Nanocarrier-based topical drug delivery for an antifungal drug

Advances in nanotechnology for improving the targeted delivery and activity of amphotericin B (2011-2023): a systematic review

Amphotericin B (AmB) is a broad-spectrum therapeutic and effective drug, but it has serious side effects of toxicity and solubility. Therefore, reducing its toxicity should be considered in therapeutic applications. Nanotechnology has paved the way to improve drug delivery systems and reduce toxicity. The present study, for the first time, comprehensively reviews the studies from 2011 to 2023 on reducing the in vitro toxicity of AmB. The findings showed that loading AmB with micellar structures, nanostructured lipid carriers, liposomes, emulsions, poly lactide-co-glycolide acid, chitosan, dendrimers, and other polymeric nanoparticles increases the biocompatibility and efficacy of the drug and significantly reduces toxicity. In addition, modified carbon nanoparticles (including graphene, carbon nanotubes, and carbon dots) with positively charged amine groups, PEI, and other components showed favorable drug delivery properties. Uncoated and coated magnetic nanoparticles and silver NPs-AmB composites had less cytotoxicity and more antifungal activity than free AmB. Citrate-reduced GNPs and lipoic acid-functionalized GNPs were also effective nanocarriers to reduce AmB cytotoxicity and improve anti-leishmania efficacy. In addition, zinc oxide-NPs and PEGylated zinc oxide-NPs showed favorable antifungal activity and negligible toxicity. According to a review study, carbon-based nanoparticles, metal nanoparticles, and especially polymer nanoparticles caused some reduction in the toxicity and improved solubility of AmB in water. Overall, considering the discussed nanocarriers, further research on the application of nanotechnology as a cost-effective candidate to improve the efficiency and reduce the cytotoxicity of AmB is recommended.

Mechanistic Insights into Luteolin-Loaded Elastic Liposomes for Transdermal Delivery: HSPiP Predictive Parameters and Instrument-Based Evidence

We evaluated mechanistic insights into luteolin (LUT)-loaded elastic liposomes (OLEL1) permeated across rat skin. HSPiP software-based parameters, thermal analysis, infrared analysis, and morphological evaluations were employed to understand mechanistic observations of drug permeation and deposition. HSPiP provided HSP values (δ_d, δ_p, and δ_h) of OLEL1 (based on composition), LUT, excipients, and rat skin (literature value and by-default value). Rat skin was studied via Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), fluorescence microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies. The δ_d and δ_h estimation of the skin and phosphatidylcholine showed close relation in terms of δ_d and δ_h. Similarly, OLEL1 and the skin might interact with each other mainly through δ_d and δ_p forces as evidenced by the predicted values. The untreated skin showed characteristic stretching and vibrations as compared to lower frequencies caused by OLEL1. DSC showed changes in the thermal behavior of the skin after OLEL1 treatment as compared to the untreated skin. Visualization of these changes was evident under fluorescence microscopy and SEM for confirmed substantial reversible surface perturbation of the skin protein layer for improved vesicle permeation and subsequent internalization with the inner skin matrix. The AFM study confirmed the nanoscale surface roughness variation caused substantially by OLEL1 and OLEL1 placebo as compared to the untreated control and drug solution. Thus, the study clearly demonstrated mechanistic insights into LUT-loaded vesicles across rat skin for enhanced permeation and drug deposition.

A Pharmaco-Technical Investigation of Thymoquinone and Peat-Sourced Fulvic Acid Nanoemulgel: A Combination Therapy

Thymoquinone has a multitude of pharmacological effects and has been researched for a wide variety of indications, but with limited clinical success. It is associated with pharmaco-technical caveats such as hydrophobicity, high degradation, and a low oral bioavailability. A prudent approach warrants its usage through an alternative dermal route in combination with functional excipients to harness its potential for treating dermal afflictions, such as psoriasis. Henceforth, the present study explores a nanoformulation approach for designing a fulvic acid (peat-sourced)-based thymoquinone nanoemulsion gel (FTQ-NEG) for an enhanced solubility and improved absorption. The excipients, surfactant/co-surfactant, and oil selected for the o/w nanoemulsion (FTQ-NE) are Tween 80/Transcutol-P and kalonji oil. The formulation methodology includes high-energy ultrasonication complemented with a three-dimensional/factorial Box-Behnken design for guided optimization. The surface morphology assessment through scanning/transmission electron microscopy and fluorescence microscopy revealed a 100 nm spherical, globule-like structure of the prepared nanoemulsion. Furthermore, the optimized FTQ-NE had a zeta potential of -2.83 ± 0.14 Mv, refractive index of 1.415 ± 0.036, viscosity of 138.5 ± 3.08 mp, and pH of 5.8 ± 0.16, respectively. The optimized FTQ-NE was then formulated as a gel using Carbopol 971^® (1%). The in vitro release analysis of the optimized FTQ-NEG showed a diffusion-dominant drug release (Higuchi model) for 48 h. The drug permeation flux observed for FTQ-NEG (3.64 μg/cm²/h) was much higher compared to that of the pure drug (1.77 mg/cm²/h). The results were further confirmed by confocal microscopy studies, which proved the improved penetration of thymoquinone through mice skin. Long-term stability studies of the purported formulation were also conducted and yielded satisfactory results.

