Srinivasa M. Sammeta

Delivery of nerve growth factor to brain via intranasal administration and enhancement of brain uptake.

The main objective of the study was to investigate the efficacy of chitosan to facilitate brain bioavailability of intranasally administered nerve growth factor (NGF). In vitro permeability studies and electrical resistance studies were carried out across the bovine olfactory epithelium using Franz diffusion cells. The bioavailability of intranasally administered NGF in rat hippocampus was determined by carrying out brain microdialysis in Sprague-Dawley rats. The in vitro permeation flux across the olfactory epithelium of NGF solution without chitosan (control) was found to be 0.37 +/- 0.06 ng/cm(2)/h. In presence of increasing concentration of chitosan (0.1%, 0.25%, and 0.5%, w/v) the permeation flux of NGF was found to be 2.01 +/- 0.12, 3.88 +/- 0.19, and 4.12 +/- 0.21 ng/cm(2)/h respectively. Trans-olfactory epithelial electrical resistance decreased approximately 34.50 +/- 4.06% in presence of 0.25% (w/v) chitosan. The C(max) in rats administered with 0.25% (w/v) chitosan and NGF was 1008.62 +/- 130.02 pg/mL, which was significantly higher than that for rats administered with NGF only 97.38 +/- 10.66 pg/mL. There was approximately 14-fold increase in the bioavailability of intranasally administered NGF with chitosan than without chitosan. Chitosan can enhance the brain bioavailability of intranasally administered NGF.

Trans-ungual iontophoretic delivery of terbinafine

Successful treatment of deep-seated nail infections remains elusive as the delivery of efficacious levels of antifungal drug to the site of action is very difficult. The aim of the present study was to attain rapid trans-ungual delivery of an antifungal agent, terbinafine, via the topical route using iontophoresis. Initial studies revealed that application of current (0.5 mA/cm(2)) could significantly enhance the trans-ungual delivery of terbinafine. An increase in the applied current or duration of current application enhanced the trans-ungual delivery of terbinafine. Permeation of terbinafine through the nail and drug load in the nail correlated well with the applied electrical dose. Release of drug from nails loaded using iontophoresis followed a two-phase release profile. Light microscopy studies substantiated the capability of iontophoresis to drive a charged molecule across the nail plate. The results of these studies indicate that iontophoresis could be developed as a potential technique for onychomycosis therapy.

TranScreen-N™: Method for rapid screening of trans-ungual drug delivery enhancers

Topical monotherapy of nail diseases such as onychomycosis and nail psoriasis has been less successful due to poor permeability of the human nail plate to topically administered drugs. Chemical enhancers are utilized to improve the drug delivery across the nail plate. Choosing the most effective chemical enhancers for the given drug and formulation is highly critical in determining the efficacy of topical therapy of nail diseases. Screening the large pool of enhancers using currently followed diffusion cell experiments would be tedious and expensive. The main objective of this study is to develop TranScreen-N, a high throughput method of screening trans-ungual drug permeation enhancers. It is a rapid microwell plate based method which involves two different treatment procedures; the simultaneous exposure treatment and the sequential exposure treatment. In the present study, several chemicals were evaluated by TranScreen-N and by diffusion studies in the Franz diffusion cell (FDC). Good agreement of in vitro drug delivery data with TranScreen-N data provided validity to the screening technique. In TranScreen-N technique, the enhancers can be grouped according to whether they need to be applied before or simultaneously with drugs (or by either procedures) to enhance the drug delivery across the nail plate. TranScreen-N technique can significantly reduce the cost and duration required to screen trans-ungual drug delivery enhancers.

Alteration of the diffusional barrier property of the nail leads to greater terbinafine drug loading and permeation.

