Oral delivery of diclofenac sodium using a novel solid-in-oil suspension

Eco-Oriented Formulation and Stabilization of Oil-Colloidal Biodelivery Systems Based on GC-MS/MS-Profiled Phytochemicals from Wild Tomato for Long-Term Retention and Penetration on Applied Surfaces for Effective Crop Protection

Vegetable oils as hydrophobic reserves in oil dispersions (OD) provide a practical approach to halt bioactive degradation for user and environment-efficient pest management. Using biodegradable soybean oil (57%), castor oil ethoxylate (5%), calcium dodecyl benzenesulfonates as nonionic and an-ionic surfactants, bentonite (2%), and fumed silica as rheology modifiers, we created an oil-colloidal biodelivery sytem (30%) of tomato extract with homogenization. The quality-influencing parameters, such as particle size (4.5 μm), dispersibility (97%), viscosity (61 cps), and thermal stability (2 years), have been optimized in accordance with specifications. Vegetable oil was chosen for its improved bioactive stability, high smoke point (257 °C), coformulant compatibility, and as a green build-in-adjuvant by improving spreadability (20-30%), retention and penetration (20-40%). In in vitro testing, it efficiently controlled aphids with 90.5% mortalities and 68.7-71.2% under field-conditions without producing phytotoxicity. Wild tomato-derived phytochemicals can be a safe and efficient alternative to chemical pesticides when combined wisely with vegetable oils.

Solid-in-Oil-in-Water Emulsion: An Innovative Paradigm to Improve Drug Stability and Biological Activity

Abstract

An emulsion is a biphasic dosage form comprising of dispersed phase containing droplets that are uniformly distributed into a surrounding liquid which forms the continuous phase. An emulsifier is added at the interface of two immiscible liquids to stabilize the thermodynamically unstable emulsion. Various types of emulsions such as water-in-oil (w-o), oil-in-water (o-w), microemulsions, and multiple emulsions are used for delivering certain drugs in the body. Water (aqueous) phase is commonly used for encapsulating proteins and several other drugs in water-in-oil-in-water (w-o-w) emulsion technique. But this method has posed certain problems such as decreased stability, burst release, and low entrapment efficiency. Thus, a novel “solid-in-oil-in-water” (s-o-w) emulsion system was developed for formulating certain drugs, probiotics, proteins, antibodies, and tannins to overcome these issues. In this method, the active ingredient is encapsulated as a solid and added to an oil phase, which formed a solid-oil dispersion. This dispersion was then mixed with water to form a continuous phase for enhancing the drug absorption. This article focuses on the various studies done to investigate the effectiveness of formulations prepared as solid-oil-water emulsions in comparison to conventional water-oil-water emulsions. A summary of the results obtained in each study is presented in this article. The s-o-w emulsion technique may become beneficial in near future as it has shown to improve the stability and efficacy of the entrapped active ingredient.

Graphical abstract

Polysaccharide-Based Supramolecular Hydrogel for Efficiently Treating Bacterial Infection and Enhancing Wound Healing

Nowadays, the rapid emergence of antibiotic-resistant pathogens has become a serious threat to human health. As an effective antimicrobial therapy, supramolecular materials show unprecedented advantages because of their flexible and adjustable interactions with biological molecules. Supramolecular hydrogels are now widely applied in biomedical fields because of their outstanding biocompatibility, high water content, easy preparation, and unique functions. Herein, we conveniently prepared a stable supramolecular hydrogel by simply mixing β-cyclodextrin-modified chitosan (CS-CD) with AgNO₃ in a basic environment. The obtained supramolecular hydrogel, which is positively charged and possesses numerous β-cyclodextrin cavities, could efficiently load anionic drug diclofenac sodium (DS) through the electrostatic interaction and host-guest inclusion. Significantly, the biological experiments demonstrated that this supramolecular hydrogel exhibited a high antibacterial effect and good ability of promoting wound healing owing to the cooperative contribution of CS, Ag⁺, and DS.

