Novel lipid-based formulations enhancing the in vitro dissolution and permeability characteristics of a poorly water-soluble model drug, piroxicam

Lipid Horizons: Recent Advances and Future Prospects in LBDDS for Oral Administration of Antihypertensive Agents

The lipid-based drug delivery system (LBDDS) is a well-established technique that is anticipated to bring about comprehensive transformations in the pharmaceutical field, impacting the management and administration of drugs, as well as treatment and diagnosis. Various LBDDSs verified to be an efficacious mechanism for monitoring hypertension systems are SEDDS (self-nano emulsifying drug delivery), nanoemulsion, microemulsions, vesicular systems (transferosomes and liposomes), and solid lipid nanoparticles. LBDDSs overcome the shortcomings that are associated with antihypertensive agents because around fifty percent of the antihypertensive agents experience a few drawbacks including short half-life because of hepatic first-pass metabolism, poor aqueous solubility, low permeation rate, and undesirable side effects. This review emphasizes antihypertensive agents that were encapsulated into the lipid carrier to improve their poor oral bioavailability. Incorporating cutting-edge technologies such as nanotechnology and targeted drug delivery, LBDDS holds promise in addressing the multifactorial nature of hypertension. By fine-tuning drug release profiles and enhancing drug uptake at specific sites, LBDDS can potentially target renin-angiotensin-aldosterone system components, sympathetic nervous system pathways, and endothelial dysfunction, all of which play crucial roles in hypertension pathophysiology. The future of hypertension management using LBDDS is promising, with ongoing reviews focusing on precision medicine approaches, improved biocompatibility, and reduced toxicity. As we delve deeper into understanding the intricate mechanisms underlying hypertension, LBDDS offers a pathway to develop next-generation antihypertensive therapies that are safer, more effective, and tailored to individual patient needs.

Formulation and evaluation of Piroxicam nanosponge for improved internal solubility and analgesic activity

Cyclodextrin nanosponges are solid nanoparticles, designed by cross-linking of cyclodextrin polymer; it has been used widely as a good delivery system for water insoluble drugs. The aim of this study is to enhance the solubility of Piroxicam (PXM) using β-Cyclodextrin based nanosponges formulations. PXM nanosponge (PXM-NS) formulations were prepared using β-cyclodextrin and carbonyldiimidazole as a cross linker, three ratios of β-cyclodextrin to crosslinker in addition to three drug to nanosponges ratios were tested. Piroxicam nanosponge formulations were characterized for its particle size, zeta potential, physical compatibility and in vitro release. Stability studies at three temperatures (4 °C, 25 °C and 40 °C) were done for optimal formula. Finally, the in vivo analgesic activity and pharmacokinetic parameters of the optimal formula were conducted. The optimized PXM-NS formula (PXM-NS10) showed particle size (362 ± 14.06 nm), polydispersity index (0.0518), zeta potential (17 ± 1.05 mV), and %EE (79.13 ± 4.33). The dissolution study showed a significant increase in the amount of PXM dissolved compared with the unformulated drug. Stability studies confirmed that nanosponge showed accepted stability for 90 days at 4 °C and 25 °C. In vivo analgesic studies verified that there was a significant enhancement in the analgesic response to PXM in mice, and 1.42 fold enhancement in the relative bioavailability of PXM-NS10 as compared to commercial tablets. Nanosponge prepared under optimal conditions is an encouraging formula for increasing the solubility and therefore the bioavailability of Piroxicam.

Nano-Emulsion Based Gel for Topical Delivery of an Anti-Inflammatory Drug: In vitro and in vivo Evaluation

Introduction

Arthritic disorder is a common disease in elderly patients and the most common cause of joint dysfunction. This study aims to design Piroxicam-loaded nanoemulsion (PXM-NE) formulations to enhance the analgesic and anti-inflammatory activity of the drug for topical use.

Methods

The nanoemulsion preparations were designed based on a high-pressure homogenization technique and were characterized for particle size (PS), poly dispersity index (Pi), zeta potential (ZP), drug content, and the selected formula was investigated for its topical analgesic activity and pharmacokinetic parameters.

Results

The characterizations showed that the PS was 310.20±19.84 nm, Pi was 0.15±0.02, and ZP was -15.74±1.6 mV for the selected formula. A morphology study showed that the PXM-NE droplets were spherical with a uniform size distribution. The in vitro release study showed a biphasic release pattern with a rapid release within the first 2 hours followed by a sustained release pattern. The analgesic activity for optimal formula was 1.66 times higher than the commercial gel with a double duration of analgesic activity. The C_max was 45.73±9.95 and 28.48±6.44 ng/mL for the gel form of the selected formula and the commercial gel respectively. The relevant bioavailability of the selected formula was 2.41 higher than the commercial gel.

Conclusion

The results showed good physicochemical properties, higher bioavailability, and a longer analgesic effect of PXM from nanoemulsion gel, as compared to the commercial product.

