TPA was characterised using FT-IR (Fourier transform-infra red), 1H-NMR (proton nuclear magnetic resonance) spectroscopy, P-XRD (powder X ray diffraction) method, and zeta potential. The analytical tools have supported the formation of TPA. The thiolated microspheres were prepared by emulsion solvent evaporation method using 0.75% w/v polymer concentration and stirring at 400 rpm for 8 hr. RESULTS: The average particle size and zeta potential of optimised formulation was found to be 25.2 ± 1.87 µm and -26.68 mV, respectively. The entrapment efficiency of the optimised formulation was obtained 67.20% for FX and 70.20% for CLX. The developed microspheres were swelled only in 4 h from 0.5 to 0.9. The in vitro mucoadhesive study and in vitro drug release studies demonstrated that microspheres showed mucoadhesive property. In in vitro drug release studies, the release of FX and CLX were observed to be 58.68% and 60.48%, respectively from microspheres in 8 h. The thiolated microspheres showed higher adhesion time (7.0 ± 0.8 h) in comparison to the plain microspheres (2.6 ± 0.4 h). CONCLUSION: The prepared TPA based mucoadhesive microspheres can be utilised as carriers for the treatment of peptic ulcer caused by Helicobacter pylori which will offer enhanced residence time for the rational drug combination in the gastric region.

Promising Antifungal Potential of Engineered Non-ionic Surfactant-Based Vesicles: In Vitro and In Vivo Studies.

Fungal keratitis (FK) is a corneal infection caused by different fungal species. It is treated by the topical application of natamycin (NAT). Nevertheless, this approach faces many limitations like toxic effects, frequent dosing, resistance, and patient discomfort. The present research reports the development of trimethyl chitosan (TMC) coated mucoadhesive cationic niosomes by a modified thin-film hydration method. TMC was synthesized using a one-step carbodiimide method and characterized by 1H-NMR and degree of quaternization (53.74 ± 1.06%). NAT, cholesterol (CHOL), span 60 (Sp60), and dicetyl phosphate (DCP) were used to prepare niosomes which were incubated with TMC to obtain mucoadhesive cationic NAT loaded niosomes (MCNNs). MCNNs showed a spherical shape with 1031.12 ± 14.18 nm size (PDI below 0.3) and 80.23 ± 5.28% entrapment efficiency. In vitro drug release studies showed gradual drug release from TMC coated niosomes as compared to the uncoated niosomes. MIC assay and disk diffusion assay revealed promising in vitro antifungal potential of MCNNs similar to the marketed formulation. For investigating in vivo performance, ocular retention and pharmacokinetics, ocular irritation, and ulcer healing studies were performed using the rabbit model. Mucoadhesive property and prolonged local drug release improved the safety and efficacy of NAT, suggesting that the developed niosomes could be an emerging system for effective treatment of fungal keratitis.

Folate Conjugated Double Liposomes Bearing Prednisolone and Methotrexate for Targeting Rheumatoid Arthritis.

PURPOSE: This investigation was aimed to explore the targeting potential of folate conjugated double liposomes (fDLs) bearing combination of synergistic drugs (Prednisolone and Methotrexate) for effective management of the rheumatoid arthritis (RA). METHODS: To overcome the drawbacks of monotherapy, a combination of prednisolone (PRD) (an anti-inflammatory agent) and methotrexate (MTX) (a disease modifying anti-rheumatoid agent, DMARDs) was chosen for dual targeting approach. fDLs were prepared in two steps i.e. development of inner liposomes (ILs) using thin film casting method followed by encapsulation of ILs within folate conjugated outer liposomes (double liposomes; fDLs). Developed liposomes were characterized for various physicochemical parameters and in vivo performance. RESULTS: fDLs were prepared using FA-PEG-4000-NH-DSPE conjugate. These double liposomes were having 429.3 ± 3.6 nm in size with 0.109 PDI, 8.01 ± 0.3 mV zeta potential (ζ) and 66.7 ± 3.9% and 45.3 ± 1.7% entrapments of PRD and MTX, respectively. After 24 h, the concentrations of PRD in blood were observed to be 8.66 ± 3.11 (ILs) and 15.13 ± 0.81% (DLs) while concentration of MTX were found to be 10.89 ± 0.69 and 2.34 ± 3.15% when given as ILs and fDLs, respectively. The concentration of both drugs in inflamed joint was observed to be higher than that in the non-inflamed joints. CONCLUSIONS: The folate conjugated double liposomes possess superior targeting efficiency than conjugated and unconjugated single liposomes.