In vitro release, ex vivo penetration, and in vivo dermatokinetics of ketoconazole-loaded solid lipid nanoparticles for topical delivery

The study focused to evaluate and investigate optimized (using QbD) and novel ketoconazole (KTZ)-loaded solid lipid nanoparticles (KTZ-SLNs; 2% w/v KTZ) for enhanced permeation across skin. KTZ-SLNs were evaluated for size, distribution, zeta potential (ZP), percent entrapment efficiency (%EE), drug release, morphology (HRTEM and FESEM), thermal behaviour (DSC), spectroscopic (FTIR), and solid-state/diffraction characterization (X-ray diffraction, XRD). Moreover, ex vivo permeation and drug deposition into rat skin were conducted using Franz diffusion cell. The same was confirmed using human dermatome skin and fluorescence, confocal Raman, and vibrational ATR-FTIR microscopic methods. An in vivo dermatokinetics study was performed in rats to assess the extent of KTZ permeation into the skin. Stability including accelerated and photostability studies were conducted at different temperatures (2-8, 30, and 40 °C) for 12 months. The spherical, optimized KTZ-SLN formulation (KOF1) showed particle size of 293 nm and high EE of 88.5%. Results of FTIR, DSC, and XRD confirmed formation of KTZ-SLNs and their amorphous nature due to presence of KTZ in a dissolved state in the lipid matrix. In vitro release was slow and sustained whereas ex vivo permeation parameters were significantly high in KTZ-SLNs as compared to free drug suspension (KTZ-SUS) and marketed product (Nizral®; 2% KTZ w/v). Drug retention was 10- and five-fold higher than KTZ-SUS and marketed product, respectively. In vivo dermatokinetics parameters improved significantly with SLN formulation (410-900% enhanced). Confocal Raman spectroscopy experiment showed that KTZ-SLNs could penetrate beyond the human stratum corneum into viable epidermis. Fluorescent microscopy also indicated improved penetration of KTZ-SLNs. KTZ-SLNs were photostable and showed long-term stability over 12 months under set conditions.

Dissolving microneedle patches loaded with amphotericin B microparticles for localised and sustained intradermal delivery: Potential for enhanced treatment of cutaneous fungal infections

Fungal infections affect millions of people globally and are often unreceptive to conventional topical or oral preparations because of low drug bioavailability at the infection site, lack of sustained therapeutic effect, and the development of drug resistance. Amphotericin B (AmB) is one of the most potent antifungal agents. It is increasingly important since fungal co-infections associated with COVID-19 are frequently reported. AmB is only administered via injections (IV) and restricted to life-threatening infections due to its nephrotoxicity and administration-related side effects. In this work, we introduce, for the first time, dissolving microneedle patches (DMP) loaded with micronised particles of AmB to achieve localised and long-acting intradermal delivery of AmB for treatment of cutaneous fungal infections. AmB was pulverised with poly (vinyl alcohol) and poly (vinyl pyrrolidone) to form micronised particles-loaded gels, which were then cast into DMP moulds to form the tips. The mean particle size of AmB in AmB DMP tips after pulverisation was 1.67 ± 0.01 μm. This is an easy way to fabricate and load microparticles into DMP, as few steps are required, and no organic solvents are needed. AmB had no covalent chemical interaction with the excipients, but the crystallinity of AmB was reduced in the tips. AmB was completely released from the tips within 4 days in vitro. AmB DMP presented inhibition of Candida albicans (CA) and the killing rate of AmB DMP against CA biofilm inside porcine skin reached 100% within 24 h. AmB DMP were able to pierce excised neonatal porcine skin at an insertion depth of 301.34 ± 46.86 μm. Ex vivo dermatokinetic and drug deposition studies showed that AmB was mainly deposited in the dermis. An in vivo dermatokinetic study revealed that the area under curve (AUC_0-inf) values of AmB DMP and IV (Fungizone® bolus injection 1 mg/kg) groups were 8823.0 d∙μg/g and 33.4 d∙μg/g, respectively (264-fold higher). AmB remained at high levels (219.07 ± 102.81 μg/g or more) in the skin until 7 days after the application of AmB DMP. Pharmacokinetic and biodistribution studies showed that AmB concentration in plasma, kidney, liver, and spleen in the AmB DMP group was significantly lower than that in the IV group. Accordingly, this system addressed the systemic side effects of intravenous injection of AmB and localised the drug inside the skin for a week. This work establishes a novel, easy and effective method for long-acting and localised intradermal drug delivery.

