Nonionic surfactant vesicular systems for effective drug delivery—an overview

Vesicular systems are a novel means of drug delivery that can enhance bioavailability of encapsulated drug and provide therapeutic activity in a controlled manner for a prolonged period of time. Liposomes were the first such system but they suffer from a number of drawbacks including high cost and lack of stability at various pHs. Niosomes are a nonionic surfactant vesicular system, which can be easily and reliably made in the laboratory. Many factors affect noisome formation such as the method of manufacture, nature of surfactant and encapsulated drug, temperature at which the lipids are hydrated and the critical packing parameter. This review describes all aspects of niosomes including their different compositions, the various methods of preparation, the effect of changing manufacturing parameters, methods of characterization, factors that affect their stability, their use by various routes of administration, their therapeutic applications and the most important patents. The review also provides detailed information of the various types of niosomes that provide effective drug delivery.     

Prodrugs for transdermal drug delivery – trends and challenges

Prodrugs continue to attract significant interest in the transdermal drug delivery field. These moieties can confer favorable physicochemical properties on transdermal drug delivery candidates. Alkyl chain lengthening, pegylation are some of the strategies used for prodrug synthesis. It is usually important to optimize partition coefficient, water and oil solubilities of drugs. In this review, progress made in the field of prodrugs for percutaneous penetration is highlighted and the challenges discussed.     

Finding the right route for insulin delivery – an overview of implantable pump therapy

Introduction: Implantable pump therapy adopting the intraperitoneal route of insulin delivery has been available for the past three decades. The key rationale for implantable pump therapy is the restoration of the portal-peripheral insulin gradient of the normal physiology. Uptake in clinical practice is limited to specialized centers and selected patient populations.

Areas covered: Implantable pump therapy is discussed, including technical aspects, rationale for its use, and glycemic and non-glycemic effects. Target populations, summaries of clinical studies and issues related to implantable pump therapy are highlighted. Limitations of implantable pump therapy and its future outlook in clinical practice are presented.

Expert opinion: Although intraperitoneal insulin delivery appears closer to the normal physiology, technical, pharmacological, and costs barriers prevent a wider adoption. Evidence from clinical studies remains scarce and inconclusive. As a consequence, the use of implantable pump therapy will be confined to a small population unless considerable technological progress is made and well-conducted studies can demonstrate glycemic and/or non-glycemic benefits justifying wider application.     

Smart polymers for the controlled delivery of drugs – a concise overview

Smart polymers have enormous potential in various applications. In particular, smart polymeric drug delivery systems have been explored as “intelligent” delivery systems able to release, at the appropriate time and site of action, entrapped drugs in response to specific physiological triggers. These polymers exhibit a non-linear response to a small stimulus leading to a macroscopic alteration in their structure/properties. The responses vary widely from swelling/contraction to disintegration. Synthesis of new polymers and crosslinkers with greater biocompatibility and better biodegradability would increase and enhance current applications. The most fascinating features of the smart polymers arise from their versatility and tunable sensitivity. The most significant weakness of all these external stimuli-sensitive polymers is slow response time. The versatility of polymer sources and their combinatorial synthesis make it possible to tune polymer sensitivity to a given stimulus within a narrow range. Development of smart polymer systems may lead to more accurate and programmable drug delivery. In this review, we discuss various mechanisms by which polymer systems are assembled in situ to form implanted devices for sustained release of therapeutic macromolecules, and we highlight various applications in the field of advanced drug delivery.KEY WORDS: Smart polymers, Temperature responsive polymers, pH responsive polymers, Field sensitive polymers, Glucose responsive polymers     

Spray dried microparticles for controlled delivery of mupirocin calcium: Process–tailored modulation of drug release

Spray dried microparticles containing mupirocin calcium were designed as acrylic matrix carriers with modulated drug release for efficient local drug delivery at minimum daily dose. Particle generation in spray drying and its effect on release performance were assessed by varying drug?:?polymer ratios with consequently altered initial saturations. Narrow-sized microparticles with mean diameters of 1.7–2.5?µm were obtained. Properties of the generated solid dispersions were examined by X-ray, thermal (thermogravimetric analysis, modulated differential scanning calorimetry) and spectroscopic (Fourier transformed infrared, Fourier transformed Raman) methods and correlated with drug loading and in vitro release. The best control over mupirocin release was achieved for 2?:?1 (w/w) drug?:?polymer ratio and found to be strongly process-dependent. For a particular ratio, increased feed concentration (>4%) boosted while increased inlet temperature (≥100°C) reduced drug release. Antimicrobial activity testing confirmed that encapsulated drug preserved its antibacterial effectiveness. Conclusively, spray drying was proven as a suitable method for preparing structured microparticles which can control drug release even at exceptionally high drug loadings.     

