The role of lipid-based nano delivery systems on oral bioavailability enhancement of fenofibrate, a BCS II drug: comparison with fast-release formulations

Exploring LIPIDs for their potential to improves bioavailability of lipophilic drugs candidates: A review

This review aims to provide a thorough examination of the benefits, challenges, and advancements in utilizing lipids for more effective drug delivery, ultimately contributing to the development of innovative approaches in pharmaceutical science. Lipophilic drugs, characterized by low aqueous solubility, present a formidable challenge in achieving effective delivery and absorption within the human body. To address this issue, one promising approach involves harnessing the potential of lipids. Lipids, in their diverse forms, serve as carriers, leveraging their unique capacity to enhance solubility, stability, and absorption of these challenging drugs. By facilitating improved intestinal solubility and selective lymphatic absorption of porously permeable drugs, lipids offer an array of possibilities for drug delivery. This versatile characteristic not only bolsters the pharmacological efficacy of drugs with low bioavailability but also contributes to enhanced therapeutic performance, ultimately reducing the required dose size and associated costs. This comprehensive review delves into the strategic formulation approaches that employ lipids as carriers to ameliorate drug solubility and bioavailability. Emphasis is placed on the critical considerations of lipid type, composition, and processing techniques when designing lipid-based formulations. This review meticulously examines the multifaceted challenges that come hand in hand with lipid-based formulations for lipophilic drugs, offering an insightful perspective on future trends. Regulatory considerations and the broad spectrum of potential applications are also thoughtfully discussed. In summary, this review presents a valuable repository of insights into the effective utilization of lipids as carriers, all aimed at elevating the bioavailability of lipophilic drugs.

The Development and Optimization of Lipid-Based Self-Nanoemulsifying Drug Delivery Systems for the Intravenous Delivery of Propofol

PURPOSE

Propofol is a relatively short-acting potent anesthetic lipophilic drug used during short surgical procedures. Despite the success of propofol intravenous emulsions, drawbacks to such formulations include inherent emulsion instability, the lack of a safe vehicle to prevent sepsis, and concern regarding hyperlipidemia-related side effects. The aim of the current investigation was to develop a novel, lipid-based self-nanoemulsifying drug delivery system (SNEDDS) for propofol with improved stability and anesthetic activity for human use.

METHODS

A series of SNEDDS formulations were developed using naturally obtained medium-chain/long-chain mono-, di-, and triglycerides, glyceryl monocaprylate, and water-soluble cosolvents with hydrogenated castor oil constructing ternary phase diagrams for propofol. The developed SNEDDS formulations were characterized using visual observation, particle size analysis, zeta potential, transmission electron microscopy, equilibrium solubility, in vitro dynamic dispersion and stability, and in vivo sleeping disorder studies in rats. The in vivo bioavailability of the SNEDDSs in rats was also studied to compare the representative formulations with the marketed product Diprivan^®.

RESULTS

Medium-chain triglycerides (M810) with mono-diglycerides (CMCM) as an oil blend and hydrogenated castor oil (KHS15) as a surfactant were selected as key ingredients in ternary phase diagram studies. The nanoemulsifying regions were identified from the studies and a number of SNEDDSs were formulated. Results from the characterization studies demonstrated the formation of efficient nanosized particles (28-45 nm globule size, 0.10-0.20 PDI) in the optimized SNEDDS with a drug loading of 50 mg/g, which is almost 500-fold higher than free propofol. TEM analysis showed the formation of spherical and homogeneous nanoparticles of less than 50 nm. The dissolution rate of the representative SNEDDS was faster than raw propofol and able to maintain 99% propofol in aqueous solution for around 24 h. The optimized liquid SNEDDS formulation was found to be thermodynamically stable. The intravenous administration of the SNEDDS in male Wistar rats induced a sleeping time of 73-88 min. The mean plasma concentrations after the IV administration of propofol nano-formulations PF2-SNEDDS and PF8-SNEDDS were 1348.07 ± 27.31 and 1138.66 ± 44.97 µg/mL, as compared to 891.44 ± 26.05 µg/mL (p = 0.05) observed after the IV administration of raw propofol.