Delivery strategies of amphotericin B for invasive fungal infections

Invasive fungal infections (IFIs) represent a growing public concern for clinicians to manage in many medical settings, with substantial associated morbidities and mortalities. Among many current therapeutic options for the treatment of IFIs, amphotericin B (AmB) is the most frequently used drug. AmB is considered as a first-line drug in the clinic that has strong antifungal activity and less resistance. In this review, we summarized the most promising research efforts on nanocarriers for AmB delivery and highlighted their efficacy and safety for treating IFIs. We have also discussed the mechanism of actions of AmB, rationale for treating IFIs, and recent advances in formulating AmB for clinical use. Finally, this review discusses some practical considerations and provides recommendations for future studies in applying AmB for combating IFIs.

Novel nanoemulsion gel containing triple natural bio-actives combination of curcumin, thymoquinone, and resveratrol improves psoriasis therapy: in vitro and in vivo studies

Curcumin, resveratrol, and thymoquinone are the potential natural bio-actives reported with good anti-psoriatic activity. However, poor aqueous solubility and limited skin permeation of these natural bio-actives hinder their effective delivery and potential therapeutic outcome. In this regard, current research work focuses on the design and optimization of nanoemulsion (NE) gel formulation for the concurrent delivery of these three drugs. The NE system is consisting of oleic acid as oil phase, Tween 20 as surfactant, and PEG 200 as co-surfactant. The optimized formulation exhibited the droplet size 76.20 ± 1.67 nm, PDI of 0.12 ± 0.05, RI of 1.403 ± 0.007, and viscosity of 137.9 ± 4.07 mp. Carbopol 940 (0.5% w/v) was used as the gelling agent to prepare the NE gel which exhibited a good texture profile. The optimized formulation exhibited a higher % of growth inhibition on A-431 cells and demonstrated good anti-angiogenic activity in the HET-CAM test. Finally, in vivo studies in Balb/c mice model showed improved anti-psoriatic conditions which indicated that the triple natural bio-actives combination in nanoemulgel formulation is effective in the management of psoriasis.

Novel Approach for Transdermal Delivery of Rifampicin to Induce Synergistic Antimycobacterial Effects Against Cutaneous and Systemic Tuberculosis Using a Cationic Nanoemulsion Gel

Purpose

This study demonstrated improved transdermal delivery of rifampicin-loaded cationic nanoemulsion gel to treat systemic and cutaneous tuberculosis using capmul, labrasol, and acconon, which exert anti-Mycobacterium activities. This approach enhanced drug permeation across the skin, increased therapeutic efficacy, and reduced dose-related side effects.

Methods

Design Expert^® was used to optimize formulations (S_mix ratio and capmul as independent factors), which were prepared using a slow spontaneous titration method. The optimized nanoemulsion was incorporated into carbopol gel to allow for topical application and comparative assessments. Nanoemulsions and gels were evaluated for size, size distribution, shape, zeta potential, percent spread, viscosity, in vitro hemolysis, in vitro release, and ex vivo skin permeation and deposition. A mechanistic evaluation was performed using scanning electron microscopy. Furthermore, in vivo pharmacokinetic and irritation studies were performed.

Results

The optimized cationic nanoemulsion (OCNE-1) was characterized by small particle size (≤100 nm), had optimal viscosity, percent spread, zeta potential, and percent drug release, and was hemocompatible. The OCNE-1T gel exhibited higher permeation flux (51.32 ± 0.5 µg/cm² hr), permeation coefficient (2.566 ± 0.08 cm/hr), drug deposition (994.404 µg/cm²), and enhancement ratio (7.16) than those of the OCNE-1 nanoemulsion or drug solution. Scanning electron microscopy was used to characterize the mechanism of enhanced permeation. An In vivo study showed that the C_max and area under the curve following transdermal application were 4.34- and 4.74-fold higher than those following oral administration.

Conclusion

Transdermal delivery of rifampicin could be a promising alternative to conventional approaches to treat systemic and local tuberculosis, and other bacterial infections.

