Formulation and characterization of Phospholipon 90 G and tween 80 based transfersomes for transdermal delivery of eprosartan mesylate

The objective of the current study was to formulate the eprosartan mesylate loaded transfersomes using different proportions of Phospholipon^® 90?G and Tween^® 80 (95–75:5–25% w/w). The prepared transfersomes were characterized for their vesicles size, shape, polydispersity index, zeta potential, entrapment efficiency, in vitro skin permeation, confocal laser scanning microscopy, and in vivo skin irritation. Results revealed that the formulated transfersomes were negatively charged, spherical unilamellar structure of 71.18–85.66?nm with entrapment efficiency of 83.00–88.19%, and presented transdermal flux of 1.78–5.02?μg/cm²/h across rat skin. Confocal laser scanning microscopy confirmed that the formulated rhodamine 6?G loaded transfersomes could penetrate deeply and uniformly into rat skin. Additionally, in vivo skin irritation studies revealed that the prepared transfersomes were devoid of any skin irritation potential (erythema and edema). Results of this study revealed that the transfersomes prepared with Tween^® 80 could be used to enhance the transdermal delivery of eprosartan mesylate. In conclusion, transdermal transfersomes formulation may prove to be an encouraging drug carrier for eprosartan mesylate and other actives, particularly owing to their simple formulation and unsophisticated scale-up methods.     

In vitro evaluation of patch formulations for topical delivery of gentisic acid in rats.

Gentisic acid (GA) is used in cosmetics as a skin-whitening agent for the treatment of skin pigmentary disorders by influencing the synthesis of melanin through inhibition of melanosomal tyrosinase activity. In order to achieve effective topical delivery of GA to the active site in the skin, a matrix-type transdermal delivery system was developed. The in vitro skin permeation as well as skin deposition of GA was studied in rats. Among the five pressure-sensitive adhesives tested, DuroTak 87-2510 was the most effective to achieve the highest permeation rate of GA. Dodecylamine showed the most potent enhancement among the enhancers tested, and significantly increased the permeation rate of GA up to 112.99 (+/-30.12) microg/cm(2) per h at the concentration of 1%, when 6% GA was incorporated in DuroTak 87-2510. Moreover, a linear relationship was observed between the skin permeation rate of GA and the amount of the skin deposition after 12 h of permeation (r(2)=0.95). Thus, the in vitro skin permeation data may be useful to determine the amount of GA actually deposited in the skin.     

脉冲电流对胰岛素经皮渗透的促进作用

实验结果表明,脉冲电流能有效地提高胰岛素的透皮扩散速率,并随着释放池中胰岛素浓度的递增,透皮扩散速率呈线性增加。同时,胰岛素在pH值偏离等电点的酸性溶液(pH3.6)中透皮速率最高,为324.2±33.4μU/(cm²·h),而在pH值高于等电点的溶液(pH7.4)中其透皮速率降至143.7±27.3μU/(cm²·h),在pH值接近等电点(pH5.3)时,胰岛素的透皮速率最低,为78.4±21.9μU/(cm²·h)。     

氧化苦参碱凝胶体外经皮渗透及大鼠药动学研究

目的 研究氧化苦参碱凝胶的体外经皮渗透影响因素,并对其在大鼠体内的药动学进行研究。方法 采用Valia-Chien 双室扩散池,以大鼠离体皮肤为渗透屏障,HPLC测定氧化苦参碱浓度,以药物累积渗透量为指标,对药物及渗透促进剂的浓度进行筛选。结果 氧化苦参碱经皮凝胶的最优处方12 h累积渗透量为(18.094±1.253)mg·cm^-2,大鼠静注与经皮给药的血浆药动学研究表明,经皮给药的AUC_(0-t)是注射给药的1.9倍(P<0.01)。结论 氧化苦参碱凝胶的经皮吸收能力良好,能长时间持续释放药物,有望成为新的给药剂型。     

A Review of: “Excipient Development for Pharmaceutical,Biotechnology, and Drug Delivery Systems”