CONCLUSION

Propofol-loaded SNEDDS formulations could be a potential pharmaceutical product with improved stability, bioavailability, and anesthetic activity.

Enhanced oral absorption of insulin: hydrophobic ion pairing and a self-microemulsifying drug delivery system using a D-optimal mixture design

The lipophilicity of a peptide drug can be considerably increased by hydrophobic ion pairing with amphiphilic counterions for successful incorporation into lipid-based formulations. Herein, to enhance the oral absorption of insulin (INS), a self-microemulsifying drug delivery system (SMEDDS) formulation was developed. Prior to optimization, INS was complexed with sodium n-octadecyl sulfate (SOS) to increase the loading into the SMEDDS. The INS–SOS complex was characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and its dissociation behavior. The SMEDDS was optimized using a D-optimal mixture design with three independent variables including Capmul MCM (X₁, 9.31%), Labrasol (X₂, 49.77%), and Tetraglycol (X₃, 40.92%) and three response variables including droplet size (Y₁, 115.2 nm), INS stability (Y₂, 46.75%), and INS leakage (Y₃, 17.67%). The desirability function was 0.766, indicating excellent agreement between the predicted and experimental values. The stability of INS-SOS against gastrointestinal enzymes was noticeably improved in the SMEDDS, and the majority of INS remained in oil droplets during release. Following oral administration in diabetic rats, the optimized SMEDDS resulted in pharmacological availabilities of 3.23% (50 IU/kg) and 2.13% (100 IU/kg). Thus, the optimized SMEDDS is a good candidate for the practical development of oral delivery of peptide drugs such as INS.

Challenges in Oral Drug Delivery and Applications of Lipid Nanoparticles as Potent Oral Drug Carriers for Managing Cardiovascular Risk Factors

BACKGROUND

The oral application of drugs is the most popular route through which the systemic effect can be achieved. Nevertheless, oral administration is limited by difficulties related to the physicochemical properties of the drug molecule, including low aqueous solubility, instability, low permeability, and rapid metabolism, all of which result in low and irregular oral bioavailability.

OBJECTIVE

The enhancement of oral bioavailability of drug molecules with such properties could lead to extreme complications in drug preparations. Oral lipid-based nanoparticles seem to possess extensive advantages due to their ability to increase the solubility, simplifying intestinal absorption and decrease or eradicate the effect of food on the absorption of low soluble, lipophilic drugs and therefore improving the oral bioavailability.

METHODS

The present review provides a summary of the general theory of lipid-based nanoparticles, their preparation methods, as well as their oral applications. Moreover, oral drug delivery challenges are discussed.

RESULTS

According to this review, the most frequent types of lipid-based nanoparticle, the solid lipid nanoparticles and nanostructured lipid carriers are potent oral carriers due to their ability to penetrate the oral drug adsorption barriers. Moreover, such lipid nanoparticles can be beneficial drug carriers against cardiovascular risk disorders as diabetes, hypertension, etc. Conclusion: In this review, the most current and promising studies involving Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as oral drug carriers are reported aiming to assist researchers who focus their research on lipid-based nanoparticles.

Optimization of Nanostructured Lipid Carriers of Fenofibrate Using a Box-Behnken Design for Oral Bioavailability Enhancement

BACKGROUND

Fenofibrate (FNB) is a commonly used hypolipidemic agent. However, the oral bioavailability of FNB is limited by slow dissolution due to its low solubility. Thus, investigations on novel FNB formulations are necessary for their use.

OBJECTIVE

To enhance the oral bioavailability of FNB using optimized Nanostructured Lipid Carrier (NLC) formulations.

