Bioadhesive monolayer film for the in vitro transdermal delivery of sumatriptan

Supersaturation-Based Drug Delivery Systems: Strategy for Bioavailability Enhancement of Poorly Water-Soluble Drugs

At present, the majority of APIs synthesized today remain challenging tasks for formulation development. Many technologies are being utilized or explored for enhancing solubility, such as chemical modification, novel drug delivery systems (microemulsions, nanoparticles, liposomes, etc.), salt formation, and many more. One promising avenue attaining attention presently is supersaturated drug delivery systems. When exposed to gastrointestinal fluids, drug concentration exceeds equilibrium solubility and a supersaturation state is maintained long enough to be absorbed, enhancing bioavailability. In this review, the latest developments in supersaturated drug delivery systems are addressed in depth.

Development and Evaluation of Liquid Plaster Loaded with Chromolaena odorata Leaf Extract Endowed with Several Beneficial Properties to Wound Healing

Liquid plaster (LP) is a recently developed wound dressing product that can be used to cover wounds in various parts of the body, especially small injuries or wounds in body parts involved in movement. Given the benefits and applications of LP, this study aimed to develop and evaluate Chromolaena odorata extract-loaded LP with antimicrobial and hemostasis effects. The study was first conducted through the extraction of Choromolaena odorata leaf by using an ethanol maceration technique and identification of the compounds with high-performance liquid chromatography. The LP loaded with Chromolaena odorata extract demonstrates an ability to inhibit S. aureus and S. epidermidis at a MIC of 0.25 mg/mL and MBC of 0.5 mg/mL. The antioxidant activity test was performed by ABTS and DPPH methods demonstrating the free-radical scavenging activity of the extract. The blood clotting activity was established by varying the concentration of Choromolaena odorata leaf extract from 0.0625 mg/mL to 1 mg/mL. The formulation of the film-forming system was developed by varying the solvent, polymer, and plasticizer proportions. The optimum formulation displayed fast film-forming with high elasticity of the film. Moreover, the 20 mg/mL herbal extract-loaded LP provided an antibacterial effect with admissible water vapor transmission and low skin irritation. As a result, the study demonstrates the possibility of introducing the Chromolaena odorata extract-loaded LP to increase the effectiveness of wound healing and the antibacterial effect on the skin.

Novel transdermal bioadhesive surfactant-based system for release and solubility improvement of antimalarial drugs artemether-lumefantrine

Artemether (ART) and lumefantrine (LUM) are the gold standard antimalarial drugs used for the treatment of malaria in children and pregnant women. Typically, ART and LUM are delivered orally in the form of a combined tablet, however, the appropriateness of this route of administration for these drugs is questionable due to the poor absorption and therefore bioavailability observed unless administered alongside lipid-rich foods. Transdermal drug delivery in the form of a patch-type system has been identified as a viable alternative to the conventional tablet-based therapy. A novel, surfactant-based ART-LUM formulation (S3AL), developed for transdermal delivery, may eliminate the shortcomings associated with oral delivery; namely poor drug absorption which is caused by the inherently low solubility of ART and LUM. Moreover, by successfully delivering these antimalarials transdermally, first-pass metabolism will be avoided leading to enhanced drug bioavailability in both cases. The S3AL formulation contained ART and LUM at equal concentrations (2.5% w/w of each) as well as Procetyl® AWS (30% w/w), oleic acid (10% w/w), 1-methyl-2-pyrrolidone (10% w/w), and water (45% w/w). The addition of LUM to the formulation changed the system from a striae structure to a dark field structure when visualized by a polarized light microscope. Additionally, this system possessed higher viscosity and superior skin bioadhesion, as evidenced by mechanical characterization, when compared to a similar formulation containing ART alone. S3AL was also proven to be biocompatible to human keratinocyte cells. Finally,in vitrostudies demonstrated the propensity of S3AL for successful delivery via the transdermal route, with 2279 ± 295 µg cm^-2of ART and 94 ± 13 µg cm^-2of LUM having permeated across dermatomed porcine skin after 24 h, highlighting its potential as a new candidate for the treatment of malaria.