The feasibility of delivering hydromorphone by transdermal iontophoresis to obtain therapeutically effective analgesic concentrations for the management of cancer-related pain was evaluated. Anodal iontophoresis was performed, and the effect of current strength, current duration, solution pH, presence of buffer ions, and drug concentration on the transdermal permeation of hydromorphone was investigated in vitro. Freshly excised full‐thickness hairless rat skin and side-by-side permeation cells connected to the Phoresor II^TM with Ag/AgCl electrodes was used. The flux of hydromorphone was observed to significantly increase (P < 0.05) from 72.04–280.30 μg/cm²/h with increase in current strength from 0.10–0.50 mA. A linear relationship was obtained between hydromorphone flux and current strength. Furthermore, the flux of hydromorphone was influenced by solution pH and presence of buffer ions. Also, the in vitro permeation flux of hydromorphone was observed to significantly increase (P < 0.05) with a 10-fold increase in hydromorphone hydrochloride concentration from 0.01–0.10 M. However, with further increase to 0.50 M, there was no significant difference in flux. These results show that by manipulating electronic and formulation variables, the transdermal iontophoretic delivery of hydromorphone can be controlled, and therapeutically effective concentrations of hydromorphone for the management of cancer-related pain can be obtained.     

In-vitro and in-vivo transdermal iontophoretic delivery of tramadol, a centrally acting analgesic

Objectives The feasibility of transdermal delivery of tramadol, a centrally acting analgesic, by anodal iontophoresis using Ag/AgCl electrodes was investigated in vitro and in vivo. Methods To examine the effect of species variation and current strength on skin permeability of tramadol, in‐vitro skin permeation studies were performed using porcine ear skin, guinea‐pig abdominal skin and hairless mouse abdominal skin as the membrane. In an in‐vivo pharmacokinetic study, an iontophoretic patch system was applied to the abdominal skin of conscious guinea pigs with a constant current supply (250 µA/cm²) for 6 h. An intravenous injection group to determine the pharmacokinetic parameters for estimation of the transdermal absorption rate in guinea pigs was also included. Key findings The in‐vitro steady‐state skin permeation flux of tramadol current‐dependently increased without significant differences among the three different skin types. In the in‐vivo pharmacokinetic study, plasma concentrations of tramadol steadily increased and reached steady state (336 ng/ml) 3 h after initiation of current supply, and the in‐vivo steady‐state transdermal absorption rate was 499 µg/cm² per h as calculated by a constrained numeric deconvolution method. Conclusions The present study reveals that anodal iontophoresis provides current‐controlled transdermal delivery of tramadol without significant interspecies differences, and enables the delivery of therapeutic amounts of tramadol.     

Penetration‐Enhancing Effect of Ethanol–Water Solvent System and Ethanolic Solution of Carvone on Transdermal Permeability of Nimodipine from HPMC Gel Across Rat Abdominal Skin

The aim of this investigation was to find the effect of the ethanol–water solvent system and the ethanolic solution of carvone on the permeation of nimodipine across rat abdominal skin in order to select a suitable solvent system and optimal concentration of carvone for the development of membrane‐moderated transdermal therapeutic system of nimodipine. The solubility of nimodipine in water, ethanol, and ethanol–water cosolvent systems, or the selected concentration of carvone [2% (w/w) to 12% (w/w)] in 60:40 (v/v) ethanol–water were determined. The effect of these solvents or cosolvent systems on the transdermal permeation of nimodipine was also studied using in vitro permeability studies across the rat abdominal skin. The cosolvent system containing 60:40 (v/v) of ethanol–water showed highest permeability across the rat abdominal skin. Further, the effect of ethanolic solution [60% (v/v) ethanol–water] of carvone [2% (w/w) to 12% (w/w)] on the in vitro permeation of nimodipine across the rat abdominal skin from 2% (w/w) hydroxypropyl methylcellulose (HPMC) gel was also investigated. The transdermal permeability of nimodipine across rat abdominal skin was enhanced further by the addition of carvone to HPMC gel prepared with 60% (v/v) of ethanol. There was a steady effect on the flux of nimodipine (161.02 ± 4.14 µg/cm²/hr) with an enhancement ratio of 4.56 when carvone was incorporated at a concentration of 10% (w/w) in HPMC gels prepared with 60% (v/v) ethanol. The Fourier transform infrared data indicated that ethanolic solution of carvone increased the transdermal permeability of nimodipine across the rat abdominal skin by partial extraction of lipids in the stratum corneum. The results suggest that 10% (w/w) of carvone in 60% (v/v) ethanol–water, along with HPMC as antinucleating agent may be useful for enhancing the skin permeability of nimodipine from the membrane‐moderated transdermal therapeutic system.     

