Transdermal iontophoresis of rotigotine: influence of concentration, temperature and current density in human skin in vitro

Carboxymethyl cellulose-based rotigotine nanocrystals-loaded hydrogel for increased transdermal delivery with alleviated skin irritation

Transdermal rotigotine (RTG) therapy is prescribed to manage Parkinson's disease (Neupro® patch). However, its use is suffered from application site reactions. Herein, drug nanocrystalline suspension (NS)-loaded hydrogel (NS-HG) employing polysaccharides simultaneously as suspending agent and hydrogel matrix was constructed for transdermal delivery, with alleviated skin irritation. RTG-loaded NS-HG was prepared using a bead-milling technique, employing sodium carboxylmethyl cellulose (Na.CMC) as nano-suspending agent (molecular weight 90,000 g/mol) and hydrogel matrix (700,000 g/mol), respectively. NS-HG was embodied as follows: drug loading: ≤100 mg/mL; shape: rectangular crystalline; crystal size: <286.7 nm; zeta potential: -61 mV; viscosity: <2.16 Pa·s; and dissolution rate: >90 % within 15 min. Nuclear magnetic resonance analysis revealed that the anionic polymers bind to RTG nanocrystals via charge interaction, affording uniform dispersion in the matrix. Rodent transdermal absorption of RTG from NS-HG was comparable to that from microemulsions, and proportional to drug loading. Moreover, NS-HG was skin-friendly; erythema and epidermal swelling were absent after repeated application. Further, NS-HG was chemically stable; >95 % of the drug was preserved up to 4 weeks under long term (25 °C/RH60%), accelerated (40 °C/RH75%), and stress (50 °C) storage conditions. Therefore, this novel cellulose derivative-based nanoformulation presents a promising approach for effective transdermal RTG delivery with improved tolerability.

Rotigotine: A Review of Analytical Methods for the Raw Material, Pharmaceutical Formulations, and Its Impurities

BACKGROUND

Rotigotine is a dopaminergic agonist developed for the treatment of Parkinson's disease and restless leg syndrome. The pure levorotatory enantiomer is marketed in several countries as a transdermal patch. Reports of oxidation and instability in a previous formulation indicate the need to evaluate impurities in both the raw material and pharmaceutical dosage forms of rotigotine to ensure product quality.

OBJECTIVE

This review examines the main analytical methods for analyzing rotigotine in raw material and its transdermal patches with the aim of assisting the development of new pharmaceutical formulations and stability studies.

METHODS

Analytical methods based on high-performance liquid chromatography for rotigotine from pharmacopoeias and literature were evaluated. A comparison was made between the methods found in the literature and official rotigotine monographs described by the United States, European, and British Pharmacopoeias, including a discussion of their acceptance limits for impurities related to the drug. The different impurities from the synthesis processes and degradation studies of rotigotine were also evaluated, as well as the main articles that describe methods for assessing their chiral purity.

RESULTS

Qualified and unofficial official impurities found in forced degradation studies were verified. The methods presented show adequate specificity and selectivity in determining the drug in the presence of its impurities.

CONCLUSIONS

The approached methods are promising, but more detailed studies on the stability of rotigotine are still lacking, mainly in the pharmacokinetic and toxicological characterization of its impurities.

Fabrication, Optimization, and Evaluation of Rotigotine-Loaded Chitosan Nanoparticles for Nose-To-Brain Delivery

