Polymeric nanoparticles: A promising strategy for treatment of Alzheimer's disease.

Alzheimer's disease (AD), is characterised by two major hallmarks: the formation of extracellular ß-amyloid (Aß) plaques and the hyperphosphorylation of tau protein, thus leading to the formation of neurofibrillary tangles. These hallmarks cause synaptic loss, neuronal damage, and the development of neuroinflammation and oxidative stress, which promote AD progression. Thus, the goal of treating AD is eliminating these hallmarks, to prevent AD progression and decrease symptoms. However, current available therapies provide symptomatic relief rather than treating the underlying cause of the disease, because the restrictive nature of the blood brain barrier (BBB) impedes the entry of drugs, thereby affecting drug efficacy and bioavailability. Researchers are focusing on developing new therapeutic approaches to bypass the BBB, for achieving site-specific drug delivery with the highest possible bioavailability and the lowest adverse effects. Recently explored therapeutic strategies include use of biologic agents such as monoclonal antibodies. Aducanumab, a strong candidate for treating AD, has been granted accelerated Food and Drug Administration approval; however, safety concerns may hinder its future use. Thus, nanotechnological approaches have led to a new era of AD treatment. Nanoparticles (NPs), because of their small particle size, can cross the BBB, thus enhancing drug pharmacokinetic properties and enabling targeted drug delivery. Polymeric NPs have been extensively studied, because of their simple production, biodegradability, biocompatibility, and unique architecture. These NPs provide a flexible vesicle that can be easily tailored to achieve desired physicochemical features. In this review, various types of polymer-based-NPs are discussed, highlighting the properties of fabricated NPs, which have multiple benefits in AD treatment, including anti-amyloid, antioxidant, and anti-inflammatory effects.

PEGylated polymeric nanocapsules for oral delivery of trypsin targeted to the small intestines.

The lack of trypsin in the intestines may end up with malnutrition; thus, trypsin replacement therapy is required in such cases. The main objective of this study is to formulate and evaluate polymeric nanocapsule (PNC) systems able to deliver trypsin to the small intestines with the minimal release in the stomach with the maximum biological activity. Four nanocapsule formulations were prepared by double emulsion/evaporation method as w/o/w and s/o/w. Particle size, encapsulation efficiencies, drug release in simulated gastric fluids (SGF) and simulated intestinal fluids (SIF), morphology, the biological activity of encapsulated trypsin and shelf-life stability were investigated for all formulations. All formulations had a spherical shape with submicron size, and encapsulation efficiency more than 80%. The biological activity of encapsulated trypsin was significantly affected by the amount of trehalose and whether the formulations were prepared as s/o/w or w/o/w (P < 0.05). Most of the encapsulated protein was released sustainedly at the target site (SIF) over 24 h with minimum amount release in the gastric fluids. Also, more than 90% of physical integrity trypsin encapsulated in all formulations was retained after storage under chilled conditions for six months. However, the enzymatic assay results show that with low trehalose content, the biological activity was low, while increasing the trehalose amount increased the shelf stability to reach around 100% after six months of the study. The results obtained in this research work clearly indicated a promising potential of controlled release polymeric nanocapsules containing trypsin to target the small intestine and protect trypsin from the harsh condition facing the proteins during the process of preparation or the period of storage.

Lysozyme and DNase I loaded poly (D, L lactide-co-caprolactone) nanocapsules as an oral delivery system.

Clinical applications of oral protein therapy for the treatment of various chronic diseases are limited due to the harsh conditions encounter the proteins during their journey in the Gastrointestinal Tract. Although nanotechnology forms a platform for the development of oral protein formulations, obtaining physiochemically stable formulations able to deliver active proteins is still challenging because of harsh preparation conditions. This study proposes the use of poly (D, L-lactic-co-caprolactone)-based polymeric nanocapsules at different monomers' ratios for protein loading and oral delivery. All formulations had a spherical shape and nano-scale size, and lysozyme encapsulation efficiency reached 80% and significantly affected by monomers' ratio. Trehalose and physical state of lysozyme had a significant effect on its biological activity (P < 0.05). Less than 10% of the protein was released in simulated gastric fluid, and 73% was the highest recorded accumulative release percentage in simulated intestinal fluid (SIF) over 24 h. The higher caprolactone content, the higher encapsulation efficiency (EE) and the lower SIF release recorded. Therefore, the formulation factors were optimised and the obtained system was PEGylated wisely to attain EE 80%, 81% SIF release within 24 h, and 98% lysozyme biological activity. The optimum formulation was prepared to deliver DNase, and similar attributes were obtained.