METHODS

Hot homogenization followed by ultrasonication was used to prepare FNB-NLCs. These formulations were optimized using a Box-Behnken design, where the amount of FNB (X1), a ratio of solid lipid/liquid lipid (X2), and the percentage of emulsifier (X3), were set as independent variables, while the particle size (Y1), and Entrapment Efficiency (EE%) (Y2), were used as dependent factors. An in vitro dissolution test was then performed using a paddle method, while an in vivo pharmacokinetic study of FNB-NLC formulation was performed in rats.

RESULTS

FNB-NLCs were successfully prepared and optimized using a Box-Behnken design. The particle size and EE% of the FNB-NLC had less than 5% difference from predicted values. The in vitro dissolution and oral bioavailability of the FNB-NLC were both higher than those of raw FNB.

CONCLUSION

A Box-Behnken design was successfully applied to optimize FNB-NLC formulation for the enhancement of the dissolution and bioavailability of FNB, a poorly water-soluble drug.

In vivo dissolution of poorly water-soluble drugs: Proof of concept based on fluorescence bioimaging

In vitro‒in vivo correlation (IVIVC) of solid dosage forms should be established basically between in vitro and in vivo dissolution of active pharmaceutical ingredients. Nevertheless, in vivo dissolution profiles have never been accurately portrayed. The current practice of IVIVC has to resort to in vivo absorption fractions (F_a). In this proof-of-concept study, in vivo dissolution of a model poorly water-soluble drug fenofibrate (FNB) was investigated by fluorescence bioimaging. FNB crystals were first labeled by near-infrared fluorophores with aggregation-caused quenching properties. The dyes illuminated FNB crystals but quenched immediately and absolutely once been released into aqueous media, enabling accurate monitoring of residual drug crystals. The linearity established between fluorescence and crystal concentration justified reliable quantification of FNB crystals. In vitro dissolution was first measured following pharmacopoeia monograph protocols with well-documented IVIVC. The synchronicity between fluorescence and in vitro dissolution of FNB supported using fluorescence as a measure for determination of dissolution. In vitro dissolution correlated well with in vivo dissolution, acquired by either live or ex vivo imaging. The newly established IVIVC was further validated by correlating both in vitro and in vivo dissolution with F_a obtained from pharmacokinetic data.

Diabetes exacerbates brain pathology following a focal blast brain injury: New role of a multimodal drug cerebrolysin and nanomedicine

Blast brain injury (bBI) is a combination of several forces of pressure, rotation, penetration of sharp objects and chemical exposure causing laceration, perforation and tissue losses in the brain. The bBI is quite prevalent in military personnel during combat operations. However, no suitable therapeutic strategies are available so far to minimize bBI pathology. Combat stress induces profound cardiovascular and endocrine dysfunction leading to psychosomatic disorders including diabetes mellitus (DM). This is still unclear whether brain pathology in bBI could exacerbate in DM. In present review influence of DM on pathophysiology of bBI is discussed based on our own investigations. In addition, treatment with cerebrolysin (a multimodal drug comprising neurotrophic factors and active peptide fragments) or H-290/51 (a chain-breaking antioxidant) using nanowired delivery of for superior neuroprotection on brain pathology in bBI in DM is explored. Our observations are the first to show that pathophysiology of bBI is exacerbated in DM and TiO₂-nanowired delivery of cerebrolysin induces profound neuroprotection in bBI in DM, not reported earlier. The clinical significance of our findings with regard to military medicine is discussed.

Improved oral bioavailability of repaglinide, a typical BCS Class II drug, with a chitosan-coated nanoemulsion