pH-sensitive liposomes bearing a chemotherapeutic agent and a natural apoptosis modulator for effective intracellular delivery to the solid tumor.

The intracellular delivery of the drug to the solid tumor is a major challenge in the treatment of solid tumors. This project aims to increase cytosolic drug delivery using the endosomal escape of drugs. Topotecan (TPT) and capsaicin were used for the treatment of solid tumors. The pH-dependent conversion of active lactone form to inactive carboxylic form is a major problem of TPT that limits its therapeutic use. Liposomal encapsulation of TPT improved the stability of active lactone form and increased the therapeutic efficacy of TPT. Endosomal degradation of liposomes may reduce the content in the target cells. To solve these problems, pH-sensitive liposomes (pSLPs) were developed which improved the intracellular drug delivery by the endosomal escape of drugs. The liposomes (LPs) bearing the drug(s) were prepared using the cast film method and optimized for various formulation and process variables using the Design-Expert 7 software by employing the Box-Behnken design (BBD). The developed hyaluronic acid (HA)-conjugated pSLPs (HA-pSLPs) displayed a vesicle size of 166.5 ± 2.31 nm, zeta potential - 30.53 ± 0.91, and entrapment efficiency of 44.39 ± 1.78%, and 73.48 ± 2.15% for TPT and CAP, respectively. HA-pSLPs displayed better cytotoxicity in comparison to free drugs either single or in combination on the MCF-7 cell line. The apoptosis and cellular uptake of HA-pSLPs were increased ⁓ 4.45-fold and ⁓ 6.95-fold as compared to unconjugated pSLPs, respectively. The pharmacokinetic studies in Balb/c mice demonstrated that HA-pSLPs increased the half-life, MRT, and AUC in comparison to the free drug solution. The HA-pSLPs formulation has shown remarkable tumor regression as compared to PpSLPs, pSLPs, and free drug combinations. These results demonstrated that TPT- and CAP-loaded HA-pSLPs offer a potential platform for targeted drug delivery to solid tumors.

Emerging potential of niosomes in ocular delivery.

INTRODUCTION: Niosomes have recently grabbed attention as one of the best tools for various site-specific drug delivery systems, including ophthalmic drug delivery. Surfactants (nonionic; tweens and spans) of different HLB values and cholesterol are the fundamental components for these formulations. It is an alternative controlled ocular drug delivery system to liposomes to overcome the problems associated with sterilization, large-scale production, and stability. It also enhances the adhesion or retention ability of drug at the ocular site. Hydrophilic or lipophilic or amphoteric drugs can be easily encapsulated in niosomes. Besides, niosomes are a leading vesicular system compatible with most of the drugs for site-specific delivery. AREAS COVERED: This article reveals challenges and barriers for ocular drug delivery, various transporters and receptors present in the ocular region for the transportation of therapeutics as well as nutrients, and various method of preparations, loading methods and application potential of niosomes in ocular drug delivery. EXPERT OPINION: Niosomes, a vesicular system offers numerous advantages and applicability because of its good stability, non-immunogenicity, permeation potential, and controlled release ability etc. This drug delivery system has been efficiently used in the treatment of many ocular diseases.

Combination Cancer Therapy Using Multifunctional Liposomes.