The objective of the present study was to develop, optimize, and evaluate rotigotine-loaded chitosan nanoparticles (RNPs) for nose-to-brain delivery. Rotigotine-loaded chitosan nanoparticles were prepared by the ionic gelation method and optimized for various parameters such as the effect of chitosan, sodium tripolyphosphate, rotigotine concentration on particle size, polydispersity index (PDI), zeta potential, and entrapment efficiency. The prepared nanoparticles were characterized using photon correlation spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, fourier-transform infrared spectroscopy, and X-ray diffraction. The developed RNPs showed a small hydrodynamic particle size (75.37 ± 3.37 nm), small PDI (0.368 ± 0.02), satisfactory zeta potential (25.53 ± 0.45 mV), and very high entrapment efficiency (96.08 ± 0.01). The 24-h in vitro release and ex vivo nasal permeation of rotigotine from the nanoparticles were 49.45 ± 2.09% and 92.15 ± 4.74% while rotigotine solution showed corresponding values of 95.96 ± 1.79%and 58.22 ± 1.75%, respectively. The overall improvement ratio for flux and permeability coefficient were found to be 4.88 and 2.67 when compared with rotigotine solution. A histopathological study showed that the nanoparticulate formulation produced no toxicity or structural damage to nasal mucosa. Our results indicated that rotigotine-loaded chitosan nanoparticles provide an efficient carrier for nose-to-brain delivery.

Rotigotine Transdermal System

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Recent trends in the transdermal delivery of therapeutic agents used for the management of neurodegenerative diseases

With the increasing proportion of the global geriatric population, it becomes obvious that neurodegenerative diseases will become more widespread. From an epidemiological standpoint, it is necessary to develop new therapeutic agents for the management of Alzheimer's disease, Parkinson's disease, multiple sclerosis and other neurodegenerative disorders. An important approach in this regard involves the use of the transdermal route. With transdermal drug delivery systems (TDDS), it is possible to modulate the pharmacokinetic profiles of these medications and improve patient compliance. Transdermal drug delivery has also been shown to be useful for drugs with short half-life and low or unpredictable bioavailability. In this review, several transdermal drug delivery enhancement technologies are being discussed in relation to the delivery of medications used for the management of neurodegenerative disorders.

Rotigotine: the first new chemical entity for transdermal drug delivery

Rotigotine is the first, and to date, the only new chemical entity to be formulated for transdermal delivery. Although first approved for the management of Parkinson's disease in Europe in 2007 and Restless Leg Syndrome in 2008, the story of rotigotine began more than twenty years earlier. In this review we outline the historical development of this molecule and its route to licensed medicine status. It has very favourable physicochemical properties for transdermal delivery but it took a significant period to develop from concept to market. The stability problems which led to the temporary withdrawal of the patch are examined and the major clinical studies demonstrating efficacy and safety are outlined. Alternative new therapeutic modalities are also considered.

Controlled delivery of ropinirole hydrochloride through skin using modulated iontophoresis and microneedles

The objective of this study was to investigate the effect of modulated current application using iontophoresis- and microneedle-mediated delivery on transdermal permeation of ropinirole hydrochloride. AdminPatch® microneedles and microchannels formed by them were characterized by scanning electron microscopy, dye staining and confocal microscopy. In vitro permeation studies were carried out using Franz diffusion cells, and skin extraction was used to quantify drug in underlying skin. Effect of microneedle pore density and ions in donor formulation was studied. Active enhancement techniques, continuous iontophoresis (74.13 ± 2.20 µg/cm(2)) and microneedles (66.97 ± 10.39 µg/cm(2)), significantly increased the permeation of drug with respect to passive delivery (8.25 ± 2.41 µg/cm(2)). Modulated iontophoresis could control the amount of drug delivered at a given time point with the highest flux being 5.12 ± 1.70 µg/cm(2)/h (5-7 h) and 5.99 ± 0.81 µg/cm(2)/h (20-22 h). Combination of modulated iontophoresis and microneedles (46.50 ± 6.46 µg/cm(2)) showed significantly higher delivery of ropinirole hydrochloride compared to modulated iontophoresis alone (84.91 ± 9.21 µg/cm(2)). Modulated iontophoresis can help in maintaining precise control over ropinirole hydrochloride delivery for dose titration in Parkinson's disease therapy and deliver therapeutic amounts over a suitable patch area and time.