The aim of the present study was to develop modified nanoemulsions to improve the oral bioavailability and pharmacokinetics of a poor water-soluble drug, repaglinide (RPG). The repaglinide-loaded nanoemulsions (RPG-NEs) were prepared from olive oil as internal phase, span 80, tween 80, and poloxamer 188 as emulsifiers, using homogenization technique. The mean droplet size, zeta potential, and entrapment efficiency of RPG-NEs were 86.5 ± 3.4 nm, -33.8 ± 2.1 mV, and 96.3 ± 2.3%, respectively. The chitosan-coated RPG-NEs (Cs-RPG-NEs) showed an average droplet size of 149.3 ± 3.9 nm and a positive zeta-potential of +31.5 ± 2.8 mV. Drug release profile of RPG-NEs was significantly higher than free drug in the simulated gastrointestinal fluids (p < .005). The in vivo study revealed 3.51- and 1.78-fold increase in the AUC_0-12h and C_max of the drug, respectively, in RPG-NEs-receiving animals in comparison to the free drug. The pharmacokinetic analysis confirmed that Cs-RPG-NEs were more efficient than uncoated ones for the oral delivery of RPG. Cs-RPG-NEs showed a longer t_1/2 and higher AUC_0-∞ compared to control group. The relative bioavailability of Cs-RPG-NEs was higher than that of uncoated RPG-NEs and free drug. Collectively, these findings suggest that chitosan-coated nanoemulsions are promising carrier for improving the oral bioavailability of RPG.

Evaluation of Self-Nanoemulsifying Drug Delivery Systems (SNEDDS) for Poorly Water-Soluble Talinolol: Preparation, in vitro and in vivo Assessment

Objective

The aim of this study was to investigate the in vitro and in vivo performance of self-nanoemulsifying drug delivery systems (SNEDDSs) of talinolol (TAL), a poorly water-soluble drug.

Methods

Self-nanoemulsifying drug delivery systems of TAL were prepared using various oils, non-ionic surfactants and/or water-soluble co-solvents and assessed visually/by droplet size measurement. Equilibrium solubility of TAL in the anhydrous and diluted SNEDDS was conducted to achieve the maximum drug loading. The in vitro dissolution experiments and human red blood cells (RBCs) toxicity test, ex vivo gut permeation studies, and bioavailability of SNEDDS in rats were studied to compare the representative formulations with marketed product Cordanum^® 50 mg and raw drug.

Results

The results from the characterization and solubility studies showed that SNEDDS formulations were stable with lower droplet sizes and higher TAL solubility. From the dissolution studies, it was found that the developed SNEDDS provided significantly higher rate of TAL release (>97% in 2.0 h) compared to raw TAL and marketed product Cordanum^®. The RBC lysis test suggested negligible toxicity of the formulation to the cells. The ex vivo permeability assessment and in vivo pharmacokinetics study of a selected SNEDDS formulation (F6) showed about four-fold increase in permeability and 1.58-fold enhanced oral bioavailability of TAL in comparison to pure drug, respectively.

Conclusion

Talinolol loaded SNEDDS formulations could be a potential oral pharmaceutical product with high drug-loading capacity, improved drug dissolution, increased gut permeation, reduced/no human RBC toxicity, and enhanced oral bioavailability.

Fenofibrate modified-release pellets with lag phase and high oral bioavailability

Purpose

Fenofibrate and statin combination therapy is highly recommended by the current clinical guidelines for treatment of mixed dyslipidemia. In this study, an innovative delayed-release preparation of fenofibrate was designed to reduce the risk of muscle toxicity, caused by simultaneous administration of this combination therapy, by altering the pharmacokinetic profile of fenofibrate, as well as to improve the oral bioavailability of the modified-release formulation.

Methods

Micronized fenofibrate was used to prepare drug-loaded cores via a powder layering process before multiparticulate pellet coating. Different coating formulations (Eudragit^® RS PO/E100, Eudragit^® RS PO/RL PO, Eudragit^® NE30D/HPMC, and EC/HPMC) were screened, and their in vitro release was compared with the commercial sustained-release pellets Lipilfen^®. Two optimized formulations were evaluated in beagle dogs using two commercial preparations of fenofibrate (the immediate-release preparation Lipanthyl^® and the sustained-release pellets Lipilfen^®) as references.

Results

The in vivo release of fenofibrate from R1 and R2 selected from in vitro tests exhibited a lag phase, and then rapid and complete drug release. The relative bioavailabilities of R1 and R2 were 100.4% and 201.1%, respectively, which were higher than that of Lipilfen^® (67.2%).