Solid-in-oil nanodispersions as a novel delivery system to improve the oral bioavailability of bisphosphate, risedronate sodium

The aim of the current study was to modify the oral absorption of risedronate sodium (RS) using solid-in-oil nanodispersions (SONDs) technology. The oral therapeutic effect of RS is limited in vivo because of its low membrane permeability and the formation of insoluble precipitates with bivalent cations (such as Ca²⁺) in the gastrointestinal (GI) tract.We used SONDs to prepare medium-chain triglyceride (MCT)-based nanodispersions of the hydrophilic drug, which used the oral absorption mechanism of MCT digestion to improve bioavailability of RS in vivo. SONDs exhibited high encapsulation efficiency of RS and excellent enzymatic degradation-dependent release behavior. The result of an everted gut sac test showed that the P_app value of the SONDs was 6.29-fold (p<0.05) higher than that of RS aqueous solutions in simulated intestinal fluid containing 5 mM Ca²⁺, this was because MCT can be digested to form the fatty acids C₈ and C₁₀, which have an adsorption-promoting effect on RS. Further, solid-in-oil-in-water (S/O/W) emulsion droplets formedafter emulsification by bile salts and MCT digestionwere effective in disrupting epithelial tight junctions (TJs), facilitating the paracellular permeation of RS throughout the intestine. Moreover, in vivo absorption study in rats revealed that the AUC_0-12h of RS in SONDs was approximately 4.56-fold (p<0.05) higher than with RS aqueous solutions at the same dose (15 mg/kg). This approach demonstrates a potential drug delivery system to improve the bioavailability of risedronate sodium.

Antifungal activity of 2'-hydroxychalcone loaded in nanoemulsion against Paracoccidioides spp

Aim: This study aimed to evaluate the activity of 2'-hydroxychalcone-loaded in nanoemulsion (NLS + 2'chalc), the cytotoxic effect and toxicity against Paracoccidioides brasiliensis and Paracoccidioides lutzii using a zebrafish model. Materials & methods: Preparation and physical-chemical characterization of nanoemulsion (NLS) and NLS + 2'chalc were performed. MIC and minimum fungicide concentration, cytotoxicity and toxicity were also evaluated in the Danio rerio model. Results: NLS + 2'chalc showed fungicidal activity against Paracoccidioides spp. without cytotoxicity in MRC5 and HepG2 lines. It also had high selectivity index values and no toxicity in the zebrafish model based on MIC values. Conclusion: NLS + 2'chalc is a potential new alternative treatment for paracoccidioidomycosis.

A novel oil-based suspension of a micro-environmental, pH-modifying solid dispersion for parenteral delivery: Formulation and stability evaluation

The objective of this study was to evaluate a novel oil-based suspension as a potential parenteral drug delivery system for drugs with poor water solubility. Most of the new active pharmaceutical ingredients are weak acid or basic drugs with pH-dependent solubility. To limit this dependence, use of micro-environmental pH-modifying solid dispersions (micro pHm SD) has been proved to increase the bioavailability of these drugs. Toltrazuril (TOL), a weakly acidic drug with poor aqueous and pH-dependent solubility, was studied as a model drug. Recently, studies on TOL with focus on the parenteral injection are rarely to find in the literature. A novel parenteral oil-based TOL suspension was prepared containing TOL micro pHm SD (TSD) powders suspended in oil-based vehicles and the optimal formulation was screened. The stability of this formulation was assessed considering particle size distribution, settling volume ratio, redispersibility, thermal stability, and drug content. The optimized white oil-based TOL pHm SD suspension (W-TSDS) showed significant improved stability and shear-thinning behavior. In particular, fumed silica as suspending agent positively influenced the physical stability of the formulation. Furthermore, W-TSDS showed good injectability using 21 G needles and more rapid and sustained drug release compared to TSD powders in vitro. In the in vivo safety evaluation, W-TSDS showed good histocompatibility in rabbits injected subcutaneously or intramuscularly. We believe these findings provide an alternative choice of dosage form for the delivery of new active pharmaceutical ingredients.

