Effect of HPbetaCD on solubility and transdermal delivery of capsaicin through rat skin

In situ triggered, floating delivery systems of capsaicin for prolonged gastroprotection

Capsaicin (CAP) has been implicated as a gastroprotective agent in the treatment of peptic ulcers. However, its oral administration is hampered by its poor aqueous solubility and caustic effect at high administered doses. To address these limitations, we describe the development of gastric floating, sustained release electrospun films loaded with CAP. The nanofiber films were formulated using the polymers Eudragit RL/RS and sodium bicarbonate (SB) as the effervescent agent. The films were tested for their physicochemical properties, and film buoyancy and in vitro release of CAP were assessed in simulated gastric fluid. The cytocompatibility and anti-inflammatory properties of the films were evaluated in lipopolysaccharide (LPS)-stimulated Caco-2 cells. The amorphous films showed improved wettability, a short floating lag time (<1 s) and a total floating time of over 24 h accompanied by sustained CAP release for up to 24 h. CAP-loaded films demonstrated biocompatibility with Caco-2 cells and potential cytoprotective effects by attenuating inflammatory cytokine and reactive oxygen species (ROS) production in LPS-stimulated Caco-2 cells. The gastric floating electrospun films could serve as a platform for sustained and stomach-specific drug delivery applications.

Adsorption of Capsaicin into the Nanoconfined Interlayer Space of Montmorillonite by DFT Calculations

Capsaicin is the main compound responsible of the hot sense of the chili fruits. This compound has interesting therapeutic properties including anticancer, anti-inflammatory effects, and analgesic. However, its use has several secondary effects, such as skin irritation and allergies. Then, new therapeutic strategies are searched in order to overcome these problems. Montmorillonite has proved to be an excellent excipient for the release of pharmaceutical drugs. In this work, the molecular structure and crystal structure of capsaicin, and the adsorption of this molecule into the interlayer space of montmorillonite have been studied using quantum mechanical calculations based on Density Functional Theory (DFT) level of theory and molecular dynamics simulations. The crystal structure has been predicted with these calculations and the intermolecular interactions have been determined with a higher resolution than the previous experimental data. The adsorption of capsaicin into the confined interlayer space of montmorillonite is energetically favourable with low and high octahedral charge. This adsorption can be monitored by IR spectroscopy observing frequency shifts in some bands during the adsorption. This enhances the use of these clay minerals for capsaicin therapeutic formulations.

Capsaicin-Cyclodextrin Complex Enhances Mepivacaine Targeting and Improves Local Anesthesia in Inflamed Tissues

Acidic environments, such as in inflamed tissues, favor the charged form of local anesthetics (LA). Hence, these drugs show less cell permeation and diminished potency. Since the analgesic capsaicin (CAP) triggers opening of the TRPV1 receptor pore, its combination with LAs could result in better uptake and improved anesthesia. We tested the above hypothesis and report here for the first time the analgesia effect of a two-drug combination (LA and CAP) on an inflamed tissue. First, CAP solubility increased up to 20 times with hydroxypropyl-beta-cyclodextrin (HP-β-CD), as shown by the phase solubility study. The resulting complex (HP-β-CD-CAP) showed 1:1 stoichiometry and high association constant, according to phase-solubility diagrams and isothermal titration calorimetry data. The inclusion complex formation was also confirmed and characterized by differential scanning calorimetry (DSC), X-ray diffraction, and ¹H-NMR. The freeze-dried complex showed physicochemical stability for at least 12 months. To test in vivo performance, we used a pain model based on mouse paw edema. Results showed that 2% mepivacaine injection failed to anesthetize mice inflamed paw, but its combination with complexed CAP resulted in pain control up to 45 min. These promising results encourages deeper research of CAP as an adjuvant for anesthesia in inflamed tissues and cyclodextrin as a solubilizing agent for targeting molecules in drug delivery.

Development and Characterization of Solid Dispersion System for Enhancing the Solubility and Dissolution Rate of Dietary Capsaicin

Background:

Capsaicin is a pungent component of chili peppers that suppresses the growth of various cancer cell lines including breast cancer. However, it shows extremely low oral bioavailability due to its poor water solubility.

Objective:

The objective of the present work was to improve the solubility and dissolution rate of capsaicin.

Methods:

Solid dispersions were prepared by the solvent evaporation method using different molar ratios of capsaicin and urea (1:1, 1:2, and 1:3). Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) study were used to characterize the solid dispersion. Solid dispersions were evaluated for solubility, dissolution rate and in vitro cytotoxicity in breast cancer cell lines.

