The expulsion of lipophilic drugs from the cores of solid lipid microspheres in diluted suspensions and in concentrates

Engineering mannose-functionalized nanostructured lipid carriers by sequential design using hybrid artificial intelligence tools

Nanostructured lipid carriers (NLCs) hold significant promise as drug delivery systems (DDS) owing to their small size and efficient drug-loading capabilities. Surface functionalization of NLCs can facilitate interaction with specific cell receptors, enabling targeted cell delivery. Mannosylation has emerged as a valuable tool for increasing the ability of nanoparticles to be recognized and internalized by macrophages. Nevertheless, the design and development of functionalized NLC is a complex task that entails the optimization of numerous variables and steps, making the process challenging and time-consuming. Moreover, no previous studies have been focused on evaluating the functionalization efficiency. In this work, hybrid Artificial Intelligence technologies are used to help in the design of mannosylated drug loaded NLCs. Artificial neural networks combined with fuzzy logic or genetic algorithms were employed to understand the particle formation processes and optimize the combinations of variables for the different steps in the functionalization process. Mannose was chemically modified to allow, for the first time, functionalization efficiency quantification and optimization. The proposed sequential methodology has enabled the design of a robust procedure for obtaining stable mannosylated NLCs with a uniform particle size distribution, small particle size (< 100 nm), and a substantial positive zeta potential (> 20mV). The incorporation of mannose on the surfaces of these DDS following the established protocols achieved > 85% of functionalization efficiency. This high effectiveness should enhance NLC recognition and internalization by macrophages, thereby facilitating the treatment of chronic inflammatory diseases.

Development of solid lipid microparticles (SLMs) containing asiatic acid for topical treatment of acne: Characterization, stability, in vitro and in vivo anti-acne assessment

Solid lipid microparticles (SLMs) represent a promising approach for drug delivery in anti-acne applications. In this study, asiatic acid-loaded SLMs (AASLMs) were prepared by melt emulsification method in conjunction with freeze-drying. Comprehensive evaluations comprised particle size, %entrapment efficiency (%EE), %labeled amount (%LA), surface morphology, stability, %release, %skin permeation, and anti-acne activity. The AASLMs exhibited an average particle size ranging from 7.46 to 38.86 µm, with %EE and %LA falling within the range of 31.56 to 100.00 and 90.43 to 95.38, respectively. The AASLMs demonstrated a spherical shape under scanning electron microscopy, and maintained stability over a 3-month period. Notably, formulations with 10 % and 15 % cetyl alcohol stabilized with poloxamer-188 (specifically F6 and F12) displayed a minimum inhibitory concentration (MIC) value of 75 mg/ml against Cutibacterium acnes. Furthermore, F12 exhibited a higher %release and %skin permeation compared to F6 over 24 h. In a single-blind clinical trial involving fifteen participants with mild-to-moderate acne, F12 showcased its potential not only in reducing porphyrin intensity and enhancing skin barriers but also in significantly improving skin hydration and brightness. However, further investigations with larger subject cohorts encompassing diverse age groups and genders are necessary to thoroughly establish the performance of the developed AASLMs.

Exploring the Nano Spray-Drying Technology as an Innovative Manufacturing Method for Solid Lipid Nanoparticle Dry Powders

To take advantage of solid-state properties, the nano spray-drying (NSD) technique was investigated as an innovative one-step method to produce solid lipid nanoparticles (SLN) in the form of a dry powder starting from a lipid/leucine O/W emulsion. Compritol was chosen as wall-forming lipid. Rapamycin (Rp) was employed as a model drug to be loaded into SLN. Based on an initial screening, Lutrol F68 was chosen as surfactant and high-shear homogenization as an emulsification method. A two-level fractional factorial design and an extended factorial design were employed to determine critical factors and best preparation conditions. Compritol concentration, L-leucine/lipid ratio, and Lutrol F68 concentration resulted critical. Best conditions granted 51% yield, 3.2 μm L-leucine/SLN particle size, and a SLN population around 150 nm. All samples showed the presence of lipid aggregates. Material loss in the emulsification step was found responsible for SLN aggregation and low yield. The almost quantitative Rp loading increased SLN population span. Replacing compritol with cetyl palmitate produced aggregation of dry powders and SLN. Overall, NSD was found a fast method to produce SLN dry powders. More insightful assessment of the emulsification step and lipid property effects will be critical to the optimization of the NSD process. Hypotheses account for direct coupling of high-pressure homogenization with NSD for future successful development of this promising manufacturing method.

