Advanced and controlled drug delivery systems in clinical disease management

Core-Shell Structure of Photopolymer-Grafted Polyurethane as a Controlled Drug Delivery Vehicle for Biomedical Application

Functionalized ultraviolet photocurable bisphenol A-glycerolate dimethacrylates with tailorable size have been synthesized as the core, which have further been grafted using the diisocyanate chain end of polyurethane (PU) as the shell to create a core-shell structure of tunable size for a controlled drug delivery vehicle. The core-shell structure has been elucidated through spectroscopic techniques like 1H NMR, FTIR, and UV-vis and their relative shape and size through TEM and AFM morphology. The greater cross-link density of the core is reflected in the higher glass transition temperature, and the improved thermal stability of the graft copolymer is proven from its thermogravimetric analyses. The flow behavior and enhanced strength of the graft copolymers have been revealed from rheological measurements. The graft copolymer exhibits sustained release of the drug, as compared to pure polyurethane and photopolymer, arising from its core-shell structure and strong interaction between the copolymer and drug, as observed through a significant shifting of absorption peaks in FTIR and UV-vis measurements. Biocompatibility has been tested for the real application of the novel graft copolymer in medical fields, as revealed from MTT assay, cell imaging, and cell adhesion studies. The efficacy of controlled release from a graft copolymer has been verified from the gradual cell killing and ∼70% killing in 3 days vs meager cell killing of ∼25% very quickly in 1 day, followed by the increased cell viability of the system treated with the pure drug. The mechanism of slow and controlled drug release from the core-shell structure has been explored. The fluorescence images support the higher cell-killing efficiency as opposed to a pure drug or a drug embedded in polyurethane. Cells seeded on 3D scaffolds have been developed by embedding a graft copolymer, and fluorescence imaging confirms the successful growth of cells within the scaffold, realizing the potential of the core-shell graft copolymer in the biomedical arena.

Design and Development of Fluorinated and Biocide-Free Sol–Gel Based Hybrid Functional Coatings for Anti-Biofouling/Foul-Release Activity

Biofouling has destructive effects on shipping and leisure vessels, thus producing severe problems for marine and naval sectors due to corrosion with consequent elevated fuel consumption and higher maintenance costs. The development of anti-fouling or fouling release coatings creates deterrent surfaces that prevent the initial settlement of microorganisms. In this regard, new silica-based materials were prepared using two alkoxysilane cross-linkers containing epoxy and amine groups (i.e., 3-Glycidyloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively), in combination with two functional fluoro-silane (i.e., 3,3,3-trifluoropropyl-trimethoxysilane and glycidyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononylether) featuring well-known hydro repellent and anti-corrosion properties. As a matter of fact, the co-condensation of alkoxysilane featuring epoxide and amine ends, also mixed with two opportune long chain and short chain perfluorosilane precursors, allows getting stable amphiphilic, non-toxic, fouling release coatings. The sol–gel mixtures on coated glass slides were fully characterized by FT-IR spectroscopy, while the morphology was studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). The fouling release properties were evaluated through tests on treated glass slides in different microbial suspensions in seawater-based mediums and in seawater natural microcosms. The developed fluorinated coatings show suitable antimicrobial activities and low adhesive properties; no biocidal effects were observed for the microorganisms (bacteria).

Sol–Gel Treatment of Textiles for the Entrapping of an Antioxidant/Anti-Inflammatory Molecule: Functional Coating Morphological Characterization and Drug Release Evaluation

The growing interest towards textile-based drug delivery systems is due to their potential innovative medical and well-being applications. In recent years, the technique of encapsulation or inclusion of the medicine/active principle into a polymer functional matrix has been employed in order to obtain textile materials with controlled drug release. In this study, a sol–gel-based coating was developed and used as an entrapping polymeric cross-linked network for a N-Palmitoyl-ethanolamine (PEA) derivative, 2-methyl-pentadecanoic acid (4-nitro-phenyl)-amide or N-Palmitoyl-(4-nitro-phenyl)-amine (PNPA), whose anti-inflammatory and antioxidant properties have already been shown. A wide series of chemical-physical methods have been used to characterize the silica-based functional sol and to ascertain the efficient and temporary deposit of PNPA on the sol–gel coated cotton fabrics. The medicine release system achieved was shown to ensure biocompatibility, PNPA reservoir and its subsequent releasing under the action of cutaneous stimuli, thus providing useful insights in the design of medical textiles.