Formulation and Evaluation of a Novel Oral Oil-Based Suspension Using Micro-environmental pH-Modifying Solid Dispersion

Drugs with pH-dependent solubility that have poor water solubility can be identified in the drug discovery pipeline. Some of them have poor oral absorption, which can result in insufficient efficacy. Micro-environmental pH-modifying solid dispersion (micro pHm SD) is a promising approach to overcome the poor oral absorption of these drugs. In the present study, toltrazuril (TOL), a weakly acidic drug with poor aqueous and pH-dependent solubility, was used as a model drug. Using micro pHm SD, a novel oral oil-based suspension of TOL SD (TSDS) was developed, and the stability of this formulation was evaluated based on particle size, settling volume ratio, redispersibility, thermal stability, and drug content. The optimized soybean oil-based TSDS (S-TSDS) had high physicochemical stability and good histocompatibility with common inflammatory reactions. The results of the in vitro dissolution analysis showed that S-TSDS rapidly and markedly released the drug and provided higher efficacy and longer persistence against coccidiosis (above 90.9%) in rabbits. This technique could increase the oral absorption and bioavailability of new drug candidates.

Could the environmental toxicity of diclofenac in vultures been predictable if preclinical testing methodology were applied?

Diclofenac, a non-steroidal anti-inflammatory pharmaceutical agent was responsible for the death of millions of Gyps vulture's in the Indian sub-region with the safety of the other non-steroidal anti-inflammatory drugs (NSAIDs) being questionable. With preclinical safety testing not well established for avian species unlike for mammalian and environmental toxicity, we ask the question if a preclinical model could have predicted the toxic effect of the drug. For this study, we test an Organisation for Economic Co-operation and Development (OECD) guideline 223 for assessing the acute toxic potential of pesticides in birds by exposing three avian species to the drug. Exposed Japanese quails (Coturnix japonica) and Muscovy ducks (Cairina moschata) demonstrated clinical signs and pathology similar to those previously reported in vultures viz. hyperuricemia, depression, death, visceral gout and nephrosis. However, exposed domestic pigeons (Columba livia domestica) were insensitive. Following a pharmacokinetic analysis, the drug was well absorbed and distributed in the pigeons with a half-life below 6 h. A toxicokinetic evaluation in quails showed poisoning was due to metabolic constraint, with a half-life and mean residence time above 6 h and 8 h respectively resulting in death. Toxicity seen in the ducks was however not related to metabolic constraint but hyperuricemia as metabolism was rapid [half-life (1-2 h) and mean residence time (2-3 h)] irrespective of survival or death. Despite succumbing to diclofenac, the established oral median lethal dose (LD₅₀) of 405.42 mg/kg and 189.92 mg/kg in Japanese quails and Muscovy ducks respectively from this study were substantially higher than those reported for Gyps vultures (0.098 mg/kg) which is as a result of the rapid elimination of the drug from the body in the former species. More importantly, it suggests that these species are not suitable as surrogates for non-steroidal anti-inflammatory drug toxicity testing and that the toxicity of diclofenac in vultures is idiosyncratic most likely as a result of species specific metabolism.

Oral Bioavailability and Lymphatic Transport of Pueraria Flavone-Loaded Self-Emulsifying Drug-Delivery Systems Containing Sodium Taurocholate in Rats