Ocular irritation and cyclosporine A distribution in the eye tissues after administration of Solid Lipid Microparticles in the rabbit model

The aim of this study was to investigate the in vivo effect of Solid Lipid Microparticles (SLM), proposed for topical ocular administration of cyclosporine, on the rabbit eye. SLM carrier is an aqueous dispersion of lipid microparticles (20% w/w) with a size up to 15 μm. Cyclosporine was dissolved in the formulation in the concentration of 0.5 or 2.0% (w/w). Ocular tolerance of microsphere dispersion was assessed in rabbit model by the Draize eye test (SLM was compared with emulsion and oily solution), and cyclosporine distribution in ocular tissues was evaluated after multiple application of tested formulations (SLM dispersions, emulsions and oily solution) for 7 days. Good tolerance of cyclosporine-SLM formulation was demonstrated in the rabbit model. Concentration of cyclosporine in the precorneal tissues, such as cornea and conjunctiva, was much higher than the therapeutic value (8.4 ng/mg and 3.2 ng/mg, respectively). After SLM administration, the cyclosporine concentrations determined in the anterior ocular tissues, were also significantly higher compared to those obtained after the application of other tested carriers (emulsions and oily solution). The obtained results prove that the recognized SLM dispersions are safe formulations for ophthalmic use. It can be concluded that lipid microparticles are highly promising for an efficient ophthalmic drug delivery, when compared to other conventional dosage forms.

Determining drug release rates of hydrophobic compounds from nanocarriers

Obtaining meaningful drug release profiles for drug formulations is essential prior to in vivo testing and for ensuring consistent quality. The release kinetics of hydrophobic drugs from nanocarriers (NCs) are not well understood because the standard protocols for maintaining sink conditions and sampling are not valid owing to mass transfer and solubility limitations. In this work, a new in vitroassay protocol based on 'lipid sinks' and magnetic separation produces release conditions that mimic the concentrations of lipid membranes and lipoproteins in vivo, facilitates separation, and thus allows determination of intrinsic release rates of drugs from NCs. The assay protocol is validated by (i) determining the magnetic separation efficiency, (ii) demonstrating that sink condition requirements are met, and (iii) accounting for drug by completing a mass balance. NCs of itraconazole and cyclosporine A (CsA) were prepared and the drug release profiles were determined. This release protocol has been used to compare the drug release from a polymer stabilized NC of CsA to a solid drug NP of CsA alone. These data have led to the finding that stabilizing block copolymer layers have a retarding effect on drug release from NCs, reducing the rate of CsA release fourfold compared with the nanoparticle without a polymer coating.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

From micro- to nanostructured implantable device for local anesthetic delivery

Local anesthetics block the transmission of painful stimuli to the brain by acting on ion channels of nociceptor fibers, and find application in the management of acute and chronic pain. Despite the key role they play in modern medicine, their cardio and neurotoxicity (together with their short half-life) stress the need for developing implantable devices for tailored local drug release, with the aim of counterbalancing their side effects and prolonging their pharmacological activity. This review discusses the evolution of the physical forms of local anesthetic delivery systems during the past decades. Depending on the use of different biocompatible materials (degradable polyesters, thermosensitive hydrogels, and liposomes and hydrogels from natural polymers) and manufacturing processes, these systems can be classified as films or micro- or nanostructured devices. We analyze and summarize the production techniques according to this classification, focusing on their relative advantages and disadvantages. The most relevant trend reported in this work highlights the effort of moving from microstructured to nanostructured systems, with the aim of reaching a scale comparable to the biological environment. Improved intracellular penetration compared to microstructured systems, indeed, provides specific drug absorption into the targeted tissue and can lead to an enhancement of its bioavailability and retention time. Nanostructured systems are realized by the modification of existing manufacturing processes (interfacial deposition and nanoprecipitation for degradable polyester particles and high- or low-temperature homogenization for liposomes) or development of novel strategies (electrospun matrices and nanogels). The high surface-to-volume ratio that characterizes nanostructured devices often leads to a burst drug release. This drawback needs to be addressed to fully exploit the advantage of the interaction between the target tissues and the drug: possible strategies could involve specific binding between the drug and the material chosen for the device, and a multiscale approach to reach a tailored, prolonged drug release.