Potential use of iontophoresis for transdermal delivery of NF-kappaB decoy oligonucleotides

Topical application of nuclear factor-kappaB (NF-kappaB) decoy appears to provide a novel therapeutic potency in the treatment of inflammation and atopic dermatitis. However, it is difficult to deliver NF-kappaB decoy oligonucleotides (ODN) into the skin by conventional methods based on passive diffusion because of its hydrophilicity and high molecular weight. In this study, we evaluated the in vitro transdermal delivery of fluorescein isothiocyanate (FITC)-NF-kappaB decoy ODN using a pulse depolarization (PDP) iontophoresis. In vitro iontophoretic experiments were performed on isolated C57BL/6 mice skin using a horizontal diffusion cell. The apparent flux values of FITC-NF-kappaB decoy ODN were enhanced with increasing the current density and NF-kappaB decoy ODN concentration by iontophoresis. Accumulation of FITC-NF-kappaB decoy ODN was observed at the epidermis and upper dermis by iontophoresis. In mouse model of skin inflammation, iontophoretic delivery of NF-kappaB decoy ODN significantly reduced the increase in ear thickness caused by phorbol ester as well as the protein and mRNA expression levels of tumor necrosis factor-alpha (TNF-alpha) in the mice ears. These results suggest that iontophoresis is a useful and promising enhancement technique for transdermal delivery of NF-kappaB decoy ODN.

Potential applications of nanotechnologies to Parkinson's disease therapy

Nanotechnology will play a key role in developing new diagnostic and therapeutic tools. Nanotechnologies use engineered materials with the smallest functional organization on the nanometre scale in at least one dimension. Some aspects of the material can be manipulated resulting in new functional properties. Nanotechnology could provide devices to limit and reverse neuropathological disease states, to support and promote functional regeneration of damaged neurons, to provide neuroprotection and to facilitate the delivery of drugs and small molecules across the blood-brain barrier. All of them are relevant to improve current therapy of Parkinson's disease (PD).

Rotigotine: transdermal dopamine agonist treatment of Parkinson's disease and restless legs syndrome

OBJECTIVE

To evaluate the pharmacology, pharmacokinetics, clinical efficacy, and tolerability of rotigotine, a nonergoline D(3)/D(2)/D(1) dopamine receptor agonist in the treatment of Parkinson's disease and restless legs syndrome (RLS).

DATA SOURCES

A literature search was conducted using MEDLINE (1996-December 2006) and International Pharmaceutical Abstracts, using the search terms rotigotine and dopamine agonist. References cited in the articles were reviewed for additional information. Information was also obtained from Schwarz Pharma. Abstracts for posters at scientific conferences were accessed from conference Web sites.

STUDY SELECTION AND DATA EXTRACTION

English-language literature reporting controlled animal and human clinical studies was reviewed to evaluate the pharmacology, pharmacokinetics, therapeutic use, and adverse effects of rotigotine. Clinical trials selected for inclusion were limited to those with human subjects; data from animal studies were included if human data were not available.

DATA SYNTHESIS

Rotigotine has been investigated in early Parkinson's disease, as adjuvant therapy to levodopa in advanced Parkinson's disease, and in RLS. It is administered transdermally, which provides the convenience of once-daily dosing, constant drug delivery, and sustained stable plasma concentrations. In clinical trials of patients with early Parkinson's disease, rotigotine has decreased combined scores on the motor and activities of daily living sections of the Unified Parkinson's Disease Rating Scale up to 85 weeks. In patients with advanced Parkinson's disease, rotigotine reduced mean off-time when used as an adjuvant to levodopa. Rotigotine has decreased the severity of RLS in Phase III trials. Acute adverse events are similar to those of other dopamine agonists and are most common during the titration phase. Mild-to-moderate application site reactions are common.

CONCLUSIONS

Longer trials are required to determine whether transdermal rotigotine will reduce development of dyskinesias and motor fluctuations in Parkinson's disease and augmentation and rebound in RLS by preventing pulsatile dopamine stimulation associated with levodopa and other dopamine agonists.