Cutaneous adverse drug reactions to psychotropic drugs and their risk factors – a case-control study

Cutaneous adverse drug reactions (CADRs) in patients with psychotropic drugs are common. Large studies on the relevant drugs and other risk factors are still scarce.594 cases of severe CADRs (“cases”) were compared with 8085 cases of other adverse drug reactions (“non-cases”) documented in a pharmacovigilance program in psychiatry (AMSP) from 1993 to 2014. Logistic regression was carried out to determine risk factors and between-drug differences.CADRs were relatively more prevalent in patients treated with clomipramine, maprotiline, carbamazepine, lamotrigine, acamprosate, clomethiazole and disulfiram as well as with antidepressants and anticonvulsants as drug classes (p?<?0.01). For these drugs, significantly more women were found in patients using maprotiline, lamotrigine (not carbamazepine) and in the groups of antidepressants, tricyclics and anticonvulsants (p?<?0.01). Women were more vulnerable to CADRs (67% in cases and 56% in non-cases, p?<?0.01). The significantly higher rate of CADRs in women was mainly observed under age of 50 years, i.e. during female reproductive years. In a multivariate logistic regression, female sex, the diagnostic group ICD F1 (substance abuse), maprotiline, carbamazepine, lamotrigine and clomethiazole were identified as risk factors of CADRs.The case/non-case approach allowed to identify risk factors based on empirical data rather than experts’ evaluations. The new findings of substance abuse and clomethiazole as risk factors for CADRs have to be confirmed in further studies. Since CADRs can be life-threatening, it is important to be aware of risk factors, especially women during their reproductive period and with lamotrigine treatment.     

Amorphous solid dispersions and nanocrystal technologies for poorly water-soluble drug delivery – An update

Poor water-solubility remains a typical property of drug candidates in pharmaceutical development pipelines today. Various processes have been developed to increase the solubility, dissolution rate, and bioavailability of these active ingredients belonging to biopharmaceutical classification system (BCS) II and IV classifications. Since the early 2000s, nanocrystal delivery and amorphous solid dispersions are more established techniques to overcome the limitations of poorly-water soluble drugs in FDA available products. This article provides an updated review of nanocrystal and amorphous solid dispersion techniques primarily for orally delivered medicaments. The thermodynamic and kinetic theories relative to these technologies are presented along with marketed product evaluations and a survey of commercially relevant scientific literature.     

TAT-based drug delivery system – new directions in protein delivery for new hopes?

There has been great progress in the use of TAT-based drug delivery systems for the delivery of different macromolecules into cells in vitro and in vivo, thus circumventing the bioavailability barrier that is a problem for so many drugs. There are many advantages to using this system, such as the ability to deliver these cargoes into all types of cells in culture and into all organs in vivo. This system can even deliver cargoes into the brain across the blood–brain barrier. In addition, the ability to target specific intracellular sub-localizations such as the nuclei, the mitochondria and lysosomes further expands the possibilities of this drug delivery system to the development of sub-cellular organelle-targeted therapy. The therapeutic applications seem almost unlimited, and the use of the TAT-based delivery system has extended from proteins to a large variety of cargoes such as oligonucleotides, imaging agents, low molecular mass drugs, nanoparticles, micelles and liposomes. In this review the most recent advances in the use of the TAT-based drug delivery system will be described, mainly discussing TAT-mediated protein delivery and the use of the TAT system for enzyme replacement therapy.     

Development of an ADME and drug–drug interactions knowledge database for the acceleration of drug discovery and development

It is widely recognised that predicting or determining the absorption, distribution, metabolism and excretion (ADME) properties of a compound as early as possible in the drug discovery process helps to prevent costly late-stage failures. Although in recent years high-throughput in vitro absorption distribution metabolism excretion toxicity (ADMET) screens have been implemented, more efficient in silico filters are still highly needed to predict and model the most relevant metabolic and pharmacokinetic end points, and thereby accelerate drug discovery and development. The usefulness of the data generated and published for the chemist, biologist or project manager who ultimately wants to understand and optimise the ADME properties of lead compounds cannot be argued with. Collecting and comparing data is an overwhelming task for the time-pressed scientist. Aureus Pharma provides a uniquely specialised solution for knowledge generation in drug discovery. AurSCOPE^® ADME/DDI (drug–drug interaction) is a fully annotated, structured knowledge database containing all the pertinent biological and chemical information on the metabolic properties of drugs. This Aureus knowledge database has proven to be highly useful in designing predictive models and identifying potential drug–drug interactions.     