We developed self-microemulsifying drug-delivery systems (SMEDDS), including bile salts, to improve the oral bioavailability of pueraria flavones (PFs). The physical properties of the SMEDDS using Cremophor RH 40, and bile salts as mixed surfactants at weight ratios of 10:0⁻0:10 were determined. The particle sizes of PFs-SMEDDS_NR containing sodium taurocholate (NaTC) and Cremophor RH 40, and PFs-SMEDDS_R containing Cremophor RH 40 were measured upon dilution with deionized water and other aqueous media. Dilution volume presented no remarkable effects on particle size, whereas dilution media slightly influenced particle size. PFs-SMEDDS_NR and PFs-SMEDDS_R provided similar release rates in pH-1.2 hydrochloride solution. However, the release rate of PFs-SMEDDS_NR was faster than that of PFs-SMEDDS_R in pH-6.8 phosphate buffer containing 20 mM NaTC and 500 U/mL porcine pancreas lipase. The pharmacokinetics and bioavailability were measured in rats. The oral bioavailability of PFs-SMEDDS_NR was 2.57- and 2.28-fold that of a suspension of PFs (PFs-suspension) before and after the blockade of the lymphatic transport route by cycloheximide, respectively. These results suggested PFs-SMEDDS_NR could significantly improve the oral relative absorption of PFs via the lymphatic uptake pathway. SMEDDS containing NaTC may provide an effective approach for enhancing the oral bioavailability of PFs.

Systematic development of design of experiments (DoE) optimised self-microemulsifying drug delivery system of Zotepine

The aim of present investigation is to improve dissolution rate of poor soluble drug Zotepine by a self-microemulsifying drug delivery system (SMEDDS). Ternary phase diagram with oil (Oleic acid), surfactant (Tween 80) and co-surfactant (PEG 400) at apex were used to identify the efficient self-microemulsifying region. Box-Behnken design was implemented to study the influence of independent variables. Principal Component Analysis was used for scrutinising critical variables. The liquid SMEDDS were characterised for macroscopic evaluation, % Transmission, emulsification time and in vitro drug release studies. Optimised formulation OL1 was converted in to S-SMEDDS by using Aerosil^® 200 as an adsorbent in the ratio of 3:1. The S-SMEDDS was characterised by SEM, DSC, globule size (152.1 nm), zeta-potential (-28.1 mV), % transmission study (98.75%), in vitro release (86.57%) at 30 min. The optimised solid SMEDDS formulation showed faster drug release properties as compared to conventional tablet of Zotepine.

Comparison of the Analgesic Effect of Diclofenac Sodium-Eudragit(®) RS100 Solid Dispersion and Nanoparticles Using Formalin Test in the Rats

PURPOSE

In this study the intensity and duration of analgesic effect of diclofenac Na - Eudragit(®) RS100 solid dispersion and nanoparticles were evaluated by using formalin test in the rats.

METHODS

The animals received different formulations of diclofenac Na and subsequently 50 μl of formalin solution (2.5%) was injected subcutaneously in the right paws after 1 h, 2 h and 3 h. The paw licking behavior was then evaluated in two phases. A dose of 20 mg/kg of pure diclofenac Na powder was determined as effective dose.

RESULTS

In the first phase, in term of reduced paw licking time, no significant differences were found in any of the groups compared to the control group. However, in the second phase, the animals which received pure drug powder and the physical mixture of diclofenac Na with Eudragit(®) RS100 showed significant differences at the first and second hours. In the animals received the nanoparticles and solid dispersion, significant differences were observed in the third hour compared to the control group.

CONCLUSION

The analgesic effect of diclofenac Na could be improved by formulating its nanoparticles and solid dispersion with Eudragit(®) RS100. However, the nanoparticles revealed significantly higher analgesic effect than solid dispersion.

Enhanced transdermal delivery of diclofenac sodium via conventional liposomes, ethosomes, and transfersomes

The aim of this study was to improve the transdermal permeation of Diclofenac sodium, a poorly water-soluble drug, employing conventional liposomes, ethosomes, and transfersomes. The prepared formulations had been characterized for the loaded drug amount and vesicle size. The prepared vesicular systems were incorporated into 1% Carbopol 914 gel, and a survey of in vitro drug release and drug retention into rat skin has been done on them using a modified Franz diffusion cell. The cumulative amount of drug permeated after 24 h, flux, and permeability coefficient were assessed. Stability studies were performed for three months. The size of vesicles ranged from 145 to 202 nm, and the encapsulation efficiency of the Diclofenac sodium was obtained between 42.61% and 51.72%. The transfersomes and ethosomes provided a significantly higher amount of cumulative permeation, steady state flux, permeability coefficient, and residual drug into skin compared to the conventional liposomes, conventional gel, or hydroethanolic solution. The in vitro release data of all vesicular systems were well fit into Higuchi model (RSD > 0.99). Stability tests indicated that the vesicular formulations were stable over three months. Results revealed that both ethosome and transfersome formulations can act as drug reservoir in skin and extend the pharmacologic effects of Diclofenac sodium.