Film-Forming Systems for Dermal Drug Delivery

Film-forming formulations represent a novel form of sustained release dermatic products. They are applied to the skin as a liquid or semi-solid preparation. By evaporation of the volatile solvent on the skin, the polymer contained in the formulation forms a solid film. Various film-forming formulations were tested for their water and abrasion resistance and compared with conventional semi-solid formulations. Penetration and permeation studies of the formulations indicate a potential utility as transdermal therapeutic systems. They can be used as an alternative to patch systems to administer a variety of drugs in a topical way and may provide sustained release characteristics.

Using Microemulsion as Carrier for Drug Transdermal Delivery: The Effect of Surfactants and Cosurfactants

BACKGROUND

The purpose of this study was to evaluate the effect of types of surfactants and cosurfactants on physicochemical properties and permeability of sumatriptan-loaded microemulsions through rat skin.

METHODS

Different types of surfactants and cosurfactants were used to prepare drug-loaded microemulsions. The physicochemical characters and permeability parameters of these formulations were measured.

RESULTS

The experimental microemulsions with varying components had small droplet size ranging from 24.6 nm to 2568.8 nm, low viscosity ranging from 7.49 to 43.34 cps and significant permeation enhancement ratio ranging from 23.0 to 98.6 when compared to the control group.

CONCLUSION

The composition and proportion of surfactants and cosurfactants were key factors for the physiochemical properties of drug-loaded microemulsions. The cumulative transdermal amount of the microemulsion containing mixture surfactant of Laureth-3/Laureth-23 was higher than that of the microemulsion with a mixture of Tween 80/Span 20. In the selected cosurfactant, diethylene glycol monoethyl ether (DEGMEE) showed highest permeation enhancement. Thermodynamic stability tests revealed that the experimental microemulsion was a stable enough formulation to be considered as a suitable carrier for sumatriptan.

Semisynthetic Derivative of Artemisia annua-Loaded Transdermal Bioadhesive for the Treatment of Uncomplicated Malaria Caused by Plasmodium falciparum in Children

According to the most recent World Health Organization statistics, malaria infected approximately 219 million people in 2017, with an estimate of 435,000 deaths (World Health Organization, 2018). Communities isolated from cities are the most deprived of access to the necessary hospital facilities. Herein we report the development of a transdermal bioadhesive containing artemether (ART), an alternative, potentially lifesaving, treatment regimen for malaria in low-resource settings. Bioadhesives were prepared from an aqueous blend of hydroxyethylcellulose (4.5% w/w), ART, propoxylated-ethoxylated-cetyl-alcohol, polysorbate 80, propyleneglycol, glycerine, mineral oil, and oleic acid. In this study, the average pore size of bioadhesive 5.5b was 52.6 ± 15.31 μm. Differential scanning calorimetry and thermogravimetric analyses confirm the thermal stability of ART bioadhesives at room temperature. Tensile tests indicated good mechanical properties for bioadhesive 5.5b, when compared to 5.5a, where 5.5b showed elastic modulus 0.19 MPa, elongation at break 204%, tensile stress 0.31 MPa, tensile strength at break 0.23 MPa. Bioadhesion assays suggested that formulations containing surfactants had higher detachment forces. Permeation studies demonstrated that the best outcome was achieved with a bioadhesive containing 25 mg ART (5.5b) that after 24 h released 6971 ± 125 μg, which represents approximately 28% of drug permeation. Data reported presents a promising candidate for a new antimalarial transdermal formulation.

Mydriatics release from solid and semi-solid ophthalmic formulations using different in vitro methods

The aim of the present paper was the development of semi-solid (hydrogels) and solid (film) ophthalmic formulations for the controlled release of two mydriatics: phenylephrine and tropicamide. The formulations - based on polyvinylalcohol and hyaluronic acid - were characterized, and release studies were performed with three different in vitro set-ups, i.e. Franz-type diffusion cell, vial method and inclined plane; for comparison, a solution and a commercial insert, both clinically used to induce mydriasis, were evaluated. Both gels and film allowed for a controlled release of drugs, appearing a useful alternative for mydriatics administration. However, the release kinetic was significantly influenced by the method used, highlighting the need for optimization and standardization of in vitro models for the evaluation of drug release from ophthalmic dosage forms.