Formulation and evaluation of different floating tablets containing metronidazole to target stomach.

The purpose of this study is to formulate and develop tablets dosage form containing Metronidazole which has swelling and floating properties as a gastroretentive controlled-release drug delivery system to improve drug bioavailability. Fifteen different formulations of effervescence-forming floating systems were designed using HPMC K15M, xanthan gum, co-povidone, Eudragit® RL PO, pluronic® F-127 and/or polypropylene foam powder as swelling agents and sodium bicarbonate with/ without citric acid as gas-forming agents at different compositions. Six out of these 15 formulations which have satisfactory tablet floating behaviour were further studied with the incorporation of Metronidazole. The tablets were evaluated based on tablet physicochemical properties, floating behaviour, swelling ability and drug dissolution studies which were carried out using 0.1M HCl at 37°C for 8 hours. Furthermore, evaluation of the powder mixtures using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscope (SEM) were investigated. Most of the tablets show good physicochemical properties except for F11 which contains pluronic® F-127 as its release-retarding matrix-forming polymer. Other formulations show high swelling capacity, ability to float for at least 8 hours in vitro and have sustained drug release characteristics. Data obtained indicated that F3 which contains HPMC (12.5%w/w), xanthan gum (25%w/w), co-povidone (12.5%w/w) and sodium bicarbonate (31.7%w/w) is a suitable formulation with short floating lag time, good floating behaviour and sustained drug release for at least 8 hours in vitro with a zero order kinetic. Combinations of HPMC K15M and xanthan gum as swelling agents show synergistic effect in retarding drug release and are suitable in providing the most sustained drug release system.

Physical Characterisation as an Insight into a Gene Delivery System Containing Cyclodextrins with Pluronic®-F127 and Folic acid as Non-Viral Vectors.

Gene delivery into cells offers opportunities to treat various human genetic diseases. Effective gene delivery is dependent on its stability and ability to transfect across cells. DNA is susceptible to enzymatic degradation and its negatively charge are barriers towards successful transfection. DNA has to be protected from degradation and neutralised. Non-viral vectors are preferred carrier systems, therefore, the use of cyclodextrins with Pluronic(®)-F127 and folic acid at different concentrations to stabilise the formulation was investigated. Formulations were characterised in fresh and freeze dried forms. DNA stability in formulations was tested by determining the stability of DNA against enzymatic degradation. Degree of DNA inclusion into cyclodextrins was investigated using fluorescence spectroscopy. Thermal behaviour was studied using Differential Scanning Calorimetry (DSC). Incorporation of Pluronic(®)-F127 produced most stable formulations regarding enzymatic degradation. These formulations show high percentage inclusion. Shift of peaks in FTIR data, appearance of uniform particulate as detected by SEM and changing in the denaturation temperature as demonstrated by DSC data for Pluronic(®)-F127 containing formulations confirm clear interaction between Pluronic(®)-F127 and cyclodextrin/ DNA complex. It was noted that γ-cyclodextrin provide better protection and inclusion compared to ß-cyclodextrin. Pluronic(®)-F127 with cyclodextrins is a promising combination to improve stability.

Liquisolid systems to improve the dissolution of furosemide.