Nanocrystals for the parenteral delivery of poorly water-soluble drugs

Nanocrystals have drawn increasing interest in pharmaceutical industry because of the ability to improve dissolution of poorly water-soluble drugs. Nanocrystals can be produced by top-down and bottom-up technologies and have been explored for a variety of therapeutic applications. Here we review the methods of nanocrystal production and parenteral applications of nanocrystals. We also discuss remaining challenges in the development of nanocrystal products.

Solid-in-oil dispersion: a novel core technology for drug delivery systems

Drug delivery systems using a solid-in-oil (S/O) dispersion as a core technology have advanced significantly over the past ten years. A novel, effective and practical preparation method for a S/O dispersion was originally established in 1997 as a tool for enzymatic catalysis in organic media. This oil-based dispersion containing proteins in non-aqueous media had great potential for applications to other research with one of the most successful being its adaptation as a drug delivery system. The history and features of novel processes for preparing S/O dispersions are presented in this article. In addition, recent research into the use of S/O dispersions for innovative oral and skin drug delivery systems is discussed.

Enhanced effect and mechanism of water-in-oil microemulsion as an oral delivery system of hydroxysafflor yellow A

Background:

A microemulsion is an effective formulation for improving the oral bioavailability of poorly soluble drugs. In this paper, a water-in-oil (w/o) microemulsion was investigated as a system for enhancing the oral bioavailability of Biopharmaceutic Classification System (BCS) III drugs.

Methods:

The microemulsion formulation was optimized using a pseudoternary phase diagram, comprising propylene glycol dicaprylocaprate (PG), Cremophor^® RH40, and water (30/46/24 w/w).

Results:

The microemulsion increased the oral bioavailability of hydroxysafflor yellow A which was highly water-soluble but very poorly permeable. The relative bioavailability of hydroxysafflor yellow A microemulsion was about 1937% compared with a control solution in bile duct-nonligated rats. However, the microemulsion showed lower enhanced absorption ability in bile duct-ligated rats, and the relative bioavailability was only 181%. In vitro experiments were further employed to study the mechanism of the enhanced effect of the microemulsion. In vitro lipolysis showed that the microemulsion was digested very quickly by pancreatic lipase. About 60% of the microemulsion was digested within 1 hour. Furthermore, the particle size of the microemulsion after digestion was very small (53.3 nm) and the digested microemulsion had high physical stability. An everted gut sac model demonstrated that cumulative transport of the digested microemulsion was significantly higher than that of the diluted microemulsion.

Conclusion:

These results suggested that digestion of the microemulsion by pancreatic lipase plays an important role in enhancing oral bioavailability of water-soluble drugs.

Preparation of pH-sensitive beads for NSAID using three-component gel systems

The aim of this study is to prepare novel pH-sensitive beads to obtain a gastric mucosa protective formulation and to ensure drug delivery into the intestine. Diclofenac sodium was used as a model drug. Bead formation was achieved by ionotropic gelation method using three-component gel system containing sodium alginate (Na-Alg), hydroxyethylcellulose (HEC) and hydroxypropylmethylcellulose (HPMC). Factors influencing the characteristics of beads (exposure time, cross-linking agent concentration, polymer ratio) were investigated by swelling and erosion tests based on gravimetric method. Drug release was tested in distilled water and/or artificial digestive fluids and evaluated with Korsmeyer-Peppas equation and Baker-Lonsdale model. The encapsulation behaviour was qualitatively indicated by differential scanning calorimetry (DSC) method. In vivo experiments were conducted to test ulcerogenicity and intestinal absorption in rats. HPMC increased the encapsulation efficiency (EE) and HEC improved the drug release in the intestinal fluids. The equilibrium water uptake (EWU) was correlated with exposure time, calcium chloride concentration and HEC amounts. Bead erosion increased proportionately to exposure time, while it reduced when calcium chloride concentrations were increased. Higher amounts of HEC increased, while higher pH values reduced the encapsulation efficacy. The in vivo experiments demonstrated that the studied encapsulation technology markedly reduced the ulcerogenic effect of diclofenac.

