Topical iontophoresis of buflomedil hydrochloride increases drug bioavailability in the mucosa: A targeted approach to treat oral submucous fibrosis

Enhanced topical paromomycin delivery for cutaneous leishmaniasis treatment: Passive and iontophoretic approaches

Conventional treatments for cutaneous leishmaniasis, a neglected vector-borne infectious disease, can frequently lead to serious adverse effects. Paromomycin (PAR), an aminoglycoside antibiotic, has been suggested for the topical treatment of disease-related lesions, but even when formulated in high drug-loading dosage forms, presents controversial efficacy. The presence of five ionizable amino groups hinder its passive cutaneous penetration but make PAR an excellent candidate for iontophoretic delivery. The objective of this study was to verify the feasibility of using iontophoresis for cutaneous PAR delivery and to propose a topical passive drug delivery system that could be applied between iontophoretic treatments. For this, in vitro iontophoretic experiments evaluated different application durations (10, 30, and 360 min), current densities (0.1, 0.25, and 0.5 mA/cm2), PAR concentrations (0.5 and 1.0 %), and skin models (intact and impaired porcine skin). In addition, 1 % PAR hydrogel had its penetration profile compared to 15 % PAR ointment in passive transport. Results showed iontophoresis could deliver suitable PAR amounts to dermal layers, even in short times and with impaired skin. Biodistribution assays showed both iontophoretic transport and the proposed hydrogel delivered higher PAR amounts to deeper skin layers than conventional ointment, even though applying 15 times less drug. To our knowledge, this is the first report of PAR drug delivery enhancement by iontophoresis. In summary, the association of iontophoresis with a topical application of PAR gel seems appropriate for improving cutaneous leishmaniasis treatment.

Iontophoresis application for drug delivery in high resistivity membranes: nails and teeth

Iontophoresis has been vastly explored to improve drug permeation, mainly for transdermal delivery. Despite the skin's electrical resistance and barrier properties, it has a relatively high aqueous content and is permeable to many drugs. In contrast, nails and teeth are accessible structures for target drug delivery but possess low water content compared to the skin and impose significant barriers to drug permeation. Common diseases of these sites, such as nail onychomycosis and endodontic microbial infections that reach inaccessible regions for mechanical removal, often depend on time-consuming and ineffective treatments relying on drug's passive permeation. Iontophoresis application in nail and teeth structures may be a safe and effective way to improve drug transport across the nail and drug distribution through dental structures, making treatments more effective and comfortable for patients. Here, we provide an overview of iontophoresis applications in these "hard tissues," considering specificities such as their high electrical resistivity. Iontophoresis presents a promising option to enhance drug permeation through the nail and dental tissues, and further developments in these areas could lead to widespread clinical use.

Photoinduced Fe-Catalyzed Bromination and Iodination of Unstrained Cyclic Alcohols

We report a photoinduced iron catalysis for the efficient C─C bond cleavage and bromination or iodination of unstrained tertiary cycloalkanols with NBS/NIS. The reaction features good functional group tolerance and...

Hydrogels for Treatment of Oral and Maxillofacial Diseases: Current Research, Challenge, and Future Directions

Oral and maxillofacial diseases such as infection and trauma often involve various organs and tissues, resulting in structural defects, dysfunctions and/or adverse effects on facial appearance. Hydrogels have been applied...

Controlled simultaneous iontophoresis of buflomedil hydrochloride and dexamethasone sodium phosphate to the mucosa for oral submucous fibrosis