Pharmacokinetics and pharmacodynamics analysis of transdermal iontophoresis of 5-OH-DPAT in rats: in vitro-in vivo correlation

Pharmacokinetics and dopaminergic effect of dopamine agonist 5-OH-DPAT in vivo were determined following transdermal iontophoresis in rats based on drug concentration in plasma (C(p)) and dopamine levels in striatum (C(DA)). Correlation of the in vitro transport with the pharmacokinetic-pharmacodynamic (PK-PD) profiles was characterized in the transport in dermatomed rat skin (DRS) and rat stratum corneum (RSC). The integrated in vivo PK-PD and in vitro transport models successfully described time course of C(p), C(DA), and in vitro flux in DRS and RSC. Population value of steady-state flux (J(ss)) in vivo (31 nmol/cm(2) . h with 95% confidence interval (CI) = 20-41) is closer to J(ss) in vitro in DRS (61 nmol/cm(2) . h, CI = 54-67) than in vitro J(ss) in RSC (98 nmol/cm(2) . h, CI = 79-117). On the other hand, skin release rate constant (K(R)) in vivo was similar to the K(R) in RSC (4.8/h, CI = 2.4-7.1 vs. 2.6/h, CI = 2.5-2.6). Kinetic lag time (t(L)) in vivo was negligible, which is close to in vitro t(L) in RSC (0.0 h, CI = 0.0-0.1). Based on nonlinear mixed-effect modeling, profiles of C(p) and C(DA) were successfully predicted using in vitro values of J(ss) in DRS with K(R) and t(L) in RSC. A considerable dopaminergic effect was achieved, indicating the feasibility to reach therapeutically effective concentrations of 5-OH-DPAT upon transdermal iontophoresis.

Visualization studies of human skin in vitro/in vivo under the influence of an electrical field

The aim of this study was to investigate the local changes in the ultrastructure of human skin after iontophoresis, using cryo-scanning, transmission and freeze fracture electron microscopy in human skin in vitro and in vivo. Human dermatomed skin was subjected to passive diffusion for 6 hours followed by nine hours of iontophoresis at 0.5 mA/cm2. The skin was processed and examined using both cryo-scanning electron microscopy (Cryo-SEM) and transmission electron microscopy (TEM). In addition, iontophoresis patches were applied to healthy volunteers for 3.5h with 0.5h of passive delivery followed by 3h of iontophoresis at a current density of 0.25 mA/cm2. Subsequently, a series of tape stripping were performed, which were visualized by freeze fracture transmission electron microscopy (FFTEM). In vitro, the cryo-scanning electron microscopy study revealed that electric current induced changes in the water distribution in the stratum corneum. Transmission electron microscopy showed no local changes in the ultrastructure of the stratum corneum; however, layers of detached corneocytes were frequently observed especially at the anodal site. In vivo, there was no evidence of perturbation of the stratum corneum lipid organization; however, changes in the fracture were noticed deeper in the stratum corneum at the anodal side, indicating a weakening of the desmosomal structure. The in vitro/in vivo studies suggest that iontophoresis results in the formation of intercellular water pools (in vitro observation) and a weakening of the desmosomal structure (in vivo observation) only in the upper part of the stratum corneum. However, no changes in the lipid organization were observed in vitro and in vivo at the current densities of 0.5 and 0.25 mA/cm2, respectively. Therefore, even at relatively high current densities, no drastic changes in the ultrastructure of the stratum corneum are observed. As far as structural changes in stratum corneum are concerned iontophoresis is therefore a safe method at the experimental conditions we used.

New insights into ultrastructure, lipid composition and organization of vernix caseosa

The upper layer of the epidermis, the stratum corneum (SC), is very important for skin barrier function. During the last trimester of gestation, the SC of the fetus is protected by a cheesy, white biofilm called vernix caseosa (VC). VC consists of water-containing corneocytes embedded in a lipid matrix and the basic structure shows certain similarities with the SC. This study aimed to characterize VC, with the main focus on an integral analysis of free and (to the corneocytes) bound lipids, on the lipid organization, and on ultrastructure. Free lipids of VC show a wide distribution in polarity; nonpolar lipids such as sterol esters and triglycerides predominate, having a chain length of up to 32 carbon atoms. The profile of fatty acids, omega-hydroxyacids and omega-hydroxyceramides - representing the bound lipids of VC - shows high similarity to that of SC. Morphological studies revealed the presence of highly hydrated corneocytes embedded in lipids, the latter being occasionally accumulated as lipid pools. Freeze fracture electron microscopy showed smooth surfaces of corneocytes and a heterogeneous appearance of intercellular lipids. The results suggest a lower degree of ordering of VC lipids as compared to the SC. A small-angle X-ray diffraction study showed similar results.