Innovative nanocompounds for cutaneous administration of classical antifungal drugs: a systematic review

Nanomedicine manipulates materials at atomic, molecular, and supramolecular scale, with at least one dimension within the nanometer range, for biomedical applications. The resulting nanoparticles have been consistently shown beneficial effects for antifungal drugs delivery, overcoming the problems of low bioavailability and high toxicity of these drugs. Due to their unique features, namely the small mean particle size, nanoparticles contribute to the enhanced drug absorption and uptake by the target cells, potentiating the therapeutic drug effect. The topical route is desirable due to the adverse effects arising from oral administration. This review provides a comprehensive analysis of the use of nano compounds for the current treatment of topical fungal infections. A special emphasis is given to the employment of lipid nanoparticles, due to their recognized efficacy, versatility, and biocompatibility, attracting the major attention as novel topical nanocompounds used for the administration of antifungal drugs.

In Vitro Drug Dissolution/Permeation Testing of Nanocarriers for Skin Application: a Comprehensive Review

This review highlights in vitro drug dissolution/permeation methods available for topical and transdermal nanocarriers that have been designed to modulate the propensity of drug release, drug penetration into skin, and permeation into systemic circulation. Presently, a few of USFDA-approved in vitro dissolution/permeation methods are available for skin product testing with no specific application to nanocarriers. Researchers are largely utilizing the in-house dissolution/permeation testing methods of nanocarriers. These drug release and permeation methods are pending to be standardized. Their biorelevance with reference to in vivo plasma concentration-time profiles requires further exploration to enable translation of in vitro data for in vivo or clinical performance prediction.

Recent insights on nanomedicine for augmented infection control

Antimicrobial agents have been widely investigated for protecting against microbial infections in modern health. Drug-related limitations, poor bioavailability, toxicity to mammalian cells, and frequent bacteria drug resistance are major challenges faced when exploited in nanomedicine forms. Specific attention has been paid to control nanomaterial-based infection against numerous challenging pathogens in addition to improved drug delivery, targeting, and pharmacokinetic (PK) profiles, and thus, efficient antimicrobials have been fabricated using diverse components (metals, metal oxides, synthetic and semisynthetic polymers, natural or biodegradable polymers, etc). The present review covers several nanocarriers delivered through various routes of administration, highlighting major findings to control microbial infection as compared to using the free drug. Results over the past decade support the consistent development of various nanomedicines capable of improving biological significance and therapeutic benefits against an array of microbial strains. Depending on the intended application of nanomedicine, infection control will be challenged by various factors such as weighing the risk-benefits in healthcare settings, nanomaterial-induced (eco)toxicological hazards, frequent development of antibiotic resistance, scarcity of in vivo toxicity data, and a poor understanding of microbial interactions with nanomedicine at the molecular level. This review summarizes well-established informative data for nanomaterials used for infection control and safety concerns of nanomedicines to healthcare sectors followed by the significance of a unique "safe-by-design" approach.

Nanoemulsions and dermatological diseases: contributions and therapeutic advances

Skin disease is one of the most common human diseases and affects between 30% and 70% of individuals, which requires a lot of attention to their treatments. The delivery of active pharmacological ingredients at the topical level is a challenge because of the difficulties in overcoming the mechanical barrier created by the skin and reaching greater depths, since delivery specificities are decisive for the degree of effectiveness. In this way, the nanoemulsions emerge as a potential system for the incorporation of active substances in the cells and for the controlled release of active principles. The present article intends to review the main treatments for which the nanoemulsions were used in the field of dermatology. In addition, it discusses the results and advantages over the other dermatological therapies that are being used. The results showed that the particle size in nanoemulsions increased the contact surface area, resulting in increased drug efficacy, even in comparison with other existing pharmaceutical formulations. In conclusion, it has been shown that nanoemulsions have a better performance in efficacy, safety, permeability profile, and bioavailability compared with other formulations studied.

Topical Treatment for Cutaneous Leishmaniasis: Dermato-Pharmacokinetic Lead Optimization of Benzoxaboroles

Cutaneous leishmaniasis (CL) is caused by several species of the protozoan parasite Leishmania, affecting an estimated 10 million people worldwide. Previously reported strategies for the development of topical CL treatments have focused primarily on drug permeation and formulation optimization as the means to increase treatment efficacy. Our approach aims to identify compounds with antileishmanial activity and properties consistent with topical administration. Of the test compounds, five benzoxaboroles showed potent activity (50% effective concentration [EC50] < 5 μM) against intracellular amastigotes of at least one Leishmania species and acceptable activity (20 μM < EC50 < 30 μM) against two more species. Benzoxaborole compounds were further prioritized on the basis of the in vitro evaluation of progression criteria related to skin permeation, such as the partition coefficient and solubility. An MDCKII-hMDR1 cell assay showed overall good permeability and no significant interaction with the P-glycoprotein transporter for all substrates except LSH002 and LSH031. The benzoxaboroles were degraded, to some extent, by skin enzymes but had stability superior to that of para-hydroxybenzoate compounds, which are known skin esterase substrates. Evaluation of permeation through reconstructed human epidermis showed LSH002 to be the most permeant, followed by LSH003 and LSH001. Skin disposition studies following finite drug formulation application to mouse skin demonstrated the highest permeation for LSH001, followed by LSH003 and LSH002, with a significantly larger amount of LSH001 than the other compounds being retained in skin. Finally, the efficacy of the leads (LSH001, LSH002, and LSH003) against Leishmania major was tested in vivo LSH001 suppressed lesion growth upon topical application, and LSH003 reduced the lesion size following oral administration.