A novel concentric experimental set-up was used to investigate short-duration topical co-iontophoresis of cationic buflomedil hydrochloride (BUF) and anionic dexamethasone phosphate (DEX-P) to the oral mucosa. A constant current of 3.0 mA (0.6 mA/cm² for BUF and 1.95 mA/cm² for DEX-P) was applied to porcine esophageal mucosa for 5, 10 and 20 min. Iontophoresis for only 5 min increased total delivery of BUF from 29.8 ± 5.1 nmol/cm² to 194.3 ± 23.8 nmol/cm² and DEX-P from 29.4 ± 1.2 nmol/cm² to 193.3 ± 19.8 nmol/cm² as compared to passive controls. Quantification of drug between the electrode compartments reported on lateral ion migration. In the absence of current, DEX-P did not migrate laterally; however, iontophoresis for 5 min increased DEX-P delivery >5-fold under the cathodal compartment (its application area) and >8-fold in the adjacent "inter-electrode" area. Similarly, delivery of BUF increased ~6.8-fold under the anodal compartment and ~12.8-fold under the cathode. The results showed that co-iontophoresis enabled the controlled simultaneous delivery of BUF and DEX-P achieving therapeutically relevant concentrations after current application for only 5 min. Short duration topical co-iontophoresis of single or multiple therapeutics to the mucosa increases local bioavailability and presents a patient-friendly treatment for diseases of the oral cavity.

Towards the advance of a novel iontophoretic patch for needle-free buccal anesthesia

The aim of this work was to develop a mucoadhesive iontophoretic patch for anesthetic delivery in the buccal epithelium. The patch was comprised of three different layers, namely i) drug release (0.64 cm²); ii) mucoadhesive (1.13 cm²); and iii) backing (1.13 cm²). Prilocaine and lidocaine hydrochlorides were used as model drugs (1:1 ratio, 12.5 mg per unit). An anode electrode (0.5 cm² spiral silver wire) was placed in between the drug release and mucoadhesive/backing layers to enable iontophoresis. Surface microscopy; mechanical and in vitro mucoadhesive properties; drug release kinetics and mechanism; and drug permeation through the porcine esophageal epithelium were assessed. Topographic analysis evidenced differences in the physical structures for the several layers. All layers presented suitable handling properties i.e., flexibility, elasticity and resistance. Both the release and mucoadhesive layers presented features of a soft and tough material, while the backing layer matched the characteristics of a hard and brittle material. A synergy between the drug release and mucoadhesive layers on the mucoadhesive force and work of adhesion of the tri-layered patch was observed. Passive drug release of both drugs fitted to First-order, Hixson-Crowell and Weibull kinetic models; and the release mechanism was attributed to anomalous transport. Iontophoresis remarkably enhanced the permeation of both drugs, but mainly prilocaine through the mucosa as evidenced by the permeability coefficient parameter (3.0-fold). The amount of these amino amide salts retained in the mucosa were also equally enhanced (4.7-fold), while the application of a tiny constant electric current (1 mA·cm^-2·h^-1) significantly decreased the lag time for lidocaine permeation by about 45%. In view of possible in vitro / in vivo correlations, the buccal iontophoretic patch displays a promising strategy for needle-free and patient-friendly local anesthesia in dentistry.

Tissue Levels of Flurbiprofen in the Rat Plantar Heel after Short-Duration Topical Iontophoresis Are Sufficient to Induce Pharmacodynamic Responses to Local Pain Stimuli

The objective of this study was to investigate the topical iontophoresis of flurbiprofen (FBF) as a means to enhance its local bioavailability and thereby provide an improved and targeted treatment of plantar heel pain. Initial in vitro experiments using porcine ear skin investigated iontophoretic transport of FBF under different conditions. Local FBF biodistribution in the rat paw in vivo was compared after topical or oral administration. Efficacy of pain management was investigated using a plantar incisional model by evaluating pharmacodynamic responses to local pain stimuli. The results demonstrated that iontophoresis of FBF significantly increased cutaneous deposition and transdermal permeation of FBF as compared to passive delivery—it also enabled drug input to be controlled by modulation of current density and drug concentration (r2 > 0.99). Topical iontophoresis of FBF in vivo enabled higher drug levels in skin and muscle in rat plantar aspect and superior pharmacodynamic responses to local pain stimuli, in comparison to oral and passive delivery. In conclusion, short-duration topical iontophoresis of FBF may better help to relieve plantar heel pain than oral or passive administration, which should be of clinical interest.