Drug Delivery Systems

Mucosal (and in minor extent transcutanous) stimulation can induce local or distant mucosa secretory IgA. Liposomes and other vesicles as mucosal and transcutaneous adjuvants are attractive alternatives to parenteral vaccination. Liposomes can be massively produced under good manufacturing practices and stored for long periods, at high antigen/vesicle mass ratios. However, their uptake by antigen-presenting cells (APC) at the inductive sites remains as a major challenge. As neurotoxicity is a major concern in intranasal delivery, complexes between archaeosomes and calcium as well as cationic liposomes complexed with plasmids encoding for antigenic proteins could safely elicit secretory and systemic antigen-specific immune responses. Oral bilosomes generate intense immune responses that remain to be tested against challenge, but the admixing with toxins or derivatives is mandatory to reduce the amount of antigen. Most of the current experimental designs, however, underestimate the mu...

Non-invasive vaccine delivery is a top priority for public health agencies because conventional immunization practices are unsafe and associated with numerous limitations. Recently, the skin has emerged as a potential alternative route for non-invasive delivery of vaccine. Topical immunization (TI), introduction of antigen through topical application onto the intact skin, has many practical merits compared to injectable routes of administration. One of the possibilities for increasing the penetration of bioactives through the skin is the use of vesicular systems. Specially designed lipid vesicles are attracting intense attention and can be used for non-invasive antigen delivery. In the present study, elastic vesicle transfersomes, non-ionic surfactant vesicles (niosomes) and liposomes were used to study their relative potential in non-invasive delivery of tetanus toxoid (TT). Transfersomes, niosomes and liposomes were prepared and characterized for shape, size and entrapment efficiency. These vesicles were extruded through polycarbonate filter (50-nm pore size) to assess the elasticity of the vesicles. The immune stimulating activity of transfersomes, niosomes and liposomes were studied by measuring the serum anti-TT IgG titre following topical immunization. The immune response elicited by topical immunization was compared with that elicited by same dose of alum-adsorbed tetanus toxoid (AATT) given intramuscularly. The results indicate that optimal formulations of transfersomes, niosomes and liposomes could entrap 72.7 ± 3.4, 42.5 ± 2.4 and 41.3 ± 2.2% of antigen and their elasticity values were 124.4 ± 4.2, 29.3 ± 2.4 and 21.7 ± 1.9, respectively. In vivo study revealed that topically given TT containing transfersomes, after secondary immunization, could elicit immune response (anti-TT-IgG) that was equivalent to one that produced following intramuscularly alum-adsorbed TT-based immunization. In comparison to transfersomes, niosomes and liposomes elicited weaker immune response. Thus transfersomes hold promise for effective non-invasive topical delivery of antigen(s).

A multicenter, 2-visit, open-label, 4-week study was conducted to determine the acceptability of hydroxypropyl cellulose ophthalmic inserts in adult patients with a history of dry eye syndrome (DES). At visit 1, patients (N = 520) were evaluated, screened by slit-lamp biomicroscopy, and completed the Ocular Surface Disease Index (OSDI), a validated measure of quality of life. Patients were trained in the proper placement and use of hydroxypropyl cellulose ophthalmic inserts and were contacted by telephone on day 3 of the study. At week 4, patients were given a clinical evaluation and completed a second questionnaire. Answers determined changes in symptoms and quality of life. Adverse events were monitored throughout the study. Four hundred eighteen patients completed the study and reported significant improvements in discomfort, burning, dryness, grittiness, stinging, and light sensitivity (P = .05) after 4 weeks use of hydroxypropyl cellulose ophthalmic inserts. Significant improve...

Novel microfluidic tools allow new ways to manufacture and test drug delivery systems. Organ-on-a-chip systems - microscale recapitulations of complex organ functions - promise to improve the drug development pipeline. This review highlights the importance of integrating microfluidic networks with 3D tissue engineered models to create organ-on-a-chip platforms, able to meet the demand of creating robust preclinical screening models. Specific examples are cited to demonstrate the use of these systems for studying the performance of drug delivery vectors and thereby reduce the discrepancies between their performance at preclinical and clinical trials. We also highlight the future directions that need to be pursued by the research community for these proof-of-concept studies to achieve the goal of accelerating clinical translation of drug delivery nanoparticles.

Novel microfluidic tools allow new ways to manufacture and test drug delivery systems. Organ-on-a-chip systems - microscale recapitulations of complex organ functions - promise to improve the drug development pipeline. This review highlights the importance of integrating microfluidic networks with 3D tissue engineered models to create organ-on-a-chip platforms, able to meet the demand of creating robust preclinical screening models. Specific examples are cited to demonstrate the use of these systems for studying the performance of drug delivery vectors and thereby reduce the discrepancies between their performance at preclinical and clinical trials. We also highlight the future directions that need to be pursued by the research community for these proof-of-concept studies to achieve the goal of accelerating clinical translation of drug delivery nanoparticles.