Conclusion

The modified fenofibrate pellets developed showed enhanced bioavailability and delayed-release properties. They have the potential to improve safety and compliance when co-administrated with statins. This is the first report of a delayed-release fenofibrate preparation.

Nanocolloidal lipidic carriers of olmesartan medoxomil surface-tailored with Concavalin-A for lectin receptor targeting

Aim: The present work involves the development of Concavalin A-conjugated nanostructured lipidic carriers (NLCs) of olmesartan medoxomil for lectin receptor targeting. Materials & methods: Excipient selection was performed by drug solubility in solid and liquid lipids. Factor screening was carried out by evaluating the impact of formulation and process variables on the critical quality attributes. Surface modification of NLCs was carried out using Concavalin A and extensively characterized. Results & conclusion: NLCs exhibited the particle size of 273.6 nm, ζ-potential of -30.2 nm, encapsulation efficiency of 73.3% and sustained drug release profile. Nearly 4.2-fold improvement in cell uptake, four- to eightfold increase in Cmax and AUC, and 37% reduction in blood pressure was observed from NLCs over the pure drug.

Biocatalytic synthesis of acylated derivatives of troxerutin: their bioavailability and antioxidant properties in vitro

Background

Flavonoid glycosides have many beneficial effects on health, but these bioactivities tend to decrease after oral administration owing to their poor lipophilicity. In this study, a facile whole-cell-based method was developed for selective preparation of monoester or diester of troxerutin, a flavonoid derivative. In addition, the bioavailabilities and antioxidant properties of troxerutin and its acylated derivatives were also investigated in cells.

Results

Pseudomonas aeruginosa and Pseudomonas stutzeri cells showed high catalytic efficiency (substrate conversion > 90%) and different preferences for troxerutin, resulting in the production of its monoester (TME) and diester (TDE), respectively. The logP values of troxerutin, TME, and TDE were − 2.04 ± 0.10, − 0.75 ± 0.08, and 1.51 ± 0.05 and their P_app values were 0.34 × 10⁻⁶ ± 0.05, 0.99 × 10⁻⁶ ± 0.12, and 1.54 × 10⁻⁶ ± 0.17 cm/s, respectively. The results of hydroxyl radical, ABTS, and ORAC assays indicated that the antiradical activities of acylated derivatives did not exceed that of troxerutin, but showed higher inhibition effects upon 2,2′-azobis(2-amidinopropane) dihydrochloride-induced erythrocyte hemolysis than that of troxerutin (P < 0.05).

Conclusion

A facile and efficient whole-cell biocatalysis method was developed to synthesize troxerutin-acylated derivatives, markedly enhancing the bioavailability and antioxidant activities of troxerutin in cells. Additionally, the mechanism underlying the observed difference in the antioxidant activities of troxerutin and its esters was ascribed to both their free radical scavenging abilities and distribution on the cell membrane surface.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-0976-x) contains supplementary material, which is available to authorized users.

Cellular Transport of Esculin and Its Acylated Derivatives in Caco-2 Cell Monolayers and Their Antioxidant Properties in Vitro

Esculin has many pharmacological effects, but these are difficult to observe after oral administration owing to poor lipid solubility. In our previous study, five acylated derivatives with different acyl chain lengths (EA, EP, EO, EL, and EM) were synthesized to improve the lipophilicity of esculin. In this study, the bioavailability and antioxidant activity of the five derivatives were investigated. The logP of esculin, EA, EP, EO, EL, and EM were -1.1 ± 0.1, -0.3 ± 0.14, 0.1 ± 0.17, 1.6 ± 0.09, 2.4 ± 0.11, and 2.8 ± 0.18, and their P_app were 0.71 ± 0.02, 1.24 ± 0.18, 1.74 ± 0.11, 11.6 ± 3.6, 4.11 ± 1.03, and 2.64 ± 0.97 × 10^-6 cm/s, respectively. Besides, the bioavailability of EO, EL, and EM were seriously affected by carboxylesterase. The results of ABTS, ORAC, and DPPH assays indicated that the antiradical ability of the five derivatives did not exceed that of esculin. However, EA, EP, and EO showed more effective inhibition of AAPH-induced oxidative hemolysis than esculin did (p < 0.05), and EL and EM were less effective than esculin (p < 0.05). The mechanism was related to the distribution and localization of the derivatives in "oil-water interface" between the cytomembrane and the aqueous phase.