The diffusional barrier property of biological systems varies with ultrastructural organization of the tissues and/or cells, and often plays an important role in drug delivery. The nail plate is a thick, hard and impermeable membrane which makes topical nail drug delivery challenging. The current study investigated the effect of physical and chemical alteration of the nail on the trans-ungual drug delivery of terbinafine hydrochloride (TH) under both passive and iontophoretic conditions. Physical alterations were carried out by dorsal or ventral nail layer abrasion, while chemical alterations were performed by defatting or keratolysis or ionto-keratolysis of the nails. Terbinafine permeation into and across the nail plate following various nail treatments showed similar trends in both passive and iontophoretic delivery, although the extent of drug delivery varied with treatment. Application of iontophoresis to the abraded nails significantly improved (P<0.05) TH permeation and loading compared to abraded nails without iontophoresis or normal nails with iontophoresis. Drug permeation was not enhanced when the nail plate was defatted. Keratolysis moderately enhanced the permeation but not the drug load. Ionto-keratolysis enhanced TH permeation and drug load significantly (P<0.05) during passive and iontophoretic delivery as compared to untreated nails. Ionto-keratolysis may be more efficient in permeabilization of nail plates than long term exposure to keratolysing agents.

Iontophoresis Across the Proximal Nail Fold to Target Drugs to the Nail Matrix

The main objective of the present study was to investigate the plausibility of iontophoretic delivery of drugs to the nail matrix via proximal nail fold. The in vitro drug transport studies were performed in Franz diffusion cells across folded epidermis, which is used as a model for the proximal nail fold. The amount of drug transported into the receiver compartment following iontophoresis for 3 h at 0.5 mA/cm(2) was 150-fold higher than the control (0.008 ± 0.002 μg/cm(2)). The amount of drug present in the skin after iontophoresis (0.45 ± 0.12 μg/mg) was approximately fivefold higher as compared with that of the control (0.08 ± 0.01 μg/mg). Iontophoresis of terbinafine across the proximal nail fold was assessed using excised cadaver toe model as well. A custom-designed foam-pad-type patch system was used for iontophoresis in cadaver toes. The amount of the drug delivered into the nail matrix following iontophoresis for 3 h was significantly higher than the minimum inhibition concentration of terbinafine. However, on the contrary, passive delivery for about 24 h did not result in any detectable drug levels in the nail matrix. Iontophoresis across the proximal nail fold could be developed as a potential method to target drugs to nail matrix.

A study on the effect of inorganic salts in transungual drug delivery of terbinafine.

Objectives The poor success rate of topical therapy in nail disorders is mainly because of the low permeability of keratinized nail plates. This can be overcome by utilizing potent perungual drug penetration enhancers that facilitate the drug permeation across the nail plate. This study evaluated the efficacy of inorganic salts in enhancing the trans‐nail permeation using a model potent antifungal agent, terbinafine hydrochloride.

Transcorneal Iontophoresis for Delivery of Ciprofloxacin Hydrochloride

Purpose: To investigate the feasibility of utilizing iontophoresis for delivery of ciprofloxacin hydrochloride to the anterior chamber of the eye and to carry out systematic studies to investigate the effect of electrical protocol on the transcorneal drug delivery. Materials and Methods: Effect of current density (0.75 mA/cm2 to 6.25 mA/cm2 applied for 5 minutes) on drug permeation across the cornea and drug load in the cornea were investigated in vitro as well as ex vivo studies in porcine cornea model. Tolerability studies were carried out in rabbits. Cytotoxicity studies were conducted in cultured corneal tissue. Results: The drug loaded in the cornea increased with increasing current density. After 5 minutes of iontophoresis, the drug concentration in the receiver compartment fluid (in vitro) or in aqueous humor (ex vivo) was not significantly higher than control (in which electric current was not applied). However, waiting for 6–12 hours after iontophoresis for 5 minutes, the concentrations of drug in aqueous humor in ex vivo studies were ∼6 and ∼5-fold higher than control (130.12 ± 78.99 ng/ml), respectively. Cytotoxicity studies demonstrated the safety of the technique. The application of 6.25 mA/cm2 for 5 minutes (right eye) did not show any sign of loss of vision and abnormal discharge, redness of eye, or edema when compared to the control left eye. Conclusions: Transcorneal iontophoresis is a potential method of delivering effective levels of ciprofloxacin hydrochloride into aqueous humor for the treatment of intraocular infections. This study unveils the ability of iontophoresis to rapidly drive ciprofloxacin into the cornea where a drug reservoir is formed, which eventually releases slowly into aqueous humor, eliciting sustained therapeutic effect.