A perspective overview on lipospheres as lipid carrier systems

Both hydrophilic and lipophilic therapeutics can be delivered successfully into deep and peripheral tissues such as cerebrospinal fluid and central nervous system by encapsulating them with crystalline lipids as lipospheres. The advent of lipospheres was meant to deliver both therapeutic moieties with enhanced efficacy and added stability to reach out intended tissue areas. Although extensive information is available on physicochemical, analytical and biopharmaceutical aspects of lipospheres, there was no specific order pertaining to critical composition and rationale of component selection available for academic and pilot scale processing of lipospheres. With the interest of compiling key points in a typical formulation of lipid lipospheres, this article was intrigued to discuss melt method, co-solvent, microemulsion, super critical fluid, spray drying and spray congealing techniques that were employed to scale up lipospheres. The selection criteria for both the drugs and lipids in liposphere formulations were demonstrated here. The quality assessment with variables like loading capacity and entrapment efficiency was explained. A note on preliminary screening factors to determine the liposphere formation such as liposphere dimensions with morphological scenario was detailed in this article. This article also includes the stability and storage issues with reference to photolysis. The marked differential in enhancing solubility and permeability characteristics of Class II and IV drug candidates by liposphere delivery systems with an evident of in vivo outcomes were emphasized.

New formulations of local anaesthetics-part I

Part 1 comments on the types of local anaesthetics (LAs); it provides a better understanding of the mechanisms of action of LAs, and their pharmacokinetics and toxicity. It reviews the newer LAs such as levobupivacaine, ropivacaine, and articaine, and examines the newer structurally different LAs. The addition of adjuvants such as adrenaline, bicarbonate, clonidine, and corticosteroids is explored. Comment is made on the delivery of topical LAs via bioadhesive plasters and gels and controlled-release local anaesthetic matrices. Encapulation matrices such as liposomes, microemulsions, microspheres and nanospheres, hydrogels and liquid polymers are discussed as well. New innovations pertaining to LA formulations have indeed led to prolonged action and to novel delivery approaches.

Controlling drug nanoparticle formation by rapid precipitation

Nanoparticles are a drug delivery platform that can enhance the efficacy of active pharmaceutical ingredients, including poorly-water soluble compounds, ionic drugs, proteins, peptides, siRNA and DNA therapeutics. To realize the potential of these nano-sized carriers, manufacturing processes must be capable of providing reproducible, scalable and stable formulations. Antisolvent precipitation to form drug nanoparticles has been demonstrated as one such robust and scalable process. This review discusses the nucleation and growth of organic nanoparticles at high supersaturation. We present process considerations for controlling supersaturations as well as physical and chemical routes for modifying API solubility to optimize supersaturation and control particle size. We conclude with a discussion of post-precipitation factors which influence nanoparticle stability and efficacy in vivo and techniques for stabilization.

Review of prolonged local anesthetic action

IMPORTANCE OF THE FIELD

Pain following surgery is often treated by local anesthetic agents. Duration of the analgesia can be extended safely following administration of encapsulated large doses of local anesthetic agents.

AREAS COVERED IN THIS REVIEW

This review considers formulations used for encapsulation of local anesthetic agents for prolonged anesthesia effect. All studies describing encapsulation of a commercial local anesthetic agent for providing prolonged analgesia were considered using the NCBI Medline site. of local anesthetic, prolonged anesthesia, polymers and liposomes were entered in order to retrieve appropriate articles and reviews from 1966 to 2010, with emphasis on the last 10 years. Reference pages were searched manually for other relevant articles. The topics covered include an overview of local anesthetic agents and a review of local anesthetic carrier agents, with emphasis on liposomes and polymer carriers. Articles were limited to the English language.

WHAT THE READER WILL GAIN

The current research areas for prolongation of local anesthetic effect are evaluated, along with their limitations. Each topic has been summarized, and the review has attempted to cover all current laboratory and clinical studies in a simple manner that should also be useful for readers without a pharmacology background. The direction of research is promising and exciting, and this review should be a useful up-to-date reference.

TAKE HOME MESSAGE

Many formulations including polymer and liposome carriers have facilitated prolonged local anesthetic action for several days, although few clinical studies have been performed. This field promises a safe way to deliver local anesthetics for effect far beyond that of commercially available agents, with potential cost and health benefits for patients suffering chronic or postoperative pain.