Nanoemulsion as pharmaceutical carrier for dermal and transdermal drug delivery: Formulation development, stability issues, basic considerations and applications

The use of nanoemulsion in augmenting dermal and transdermal effectiveness of drugs has now well established. The development of nanoemulsion based semisolid dosage forms is an active area of present research. However, thickening or liquid-to-semisolid conversion of the nanoemulsions provides opportunities to the formulation scientist to explore novel means of solving instability issues during transformation. Extending knowledge about the explicit role of nature/magnitude of zeta potential, types of emulsifiers and selection of appropriate semisolid bases could place these versatile carriers from laboratory to industrial scale. This article reviews the progressive advancement in the delivery of medicament via nanoemulsion with special reference to the dermal and transdermal administration. It is attempted to explore the most suitable semi solid dosage form for the particular type of nanoemulsion (o/w, w/o and others) and effect of particle size and zeta potential on the delivery of drugs through dermal or transdermal route. Finally, this review also highlights the basic principles and fundamental considerations of nanoemulsion manufacture, application of nanoemulsion based semisolid dosage forms in the dermal/transdermal administration and basic considerations during the nanoemulsion absorption into and through skin.

Topical Nano and Microemulsions for Skin Delivery

Nanosystems such as microemulsions (ME) and nanoemulsions (NE) offer considerable opportunities for targeted drug delivery to and via the skin. ME and NE are stable colloidal systems composed of oil and water, stabilised by a mixture of surfactants and cosurfactants, that have received particular interest as topical skin delivery systems. There is considerable scope to manipulate the formulation components and characteristics to achieve optimal bioavailability and minimal skin irritancy. This includes the incorporation of established chemical penetration enhancers to fluidize the stratum corneum lipid bilayers, thus reducing the primary skin barrier and increasing permeation. This review discusses nanosystems with utility in skin delivery and focuses on the composition and characterization of ME and NE for topical and transdermal delivery. The mechanism of skin delivery across the stratum corneum and via hair follicles is reviewed with particular focus on the influence of formulation.

Elastic liposomes as novel carriers: recent advances in drug delivery

Elastic liposomes (EL) are some of the most versatile deformable vesicular carriers that comprise physiologically biocompatible lipids and surfactants for the delivery of numerous challenging molecules and have marked advantages over other colloidal systems. They have been investigated for a wide range of applications in pharmaceutical technology through topical, transdermal, nasal, and oral routes for efficient and effective drug delivery. Increased drug encapsulation efficiency, enhanced drug permeation and penetration into or across the skin, and ultradeformability have led to widespread interest in ELs to modulate drug release, permeation, and drug action more efficiently than conventional drug-release vehicles. This review provides insights into the versatile role that ELs play in the delivery of numerous drugs and biomolecules by improving drug release, permeation, and penetration across the skin as well as stability. Furthermore, it provides future directions that should ensure the widespread use of ELs across all medical fields.

Alkyl Protocatechuate-Loaded Nanostructured Lipid Systems as a Treatment Strategy for Paracoccidioides brasiliensis and Paracoccidioides lutzii In Vitro

Dodecyl protocatechuate (dodecyl) is a derivative of protocatechuic acid (3,4-dihydroxybenzoic acid) that possesses anti-oxidant and antifungal properties. Nanostructured lipid systems (NLS) can potentiate the action of many antifungal agents, reducing the required dose and side effects by improving their activity. This work aimed to evaluate dodecyl protocatechuate loaded into a NLS (NLS+dodecyl) as a strategy for the treatment of Paracoccidioides brasiliensis and P. lutzii in vitro. Antifungal activity against P. brasiliensis and P. lutzii was evaluated using the microdilution technique. NLS+dodecyl showed high antifungal activity with a minimum inhibitory concentration ranging from 0.06 to 0.03 μg/mL; 4- to 16-fold higher than that of free dodecyl. NLS+dodecyl was able to inhibit fungal adhesion of the extracellular artificial matrix proteins (laminin and fibronectin), resulting in 82.4 and 81% inhibition, respectively, an increase of 8–17% compared with free dodecyl. These findings corroborate previous results demonstrating 65 and 74% inhibition of fungal adhesion in pulmonary fibroblast cells by dodecyl and NLS+dodecyl, respectively, representing a 9% increase in inhibition for NLS+dodecyl. Subsequently, cytotoxicity was evaluated using the 0.4% sulforhodamine B assay. NLS+dodecyl did not exhibit cytotoxicity in MRC5 (human pneumocyte) and HepG2 (human hepatic carcinoma) cells, thus increasing the selectivity index for NLS+dodecyl. In addition, cytotoxicity was evaluated in vivo using the Caenorhabditis elegans model; neither dodecyl nor NLS+dodecyl exhibited any toxic effects. Taken together, these results suggest that NLS can be used as a strategy to improve the activity of dodecyl against P. brasiliensis and P. lutzii because it improves antifungal activity, increases the inhibition of fungal adhesion in lung cells and the extracellular matrix in vitro, and does not exhibit any toxicity both in vitro and in vivo.