Novel poly(ε-caprolactone)/gelatin wound dressings prepared by emulsion electrospinning with controlled release capacity of Ketoprofen anti-inflammatory drug

In the present study, a single and binary Ketoprofen-loaded mats of ultrathin fibers were developed by electrospinning and their physical properties and drug release capacity was analyzed. The single mat was prepared by solution electrospinning of poly(ε-caprolactone) (PCL) with Ketoprofen at a weight ratio of 5wt%. This Ketoprofen-containing PCL solution was also used as the oil phase in a 7:3 (wt/wt) emulsion with gelatin dissolved in acidified water. The resultant stable oil-in-water (O/W) emulsion of PCL-in-gelatin, also containing Ketoprofen at 5wt%, was electrospun to produce the binary mat. Cross-linking process was performed by means of glutaraldehyde vapor on the electrospun binary mat to prevent dissolution of the hydrophilic gelatin phase. The performed characterization indicated that Ketoprofen was successfully embedded in the single and binary electrospun mats, i.e. PCL and PCL/gelatin, and both mats showed high hydrophobicity but poor thermal resistance. In vitro release studies interestingly revealed that, in comparison to the single PCL electrospun mat, the binary PCL/gelatin mat significantly hindered Ketoprofen burst release and exhibited a sustained release capacity of the drug for up to 4days. In addition, the electrospun Ketoprofen-loaded mats showed enhanced attachment and proliferation of L929 mouse fibroblast cells, presenting the binary mat the highest cell growth yield due to its improved porosity. The here-developed electrospun materials clearly show a great deal of potential as novel wound dressings with an outstanding controlled capacity to release drugs.

Novel controlled drug delivery system for multiple drugs based on electrospun nanofibers containing nanomicelles

This research described a novel composite electrospun nanofibers, which were consisted of MPEG-b-PLA micelles, chitosan, and PEO, realizing controlled release of both hydrophobic and hydrophilic drugs. 5-FU and Cefradine used as model drugs were successfully loaded in the nanofibers. The in vitro studies showed there was a low initial burst release of 5-FU from micelles-loaded nanofibers, and the final release proportion was about 91.4% after continually releasing for 109 h. In vitro cytotoxicity studies revealed that 5-FU-loaded nanofibers restrained HepG-2 cells efficiently, and the cell viability was 45.9% after three days of cultivation in solutions containing micelles-loaded nanofibers with 21.6 μg 5-FU. All results suggested that micelles-loaded nanofibers with two kinds of drugs can be used as an effective controlled drug delivery vehicle and may have a bright future in cancer chemotherapy or clinical treatments.

Mechanisms of monoclonal antibody stabilization and release from silk biomaterials

The availability of stabilization and sustained delivery systems for antibody therapeutics remains a major clinical challenge, despite the growing development of antibodies for a wide range of therapeutic applications due to their specificity and efficacy. A mechanistic understanding of protein-matrix interactions is critical for the development of such systems and is currently lacking as a mode to guide the field. We report mechanistic insight to address this need by using well-defined matrices based on silk gels, in combination with a monoclonal antibody. Variables including antibody loading, matrix density, charge interactions, hydrophobicity and water access were assessed to clarify mechanisms involved in the release of antibody from the biomaterial matrix. The results indicate that antibody release is primarily governed by hydrophobic interactions and hydration resistance, which are controlled by silk matrix chemistry, peptide domain distribution and protein density. Secondary ionic repulsions are also critical in antibody stabilization and release. Matrix modification by free methionine incorporation was found to be an effective strategy for mitigating encapsulation induced antibody oxidation. Additionally, these studies highlight a characterization approach to improve the understanding and development of other protein sustained delivery systems, with broad applicability to the rapidly developing monoclonal antibody field.

Drug Delivery Devices Based on Mesoporous Silicate

A mesoporous material based on aluminosilicate mixture was studied to investigate its ability to include drugs and then release them. Nonsteroidal anti-inflammatory agents such as diflunisal, naproxen, ibuprofen and its sodium salt have been used in this study. The preparation of the mesoporous material and its characterization by X-ray, N2 absorption-desorption isotherm, and thermogravimetry analysis have been described. Drug loading was performed by a soaking procedure. Drug-loaded matrices were characterized for entrapped drug amount, water absorption ability, and thermogravimetric behavior. Drug release studies also were performed at pH 1.1 and 6.8 mimicking gastrointestinal fluids. Experimental results showed that this type of matrix is able to trap the bioactive agents by a soaking procedure and, then, to release them in conditions mimicking the biological fluids. Also, the high affinity of these matrices for water makes them potentially biocompatible. Release data suggest that the matrix impregnated with diflunisal offers good potential as a system for the modified drug release.