Design and evaluation of San-huang dispersible tablet – an efficient delivery system for Traditional Chinese Medicine

San-huang dispersible tablet (SHDT) was designed with a patented technology to enrich the active ingredients in rhubarb and with a wide selection of excipients in the new manufacturing procedure. The total rhubarb anthraquinones were first enriched in the extract by our patented technology. Eudragit L100, S100 and PEG-6000 were used to release a part of the total rhubarb anthraquinones at the colon to induce the cathartic effect of the anthraquinones by another patented technology. Microcrystalline Cellulose (MCC), low-substituted hydroxypropyl cellulose (L-HPC), sodium carboxymethyl starch (CMS-Na), and hydroxypropyl methylcellulose (HPMC) were used to ensure quick release of baicalin and berberine hydrochloride in the stomach. The dissolution of SHDT was evaluated by a method in 2005 Chinese Pharmacopoeia along with San-huang tablet (SHT), and the results demonstrated that the dissolution of baicalin and berberine hydrochloride more than double that of SHT and release of half of the rhubarb anthraquinones in colon.     

WTX101 – an investigational drug for the treatment of Wilson disease

Introduction: Wilson disease (WD) is a genetic disorder in which excess toxic copper accumulates in the liver, brain, and other tissues leading to severe and life-threatening symptoms. Copper overload can be assessed as non-ceruloplasmin-bound copper non-ceruloplasmin-bound copper (NCC) in blood. Current therapies are limited by efficacy, safety concerns, and multiple-daily dosing.

Areas covered: This article reviews the literature on WTX101 (bis-choline tetrathiomolybdate), an oral first-in-class copper–protein-binding agent in development for the treatment of WD.

Expert opinion: In a proof-of-concept phase II trial, once-daily WTX101 over 24 weeks rapidly lowered NCC levels and this was accompanied by improved neurological status without apparent initial drug-induced paradoxical worsening, reduced disability, stable liver function, with a favorable safety profile. WTX101 directly removes excess copper from intracellular hepatic copper stores and also forms an inert tripartite complex with copper and albumin in the circulation and promotes biliary copper excretion. These mechanisms may explain the rapid biochemical and clinical improvements observed. A phase III trial of WTX101 is ongoing and results are eagerly awaited to confirm if WTX101 can improve the treatment of this devastating disease.     

Novel oral dosage regimen based on self-nanoemulsifying drug delivery systems for codelivery of phytochemicals – Curcumin and thymoquinone

BackgroundCurcumin and Thymoquinone are very well-known phytochemicals for their potent anti-inflammatory and anticancer properties. The major challenges for curcumin is its poor aqueous solubility and erratic oral bioavailability.ObjectiveTo develop a novel liquid self-nanoemulsifying drug delivery system (SNEDDS) containing curcumin and thymoquinone and further converted into a solid dosage form using adsorbents Syloid® and Neusilin® as the solid carrier.MethodsThe characterization of the liquid and solid SNEDDS was performed by particle size & zeta potential analysis, scanning electron microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy and X-ray powder diffraction. The drug loading, and in vitro release studies were carried out to investigate the efficiency of curcumin release from SNEDDS.ResultsThe liquid SNEDDS containing black seed oil showed excellent self-emulsification performance with transparent appearance. The results of characterization studies showed that solidification using 50% (w/w) Syloid® and Neusilin® in the liquid formulation yield free flowing powder with no agglomeration but Neusilin® produced smooth granules than Syloid® and kept the drugs stable in amorphous state. In vitro dissolution studies indicated that liquid SNEDDS formulations of F4 and its solid SNEDDS using Neusilin® provided high dissolution efficiency and reproducibility for curcumin and thymoquinone. However, Neusilin® showed higher rate of dissolution (more than 65%, p < 0.05) compared to Syloid® for curcumin.ConclusionsCurcumin loaded-SNEDDS formulation containing thymoquinone in liquid & solid dosage forms were successfully developed with an increased drug loading and dissolution rate, which could be the potential combined delivery system for various anti-inflammatory and anti-cancer treatments.     

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02?µm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.     

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02?μm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.     