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

Abstract

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/cm²) and microneedles (66.97?±?10.39?µg/cm²), significantly increased the permeation of drug with respect to passive delivery (8.25?±?2.41?µg/cm²). Modulated iontophoresis could control the amount of drug delivered at a given time point with the highest flux being 5.12?±?1.70?µg/cm²/h (5–7?h) and 5.99?±?0.81?µg/cm²/h (20–22?h). Combination of modulated iontophoresis and microneedles (46.50?±?6.46?µg/cm²) showed significantly higher delivery of ropinirole hydrochloride compared to modulated iontophoresis alone (84.91?±?9.21?µg/cm²). 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.     

Microencapsulation decreases the skin absorption of N,N-diethyl-m-toluamide (DEET).

The insect repellent N,N-diethyl-3-methylbenzamide (DEET) is widely used and is generally regarded as safe when used according to label instructions. Yet many studies have shown it to be absorbed through the skin. The objective of this study was to determine whether the skin absorption rate of DEET could be decreased while maintaining an evaporation rate consistent with effective repellency. To this end, an aqueous suspension containing 14C-DEET (15%w/w) entrapped in walled polysaccharide microcapsules was prepared and tested for skin absorption in vitro using modified Franz cells maintained in a fume hood. The control formulation was 15%w/w DEET in ethanol. Two doses (3 microL and 5 microL per 0.79 cm2 cell) of each formulation were applied to split-thickness human cadaver skin (n=8/dose), and permeation was monitored for 24h. The microencapsulated DEET formulation lead to a 25-35% reduction of radiolabel permeation compared to the ethanolic DEET formulation. Skin levels of radioactivity at 24h were comparable, indicating that DEET evaporation from the microencapsulated formulation was comparable to or greater than that from ethanol. Hence microencapsulation increased the ratio of DEET evaporation rate to skin penetration rate relative to unencapsulated control in this in vitro study.     

Development of Matrix-Membrane Transdermal Drug Delivery System for Atenolol

A polymer matrix system for transdermal delivery of Atenolol was developed for its prolonged and controlled release systemic availability. To achieve the desired and controlled release rate, different combinations of Eudragit RL with polyvinyl pyrrolidone and polyethylene glycol 4000 were used in the preparations of polymeric matrix system. These preparations were evaluated for in vitro release and permeation of the drug across pig skin. The desired systems exhibited linear relationship between drug release (Q) versus ne^0.8(hr^0.8). The product exhibiting required skin permeation 64 mcg/h/cm² to achieve an effective plasma concentration was selected for the in vivo performance evaluation. The drug plasma profile was compared with the plasma profile obtained following the administration of a conventional oral dose of Atenolol. The study revealed that the designed polymeric matrix transdermal drug delivery system of Atenolol could be successful with improved performance.     

A bioassay for mosquito repellency against Aedes aegypti: method validation and bioactivities of DEET analogues

Objectives Vector‐borne diseases are still a major mortality factor in Africa and South‐east Asia and effective mosquito repellents are therefore needed. An efficient and safe in‐vitro assay system using artificial blood and skin substitute could facilitate the development of novel repellents, as most assays currently rely on human subjects or vertebrate whole blood. Moreover, examining the skin permeation profiles could provide safer mosquito repellents. The new assay system could serve as an initial system for testing new repellent candidates upon validation with DEET and its analogues. Methods N,N‐Diethyl‐meta‐toluamide (DEET) and five analogues were synthesised and used to validate a novel in‐vitro bioassay using artificial blood and collagen membrane. Repellency against Aedes aegypti was correlated with lipophilicity and skin permeation. Key findings The new in‐vitro assay showed good reproducibility (interday relative standard deviation <10% at high concentrations). Four of the five DEET analogues showed repellency similar or superior to that of DEET. Repellency correlated linearly with lipophilicity but stronger repellents tended to permeate skin better. Conclusions The new in‐vitro assay using blood substitute and collagen membrane significantly simplifies screening of possible mosquito repellents. Lipophilicity as well as skin permeation profiles should be considered before testing of compounds that are candidates for mosquito repellents.     