[Treatment strategies in rhinoconjunctivitis and asthma during pregnancy]

BACKGROUND

The incidence of asthma is high, especially in young people, a population group that includes women of reproductive age. We reviewed recent publications on asthma control during pregnancy to avoid undesired effects on both the mother and fetus. The prevalence of rhinoconjunctivitis is also high, although this disease is often under-treated by physicians. The use of beta2-agonists, corticoids (systemic/inhaled/nebulized), epinephrine and specific allergen immunotherapy is discussed.

METHODS

We reviewed recent publications on asthma during pregnancy as well as other articles of interest. Articles providing data on drug therapy, overall strategies and patient education were selected. Sufficient drugs are available for the management of this disease and under-treatment cannot be justified.

CONCLUSIONS

Pregnancy is not a disease, but constitutes a period when special care must be taken with underlying diseases. The aim of asthma treatment during pregnancy is to prevent fetal complications due to the effects of medication and asthma crises by keeping the mother symptom free and preventing possible exacerbations. Almost all authors agree that asthma crises in pregnant women should be treated no differently from those in non-pregnant women. Treatment of rhinoconjunctivitis should not be stopped during pregnancy since a wide variety of FDA category B drugs is available. Specific allergen immunotherapy should not be suspended during pregnancy as it is not contraindicated. However, this therapy should not be initiated during pregnancy.

Synthetic polymer systems in drug delivery

The development of synthetic polymers for applications in drug delivery is reviewed, with particular reference to polymers that can be activated to release a medicinal agent in vivo or that can respond to changes in environment to enhance the effectiveness of therapy. The mechanisms by which these polymers are designed to deliver drugs are highlighted, along with the challenges facing synthetic chemists and pharmaceutical scientists in designing new and more active therapeutic vehicles. Currently, synthetic materials with biomimetic properties are attracting growing attention as possible new dosage formulations and the potential applications of these increasingly sophisticated polymers in cell-specific drug targeting and in the emerging field of gene therapy are also considered. Finally, the potential development issues for delivery of therapeutics using active or 'smart' polymers are discussed with an analysis of the future trends in this rapidly expanding area of research.

General strategy for the management of bronchial asthma in pregnancy

Epidemiological studies showed that bronchial asthma is one of the most common diseases which can complicate pregnancy (1-7%). In about 0.05-2% of the cases, asthma occurs as a life-threatening event. In the common medical practice a waiting strategy or, even, the complete refusal for drug therapies are frequently observed. This is justified by the fear of the possible adverse effects of drugs on developing fetus. On the contrary, several studies have demonstrated that severe and uncontrolled asthma may produce serious maternal and fetal complications, such as gestational hypertension and eclampsia, fetal hypoxemia and an increased risk of perinatal death. Therefore, all pregnant women suffering from bronchial asthma should be considered as potentially at high risk of complications and adequately treated. Since asthma is a chronic disease with acute exacerbations, a continuous treatment is mandatory to control symptoms, to prevent acute episodes and to reduce the degree of airway inflammation. The global strategy for asthma management in pregnancy includes five main topics: (1) objective evaluation of maternal/ fetal clinical conditions; (2) avoidance/control of triggering factors; (3) pharmacological treatment; (4) educational support; (5) psychological support. As far as drug therapy is concerned, the International Guidelines and Recommendations suggest that the general strategy does not differ significantly from management outside pregnancy. We herein review and discuss the available data and the criteria for the management of asthma in pregnant patients.