Nanoparticles as safe and effective delivery systems of antifungal agents: Achievements and challenges

Invasive fungal infections are becoming a major health concern in several groups of patients leading to severe morbidity and mortality. Moreover, cutaneous fungal infections are a major cause of visits to outpatient dermatology clinics. Despite the availability of several effective agents in the antifungal drug arena, their therapeutic outcome is less than optimal due to limitations related to drug physicochemical properties and toxicity. For instance, poor aqueous solubility limits the formulation options and efficacy of several azole antifungal drugs while toxicity limits the benefits of many other drugs. Nanoparticles hold great promise to overcome these limitations due to their ability to enhance drug aqueous solubility, bioavailability and antifungal efficacy. Further, drug incorporation into nanoparticles could greatly reduce its toxicity. Despite these interesting nanoparticle features, there are only few marketed nanoparticle-based antifungal drug formulations. This review sheds light on different classes of nanoparticles used in antifungal drug delivery, such as lipid-based vesicles, polymeric micelles, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and dendrimers with emphasis on their advantages and limitations. Translation of these nanoformulations from the lab to the clinic could be facilitated by focusing the research on overcoming problems related to nanoparticle stability, drug loading and high cost of production and standardization.

Experimental design-based optimization of lipid nanocarrier as delivery system against Mycobacterium species: in vitro and in vivo evaluation

The study aimed to optimize self-nanoemulsifying drug delivery system using experimental design using excipients holding innate anti-mycobacterium activities followed with characterizations for responses such as optical clarity (Y₁), zone of inhibition (ZOI) against Mycobacterium smegmatis strains (Y₂, Y₃), and globular size (Y₄). The optimized formulations (OF1-OF3) were further characterized for responses and evaluated for zeta potential, minimum inhibition concentration (MIC) against non-pathogenic and tubercular strains, morphological (electron microscopy and atomic force microscopy), and confocal laser scanning microscopy (CLSM) studies. The desirability analysis suggested that the predicted values of the OF1 for the responses Y₁, Y₂, Y₃, and Y₄ were 0.137, 22.77 mm, 21.9 mm, and 191.11 nm, respectively. The morphological assessment confirmed the in vitro studies and established the inhibition mechanism as evidenced with oozing, ablation, and cell-wall fragmentation followed with cell disruption. The OF1, OF2, and OF3 showed an MIC value at 8.8 ± 0.56 mg/ml, 12.5 ± 0.22 mg/ml, and 15.0 ± 0.4 mg/ml, respectively, corroborating effectiveness against tubercular strain. CLSM studies revealed 75.1, 80.3, and 88.7% as an intense fluorescence intensity of OF1, OF2, and OF3, respectively, as compared with dye solution (∼53%). Conclusively, it can be inferred that the delivery of anti-tubercular drugs might be reassessed using excipients with inherent anti-mycobacterium activities.

Drug permeation and barrier damage in Leishmania-infected mouse skin

OBJECTIVES

Pathological disorder can disrupt the barrier integrity of the skin, thereby altering the drug delivery from topical formulations to the target site. Cutaneous leishmaniasis (CL) is an infection of the dermal layers of the skin and manifests as a variety of skin lesions from defined nodular forms to plaques and chronic ulcers. The aim of this work was to characterize the physiology and barrier integrity of the Leishmania-infected BALB/c mouse skin and how they impacted delivery of drugs into the skin.

METHODS

A histological evaluation of the structural differences between uninfected and infected skin was performed using haematoxylin/eosin, elastic Van Gieson and Iba-1 stains. As a CL nodule developed and progressed, the skin pH, hydration and trans-epidermal water loss (TEWL) were recorded. Finally, Franz diffusion cells were used to evaluate the influence of the infection on drug delivery through the skin.