Piroxicam Loading onto Mesoporous Silicas by Supercritical CO2 Impregnation

Piroxicam (PRX) is a commonly prescribed nonsteroidal anti-inflammatory drug. Its efficacy, however, is partially limited by its low water solubility. In recent years, different studies have tackled this problem and have suggested delivering PRX through solid dispersions. All these strategies, however, involve the use of potentially harmful solvents for the loading procedure. Since piroxicam is soluble in supercritical CO₂ (scCO₂), the present study aims, for the first time, to adsorb PRX onto mesoporous silica using scCO₂, which is known to be a safer and greener technique compared to the organic solvent-based ones. For comparison, PRX is also loaded by adsorption from solution and incipient wetness impregnation using ethanol as solvent. Two different commercial mesoporous silicas are used (SBA-15 and Grace Syloid^® XDP), which differ in porosity order and surface silanol population. Physico-chemical analyses show that the most promising results are obtained through scCO₂, which yields the amorphization of PRX, whereas some crystallization occurs in the case of adsorption from solution and IWI. The highest loading of PRX by scCO₂ is obtained in SBA-15 (15 wt.%), where molecule distribution appears homogeneous, with very limited pore blocking.

Improving solubility and oral bioavailability of a novel antimalarial prodrug: comparing spray-dried dispersions with self-emulsifying drug delivery systems

To improve the solubility and oral bioavailability of a novel antimalarial agent ELQ-331(a prodrug of ELQ-300), spray-dried dispersions (SDD) and a self-emulsifying drug delivery system (SEDDS) were developed. SDD were prepared with polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus^®) polymer carrier and Aeroperl^® 300 Pharma and characterized by differential scanning calorimetry, powder X-ray diffraction. For SEDDS, solubility in oils, surfactants, and co-surfactants was determined and ternary phase diagram was constructed to show self-emulsifying area. SEDDS were characterized for spontaneous emulsification and droplet size distribution. The amorphous ELQ-331 SDD improved the solubility to 10× in fast-state simulated intestinal fluid and addition of sodium lauryl sulphate externally to SDDs further improved the solubility to ∼28.5× versus non-formulated drug. SEDDS had good self-emulsifying characteristics with small emulsion droplet sizes and narrow particle distribution. Oral pharmacokinetic studies for SDD and SEDDS formulations were performed in rats. The ELQ-331 rapidly converted to ELQ-300 soon after oral administration in rats. Exposure levels of ELQ-300 were about 1.4-fold higher (based on AUC) in SEDDS than SDD formulations. Poorly soluble drugs like ELQ-331 can be formulated using SDD or SEDDS to improve solubility and oral bioavailability.

Piroxicam

A comprehensive profile of piroxicam including the nomenclatures, formulae, elemental composition, appearance, uses and applications. The methods which were utilized for the preparation of the drug substance and their respective schemes are outlined. The physical characteristics of the drug including the ionization constant, solubility, x-ray powder diffraction pattern, differential scanning calorimetry, thermal behavior and spectroscopic studies are described. The methods which were used for the analysis of the drug substance in bulk drug and/or in pharmaceutical formulations including the compendial, spectrophotometric, electrochemical and the chromatographic methods are reported. The stability, toxicity, pharmacokinetics, bioavailability, drug evaluation, comparison, in addition to compiled reviews on the drug substance are involved. Finally, more than four hundred and fifty references are listed at the end of this profile.

Self-microemulsifying Drug Delivery System for Problematic Molecules: An Update

BACKGROUND

The poor bioavailability of a problematic molecule is predominantly due to its high lipophilicity, low solubility in gastric fluids and/or high fist pass metabolism. Self microemulsifying drug delivery system (SMEDDS), a lipidic type IV nano-formulation has been of interest in the field of pharmaceutical research due to its potential for tailoring the physicochemical properties of pharmaceutical molecules.

METHODS

This review provides insights on various recent innovations and reports from the past seven years (2012-2019) of self-emulsifying formulations for the delivery of various types of poorly soluble drugs, phytoconstituents and high molecular peptides and gives exhaustive details of the outcome of the endeavors in this field.

RESULTS

Various types of innovative formulations have been molded from SMEDDS like selfemulsifying powders, granules, tablets, pellets, eutectic and cationic formulations. Till date, many research reports and patents have been filed on self-emulsifying dosage forms and many formulations have gained US-FDA approvals which are summarized in the review article.

CONCLUSION

This review content highlighted the increasing scope of SMEDDS in augmenting the physiochemical properties of an API, the variegated formulation types and the attributes of API that can be improved by SMEDD based formulations.

Lipid-Based Oral Formulation Strategies for Lipophilic Drugs

Partition coefficient (log P) is a key physicochemical characteristic of lipophilic drugs which plays a significant role in formulation development for oral administration. Lipid-based formulation strategies can increase lymphatic transport of these drugs and can enhance bioavailability many folds. The number of lipophilic drugs in pharmacopoeias and under discovery are continuously increasing and making the job of the formulation scientist difficult to develop suitable formulation of these drugs due to potent nature and water insolubility of these drugs. Recently, many natural and synthetic lipids are appearing in the market which are helpful in the development of lipid-based formulations of these types of drugs having enhanced solubility and bioavailability. One such reason for this enhanced bioavailability is the accessibility of the lymphatic transport as well as avoidance of first-pass effect. This review discusses the impact of lipophilicity in enhancing the intestinal lymphatic drug transport thereby reducing first-pass metabolism. The most appropriate strategy for developing a lipid-based formulation depending upon the degree of lipophilicity has been critically discussed and provides information on how to develop optimum formulation. Various formulation strategies are discussed in-depth by classifying lipid-based oral drug delivery systems with case studies of few marketed formulations with challenges and opportunities for the future of the formulations.