Sulindac loaded alginate beads for a mucoprotective and controlled drug release

Ionotropic gelation was used to entrap sulindac into calcium alginate beads as a potential drug carrier for the oral delivery of this anti-inflammatory drug. Beads were investigated in vitro for a possible sustained drug release and their use in vivo as a gastroprotective system for sulindac. Process parameters such as the polymer concentration, polymer/drug ratio, and different needle diameter were analysed for their influences on the bead properties. Size augmented with increasing needle diameter (0.9 mm needle: 1.28 to 1.44 mm; 0.45 mm needle: 1.04 to 1.07 mm) due to changes in droplet size as well as droplet viscosity. Yields varied between 87% and 98% while sulindac encapsulation efficiencies of about 88% and 94% were slightly increasing with higher alginate concentrations. Drug release profiles exhibited a complete release for all formulations within 4 hours with a faster release for smaller beads. Sulindac loaded alginate beads led to a significant reduction of macroscopic histological damage in the stomach and duodenum in mice. Similarly, microscopic analyses of the mucosal damage demonstrated a significant mucoprotective effect of all bead formulation compared to the free drug. The present alginate formulations exhibit promising properties of a controlled release form for sulindac; meanwhile they provide a distinct tissue protection in the stomach and duodenum.

Reduction of Gastric Ulcerogenicity During Multiple Administration of Diclofenac Sodium by a Novel Solid-in-Oil Suspension

This article reports a significant reduction of gastric ulcerogenicity by complex formation of a nonsteroidal anti-inflammatory drug with surfactants. Diclofenac sodium (DFNa) was suspended in medium chain triglyceride (MCT) by forming a complex with an edible lipophilic surfactant. Two types of suspensions, prepared through a membrane emulsification with different pore sizes, were evaluated according to the degree of gastric damage following multiple oral administration in rats. It was shown that gastric ulcerogenicity of DFNa was reduced by the surfactant-drug complexes, at doses up to 12 mg/kg, whereas severe gastric damage was observed upon oral administration of the aqueous solution at doses of 6 mg/kg. Comparable blood levels of DFNa were observed after administration of solution and suspension formulations.

A Novel Solid-in-oil Nanosuspension for Transdermal Delivery of Diclofenac Sodium

PURPOSE

We formulated a solid-in-oil nanosuspension (SONS) as a novel transdermal delivery carrier for diclofenac sodium (DFNa). The basic transdermal characteristics of the SONS were evaluated using a Yucatan micropig (YMP) skin model.

METHODS

DFNa-sucrose erucate (i.e. surfactant) complexes were prepared via the formation of a water-in-oil emulsion. The complexes were suspended in isopropyl myristate (IPM) to form a SONS. The basic transdermal characteristics of the SONS were examined using full-thickness YMP dorsal skin in a Franz-type diffusion cell. DFNa powder suspended in IPM without complex formation was used as a control. The effect of the weight ratio of surfactant to DFNa on DFNa penetration of the skin was evaluated.

RESULTS

DFNa was successfully dispersed into IPM as a nanosized suspension via complex formation with sucrose erucate. The resultant SONS increased the permeability flux of DFNa across the YMP skin by up to 3.8-fold compared with the control. The size of the SONS depended on the weight ratio of the surfactant to DFNa. The optimal weight ratio for the highest DFNa permeation was 8.8, at which point the mean diameter of the SONS was 14.4 nm.

CONCLUSION

The SONS formulation can enhance the percutaneous absorption of DFNa.