Results:

XRD and DSC studies exhibited the reduced crystallinity of a drug in solid dispersion. Phase solubility study shows that the drug solubility increased by increasing carrier concentration. In vitro release study of the solid dispersion showed the faster dissolution of a drug with increasing carrier concentration. Solid dispersion formulation effectively inhibited the growth of MCF-7 human breast cancer and MDA-MB-231 triple negative human breast cancer cells in an MTT assay that measures metabolic activity, but only slightly decreased cell viability when compared to capsaicin alone.

Conclusion:

The present study demonstrated that solid dispersion of capsaicin in PEG 6000 overcomes the problems related to the poor aqueous solubility of this drug and improving its dissolution rate.

Development of self-repair nano-rod scaffold materials for implantation of osteosarcoma affected bone tissue

Nano-hydroxyapatite with a xylitol based co-polymer and a capsaicin loaded scaffold was investigated as a natural antioxidant loaded bone implant material on osteosarcoma cells.

Hydrogels with smart systems for delivery of hydrophobic drugs

INTRODUCTION

Smart hydrogel systems present opportunities to not only provide hydrophobic molecule encapsulation capability but to also respond to specific delivery routes. Areas covered: An overview of the design principles, preparation methods and applications of hydrogel systems for delivery of hydrophobic drugs is given. It begins with a summary of the advantages of hydrogels as delivery vehicles over other approaches, particularly macromolecular nanocarriers, before proceeding to address the design and preparation strategies and chemistry involved, with a particular focus on the introduction of hydrophobic domains into (naturally) hydrophilic hydrogels. Finally, the applications in different delivery routes are discussed. Expert opinion: Modifications to conventional hydrogels can endow them with the capability to carry hydrophobic drugs but other functions as well, such as the improved mechanical stability, which is important for long-term in vivo residence and/or self-healing properties useful for injectable delivery pathways. These modifications harness hydrophobic-hydrophobic forces, physical interactions and inclusion complexes. The lack of in-depth understanding of these interactions, currently limits more delicate and application-oriented designs. Increased efforts are needed in (i) understanding the interplay of gel formation and simultaneous drug loading; (ii) improving hydrogel systems with respect to their biosafety; and (iii) control over release mechanism and profile.

Development of Organogel-Derived Capsaicin Nanoemulsion with Improved Bioaccessibility and Reduced Gastric Mucosa Irritation

Capsaicin (CAP) is the major active component in chili peppers with health-promoting benefits. However, the low bioavailability and irritating quality of CAP greatly limit its applications in functional foods. The objective of this study was to develop a food-grade nanoemulsion to increase the dissolution and bioaccessibility of CAP and to alleviate its irritating effects. To achieve this goal, CAP was first dissolved in medium-chain triacylglycerol (MCT), followed by the addition of sucrose stearate S-370 as organogelator to develop CAP-loaded organogel. The oil-in-water (O/W) emulsion was formed using organogel as the oil phase and Tween 80 as the emulsifier. After ultrasonication treatment, droplet sizes of emulsion were decreased to 168 nm with enhanced dissolution rate and bioaccessibility. In vivo study further confirmed the reduced rat gastric mucosa irritation caused by CAP. The organogel-derived nanoemulsion was proved to be an effective delivery system for CAP-based functional food products.

In vitro and in vivo evaluation of capsaicin-loaded microemulsion for enhanced oral bioavailability

BACKGROUND

Capsaicin, as a food additive, has attracted worldwide concern owing to its pungency and multiple pharmacological effects. However, poor water solubility and low bioavailability have limited its application. This study aims to develop a capsaicin-loaded microemulsion to enhance the oral bioavailability of the anti-neuropathic-pain component, capsaicin, which is poorly water soluble.

RESULTS

In this study, the microemulsion consisting of Cremophor EL, ethanol, medium-chain triglycerides (oil phase) and water (external phase) was prepared and characterized (particle size, morphology, stability and encapsulation efficiency). The gastric mucosa irritation test of formulated capsaicin was performed in rats to evaluate its oral feasibility, followed by the pharmacokinetic study in vivo. Under these conditions, the encapsulated capsaicin revealed a faster capsaicin release in vitro coupled with a greater absorption in vivo when compared to the free capsaicin. The oral bioavailability of the formulated capsaicin-loaded microemulsions was 2.64-fold faster than that of free capsaicin. No significant irritation was observed on the mucosa from the pathological section of capsaicin-loaded microemulsion treated stomach.

CONCLUSION

These results indicate that the developed microemulsion represents a safe and orally effective carrier for poorly soluble substances. The formulation could be used for clinical trials and expand the application of capsaicin.

Oral delivery of capsaicin using MPEG-PCL nanoparticles

AIM

To prepare a biodegradable polymeric carrier for oral delivery of a water-insoluble drug capsaicin (CAP) and evaluate its quality.