Optimisation of treatment by applying programmable rate-controlled drug delivery technology

A number of programmable rate-controlled drug delivery technologies have been developed during the last two decades with the aim of regulating the rate of drug delivery, sustaining the duration of therapeutic action and/or targeting the delivery of drug to a specific tissue. As a result, several therapeutically beneficial outcomes can be achieved, such as: (i) controlled delivery of a therapeutic dose at a desirable rate of delivery; (ii) maintenance of drug concentrations within an optimal therapeutic range for prolonged duration of treatment; (iii) maximisation of efficacy-dose relationship; (iv) reduction of adverse effects; (v) minimisation of the need for frequent dose intake; and (vi) enhancement of patient compliance. The treatment of illness can thus be optimised. To gain a better understanding of how to optimise the treatment of illnesses by applying programmable rate-controlled drug delivery technologies, this article reviews the scientific concepts and technical principles behind the development of various programmable rate-controlled drug delivery systems that have been marketed or are under active development. Finally, the roles of these technologies in optimising therapeutic outcomes in nine therapeutic areas are discussed.

In vitro and in vivo evaluations of biodegradable implants for hormone replacement therapy: effect of system design and PK-PD relationship

This investigation evaluated the feasibility of using subdermally implantable devices fabricated by nonconventional 3-dimensional printing technology for controlled delivery of ethinyl estradiol (EE2). In vitro release kinetics of EE2 and in vivo pharmacokinetics/pharmacodynamics in ovariectomized New Zealand White rabbits were carried out to study 3 implant prototypes: implant I (single-channel EE2 distribution in polycaprolactone polymer core), implant II (homogeneous EE2 distribution in polycaprolactone polymer matrix), and implant III (concentration-gradient EE2 distribution in polycaprolactone and poly(dl-lactide-co-glycolide) (50:50 matrix). EE2 was found to be released from all the implants in a nonlinear pattern with an order of implant III > implant II > implant I. The noncompartmental pharmacokinetic analysis of plasma EE2 profiles in rabbits indicated a significant difference (p < .05) in Cmax, tmax, and mean residence time between implant I and implants II and III, but no difference in the area under the plasma concentration time curves calculated by trapezoidal rule (AUC) among the implants. For pharmacodynamic studies, endogenous follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were observed to be suppressed following implantation of all implants, which demonstrated that a therapeutically effective dose of EE2 had been delivered. Furthermore, the noncompartmental analysis of plasma FSH and LH profiles in rabbits showed a significant difference (p < .05) in AUC and the mean residence time between implant III and implants I and II. A good in vivo/in vitro relationship was observed between daily amounts of EE2 released and plasma profiles of EE2 for all implants. This relationship suggests that plasma profiles of EE2 could be predicted from in vitro measurement of daily amount of EE2 released. Therefore, performing in vitro drug release studies may aid in the development of an EE2 implant with the desired in vivo release rate.

A comparative in vitro study of percutaneous penetration of beta-blockers in human skin

In vitro diffusion experiments with propranolol, oxprenolol, metoprolol and atenolol were carried out using excised human abdominal skin. The main permeation parameters (permeability coefficient, flow and lag time) were calculated and compared as measurement of intrinsic permeability across human skin. A long lag time and a low steady-state flow were found for all drugs assayed. Skin permeability predicted at steady state did not reach therapeutic concentrations, which indicated the need for appropriate chemical penetration enhancers or vehicles to overcome limiting factors. The results, including those of celiprolol and bisoprolol reported previously, correlated with physicochemical properties, especially with lipophilicity, one of the main factors in drug permeability prediction through human skin.

Clinical pharmacology of anticancer agents in relation to formulations and administration routes

In the past years, alternative administration routes and pharmaceutical formulations of anticancer agents have been investigated in order to improve conventional chemotherapy treatment. The impact of these adjustments on the pharmacokinetics and pharmacodynamics is discussed. A review of the literature shows many examples of alternative administration forms of anticancer agents with improved pharmacokinetics. Local administration routes have been investigated in order to reduce the systemic toxicity and to enhance the local efficacy of conventional chemotherapy. Oral administration of anticancer agents is preferred by patients for its convenience and its potential for outpatient treatment. In addition, oral administration facilitates a prolonged exposure to the cytotoxic agent. However, poor bioavailability and substantial interpatient variability are noted as limitations for oral chemotherapy. Increased tumour selectivity can also be achieved by the use of specific pharmaceutical formulations, such as liposomes and macromolecular drug conjugates. The composition of these formulations often determine the pharmacokinetic behaviour of the formulated drug. In conclusion, several alternative administration forms of anticancer agents have been designed in the past years, with the potential for improvement of conventional chemotherapy, however, more extensive clinical evaluation of these novel strategies is warranted to prove their real clinical value.