Lipid-associated oral delivery: Mechanisms and analysis of oral absorption enhancement

The majority of newly discovered oral drugs are poorly water soluble, and co-administration with lipids has proven effective in significantly enhancing bioavailability of some compounds with low aqueous solubility. Yet, lipid-based delivery technologies have not been widely employed in commercial oral products. Lipids can impact drug transport and fate in the gastrointestinal (GI) tract through multiple mechanisms including enhancement of solubility and dissolution kinetics, enhancement of permeation through the intestinal mucosa, and triggering drug precipitation upon lipid emulsion depletion (e.g., by digestion). The effect of lipids on drug absorption is currently not quantitatively predictable, in part due to the multiple complex dynamic processes that can be impacted by lipids. Quantitative mechanistic analysis of the processes significant to lipid system function and overall impact on drug absorption can aid in the understanding of drug-lipid interactions in the GI tract and exploitation of such interactions to achieve optimal lipid-based drug delivery. In this review, we discuss the impact of co-delivered lipids and lipid digestion on drug dissolution, partitioning, and absorption in the context of the experimental tools and associated kinetic expressions used to study and model these processes. The potential benefit of a systems-based consideration of the concurrent multiple dynamic processes occurring upon co-dosing lipids and drugs to predict the impact of lipids on drug absorption and enable rational design of lipid-based delivery systems is presented.

Development of self-nanoemulsifying drug delivery systems for the enhancement of solubility and oral bioavailability of fenofibrate, a poorly water-soluble drug

Background

Self-nanoemulsifying drug delivery systems (SNEDDS) have become a popular formulation option as nanocarriers for poorly water-soluble drugs. The objective of this study was to investigate the factor that can influence the design of successful lipid formulation classification system (LFCS) Type III SNEDDS formulation and improve the oral bioavailability (BA) of fenofibrate.

Materials and methods

LFCS Type III SNEDDS were designed using various oils, water-soluble surfactants, and/or cosolvents (in considering the polarity of the lipids) for the model anticholesterol drug, fenofibrate. The developed SNEDDS were assessed visually and by measurement of the droplet size. Equilibrium solubility of fenofibrate in the SNEDDS was conducted to find out the maximum drug loading. Dynamic dispersion studies were carried out (1/100 dilution) in water to investigate how much drug stays in solution after aqueous dispersion of the formulation. The BA of SNEDDS formulation was evaluated in the rat.

Results

The results from the characterization and solubility studies showed that formulations containing mixed glycerides were highly efficient SNEDDS as they had higher solubility of the drug and produced nanosized droplets. The dispersion studies confirmed that SNEDDS (containing polar mixed glycerides) can retain >98% drug in solution for >24 hours in aqueous media. The in vivo pharmacokinetics parameters of SNEDDS formulation in comparison with pure drug showed significant increase in C_max and AUC_0–t, ~78% and 67%, respectively. The oral BA of fenofibrate from SNEDDS in rats was ~1.7-fold enhanced as compared with the BA from pure drug.

Conclusion

Fenofibrate-loaded LFCS Type III SNEDDS formulations could be a potential oral pharmaceutical product for administering the poorly water-soluble drug, fenofibrate, with an enhanced oral BA.