Improving In Vivo Efficacy of Bioactive Molecules: An Overview of Potentially Antitumor Phytochemicals and Currently Available Lipid-Based Delivery Systems

Cancer is among the leading causes of morbidity and mortality worldwide. Many of the chemotherapeutic agents used in cancer treatment exhibit cell toxicity and display teratogenic effect on nontumor cells. Therefore, the search for alternative compounds which are effective against tumor cells but reduce toxicity against nontumor ones is of great importance in the progress or development of cancer treatments. In this sense, scientific knowledge about relevant aspects of nutrition intimately involved in the development and progression of cancer progresses rapidly. Phytochemicals, considered as bioactive ingredients present in plant products, have shown promising effects as potential therapeutic/preventive agents on cancer in several in vitro and in vivo assays. However, despite their bioactive properties, phytochemicals are still not commonly used in clinical practice due to several reasons, mainly attributed to their poor bioavailability. In this sense, new formulation strategies are proposed as carriers to improve their bioefficacy, highlighting the use of lipid-based delivery systems. Here, we review the potential antitumoral activity of the bioactive compounds derived from plants and the current studies carried out in animal and human models. Furthermore, their association with lipids as a formulation strategy to enhance their efficacy in vivo is also reported. The development of high effective bioactive supplements for cancer treatment based on the improvement of their bioavailability goes through this association.

Self-Nanoemulsifying Lyophilized Tablets for Flash Oral Transmucosal Delivery of Vitamin K: Development and Clinical Evaluation

Owing to limited solubility, vitamin K undergoes low bioavailability with large inter-individual variability after oral administration. This article aimed to prepare self-nanoemulsifying lyophilized tablets (SNELTs) for the flash oral transmucosal delivery of vitamin K. Twenty-one formulae of vitamin K self-nanoemulsifying drug delivery systems (SNEDDS) were prepared using different concentrations of vitamin K, Labrasol, and Transcutol according to mixture design. The SNEDDS was loaded on porous carriers and formulated as lyophilized tablets. The release profile and the pharmacokinetic parameters of vitamin K SNELTs were evaluated in comparison with commercial tablets and ampoules on human volunteers. Results revealed that the optimized SNEDDS showed the smallest and most stable nanoemulsion globules. SNELTs were prepared successfully and showed substantial superiority drug release compared with the commercial tablets. Interestingly, SNELTs enhanced both rate and extent of vitamin K absorption as well as relative bioavailability (169.67%) in healthy subjects compared with the commercial tablets. SNELTs revealed promising no significant difference in the area under the curve compared with the commercial intramuscular injection. SNELTs enhanced dissolution and bioavailability that expected to have the strong impact on the efficiency of vitamin K in the prophylaxis and treatment of bleeding disorders in patients with hepatic dysfunction.

Improvement of Meloxicam Solubility Using a β-Cyclodextrin Complex Prepared via the Kneading Method and Incorporated into an Orally Disintegrating Tablet

Purpose: The aim of this research was to formulate and develop an orally disintegrating tablet (ODT) that incorporated a MEL/β-CD complex, using a quality by design (QbD) approach to enhance solubility and drug release. Methods: Multiple regression linear analysis was conducted to develop the kneading process and ODT formulation. Mixing time and amount of solvent were used as independent variables in kneading process optimisation, while the superdisintegrants were used to obtain the desired formulation. Fourier transform infrared spectroscopy and differential scanning calorimetry were performed for complex characterization. Results: MEL/β-CD complexation was successful in enhancing MEL solubility. The results suggest that increasing the amount of solvent and mixing time enhances drug loading and drug release. However, increased solvent amounts present the problem of removing the solvent. Primojel and Polyplasdone had a significant effect on the water wicking and tablet disintegration process (p<0.05), although Polyplasdone negatively affected tablet hardness. Both an optimized KN process and ODT formulation were obtained using a QbD approach. Conclusion: Incorporation of the MEL/β-CD complex during ODT formulation using the QbD approach serves as a model for ODT product development, with optimal product performance based on the specification of quality target product profiles. To understand more specific phenomena, one point in the middle of the design for each factor should be added to more powerfully estimate this effect and avoid the lack of estimate due to an inadequate equation.

Amorphous solid dispersions: Rational selection of a manufacturing process

Amorphous products and particularly amorphous solid dispersions are currently one of the most exciting areas in the pharmaceutical field. This approach presents huge potential and advantageous features concerning the overall improvement of drug bioavailability. Currently, different manufacturing processes are being developed to produce amorphous solid dispersions with suitable robustness and reproducibility, ranging from solvent evaporation to melting processes. In the present paper, laboratorial and industrial scale processes were reviewed, and guidelines for a rationale selection of manufacturing processes were proposed. This would ensure an adequate development (laboratorial scale) and production according to the good manufacturing practices (GMP) (industrial scale) of amorphous solid dispersions, with further implications on the process validations and drug development pipeline.