Transdermal iontophoresis

Iontophoresis is a technique used to enhance the transdermal delivery of compounds through the skin via the application of a small electric current. By the process of electromigration and electro-osmosis, iontophoresis increases the permeation of charged and neutral compounds, and offers the option for programmed drug delivery. Interest in this field of research has led to the successful delivery of both low (lidocaine) and high molecular drugs, such as peptides (e.g., luteinising hormone releasing hormone, nafarelin and insulin). Combinations of iontophoresis with chemical enhancers, electroporation and sonophoresis have been tested in order to further increase transdermal drug permeation and decrease possible side effects. In addition, rapid progress in the fields of microelectronics, nanotechnology and miniaturisation of devices is leading the way to more sophisticated iontophoretic devices, allowing improved designs with better control of drug delivery. Recent successful designing of the fentanyl E-TRANS iontophoretic system have provided encouraging results. This review will discuss basic concepts, principles and applications of this delivery technique.

Transdermal iontophoresis: combination strategies to improve transdermal iontophoretic drug delivery

For several decades, there has been interest in using the skin as a port of entry into the body for the systemic delivery of therapeutic agents. However, the upper layer of the skin, the stratum corneum, poses a barrier to the entry of many therapeutic entities. Given a compound, passive delivery rate is often dependent on two major physicochemical properties: the partition coefficient and solubility. The use of chemical enhancers and modifications of the thermodynamic activity of the applied drug are two frequently employed strategies to improve transdermal permeation. Chemical enhancers are known to enhance drug permeation by several mechanisms which include disrupting the organized intercellular lipid structure of the stratum corneum , 'fluidizing' the stratum corneum lipids , altering cellular proteins, and in some cases, extracting intercellular lipids . However, the resulting increase in drug permeation using these techniques is rather modest especially for hydrophilic drugs. A number of other physical approaches such as iontophoresis, sonophoresis, ultrasound and the use of microneedles are now being studied to improve permeation of hydrophilic as well as lipophilic drugs. This article presents an overview of the use of iontophoresis alone and in conjunction with other approaches such as chemical enhancement, electroporation, sonophoresis, and use of microneedles and ion-exchange materials.

Transdermal iontophoresis of the dopamine agonist 5-OH-DPAT in human skin in vitro

The feasibility of transdermal iontophoretic delivery of a potent dopamine agonist 5-OH-DPAT was studied in vitro in side by side diffusion cells across human stratum corneum (HSC) and dermatomed human skin (DHS) according to the following protocol: 6 h of passive diffusion, 9 h of iontophoresis and 5 h of passive diffusion. The influences of the following parameters on the flux were studied: donor solution pH, NaCl concentration, drug donor concentration, current density and skin type. A current density of 0.5 mA cm(-2) was used, except for one series of experiments to study the current density effect. Probably due to the influence of the skin perm-selectivity and the competition with H(+), increase in pH from 3 to 5 resulted in a significant increase in flux. Further increase in pH to 6 did not further increase the flux. The iontophoretic transport was found to increase linearly with concentration and current density, providing a convenient way to manage dose titration for Parkinson's disease therapy. Increase in concentration of NaCl dramatically reduced the flux of 5-OH-DPAT as a result of ion competition to the transport. When DHS was used, the iontophoretic transport was less. Also, with DHS the response in flux profile, by switching the current on and off, was shallower than that with HSC. With the optimum condition, a delivery of 104 microg of 5-OH-DPAT per cm(2) patch per hour is feasible, indicating that the therapeutic level could be achieved with a smaller patch size than required in case of rotigotine. Thus, based on this in vitro study, transdermal iontophoretic delivery of 5-OH-DPAT is very promising.