Magnetophoresis in combination with chemical enhancers for transdermal drug delivery

Purpose: The objective of the present work was to investigate the effect of combination of a novel physical permeation enhancement technique, magnetophoresis with chemical permeation enhancers on the transdermal delivery of drugs. Methods: The in vitro drug transport studies were carried out across the freshly excised abdominal skin of Sprague-Dawley rats using transdermal patch systems (magnetophoretic and non-magnetophoretic) of lidocaine hydrochloride (LH). LH gel prepared using hydroxypropyl methylcellulose (HPMC) was spread over the magnets as a thin layer. To investigate the effect of chemical permeation enhancers, menthol, dimethyl sulfoxide, sodium lauryl sulfate and urea (5% w/v) were incorporated in the gels prior to loading on the patch system. Results: The flux of lidocaine from magnetophoretic patch was ~3-fold higher (3.07 ± 0.43 µg/cm2/h) than that of the control (non-magnetophoretic patch) (0.94 ± 0.13 µg/cm2/h). Incorporation of chemical permeation enhancers in the gel enhanced the magnetophoretic delivery flux by ~4 to 7-fold. Conclusions: The enhancement factor due to combination of chemical permeation enhancer was additive and not synergistic. Mechanistic studies indicated that magnetophoresis mediated drug delivery enhancement was via appendageal pathway.

Transdermal drug delivery enhanced by low voltage electropulsation (LVE)

The efficiency of low voltage electropulsation (LVE) technique for delivery of drugs and macromolecules across the skin was investigated. The in vitro studies were carried out across the porcine epidermis in Franz diffusion cells using salicylic acid and fluorescein labeled Dextran of molecular weight 10,000 Da (FD10K). LVE enhanced the transport of salicylic acid and FD10K by ~ 4-fold and ~ 2-fold, respectively over the control. The potential application of LVE in transdermal drug delivery was studied in the case of lidocaine hydrochloride. The transport of lidocaine hydrochloride was enhanced by ~ 8-fold over the control. The transport enhancement by LVE was compared with that of 1 min and 20 min constant DC iontophoresis at 0.5 mA/cm2. Iontophoresis applied for 1 min delivers equivalent electrical dose as that of LVE (50 ms pulses for 20 min at 1 Hz) in the current set up. The transport by application of iontophoresis for 1 min was significantly less than the control (passive diffusion for 20 min). However, the application of iontophoresis for 20 min (electrical dose ~ 20-fold more than that of LVE) resulted in comparable drug transport as that of LVE. It is evident from the results of this experiment that the transdermal delivery of drugs could be enhanced by LVE which is a rather mild technique than electroporation or iontophoresis.

Dermal Drug Levels of Antibiotic (Cephalexin) Determined by Electroporation and Transcutaneous Sampling (ETS) Technique

The purpose of this project was to assess the validity of a novel Electroporation and transcutaneous sampling (ETS) technique for sampling cephalexin from the dermal extracellular fluid (ECF). This work also investigated the plausibility of using cephalexin levels in the dermal ECF as a surrogate for the drug levels in the synovial fluid. In vitro and in vivo studies were carried out using hairless rats to assess the workability of ETS. Cephalexin (20 mg/kg) was administered (i.v.) through tail vein and the time course of drug concentration in the plasma was determined. In the same rats, cephalexin concentration in the dermal ECF was determined by ETS and microdialysis techniques. In a separate set of rats, only intraarticular microdialysis was carried out to determine the time course of cephalexin concentration in synovial fluid. The drug concentration in the dermal ECF determined by ETS and microdialysis did not differ significantly from each other and so as were the pharmacokinetic parameters. The results provide validity to the ETS technique. Further, there was a good correlation ( approximately 0.9) between synovial fluid and dermal ECF levels of cephalexin indicating that dermal ECF levels could be used as a potential surrogate for cephalexin concentration in the synovial fluid.