In-vitro characterization of buccal iontophoresis: the case of sumatriptan succinate

Buccal administration of sumatriptan succinate might be an interesting alternative to the present administration routes, due to its non-invasiveness and rapid onset of action, but because of its low permeability, a permeation enhancement strategy is required. The aim of this work was then to study, in-vitro, buccal iontophoresis of sumatriptan succinate. Permeation experiments were performed in-vitro across pig esophageal epithelium, a recently proposed model of human buccal mucosa, using vertical diffusion cells. The iontophoretic behavior of the tissue was characterized by measuring its isoelectric point (Na(+) transport number and the electroosmotic flow of acetaminophen determination) and by evaluating tissue integrity after current application. The results obtained confirm the usefulness of pig esophageal epithelium as an in-vitro model membrane for buccal drug delivery. The application of iontophoresis increased sumatriptan transport, proportionally to the current density applied, without tissue damage: electrotransport was the predominant mechanism. Integrating the results of the present work with literature data on the transport of other molecules across the buccal mucosa and across the skin, we can draw a general conclusion: the difference in passive transport across buccal mucosa and across the skin is influenced by permeant lipophilicity and by the penetration pathway. Finally, buccal iontophoretic administration of sumatriptan allows to administer 6mg of the drug in 1h, representing a promising alternative to the current administration routes.

Elastic vesicles of sumatriptan succinate for transdermal administration: characterization and in vitro permeation studies

Elastic liposomes, including sumatriptan succinate, were prepared for their transdermal administration. Lipid vesicles containing 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or l-α-phosphatidylcholine dilauroyl (DLPC) phospholipids were characterized for various parameters, including size, particle-size distribution (i.e., polydispersity index), and elasticity. In vitro transdermal experiments for the study of the skin penetration of sumatriptan succinate contained in liposomes were performed by using flow-through diffusion cells. The diameter of sumatriptan liposomes with different lipid compositions varied between 279 and 282 nm, and the polydispersity index value for the size distribution of liposomal formulations was <0.5. DLPC vesicles proved to be more elastic and provided a higher sumatriptan transdermal flux than vesicles formulated with DOPC phospolipid.

Bioadhesive films containing benzocaine: correlation between in vitro permeation and in vivo local anesthetic effect

PURPOSE

The aim of this work was to develop anesthetic bioadhesive films containing benzocaine and study their in vitro skin permeation and in vivo performance, in comparison with commercial formulations.

METHODS

Films containing 3% and 5% w/w of benzocaine were prepared and characterized by weight, drug content, thickness and morphology. In vitro permeation assays were performed in vertical diffusion cells using full-thickness pig ear skin as barrier. Intensity and duration of analgesia were evaluated in rats by tail-flick test, and skin histological analysis was carried out.

RESULTS

Tail-flick test showed that the duration of benzocaine-induced analgesia was significantly prolonged with the films compared to commercial creams, in agreement with the higher in vitro permeation. Histological analysis of the rat tail skin did not reveal morphological tissue changes nor cell infiltration signs after application of the commercial creams or films.

CONCLUSIONS

Results from our study indicate that the films developed in this work can be considered as innovative dermal/transdermal therapeutic systems for benzocaine local delivery.