Development and validation of bioanalytical UHPLC-UV method for simultaneous analysis of unchanged fenofibrate and its metabolite fenofibric acid in rat plasma: Application to pharmacokinetics

A simple, precise, selective and fast ultra-high performance liquid chromatography (UHPLC-UV) method has been developed and validated for the simultaneous determination of a lipid regulating agent fenofibrate and its metabolite fenofibric acid in rat plasma. The chromatographic separation was carried out on a reversed-phase Acquity® BEH C₁₈ column using methanol–water (65:35, v/v) as the mobile phase. The isocratic flow was 0.3 ml/min with rapid run time of 2.5 min and UV detection was at 284 nm. The method was validated over a concentration range of 100–10000 ng/ml (r² ⩾ 0.9993). The selectivity, specificity, recovery, accuracy and precision were validated for determination of fenofibrate/fenofibric acid in rat plasma. The lower limits of detection and quantitation of the method were 30 and 90 ng/ml for fenofibrate and 40 and 100 ng/ml for fenofibric acid, respectively. The within and between-day coefficients of variation were less than 5%. The validated method has been successfully applied to measure the plasma concentrations in pharmacokinetics study of fenofibrate in an animal model to illustrate the scope and application of the method.

Key Considerations in Designing Oral Drug Delivery Systems for Dogs

The present review discusses the pharmaceutical impact of the anatomy and physiology of the canine gastrointestinal tract to provide a comprehensive guide to the theories and challenges associated with the development of oral drug delivery systems for dogs. Novel pharmaceutical technologies applied to veterinary drugs are discussed indicating the advantages and benefits for animals. There are currently immense research and development efforts being funneled into novel canine health products. Such products are being used to overcome limitations of drugs that display site-dependent absorption or possess poor biopharmaceutical properties. Techniques that are employed to increase bioavailability of the Biopharmaceutics Classification System class II drugs are discussed in this article. Furthermore, an overview of palatable oral formulations for dog care is provided as an approach to easy administration. In vitro and in vivo evaluation and correlation of oral drug formulations in dogs are also addressed. This article assesses the outlook of canine oral drug development recognizing substantial growth forecasts of the dog care market.

Role of Components in the Formation of Self-microemulsifying Drug Delivery Systems

Pharmaceutical research is focused in designing novel drug delivery systems to improve the bioavailability of poorly water soluble drugs. Self-microemulsifying drug delivery systems, one among the lipid-based dosage forms were proven to be promising in improving the oral bioavailability of such drugs by enhancing solubility, permeability and avoiding first-pass metabolism via enhanced lymphatic transport. Further, they have been successful in avoiding both inter and intra individual variations as well as the dose disproportionality. Aqueous insoluble drugs, in general, show greater solubility in lipid based excipients, and hence they are formulated as lipid based drug delivery systems. The extent of solubility of a hydrophobic drug in lipid excipients i.e. oil, surfactant and co-surfactant (components of self-microemulsifying drug delivery systems) greatly affects the drug loading and in producing stable self-microemulsifying drug delivery systems. The present review highlighted the influence of physicochemical factors and structural features of the hydrophobic drug on its solubility in lipid excipients and an attempt was made to explore the role of each component of self-microemulsifying drug delivery systems in the formation of stable microemulsion upon dilution.

Oral lipid-based nanoformulation of tafenoquine enhanced bioavailability and blood stage antimalarial efficacy and led to a reduction in human red blood cell loss in mice

Tafenoquine (TQ), a new synthetic analog of primaquine, has relatively poor bioavailability and associated toxicity in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. A microemulsion formulation of TQ (MTQ) with sizes <20 nm improved the solubility of TQ and enhanced the oral bioavailability from 55% to 99% in healthy mice (area under the curve 0 to infinity: 11,368±1,232 and 23,842±872 min·μmol/L) for reference TQ and MTQ, respectively. Average parasitemia in Plasmodium berghei-infected mice was four- to tenfold lower in the MTQ-treated group. In vitro antiplasmodial activities against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum indicated no change in half maximal inhibitory concentration, suggesting that the microemulsion did not affect the inherent activity of TQ. In a humanized mouse model of G6PD deficiency, we observed reduction in toxicity of TQ as delivered by MTQ at low but efficacious concentrations of TQ. We hereby report an enhancement in the solubility, bioavailibility, and efficacy of TQ against blood stages of Plasmodium parasites without a corresponding increase in toxicity.