Ultrasound influence on the solubility of solid dispersions prepared for a poorly soluble drug

Solid dispersions have been successfully used to enhance the solubility of several poorly water soluble drugs. Solid dispersions are produced by melting hydrophilic carriers and mixing in the poorly water soluble drug. Supersaturation is obtained by quickly cooling the mixture until it solidifies, thereby entrapping the drug. The effects of using ultrasound to homogenize the molten carrier and drug mixture were studied. In particular, the increase in drug solubility for the resulting solid dispersions was analyzed. Piroxicam, which has very low water solubility, was used as a model drug. A full factorial design was used to analyze how sonication parameters affected the solubility and in vitro release of the drug. The results show that the use of ultrasound can significantly increase the solubility and dissolution rate of the piroxicam solid dispersion. Pure piroxicam presented a solubility of 13.3 μg/mL. A maximum fourfold increase in solubility, reaching 53.8 μg/mL, was observed for a solid dispersion sonicated at 19 kHz for 10 min and 475 W. The in vitro dissolution rate test showed the sonicated solid dispersion reached a maximum rate of 18%/min, a sixfold increase over the piroxicam rate of 2.9%/min. Further solid state characterization by thermal, X-ray diffraction and Fourier transform infrared analyses also showed that the sonication process, in the described conditions, did not adversely alter the drug or significantly change its polymorphic form. Ultrasound is therefore an interesting technique to homogenize drug/carrier mixtures with the objective of increasing the solubility of drugs with poor water solubility.

Phospholipid-based solid drug formulations for oral bioavailability enhancement: A meta-analysis

Low bioavailability nowadays often represents a challenge in oral dosage form development. Solid formulations composed of drug and phospholipid (PL), which, upon contact with water, eventually form multilamellar liposomes (i.e. 'proliposomes'), are an emerging approach to solve such issue. Regarded as an 'improved' version of liposomes concerning storage stability, the potential and versatility of a range of such formulations for oral drug delivery have been extensively discussed. However, a systematic and quantitative analysis of the studies that applied solid PL for oral bioavailability enhancement is currently lacking. Such analysis is necessary for providing an overview of the research progress and addressing the question on how promising this approach can be on bioavailability enhancement. The current review performed a systematic search of references in three evidence-based English databases, Medline, Embase, and SciFinder, from the year of 1985 up till March 2015. A total of 112 research articles and 82 patents that involved solid PL-based formulations were identified. The majority of such formulations was intended for oral drug delivery (55%) and was developed to address low bioavailability issues (49%). A final of 54 studies that applied such formulations for bioavailability enhancement of 43 different drugs with poor water solubility and/or permeability were identified. These proof-of-concept studies with in vitro (n=31) and/or animal (n=23) evidences have been systematically summarized. Meta-analyses were conducted to measure the overall enhancement power (percent increase compared to control group) of solid PL formulations on drugs' solubility, permeability and oral bioavailability, which were found to be 127.4% (95% CI [86.1, 168.7]), 59.6% (95% CI [30.1, 89.0]), and 18.5% (95% CI [10.1, 26.9]) respectively. Correlations between the enhancement factors and in silico physiochemical properties of drugs were also performed to check if such approach can be used to identify the best candidates for oral solid PL formulation. In addition to scientific literature, 13 solid PL formulation-related patents that addressed the issue of low oral bioavailability have been identified and summarized; whereas no clinical study was identified from the current search. By providing systematic information and meta-analysis on studies that applied the principle of 'proliposomes' for oral bioavailability enhancement, the current review should be insightful for formulation scientists who wish to adopt the PL based approach to overcome the solubility, permeability and bioavailability issues of orally delivered drugs.

From molecular modelling to photophysics of neutral oligo- and polyfluorenes incorporated into phospholipid bilayers

The combination of various experimental techniques with theoretical simulations has allowed elucidation of the mode of incorporation of fluorene based derivatives into phospholipid bilayers. Molecular dynamics (MD) simulations on a fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) bilayer, with benzene (B), biphenyl (BP), fluorene (F) and tri-(9,9-di-n-octylfluorenyl-2,7-diyl), TF, have provided insights into the topography of these molecules when they are present in the phospholipid bilayer, and suggest marked differences between the behavior of the small molecules and the oligomer. Further information on the interaction of neutral fluorenes within the phospholipid bilayer was obtained by an infrared (IR) spectroscopic study of films of DMPC and of the phospholipid with PFO deuterated specifically on its alkyl chains (DMPC-PFO-d34). This was complemented by measurements of the effect of F, TF and two neutral polymers: polyfluorene poly(9,9-di-n-octylfluorenyl-2,7-diyl), PFO, and poly(9,9-di-n-dodecylfluorenyl-2,7-diyl), PFD, on the phospholipid phase transition temperature using differential scanning calorimetry (DSC). Changes in liposome size upon addition of F and PFO were followed by dynamic light scattering. In addition, the spectroscopic properties of F, TF, PFO and PFD solubilised in DMPC liposomes (absorption, steady-state and time-resolved fluorescence) were compared with those of the same probes in typical organic solvents (chloroform, cyclohexane and ethanol). Combining the insight from MD simulations with the results at the molecular level from the various experimental techniques suggests that while the small molecules have a tendency to be located in the phospholipid head group region, the polymers are incorporated within the lipid bilayers, with the backbone predominantly orthogonal to the phospholipid alkyl chains and with interdigitation of them and the PFO alkyl chains.