Chemotherapy of cancer is still considered a complex phenomenon given that single chemotherapeutic agents cannot be administered for a long period of time because of the development of drug resistance and severe side effects. Nanodrug delivery systems (NDDSs) such as nanoparticles and liposomes are being investigated to enhance the safety and efficacy of anticancer agents. NDDS-based delivery of a single agent is not found to be effective in long-term anticancer therapy. Codelivery of more than one anticancer agent using liposomes shows great potential since it exhibits simultaneous synergistic therapeutic manifestations at the tumor site and enhances therapeutic efficacy in terms of the low-dose requirement of each agent and diminished side effects. Liposomes are lipid vesicles arranged in concentric bilayers with an aqueous core; they are versatile nanocarriers that accommodate the diverse nature of anticancer drugs (both hydrophobic and hydrophilic) at the same time. They offer a number of advantages for combinatorial drug delivery in terms of increased blood circulation, selective accumulation at tumor tissues, and stimuli responsiveness. Various combination of drugs such as paclitaxel (PTX) and topotecan, sunitinib and irinotecan, and combretastin A-4 and doxorubicin have been reported for cancer chemotherapy using liposomes. This review focuses on recent scenarios of combinatorial drug delivery using liposomes for better chemotherapeutic outcomes. This assemblage can be of great importance to researchers looking for advances in novel drug delivery approaches for better cancer treatment.

Systematic optimization of cationic surface engineered mucoadhesive vesicles employing Design of Experiment (DoE): A preclinical investigation.

Fungal keratitis (FK) is treated by topical natamycin (Nat) which is an effective antifungal agent. However, it has numerous therapeutic limitations i.e. toxicity, tolerance, need of frequent dosing and patient incompliance. The aim of the present study was to develop Nat loaded trimethyl chitosan (TMC) coated mucoadhesive cationic niosomes (Muc-Cat-Nios) for prolonged and effective delivery to eyes. Niosomes were prepared using thin film hydration method and optimized using a Box-Behnken design (BBD) with the help of Design-Expert® Software. Three independent variables were considered: amount of Span 60 (X1), amount of Cholesterol [Chol(X2)] and TMC concentration (X3). The encapsulation efficiency (R1: EE%), vesicle size (R2: VS) and Zeta potential (R3: ZP) were selected as dependent variables or responses. The optimized Nios displayed spherical shape, 1034.14 nm vesicle size and 81.76% EE. Nat loaded niosomes were incubated with TMC to get mucoadhesive cationic vesicular system. Uncoated and TMC coated niosomes were characterized for mucoadhesive properties, in vitro drug release, rheological behaviour, and ex vivo permeation studies. Cationic Nios showed greater mucoadhesive potential that provided drug release for a long period of time. The promising outcomes suggest that natamycin delivery using cationic mucoadhesive niosomes could be employed for the effective treatment of fungal keratitis.

Topotecan Liposomes: A Visit from a Molecular to a Therapeutic Platform.

Topotecan (TPT), a potent anticancer camptothecin analog, is well described for the treatment of ovarian cancer, but has also anticancer activity against small-cell and non-small-cell lung cancer, breast cancer, and acute leukemia. Various nanocarriers, including liposomes, have been exploited for targeted delivery of TPT. However, there are a number of challenges with TPT delivery using TPT liposomes (TLs), such as low encapsulation efficiency, physiological pH labile E ring (hydrolysis), accelerated blood clearance, multidrug resistance, and cancer metastases. This review discusses these problems and the means to overcome them, including modification of TLs using zwitterionic poly(carboxybetaine), prolongation in dosing interval (long-term therapy), and modified liposomal encapsulation techniques including active loading methods. We also explore engineered TLs (surface and integral modifications) such as PEGylated TLs, ligand-anchored TLs, and stimuli-sensitive TLs. Further, potential applications, manifestations at the molecular level, patents granted, and preclinical and clinical outlook for TLs are discussed.