METHODS

CAP-loaded methoxy poly (ethylene glycol)-poly(ε-caprolactone) nanoparticles (CAP/NPs) were prepared using a modified emulsification solvent diffusion technique. The quality of CAP/NPs were evaluated using transmission electron microscopy, powder X-ray diffraction, differential scanning calorimetry and Fourier transform infrared techniques. A dialysis method was used to analyze the in vitro release profile of CAP from the CAP/NPs. Adult male rats were orally administered CAP/NPs (35 mg/kg), and the plasma concentrations of CAP were measured with a validated HPLC method. The morphology of rat gastric mucosa was studied with HE staining.

RESULTS

CAP/NPs had an average diameter of 82.54 ± 0.51 nm, high drug-loading capacity of 14.0% ± 0.13% and high stability. CAP/NPs showed a biphasic release profile in vitro: the burst release was less than 25% of the loaded drug within 12 h followed by a more sustained release for 60 h. The pharmacokinetics study showed that the mean maximum plasma concentration was observed 4 h after oral administered of CAP/NPs, and approximately 90 ng/mL of CAP was detected in serum after 36 h. The area under the curve for the CAP/NPs group was approximately 6-fold higher than that for raw CAP suspension. Histological studies showed that CAP/NPs markedly reduced CAP-caused gastric mucosa irritation.

CONCLUSION

CAP/NPs significantly enhance the bioavailability of CAP and markedly reduce gastric mucosa irritation in rats.

Bioavailability of capsaicin and its implications for drug delivery

The dietary compound capsaicin is responsible for the "hot and spicy" taste of chili peppers and pepper extracts. It is a valuable pharmacological agent with several therapeutic applications in controlling pain and inflammation. Emerging studies show that it displays potent anti-tumor activity in several human cancers. On a more basic research level, capsaicin has been used as a ligand to activate several types of ion-channel receptors. The pharmacological activity of capsaicin-like compounds is dependent on several factors like the dose, the route of administration and most importantly on its concentration at target tissues. The present review describes the current knowledge involving the metabolism and bioavailability of capsaicinoids in rodents and humans. Novel drug delivery strategies used to improve the bioavailability and therapeutic index of capsaicin are discussed in detail. The generation of novel capsaicin-mimetics and improved drug delivery methods will foster the hope of innovative applications of capsaicin in human disease.

A nanovesicle topical formulation of Bhut Jolokia (hottest capsicum): a potential anti-arthritic medicine

OBJECTIVES

Bhut Jolokia is a capsicum variety indigenous to Northeast India and is recognized as the hottest capsicum variety of the world. The ethnobotanical survey revealed that it has potential anti-arthritic activity but its topical adverse events restrict its usability. In the present study, the semipurified capsaicinoids extract of Bhut Jolokia was formulated as a topical formulation via ethosomal nanovesicle approach, which enhanced the acceptability.

METHODS

Prepared formulation was optimized by surface response methodology and characterized for morphology, zeta potential, differential scanning calorimetry study and permeation and penetration studies. The experimental formulations were characterized on Freunds complete adjuvant-induced chronic arthritis model.

RESULTS

Ethosomal nanovesicles prepared with the semipurified capsaicinoids extract demonstrated good anti-arthritic activity in rat model, superior to Thermagel (a marketed formulation of capsaicin) in the reduction of joint swelling and pain throughout the observation period. Nanovesicle formulation showed better tolerability and acceptance on both animal and human models. Results obtained from the study strengthen the potential application of Bhut Jolokia semipurified extract in an ethosomal nanovesicle carrier as a topical analgesic as well as an anti-arthritic.

CONCLUSION

The significant positive results, with reduced irritant effect of the semipurified capsaicinoids extract of Bhut Jolokia-loaded ethosomal nanovesicle carrier, suggest that it could be one of the choices for formulation development in anti-arthritic medicine.

The use of nanoencapsulation to decrease human skin irritation caused by capsaicinoids

Capsaicin, a topical analgesic used in the treatment of chronic pain, has irritant properties that frequently interrupt its use. In this work, the effect of nanoencapsulation of the main capsaicinoids (capsaicin and dihydrocapsaicin) on skin irritation was tested in humans. Skin tolerance of a novel vehicle composed of chitosan hydrogel containing nonloaded nanocapsules (CH-NC) was also evaluated. The chitosan hydrogel containing nanoencapsulated capsaicinoids (CH-NC-CP) did not cause skin irritation, as measured by an erythema probe and on a visual scale, while a formulation containing free capsaicinoids (chitosan gel with hydroalcoholic solution [CH-ET-CP]) and a commercially available capsaicinoids formulation caused skin irritation. Thirty-one percent of volunteers reported slight irritation one hour after application of CH-NC-CP, while moderate (46% [CH-ET-CP] and 23% [commercial product]) and severe (8% [CH-ET-CP] and 69% [commercial product]) irritation were described for the formulations containing free capsaicinoids. When CH-NC was applied to the skin, erythema was not observed and only 8% of volunteers felt slight irritation, which demonstrates the utility of the novel vehicle. A complementary in vitro skin permeation study showed that permeation of capsaicinoids through an epidermal human membrane was reduced but not prevented by nanoencapsulation.