Permeability enhancing lipid-based co-solvent and SEDDS formulations of SQ641, an antimycobacterial agent

CONTEXT

Tuberculosis (TB) is a common and often deadly infectious disease caused by strains of Mycobacteria. Development of new anti-tubercular drugs is essential to control the emergence and severity of multidrug-resistant TB.

OBJECTIVE

The objective of this study was to develop an oral preclinical liquid formulation of SQ641 and to determine the permeability across rat intestinal tissue by Ussing chamber.

METHODS

Thermal and chemical characterization of SQ641 was performed by differential scanning calorimetric analysis, thermogravimetric analysis and high performance liquid chromatography. A high throughput solubility screening technique was utilized to determine the solubility of SQ641 in different solvents and co-solvents. Several co-solvent and self-emulsifying drug delivery system (SEDDS) formulations were selected for Ussing chamber permeability studies.

RESULTS AND DISCUSSION

Calculated average apparent permeability coefficients of SEDDS formulations of SQ641 (ranging from 0.03 × 10(-6) to 0.33 × 10(-6)) were found to be higher than the permeability coefficients of co-solvent formulations (ranging from 0.00 × 10(-6) to 0.09 × 10(-6)) and those of the neat drug SQ641 in buffer (0.00 × 10(-6)).

CONCLUSION

SEDDS formulations with superior permeability characteristics may provide a useful dosage form for oral intake of anti-tubercular drug SQ641, possibly due to the increase in solubility and immediate dispersion of drug.

Lipid-Based Drug Delivery Systems

The principle objective of formulation of lipid-based drugs is to enhance their bioavailability. The use of lipids in drug delivery is no more a new trend now but is still the promising concept. Lipid-based drug delivery systems (LBDDS) are one of the emerging technologies designed to address challenges like the solubility and bioavailability of poorly water-soluble drugs. Lipid-based formulations can be tailored to meet a wide range of product requirements dictated by disease indication, route of administration, cost consideration, product stability, toxicity, and efficacy. These formulations are also a commercially viable strategy to formulate pharmaceuticals, for topical, oral, pulmonary, or parenteral delivery. In addition, lipid-based formulations have been shown to reduce the toxicity of various drugs by changing the biodistribution of the drug away from sensitive organs. However, the number of applications for lipid-based formulations has expanded as the nature and type of active drugs under investigation have become more varied. This paper mainly focuses on novel lipid-based formulations, namely, emulsions, vesicular systems, and lipid particulate systems and their subcategories as well as on their prominent applications in pharmaceutical drug delivery.

Nanomedicine-based neuroprotective strategies in patient specific-iPSC and personalized medicine

In recent decades, nanotechnology has attracted major interests in view of drug delivery systems and therapies against diseases, such as cancer, neurodegenerative diseases, and many others. Nanotechnology provides the opportunity for nanoscale particles or molecules (so called “Nanomedicine”) to be delivered to the targeted sites, thereby, reducing toxicity (or side effects) and improving drug bioavailability. Nowadays, a great deal of nano-structured particles/vehicles has been discovered, including polymeric nanoparticles, lipid-based nanoparticles, and mesoporous silica nanoparticles. Nanomedical utilizations have already been well developed in many different aspects, including disease treatment, diagnostic, medical devices designing, and visualization (i.e., cell trafficking). However, while quite a few successful progressions on chemotherapy using nanotechnology have been developed, the implementations of nanoparticles on stem cell research are still sparsely populated. Stem cell applications and therapies are being considered to offer an outstanding potential in the treatment for numbers of maladies. Human induced pluripotent stem cells (iPSCs) are adult cells that have been genetically reprogrammed to an embryonic stem cell-like state. Although the exact mechanisms underlying are still unclear, iPSCs are already being considered as useful tools for drug development/screening and modeling of diseases. Recently, personalized medicines have drawn great attentions in biological and pharmaceutical studies. Generally speaking, personalized medicine is a therapeutic model that offers a customized healthcare/cure being tailored to a specific patient based on his own genetic information. Consequently, the combination of nanomedicine and iPSCs could actually be the potent arms for remedies in transplantation medicine and personalized medicine. This review will focus on current use of nanoparticles on therapeutical applications, nanomedicine-based neuroprotective manipulations in patient specific-iPSCs and personalized medicine.