Transdermal delivery of sumatriptan for the treatment of acute migraine

SUMMARY

Migraine is a common, multisymptom disorder that can severely impact the daily activities of migraineurs. Triptans (primarily sumatriptan) are the most commonly prescribed treatment for migraine and are considered a relatively safe and effective initial therapy. Unfortunately, current sumatriptan formulations (i.e., oral, nasal, subcutaneous) may be associated with limitations that can result in patients' delaying or avoiding treatment. For oral formulations, these limitations include difficulty in taking an oral medication due to the nausea and vomiting that often accompany migraine, and inconsistent absorption, whereas nasal and subcutaneous formulations may be associated with low bioavailability and an undesirable rate of adverse events, respectively. An alternative to current formulations is transdermal drug delivery, particularly iontophoresis. Transdermal delivery has several advantages over current formulations, including avoidance of the gastrointestinal tract, controlled and sustained delivery, and convenient administration. This article reviews the in vitro, in vivo, and preclinical data supporting the use of iontophoresis for the delivery of sumatriptan, as well as the recent clinical data for Zelrix (NuPathe Inc., Conshohocken, PA), an iontophoretic sumatriptan patch currently in phase III development for the treatment of migraine.

Sumatriptan succinate transdermal delivery systems for the treatment of migraine

We have successfully obtained sumatriptan transdermal systems with different polymer compositions: methyl cellulose (MC), polyvinyl pyrrolidone (PVP) and a polyvinyl pyrrolidone (PVP)-polyvinyl alcohol (PVA) mixture. The systems contained 1,2-propylenglycol (MC) or sorbitol as a plasticizer (PVP and PVP-PVA), methacrylate copolymer as an adhesive agent, and an occlusive liner. Azone (5%, w/w) was incorporated into all the systems as a percutaneous enhancer. Transdermal systems are thin, transparent and non-adhesive when in a dry state. The permeation of sumatriptan succinate across pig ear skin was studied using the systems prepared. The formulation with MC polymer produced a statistically significant increment with respect to the PVP and PVP-PVA formulations (p < 0.05). Azone incorporation into the systems produced an increment in the sumatriptan flux values of all three transdermal systems with respect to those of the controls (p < 0.05). In addition, the application of iontophoresis to the wet methyl cellulose-Azone formulation produced a much higher increase of sumatriptan transdermal flux.

Physical characterization of a new skin bioadhesive film

Physical properties (roughness, gloss, mechanical, surface topography and adhesive) of a bioadhesive film for the transdermal delivery of drugs and its interactions with a skin model surface were studied. Roughness is a measurement of the small-scale variations in the height of a physical surface. No significant differences in Ra between the "x" and "y" dimensions for both the skin model and patch were detected, due to uniformity in their production. Scanning electron microscope pictures showed small particles projected from the film. Those particles resulted in increasing roughness and surface area. For the patch, gloss values measured at 20 degrees were 6.0 +/- 0.9 and at 60 degrees , 32.2 +/- 2.2 gloss units, respectively, indicating a semi-gloss material. Concerning the mechanical properties, the tensile strength of the film resulted four- to sevenfold greater than the peel force from the model skin used, indicating the suitability of the film for skin application. The adhesion to skin model depended on the amount of water used for film application and on the elapsed time between film application and removal. Finally, the model skin that was invented by Charkoudian can be used as an alternative to costly and highly variable human skin substrates since it possesses human topography.

New transdermal bioadhesive film containing oxybutynin: In vitro permeation across rabbit ear skin

Oxybutynin is used extensively in the treatment of patients with overactive bladder. The aim of this work was to realize and test in vitro a new transdermal bioadhesive film containing oxybutynin. Transdermal films were prepared by dissolving in water an adhesive (Plastoid), a film-forming polymer (polyvinyl alcohol), a plasticizer (sorbitol) and the drug. The mixture was then spread on siliconized paper and oven-dried. Permeation experiments were conducted in Franz-type diffusion cells using rabbit ear skin as barrier. The donor compartment contained a water solution, the prepared film (with or without backing) or the commercial patch (Oxytrol). The experiments were performed for 24h. Oxybutynin showed good permeation characteristics across the skin. When the film was applied in occlusive conditions the release profiles were much higher than in non-occlusive conditions, reaching 50% of drug permeated after 24h. Compared to the commercial patch Oxytrol, the film was more efficient suggesting that a smaller area or a lower drug loading could be employed. The results obtained show that the bioadhesive film can be a promising and innovative therapeutic system for the transdermal administration of oxybutynin.