A liquisolid system has the ability to improve the dissolution properties of poorly water soluble drugs. Liquisolid compacts are flowing and compactable powdered forms of liquid medications. The aim of this study was to enhance the in vitro dissolution properties of the practically water insoluble loop diuretic furosemide, by utilising liquisolid technique. Several liquisolid tablets were prepared using microcrystalline cellulose (Avicel pH-101) and fumed silica (Cab-O-Sil M-5) as the carrier and coating materials, respectively. Polyoxy-ethylene-polyoxypropylene-polyoxyethylene block copolymer (Synperonic PE/L 81); 1,2,3-propanetriol, homopolymer, (9Z)-9-octadecenoate (Caprol PGE-860) and polyethylene glycol 400 (PEG 400) were used as non- volatile water-miscible liquid vehicles. The liquid loading factors for such liquid vehicles were calculated to obtain the optimum amounts of carrier and coating materials necessary to produce acceptable flowing and compactible powder admixtures viable to produce compacts. The ratio of carrier to coating material was kept constant in all formulations at 20 to 1. The formulated liquisolid tablets were evaluated for post compaction parameters such as weight variation, hardness, drug content uniformity, percentage friability and disintegration time. The in-vitro release characteristics of the drug from tablets formulated by direct compression (as reference) and liquisolid technique, were studied in two different dissolution media. Differential scanning calorimetry (DSC) and Fourier-Transform infrared spectroscopy (FT-IR) were performed. The results showed that all formulations exhibited higher percentage of drug dissolved in water (pH 6.4â6.6) compared to that at acidic medium (pH 1.2). Liquisolid compacts containing Synperonic PE/L 81 demonstrated higher release rate at the different pH values. Formulations with PEG 400 displayed lower drug release rate, compared to conventional and liquisolid tablets. DSC and FT-IR indicated a possible interaction between furosemide and tablet excipients that could explain the dissolution results. Caprol PGE-860, as a liquid vehicle, failed to produce furosemide liquisolid compacts.

Dissolution of ibuprofen from spray dried and spray chilled particles.

The formulation of hydrophobic drugs for oral drug delivery is challenging due to poor solubility, poor dissolution and poor wetting of these drugs. Consequently, the aim of this study was to improve the dissolution of a model poorly water soluble drug, ibuprofen. Microparticles containing ibuprofen were produced by spray drying and spray chilling technology in the absence/presence of a hydrophilic surfactant. Poloxamer 127, tri-block copolymer, was chosen as the hydrophilic surfactant to improve drug particle wettability and hence the dissolution rate. The prepared formulations were evaluated for in vitro dissolution and intrinsic solubility. In addition, the produced drug particles were characterised by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy (FT-IR). SEM revealed changes in the surface morphology of processed ibuprofen, suggesting the effective formation of the drug particles. DSC data showed shifting of the melting peak of the drug towards lower melting temperature in the prepared particles, indicating the possibility of drug /polymer interaction. The results of the dissolution studies of spray dried ibuprofen and spray dried ibuprofen/Poloxamer 127 particles showed significantly (P<0.05) increased percentage drug release compared to control (ibuprofen raw material). For spray chilling, the prepared particles did not improve the dissolution of the drug, the dissolution was even less than that of the control. DSC and FT-IR results demonstrated that spray drying reduced drug crystallinity, but for spray chilled particles there was evidence of polymorphic changes in the drug with and without the surfactant. Consequently, it is believed that spray drying of ibuprofen is a useful tool to improve wettability, solubility and hence the dissolution behaviour of poorly water soluble drugs, in contrast to spray chilling technique.

Effects of liquisolid formulations on dissolution of naproxen.

The aim of this study was to investigate the use of liquisolid technique in improving the dissolution profiles of naproxen in a solid dosage form. This study was designed to evaluate the effects of different formulation variables, i.e. type of non-volatile liquid vehicles and drug concentrations, on drug dissolution rates. The liquisolid tablets were formulated with three different liquid vehicles, namely Cremophor EL (polyoxyl 35 castor oil), Synperonic PE/L61 (poloxamer 181, polyoxyethylene-polyoxypropylene copolymer) and poly ethylene glycol 400 (PEG400) at two drug concentrations, 20%w/w and 40%w/w. Avicel PH102 was used as a carrier material, Cab-o-sil M-5 as a coating material and maize starch as a disintegrant. The empirical method as introduced by Spireas and Bolton (1999) [1] was applied strictly to calculate the amounts of coating and carrier materials required to prepare naproxen liquisolid tablets. Quality control tests, i.e. uniformity of tablet weight, uniformity of drug content, tablet hardness, friability test, disintegration and dissolution tests were performed to evaluate each batch of prepared tablets. In vitro drug dissolution profiles of the liquisolid formulations were studied and compared with conventional formulation, in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.2) without enzyme. Stability studies were carried out to evaluate the stability of the tablets under humid conditions. Differential scanning calorimetry and Fourier transform infrared were used to investigate physicochemical interaction between naproxen and the excipients. It was found that liquisolid tablets formulated with Cremophor EL at drug concentration of 20%w/w produced high dissolution profile with acceptable tablet properties. The stability studies showed that the dissolution profiles of liquisolid tablets prepared with Cremophor EL were not affected by ageing significantly. Furthermore, DSC revealed that drug particles in liquisolid formulations were completely solubilised.