Effect of binders on the release rates of direct molded verapamil tablets using twin-screw extruder in melt granulation

Conventional manufacturing of pharmaceutical tablets often involves single processes such as blending, granulation, milling and direct compression. A process that minimizes and incorporates all these in a single continuous step is desirable. The concept of omitting milling step followed by direct-molding of tablets utilizing a twin-screw extruder in a melt granulation process using thermoplastic binders was explored. The objective of this study was to investigate the effect of combining hydrophilic binder (HPMC K4M, PEO 1M), and hydrophobic binder (Compritol® ATO 888, Precirol® ATO 5) on the release profiles of direct-molded tablets and direct-compressed tablets from milled extrudates using a quality-by-design approach. It was identified that hydrophilic binder type and process significantly affects (p=0.005) the release profiles of verapamil. Moreover, two-way interaction analysis demonstrated that the combination of process with type of hydrophilic polymer (p=0.028) and the type of hydrophilic polymer with polymer ratio (p=0.033) significantly affected the release profiles. The formulation release kinetics correlated to Higuchi release model and the mechanism correlated to a non-Fickian release mechanism. The results of the present study indicated that direct-molded tablets with different release profiles can be manufactured without milling process and through a continuous melt granulation using twin-screw extruder with appropriate thermoplastic binder ratio.

Diclofenac sodium sustained release hot melt extruded lipid matrices

Sustained release diclofenac sodium (Df-Na) solid lipid matrices with Compritol® 888 ATO were developed in this study. The drug/lipid powders were processed via cold and hot melt extrusion at various drug loadings. The influence of the processing temperatures, drug loading and the addition of excipients on the obtained dissolution rates was investigated. The physicochemical characterization of the extruded batches showed the existence of crystalline drug in the extrudates with a small amount being solubilized in the lipid matrix. The drug content and uniformity on the tablet surface were also investigated by using energy dispersive X-ray microanalysis. The dissolution rates were found to depend on the actual Df-Na loading and the nature of the added excipients, while the effect of the processing temperatures was negligible. The dissolution mechanism of all extruded formulations followed Peppas-Korsemeyer law, based on the estimated determination coefficients and the dissolution constant rates, indicating drug diffusion from the lipid matrices.

In Vitro and In Vivo Evaluation of Oxatomide β -Cyclodextrin Inclusion Complex

The objective of this study was to evaluate the influence of oxatomide β-cyclodextrin inclusion complex on the physicochemical properties and bioavailability of the drug. Oxatomide β-cyclodextrin solid complex was prepared with equimolar ratio of both oxatomide and β-cyclodextrin in presence or absence of water soluble polymers using different techniques. The coevaporated complex prepared in presence of PVP-K15 showed a prompt drug release and significantly increased % dissolution efficiency (P < 0.05) compared to the pure oxatomide. Moreover, the results of bioavailability evaluation of this complex in rabbits compared to commercial drug product indicated a 73.15% increase in the oral bioavailability of oxatomide. In conclusion, inclusion complex of oxatomide with β-cyclodextrin prepared by coevaporation in presence of PVP-K15 not only results in an enhancement of the oxatomide dissolution rate but also improves the bioavailability of oxatomide.

Efavirenz dissolution enhancement I: co-micronization

AIDS constitutes one of the most serious infectious diseases, representing a major public health priority. Efavirenz (EFV), one of the most widely used drugs for this pathology, belongs to the Class II of the Biopharmaceutics Classification System for drugs with very poor water solubility. To improve EFV’s dissolution profile, changes can be made to the physical properties of the drug that do not lead to any accompanying molecular modifications. Therefore, the study objective was to develop and characterize systems with efavirenz able to improve its dissolution, which were co-processed with sodium lauryl sulfate (SLS) and polyvinylpyrrolidone (PVP). The technique used was co-micronization. Three different drug:excipient ratios were tested for each of the two carriers. The drug dispersion dissolution results showed significant improvement for all the co-processed samples in comparison to non-processed material and corresponding physical mixtures. The dissolution profiles obtained for dispersion with co-micronized SLS samples proved superior to those of co-micronized PVP, with the proportion (1:0.25) proving the optimal mixture. The improvements may be explained by the hypothesis that formation of a hydrophilic layer on the surface of the micronized drug increases the wettability of the system formed, corroborated by characterization results indicating no loss of crystallinity and an absence of interaction at the molecular level.

Preparation of lipid aspirin sustained-release pellets by solvent-free extrusion/spheronization and an investigation of their stability

A novel solvent-free extrusion/spheronization technique was investigated for preparing stable aspirin sustained-release pellets. Lipids as binders and the matrix in this technique were extruded below their melting points, and spheronized in a thermomechanical process. Four types of lipids (adeps solidus, Compritol(®) 888 ATO, Precirol(®) ATO5 and Compritol(®) HD5 ATO) and their admixture in different ratios were used to obtain spherical and extended-release pellets. Pellets containing 80% aspirin, 15% adeps solidus and 5% Compritol(®) 888 ATO had the best spherical geometry and met the dissolution requirements of aspirin extended-release tablets in USP 31. Storage stability studies showed that the content of free salicylic acid increased sharply in the traditional pellets produced by wet extrusion/spheronization, from 1.91 to 7.84%, whereas there was little increase in the lipid pellets (from 0.48 to 1.08%). The dissolution rate from the optimal pellets (F11) stored at 26°C did not change, but became faster at 40°C/RH75% after 5 months. Powder X-ray diffraction, scanning electron microscopy (SEM) and differential scanning calorimetry were used to investigate the physical properties of the pellets during stability testing. The increase in the rate of drug release from aged pellets (40°C/RH75%) may result from the partially melted adeps solidus observed in SEM photographs. This study suggests that it is possible to prepare sustained-release pellets by solvent-free extrusion/spheronization using an appropriate mixture of lipids with high stability. In particular, this novel technique is excellent for hygroscopic drugs.