RESULTS

We found: (i) structural changes in both the epidermal and dermal layers due to the ingress of inflammatory cells, as shown by immunohistochemistry; (ii) a significant increase in TEWL; and (iii) significantly higher permeation of the model permeants caffeine and ibuprofen and the antileishmanial drugs buparvaquone and paromomycin, for Leishmania-infected skin compared with uninfected skin. The infection had no measurable influence on skin pH and hydration.

CONCLUSIONS

We report profound changes in the skin barrier physiology, function and permeability to drugs of Leishmania-infected skin.

Development, optimization, and characterization of a novel tea tree oil nanogel using response surface methodology

PURPOSE

To develop and optimize nanoemulsion (NE)-based emulgel (EG) formulation as a potential vehicle for topical delivery of tea tree oil (TTO).

METHODOLOGY

Central composite design was adopted for optimizing the processing conditions for NE preparation by high energy emulsification method viz. surfactant concentration, co-surfactant concentration, and stirring speed. The optimized NE was developed into emulgel (EG) using pH sensitive polymer Carbopol 940 and triethanolamine as alkalizer. The prepared EG was evaluated for its pH, viscosity, and texture parameters, ex vivo permeation at 37 °C and stability. Antimicrobial evaluation of EG in comparison to conventional gel and pure TTO was also carried out against selected microbial strains.

RESULTS AND DISCUSSION

Optimized NE had particle size and zeta potential of 16.23 ± 0.411 nm and 36.11 ± 1.234 mV, respectively. TEM analysis revealed the spherical shape of droplets. The pH of EG (5.57 ± 0.05 ) was found to be in accordance with the range of human skin pH. EG also illustrated efficient permeation (79.58 μL/cm(2)) and flux value (JSS) of 7.96 μL cm(2)/h through skin in 10 h. Viscosity and texture parameters, firmness (9.3 ± 0.08 g), spreadability (2.26 ± 0.06 mJ), extrudability (61.6 ± 0.05 mJ), and adhesiveness (8.66 ± 0.08 g) depict its suitability for topical application. Antimicrobial evaluation of EG with same amount of TTO as conventional gel revealed broader zones of growth inhibitions against all the selected microbial strains. Moreover, EG was also found to be nonirritant (PII 0.0833). These parameters were consistent over 90 d.

CONCLUSION

TTO EG turned out to be a promising vehicle for the topical delivery of TTO with enhanced therapeutic efficacy.

In vitro–in vivo–in silico simulation studies of anti-tubercular drugs doped with a self nanoemulsifying drug delivery system

This study aimed to formulate a self-nanoemulsifying drug delivery system (SNEDDS) for enhanced pharmacokinetic (PK) behavior of rifampicin and isoniazid using excipients holding innate anti-mycobacterial activity followed within vivo–in silicopredictions using GastroPlus™.

Evidences for anti-mycobacterium activities of lipids and surfactants

Tuberculosis is the most widespread and deadly airborne disease caused by Mycobacterium tuberculosis. The two-pronged lethal effect on the bacteria using lipids/surfactants and anti-tubercular drugs may render the miniaturization of dose owing to synergistic and tandem effect of both. The current research has been focused on screening and evaluating various lipids/surfactants possessing inherent anti-mycobacterium activity that can ferry the anti-tubercular drugs. In vitro anti-mycobacterium activity was evaluated using agar well diffusion method. Furthermore, time-concentration dependent killing and DNA/RNA content release studies were performed to correlate the findings. The exact mechanism of bacterial killing was further elucidated by electron/atomic force microscopy studies. Finally, to negate any toxicity, in vitro hemolysis and toxicity studies were performed. The study revealed that capmul MCM C-8, labrasol and acconon C-80 possessed highest in vitro anti-mycobacterium activity. Electron/atomic force microscopy results confirmed in vitro studies and verified the killing of Mycobacterium owing to the release of cytoplasmic content after cell wall fragmentation and disruption. Moreover, the least hemolysis and hundred percent survivals rate of mice using the excipients demonstrated the safety aspects of explored excipients that can ferry the anti-tubercular drugs. The present study concluded the safe, efficient and synergistic activity of the explored excipients and anti-tubercular drugs in controlling the menace of tuberculosis.