Preparation and characterisation of spray-dried and crystallised trypsin: FT-Raman study to detect protein denaturation after thermal stress.

The production of stable protein formulations is difficult due to unique properties of proteins. Accordingly, spray drying and crystallisation techniques were assessed for their effects on trypsin, a model protein. Samples were investigated using polarising microscopy, thermogravimetry, differential scanning calorimetry (DSC), FT-Raman spectroscopy and enzymatic assay. Unprocessed, spray-dried and crystallised trypsin were evaluated in solution for secondary structure in low and high protein concentrations using aqueous state FT-Raman spectroscopy and for folding reversibility employing high sensitivity differential scanning calorimetry. Spray-dried trypsin showed FT-Raman spectral changes and less biological activity, after rehydration, compared with unprocessed and crystallised trypsin. Crystals maintained activity better than did the spray-dried form and retained a higher folding reversibility compared to unprocessed and spray-dried protein. Proteins may denature with structural changes under thermal stress and lose their activities. Thus, this research studied the effect of heating solid unprocessed, spray-dried and crystallised trypsin samples on their secondary structures, using FT-Raman spectroscopy, to identify the influence of the initial solid form on its propensity for thermal denaturation and whether this can be correlated with catalytic activity. DSC heated protein samples to two temperatures, one before the apparent denaturation temperature (T(m)) and the other after the T(m). Samples heated below their T(m) showed some perturbations of the secondary structure and some activity, whilst materials rose to the higher temperature were insoluble with complete loss of activity.

Stability of crystallised and spray-dried lysozyme.

Moisture and temperature promote protein degradation. The stabilities of commercial, crystallised and spray-dried lysozyme, a model protein, were assessed under these stresses to explore whether a crystalline protein had better storage stability than a conventionally produced one. Samples were maintained at different relative humidities (RH) and temperatures for 20 weeks and stabilities estimated in solid and aqueous states. Differential scanning calorimetry (DSC) and thermogravimetry (TGA) characterised solid samples. Fourier transform Raman (FT-Raman) spectroscopy analysed solid material and aqueous solutions. High sensitivity differential scanning calorimetry (HSDSC) and enzymatic assays were used to monitor solutions. DSC and HSDSC data revealed that crystals maintained thermal stability at high RH; spray drying appreciably changed melting characteristics. These results correlated with enzymatic assays that demonstrated good activity retention for crystals but less so for spray-dried material (e.g. 95 and 87% relative to fresh samples after 20 weeks at 40 degrees C/75% RH). FT-Raman analysis showed that crystallised lysozyme better-maintained protein conformational integrity compared to spray-dried samples in accelerated stability studies. Based on TGA data, spray-dried protein absorbed water on storage under humid conditions, which induced instability. Thus, crystallisation enhanced storage stability of lysozyme with negligible loss of activity.

Integrity of crystalline lysozyme exceeds that of a spray-dried form.

The development of proteins as therapeutic agents is challenging partly due to their inherent instabilities. Consequently, crystallisation and spray drying techniques were assessed to determine their effects on protein integrity using lysozyme as a model protein. Unprocessed, crystallised and spray-dried lysozyme were characterised by: thermal analysis using hot stage microscopy (HSM), differential scanning calorimetry (DSC), high sensitivity differential scanning calorimetry (HSDSC) and thermogravimetry (TGA); and spectroscopic analysis employing Fourier transform Raman (FT-Raman). Moisture contents were determined by TGA and Karl Fisher titration (KFT). Enzymatic assay measured biological activity. HSM showed no changes in crystals until complete melting. TGA and KFT indicated that spray-dried lysozyme contained a lower moisture content than crystals, hence the higher apparent thermal stability was shown by DSC. HSDSC revealed that crystallisation and spray drying did not affect the denaturation temperature of lysozyme in solution when compared with unprocessed material. However, in the solid state, FT-Raman spectra showed perturbation of the conformational structure of spray-dried sample, whereas crystal conformation remained intact. Enzymatic assay revealed increased activity retention of crystals compared with spray-dried powder. Hence, crystals maintained the conformational integrity and activity of lysozyme in solution.