Most patients with schizophrenia exhibit negative symptoms, even during acute episodes. These difficult-to-treat symptoms are often associated with poor functioning and outcomes. A post-hoc analysis of pooled data from three 6-week double-blind studies included patients in an acute episode of schizophrenia who received paliperidone extended-release (ER) (3, 6, 9, or 12 mg) or placebo. Based on criteria developed by the authors, patients were stratified by the presence or absence of predominant negative symptoms at baseline (>or=40% of the maximum negative factor score and <40% of the maximum positive factor score on the Positive and Negative Syndrome Scale [PANSS]). Although these studies were not designed to examine patients with predominant negative symptoms, the criteria identified 23% of acutely ill patients (270/1193). The mean (SD) baseline PANSS negative symptoms factor score, 27.4 (3.3), was 49% of the maximum; the positive symptoms factor score, 23.7 (2.8), was 33% of the maximum. Completion rates with paliperidone ER (n=195) and placebo (n=75) were 64.6% and 44.0%, respectively. Greater improvements occurred with paliperidone ER vs placebo on PANSS (total, negative and other factors), Clinical Global Impressions-Severity and Personal and Social Performance scores at endpoint (all P values <0.05). Adverse events reported in >or=10% of patients were (paliperidone ER vs placebo): headache (14.4% vs 6.7%), insomnia (13.8% vs 21.3%) and sinus tachycardia (10.3% vs 1.3%). Paliperidone ER treatment was associated with a similar response profile in patients without predominant negative symptoms (paliperidone ER, n=647; placebo, n=276). Schizophrenia patients with predominant negative symptoms were identified in a population of acutely ill patients. Findings of this post-hoc analysis suggest that acutely ill patients with or without predominant negative symptoms respond similarly to treatment with paliperidone ER. No unexpected tolerability findings were observed.

Locally recurrent prostate cancer can lead to significant morbidity, metastasis, and even death. The objective of this study was to evaluate the efficacy of an injectable polymeric paste formulation containing paclitaxel against orthotopic prostate tumor in rats. The Dunning R-3327 rat prostate adenocarcinoma is experimental tumor model used to study tumor progression. The polymer loaded with paclitaxel was injected into the tumor bearing prostate glands of the rats 3 days after tumor cell inoculation. In control untreated rats, tumor volume reached 14 cm3 after 25 days, while in rats treated with intratumoral injection of polymer/paclitaxel formulation the prostate volume with the tumor was only 0.9 cm3, 35 days posttumor cells inoculation. In the group treated with intratumoral injection of paclitaxel suspension, the tumor volume was 6.6 cm3, and in the group treated with intraperitonial (IP) paclitaxel formulation, the tumor volume reached 13.9 cm3 25 days posttumor cells inoculation. No metastases were found in rats treated intratumorally with 200 µL of polymer/paclitaxel formulation, while rats in other treatment groups developed metastases in the lungs and lymph nodes. The results of this study indicated that a site-directed, injectable, controlled release formulation of paclitaxel is effective against localized prostate tumors and metastasis. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1005–1014, 2009

This paper presents state-of-the-art micro and nano-fabrication techniques for biodegradable polymers. Replication molding, using a rigid or elastic master, can pattern structures on a polymer surface in a submicron resolution at a low cost. Layer-by-layer rapid prototyping methods are promising in producing controlled release units with complicated geometries, release mechanisms and the ability to control microstructure and composition. Special attention is paid to the fast, flexible, and non-invasive laser fabrication techniques that have great potential in the fabrication of biodegradable polymer drug delivery devices in both a laboratory and industry scale.

A new strategy for the skin delivery of bioactive compounds has been developed, using enzymes involved in the maintenance of the epidermal barrier function and the enzymatic transformation of corresponding precursors. This new strategy has been tested with regard to two enzymatic activities of the skin barrier: extracellular glucosidase and esterase/lipase. An analysis of the requirements for the glycosidic bond hydrolysis of any glycoconjugate by beta-glucocerebrosidase indicates that the release of the moiety linked to the glucose unit is obtained as long as the glycosidic bond being broken is not hindered, and as long as the leaving group property of the released moiety is good enough. This strategy was first applied to the release of the antioxidant delta-tocopherol. It was then extended to retinoic acid by introducing a spacer between the glucose unit and the bioactive moiety. This spacer was either a good leaving group such as hydroquinone, or a structure akin to a ceramide, n...

The large surface area, good vascularization, immense capacity for solute exchange and ultra-thinness of the alveolar epithelium are unique features of the lung that can facilitate systemic delivery via pulmonary administration of peptides and proteins. Physical and biochemical barriers, lack of optimal dosage forms and delivery devices limit the systemic delivery of biotherapeutic agents by inhalation. Current efforts to overcome these difficulties in order to deliver metabolic hormones (insulin, calcitonin, thyroid-stimulating hormone [TSH], follicle-stimulating hormone [FSH] and growth hormones) systemically, to induce systemic responses (immunoglobulins, cyclosporin A [CsA], recombinant-methionyl human granulocyte colony-stimulating factor [r-huG-CSF], pancreatic islet autoantigen) and to modulate other biological processes via the lung are reviewed. Safety aspects of pulmonary peptide and protein administration are also discussed.