Solubilization Behavior of Polyene Antibiotics in Nanomicellar System: Insights from Molecular Dynamics Simulation of the Amphotericin B and Nystatin Interactions with Polysorbate 80

Amphotericin B (AmB) and Nystatin (Nys) are the drugs of choice for treatment of systemic and superficial mycotic infections, respectively, with their full clinical potential unrealized due to the lack of high therapeutic index formulations for their solubilized delivery. In the present study, using a coarse-grained (CG) molecular dynamics (MD) simulation approach, we investigated the interaction of AmB and Nys with Polysorbate 80 (P80) to gain insight into the behavior of these polyene antibiotics (PAs) in nanomicellar solution and derive potential implications for their formulation development. While the encapsulation process was predominantly governed by hydrophobic forces, the dynamics, hydration, localization, orientation, and solvation of PAs in the micelle were largely controlled by hydrophilic interactions. Simulation results rationalized the experimentally observed capability of P80 in solubilizing PAs by indicating (i) the dominant kinetics of drugs encapsulation over self-association; (ii) significantly lower hydration of the drugs at encapsulated state compared with aggregated state; (iii) monomeric solubilization of the drugs; (iv) contribution of drug-micelle interactions to the solubilization; (v) suppressed diffusivity of the encapsulated drugs; (vi) high loading capacity of the micelle; and (vii) the structural robustness of the micelle against drug loading. Supported from the experimental data, our simulations determined the preferred location of PAs to be the core-shell interface at the relatively shallow depth of 75% of micelle radius. Deeper penetration of PAs was impeded by the synergistic effects of (i) limited diffusion of water; and (ii) perpendicular orientation of these drug molecules with respect to the micelle radius. PAs were solvated almost exclusively in the aqueous poly-oxyethylene (POE) medium due to the distance-related lack of interaction with the core, explaining the documented insensitivity of Nys solubilization to drug-core compatibility in detergent micelles. Based on the obtained results, the dearth of water at interior sites of micelle and the large lateral occupation space of PAs lead to shallow insertion, broad radial distribution, and lack of core interactions of the amphiphilic drugs. Hence, controlled promotion of micelle permeability and optimization of chain crowding in palisade layer may help to achieve more efficient solubilization of the PAs.

A novel osmotic pump-based controlled delivery system consisting of pH-modulated solid dispersion for poorly soluble drug flurbiprofen: in vitro and in vivo evaluation

In this study, a novel controlled release osmotic pump capsule consisting of pH-modulated solid dispersion for poorly soluble drug flurbiprofen (FP) was developed to improve the solubility and oral bioavailability of FP and to minimize the fluctuation of plasma concentration. The pH-modulated solid dispersion containing FP, Kollidon® 12 PF and Na2CO3 at a weight ratio of 1/4.5/0.02 was prepared using the solvent evaporation method. The osmotic pump capsule was assembled by semi-permeable capsule shell of cellulose acetate (CA) prepared by the perfusion method. Then, the solid dispersion, penetration enhancer, and suspending agents were tableted and filled into the capsule. Central composite design-response surface methodology was used to evaluate the influence of factors on the responses. A second-order polynomial model and a multiple linear model were fitted to correlation coefficient of drug release profile and ultimate cumulative release in 12 h, respectively. The actual response values were in good accordance with the predicted ones. The optimized formulation showed a complete drug delivery and zero-order release rate. Beagle dogs were used to be conducted in the pharmacokinetic study. The in vivo study indicated that the relative bioavailability of the novel osmotic pump system was 133.99% compared with the commercial preparation. The novel controlled delivery system with combination of pH-modulated solid dispersion and osmotic pump system is not only a promising strategy to improve the solubility and oral bioavailability of poorly soluble ionizable drugs but also an effective way to reduce dosing frequency and minimize the plasma fluctuation.

Curcumin nanoemulsion for transdermal application: formulation and evaluation

The aim of this work is to develop a curcumin nanoemulsion for transdermal delivery. The incorporation of curcumin inside a nanoglobul should improve curcumin stability and permeability. A nanoemulsion was prepared by the self-nanoemulsification method, using an oil phase of glyceryl monooleate, Cremophor RH40 and polyethylene glycol 400. Evaluation of the nanoemulsion included analysis of particle size, polydispersity index, zeta potential, physical stability, Raman spectrum and morphology. In addition, the physical performance of the nanoemulsion in Viscolam AT 100P gel was studied. A modified vertical diffusion cell and shed snake skin of Python reticulatus were used to study the in vitro permeation of curcumin. A spontaneously formed stable nanoemulsion has a loading capacity of 350 mg curcumin/10 g of oil phase. The mean droplet diameter, polydispersity index and zeta potential of optimized nanoemulsion were 85.0 ± 1.5 nm, 0.18 ± 0.0 and -5.9 ± 0.3 mV, respectively. Curcumin in a nanoemulsion was more stable than unencapsulated curcumin. Furthermore, nanoemulsification significantly improved the permeation flux of curcumin from the hydrophilic matrix gel; the release kinetic of curcumin changed from zero order to a Higuchi release profile. Overall, the developed nanoemulsion system not only improved curcumin permeability but also protected the curcumin from chemical degradation.