Comparison of the intestinal absorption and bioavailability of γ-tocotrienol and α-tocopherol: in vitro, in situ and in vivo studies

The aim of this work was to compare the intestinal absorption kinetics and the bioavailability of γ-tocotrienol (γ-T3) and α-tocopherol (α-Tph) administered separately as oil solutions to rats in vivo. Also, to explain the significant difference in the oral bioavailability of the compounds: (1) the release profiles using the dynamic in vitro lipolysis model, (2) the intestinal permeability and (3) carrier-mediated uptake by Niemann-Pick C1-like 1 (NPC1L1) transporter were examined. Absolute bioavailability studies were conducted after oral administration of γ-T3 or α-Tph prepared in corn oil to rats. In situ rat intestinal perfusion with ezetimibe (a NPC1L1 inhibitor) was performed to compare intestinal permeability. The in vitro interaction kinetics with NPC1L1 was examined in NPC1L1 transfected cells. While the in vitro release studies demonstrated a significantly higher release rate of γ-T3 in the aqueous phase, the oral bioavailability of α-Tph (36%) was significantly higher than γ-T3 (9%). Consequent in situ studies revealed significantly higher intestinal permeability for α-Tph compared with γ-T3 in rats. Moreover, the NPC1L1 kinetic studies demonstrated higher Vmax and Km values for α-Tph compared with γ-T3. Collectively, these results indicate that intestinal permeability is the main contributing factor for the higher bioavailability of α-Tph. Also, these results emphasize the potentially important role of intestinal permeability in the bioavailability of γ-T3, suggesting that enhancing its permeability would increase its oral bioavailability.

Influence of solvent evaporation rate and formulation factors on solid dispersion physical stability

New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical process factor (solvent evaporation rate) and two formulation factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (P(MW))) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in factors contributing to a decrease in the extent of PRX nucleation being evaporation rate>PVP:PRX>P(MW). The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12days the rank became PVP:PRX>evaporation rate>P(MW). The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from P(MW) was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald's step rule, and an increase in the three factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multifactorial analysis.

Systems biology approach to study permeability of paracetamol and its solid dispersion

Physiological changes that take place at cellular level are usually reflective of their level of gene expression. Different formulation excipients have an impact on physiological behavior of the exposed cells and in turn affect transporter genes, enterocyte-mediated metabolism and toxicity biomarkers. The aim of this study was to prepare solid dispersion of paracetamol and evaluate genetic changes that occur in Caco-2 cell lines during the permeability of paracetamol alone and paracetamol solid dispersion formulations. Paracetamol-PEG 8000 solid dispersion was prepared by melt fusion method and the formulation was characterised using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Formulation of solid dispersion resulted in the conversion of crystalline drug into an amorphous form. Permeability studies showed that paracetamol absorption was higher from the solid dispersion formulation. DNA microarrays analysis was carried out in order to investigate the involvement of any efflux/uptake transporters in paracetamol or its solid dispersion permeability. Neither transporter carriers nor efflux proteins were found to be involved in the absorption of paracetamol or its PEG solid dispersion. Gene expression analysis established that paracetamol toxicity was potentially reduced upon formulation into solid dispersion when ATP binding cassette (ABC) and solute carrier transporter (SLC) genes were analyzed.

An investigation into the mechanism of dissolution rate enhancement of poorly water-soluble drugs from spray chilled gelucire 50/13 microspheres

The production and physicochemical characterisation of spray chilled Gelucire 50/13 microspheres is described with a view to improving the dissolution of a poorly water-soluble drug, piroxicam, and understanding the fundamental mechanisms associated with the improved drug release. Thermorheological testing was developed as a fast screening method for predicting the processability of dispersions for spray chilling preparation. Spray chilled piroxicam loaded microspheres were spherical in shape with a median diameter of circa 150 microm. DSC indicated no interaction between piroxicam and lipid matrix, while HSM studies performed in polarized light mode indicated that the spheres contained distinct drug crystals. Polarising light microscopy and small-angle XRD investigations on the hydration behaviour of the lipid and the spray chilled microspheres revealed the formation of liquid crystalline phases depending on the degree of hydration. The dissolution behaviour of the piroxicam loaded microspheres showed significant improvements compared to drug alone. The particle size, drug loading and aging of the microspheres were all found to have an influence on the release behaviour. It was proposed that Gelucire 50/13 microspheres release the entrapped piroxicam via formation of a lyotropic liquid crystalline phase, which allows dissolution of the drug particles in a finely divided, high surface area and well-wetted state.