Recent expansions in an emergent novel drug delivery technology: Emulgel

Emulgel is an emerging topical drug delivery system to which if more effort is paid towards its formulation & development with more number of topically effective drugs it will prove a boon for derma care & cosmetology. Emulgels are either emulsion of oil in water or water in oil type, which is gelled by mixing it with gelling agent. Incorporation of emulsion into gel increases its stability & makes it a dual control release system. Due to lack of excess oily bases & insoluble excipients, it shows better drug release as compared to other topical drug delivery system. Presence of gel phase makes it a non greasy & favors good patient compliance. These reviews give knowledge about Emulgel including its properties, advantages, formulation considerations, and its recent advances in research field. All factors such as selection of gelling agent, oil agent, emulsifiers influencing the stability and efficacy of Emulgel are discussed. All justifications are described in accordance with the research work carried out by various scientists. These brief reviews on formulation method have been included. Current research works that carried out on Emulgel are also discussed and highlighted the wide utility of Emulgel in topical drug delivery system. After the vast study, it can be concluded that the Emulgels appear better & effective drug delivery system as compared to other topical drug delivery system. The comprehensive analysis of rheological and release properties will provide an insight into the potential usage of Emulgel formulation as drug delivery system.

Effect of Different Carriers on in vitro Permeation of Meloxicam through Rat Skin

The ability of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, polyvinyl pyrrolidone and urea to influence the percutaneous absorption of meloxicam through isolated rat skin was evaluated. Carrier complex were prepared by kneading method in 1:1 and 1:2 in molar ratios for β-cyclodextrin and hydroxypropyl-β-cyclodextrin and in 1:1, 1:3 and 1:5 in weight ratios for polyvinyl pyrrolidone and urea. The complexes were characterized by IR, DSC and evaluated for solubility, dissolution and skin permeability. The solubility, dissolution and permeability of meloxicam were enhanced by using the carriers. The influence of cyclodextrins, polyvinyl pyrrolidone and urea on in vitro permeation of meloxicam through rat skin was investigated by incorporation of prepared carrier complex in 1% carbopol gel. The prepared gel was evaluated for drug content, pH and viscosity and in vitro permeation. All the percutaneous parameters like flux (Jss), amount permeated (Q₆), diffusivity (D), permeability coefficient (K_p), partition coefficient (K) and release rate constant (k) were calculated statistically. In vitro permeation study showed the trend that the penetration flux and enhancement factor increases with increasing concentration of β-cyclodextrin and hydroxypropyl-β-cyclodextrin and then decrease dramatically in case of hydroxypropyl-β-cyclodextrin gel formulation with the increase to 1:2 ratio. Similar changes in pattern of permeation were also observed with polyvinyl pyrrolidone and urea carrier complex. These findings concluded that the carriers cyclodextrins, polyvinyl pyrrolidone and urea could be used as transdermal permeation enhancer in topical preparation of meloxicam.

Pharmaceutical applications of cyclodextrins: effects on drug permeation through biological membranes

Objectives

Cyclodextrins are useful solubilizing excipients that have gained currency in the formulator's armamentarium based on their ability to temporarily camouflage undesirable physicochemical properties. In this context cyclodextrins can increase oral bioavailability, stabilize compounds to chemical and enzymatic degradation and can affect permeability through biological membranes under certain circumstances. This latter property is examined herein as a function of the published literature as well as work completed in our laboratories.

Key findings

Cyclodextrins can increase the uptake of drugs through biological barriers if the limiting barrier component is the unstirred water layer (UWL) that exists between the membrane and bulk water. This means that cyclodextrins are most useful when they interact with lipophiles in systems where such an UWL is present and contributes significantly to the barrier properties of the membrane. Furthermore, these principles are used to direct the optimal formulation of drugs in cyclodextrins. A second related critical success factor in the formulation of cyclodextrin-based drug product is an understanding of the kinetics and thermodynamics of complexation and the need to optimize the cyclodextrin amount and drug-to-cyclodextrin ratios. Drug formulations, especially those targeting compartments associated with limited dissolution (i.e. the eye, subcutaneous space, etc.), should be carefully designed such that the thermodynamic activity of the drug in the formulation is optimal meaning that there is sufficient cyclodextrin to solubilize the drug but not more than that. Increasing the cyclodextrin concentration decreases the formulation ‘push’ and may reduce the bioavailability of the system.

Conclusions

A mechanism-based understanding of cyclodextrin complexation is essential for the appropriate formulation of contemporary drug candidates.