Epidemiology and characteristics of adverse drug reactions caused by drug–drug interactions

Introduction: Drug–drug interactions (DDIs) arise in numerous different ways, involving pharmacokinetic or pharmacodynamic mechanisms. Adverse drug reactions are a possible consequence of DDIs and health operators are often unaware of the clinical risks of certain drug combinations. Many papers on drug interactions have been published in recent years, but most of them focused on potential DDIs while few studies have been conducted on actual interactions.

Areas covered: This paper reviews the epidemiology of actual DDIs in outpatients as well as in hospital settings and in spontaneous reporting databases. The incidence of actual DDIs is consistently lower than that of potential DDIs. However, the absolute number of patients involved is high, representing a significant proportion of adverse drug reactions. The importance of risk factors such as age, polypharmacy and genetic polymorphisms is also evaluated. The relevance and efficacy of tools for recognizing and preventing DDIs are discussed.

Expert opinion: Potential DDIs far outnumber actual drug interactions. The potential for an adverse interaction to occur is often theoretical, and clinically important adverse effects occur only in the presence of specific risk factors. Several studies have shown the efficacy of computers in early detection of DDIs. However, a correct risk–benefit evaluation by the prescribing physician, together with a careful clinical, physiological and biochemical monitoring of patients, is essential. Future directions of drug interaction research include the increasing importance of pharmacogenetics in preventing DDIs and the evaluation of interactions with biological drugs.     

Mesalazine for diverticular disease of the colon – a new role for an old drug

Colonic diverticulosis is among the most common diseases of developed countries. Its prevalence is ～ 5 – 10% of the population by age 50, and 30, 50 and 66% of those > 50, > 70 and > 85years of age, respectively. Antibiotics have been successfully used in the treatment of uncomplicated diverticular disease; however, the use of mesalazine (alone or in combination with antibiotics) in treating uncomplicated diverticulitis has been successfully developed in recent years. Indeed, mesalazine (with or without antibiotics) showed significant superiority in improving the severity of symptoms, bowel habits, and in preventing symptomatic recurrence of diverticulitis over antibiotics alone. More-over, in light of some preliminary results, it is probable that the association of mesalazine with probiotics may in the future be the first-choice treatment for mild-to-moderate uncomplicated attacks of acute diverticulitis.     

Hybrid drug delivery system for oropharyngeal,cervical and colorectal cancer – in vitro and in vivo evaluation

The present investigation was designed with the intention to formulate a versatile 5-fluorouracil(5-FU) matrix tablet surpassing issues associated with current conventional chemotherapeutic drug delivery systems. The novel 5-FU matrix tablet fulfills therapeutic needs by engineering matrix tablets utilizing chitosan–sodium alginate interpolyelectrolyte complex (IPEC). IPEC was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The matrix tablets were formulated utilizing IPEC alone and in combination with chitosan, sodium alginate and sodium deoxycholate as permeation enhancer. Pharmaceutical properties, swelling studies, in vitro dissolution and diffusion studies, mucoadhesive studies and in vivo studies were performed for formulated 5-FU. The selected chitosan–sodium alginate IPEC offers pH independent 5-FU release in comparison to alone or physical mixture of chitosan and sodium alginate. Furthermore, novel matrix tablets demonstrated significantly higher bioadhesive properties with controlled 5-FU release without the initial burst effect and also demonstrated a higher permeation of 5-FU. To conclude, the developed novel 5-FU matrix tablets pave way as an excellent alternative for cancer treatment which could potentially minimize the dose dependent side effects and provide better patient compliance.     

Drug crystallization – implications for topical and transdermal delivery

ABSTRACT

Introduction: Crystallization of actives in skin following topical application was suggested by studies in the 1950s and 1960s but is poorly understood. In contrast, the problem of crystallization of actives on skin and in transdermal formulations has been known for many years.

Areas covered: With respect to crystallization in skin, this review describes early reports of a skin ‘reservoir’ and possible reasons underlying its genesis. Techniques to study crystallization on and in skin and in transdermal patches are outlined. The role of the vehicle in skin delivery is emphasised. Studies which have investigated permeation from crystalline particles are described. Approaches to limit crystallization of actives are discussed. Using supersaturation and antinuclean polymers, control of crystal size is possible; controlled release from crystals is also employed in transdermal patches.

Expert Opinion: Drug crystallization has significant implications for topical and transdermal delivery. Approaches have been developed to counteract the issue for transdermal patches but crystallization in and on the skin for other formulations remains unresolved. Greater knowledge of residence time of excipients and their interaction with skin at the molecular level is critical in order to address the problem. This will lay the foundations for better design of topical/transdermal formulations.