Enhanced Dissolution and Oral Bioavailability of Piroxicam Formulations: Modulating Effect of Phospholipids

Several biologically relevant phospholipids were assessed as potential carriers/additives for rapidly dissolving solid formulations of piroxicam (Biopharmaceutics Classification System Class II drug). On the basis of in vitro dissolution studies, dimyristoylphosphatidylglycerol (DMPG) was ranked as the first potent dissolution rate enhancer for the model drug. Subsequently, the solid dispersions of varying piroxicam/DMPG ratios were prepared and further investigated. Within the concentration range studied (6.4-16.7 wt %), the dissolution rate of piroxicam from the solid dispersions appeared to increase as a function of the carrier weight fraction, whereas the cumulative drug concentration was not significantly affected by piroxicam/DMPG ratio, presumably due to a unique phase behavior of the aqueous dispersions of this carrier phospholipid. Solid state analysis of DMPG-based formulations reveled that they are two-component systems, with a less thermodynamically stable form of piroxicam (Form II) being dispersed within the carrier. Finally, oral bioavailability of piroxicam from the DMPG-based formulations in rats was found to be superior to that of the control, as indicated by the bioavailability parameters, c_max and especially T_max (53 µg/mL within 2 h vs. 39 µg/mL within 5.5 h, respectively). Hence, DMPG was regarded as the most promising carrier phospholipid for enhancing oral bioavailability of piroxicam and potentially other Class II drugs.

Nanoparticulate strategies for effective delivery of poorly soluble therapeutics

The pharmacological activity of a drug molecule depends on its ability to dissolve and interact with its biological target, either through dissolution and absorption, or through dissolution and receptor interaction. The low bioavailability that characterizes poorly water-soluble drugs is usually attributed to the dissolution kinetic profile. Novel strategies to effectively deliver these drugs include nanoparticulate approaches that either increase the surface area of the drug or improve the solubility characteristics of the drug. Nanosizing approaches are based on the production of drug nanocrytals dispersed in an aqueous surfactant solution, whereas other possibilities include drug loading in nanoparticles. Promising nanoparticulate approaches include the development of lipid-based nanocarriers to increase drug solubility followed by enhanced bioavailability. To select the best approach there are, however, some critical considerations to take into account, for example the physicochemical properties of the drug, the possibility to scale-up the production process, the toxicological considerations of the use of solvents and cosolvents, the selection of an environmentally sustainable methodology and the development of a more patient-friendly dosage form. This article addresses these relevant questions and provides feasible examples of novel strategies with respect to relevant administration routes.

Two-step solid lipid extrusion as a process to modify dissolution behavior

Extrudates based on varying ratios of the triglyceride tripalmitin and the hydrophilic polymer polyethylene glycol as matrix formers were produced as oral dosage forms with controlled release characteristics. The extrudates were processed below the melting points of the excipients and contained the hydrophobic model drug chloramphenicol. The influence of the ratio of the matrix formers on drug dissolution was investigated, with an increase in the water-soluble polymer content increasing the drug release rate. In addition, the effect of varying the extrusion process on the extrudate structure and drug dissolution was investigated. Two-step extrusion was performed, which comprised an initial extrusion step of drug and one matrix component followed by milling these extrudates and a second extrusion step for the milled extrudates mixed with the second matrix component. Initial extrusion with polyethylene glycol led to increased dissolution rates, while initial extrusion with tripalmitin led to decreased dissolution rates compared to the dissolution characteristics of extrudates containing the same composition produced by one-step extrusion. Thus, two-step solid lipid extrusion can successfully be used as a process to modify the dissolution behavior of extrudates.

Cefuroxime axetil solid dispersion with polyglycolized glycerides for improved stability and bioavailability

Objectives

Cefuroxime axetil (CA), a poorly soluble, broad spectrum cephalosporin ester prodrug, is hydrolysed by intestinal esterase prior to absorption, leading to poor and variable bioavailability. The objective was therefore to formulate a stable amorphous solid dispersion of the drug with enhanced solubility and stability against enzymatic degradation.

Methods

Spray drying was used to obtain a solid dispersion of CA with Gelucire 50/13 and Aerosil 200 (SDCAGA), and a solid dispersion of CA with polyvinyl pyrrolidone (SDCAP); amorphous CA (ACA) was obtained by spray drying CA alone. The formulations were characterized by differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy studies, and compared for solubility, dissolution and bioavailability in rats.

Key findings

SDCAP and SDCAGA showed improved solubility and dissolution profiles owing to amorphization and formation of solid dispersions with hydrophilic carriers. The improved stability of amorphous CA in solid dispersions compared to ACA alone was attributed to hydrogen bonding interactions involving the amide of CA with the carbonyl of polyvinyl pyrrolidone in SDCAP, whereas in SDCAGA the interactions were at multiple sites involving the amide and carbonyl of CA with the carbonyl and hydroxyl of Gelucire 50/13. However, SDCAGA showed superior bioavailability compared to SDCAP, ACA and CA.

Conclusions

Improvement in physical stability of solid dispersions was attributed to hydrogen bonding, while improvement in bioavailability of SDCAGA compared to SDCAP, in spite of comparable solubility and dissolution profile, may be attributed to Gelucire, which utilizes intestinal esterase for lipolysis, protecting the prodrug from enzymatic degradation to its non-absorbable base form.