Design,development, physicochemical,in vitro and in vivo evaluation of monolithic matrix type transdermal patches containing nitrendipine

The matrix type transdermal drug delivery systems (patches) of Nitrendipine were prepared by film casting technique. The patches were characterized for physical, in vitro release studies and ex-vivo permeation studies (human cadaver skin). On the basis of in vitro drug release and skin permeation performance, formulation B3 was found to be better than the other formulations and it was selected as the optimized formulation. The final optimized formulation (B3) was subjected to skin irritation, pharmacokinetic, pharmacodynamic and stability studies. The maximum percentage drug release in 48 hours was 94.67 ± 3.25 for B3 and 91.43 ± 2.106 for A2 formulation. Again formulation B3 (0.0627 mg/cm²/h) and A2 (0.0566 mg/cm²/h) showed maximum skin flux in the respective series. Patches prepared with Plasdone S-630 were more flexible as compared to PVP K 30 containing patches. Patches prepared with PVP K 30 showed drug release and skin permeation at higher percentage as compared to those containing Plasdone S-630. The interaction studies carried out by comparing the results of ultraviolet, infrared, TLC and DSC analyses for the pure drug, medicated and placebo formulations indicated no chemical interaction between the drug and excipients. The TDDS was found to be free of any skin irritation as suggested by skin irritation score of 1.16 (< 2.00) under Draize score test.     

Effect of fatty acids on the transdermal delivery of donepezil: in vitro and in vivo evaluation

The effect of fatty acids on the skin permeation of donepezil base (DPB) and its hydrochloride salt (DPH) were studied in vitro using hairless mouse and human cadaver skin. DPB and DPH were solubilized in propylene glycol (PG) containing 1% (w/v) fatty acid, after which the in vitro permeation through hairless mouse skin and human cadaver skin were evaluated using Keshary-Chien diffusion cells. The optimized formulation obtained from the in vitro study was then tested in rats for an in vivo pharmacokinetic study. The relative in vitro skin permeation rate of donepezil (DP) through the hairless mouse skin showed a parabolic relationship with increased carbon length of the fatty acid enhancers. Among the fatty acids tested, oleic acid for DPB and palmitoleic acid for DPH showed the highest enhancing effect, respectively. Both the permeation rates of DPB and DPH evaluated in human cadaver skin were in good correlation with those in hairless mouse skin, regardless of the presence of fatty acids. This suggests that the mouse skin model serves as a useful in vitro system that satisfactorily represents the characteristics of the human skin. Moreover, based on the in vitro results, the optimal formulation that could maintain the human plasma concentration of 50 ng/mL was determined to be 10mg DP with 1% (w/v) enhancer. When the DP transdermal formulations were applied to the abdominal skin of rats (2.14 cm(2)), the C(ss) was maintained for 48 h, among which the highest value of 52.21 ± 2.09 ng/mL was achieved with the DPB formulation using oleic acid. These results showed that fatty acids could enhance the transdermal delivery of DP and suggested the feasibility of developing a novel transdermal delivery system for clinical use.     

Transdermal Controlled Delivery of Propranolol from a Multilaminate Adhesive Device

The feasibility of transdermal controlled delivery of propranolol was investigated by conducting in vitro skin permeation studies using rabbit pinna (ear) skin. A new multilaminate adhesive device which is capable of releasing propranolol in a controlled fashion over a 24-hr period had been developed and was evaluated transdermally using rabbit pinna skin. Skin permeation of propranolol from the device was found to be controlled by the stratum corneum during the early phase of permeation and then by the adhesive device during steady-state permeation. The rabbit pinna skin was shown to be a good animal model for studying the transdermal permeation of propranolol from the device, when compared to human cadaver skin.     

Use of an 8(1)3(2) asymmetrical factorial design for the in vitro evaluation of ondansetron permeation through human epidermis

The in vitro permeation of ondansetron through human cadaver epidermis, as a preliminary step toward the development of a transdermal therapeutic system, was investigated. In vitro release studies were carried out using modified Franz diffusion cells and human epidermis, taken from cadaver skin by heat separation technique. To estimate the effect of the type and concentration of the penetration enhancers and the skin from different donors, an 8(1)3(2) asymmetrical factorial design was used. Formulations containing lauric acid and oleic acid as penetration enhancers, showed the largest Q values [amounts of ondansetron permeated per unit area of epidermal membrane (microg/cm2)] at 24, 48, and 72 hr, as well as steady-state flux values, among all formulations tested. The other enhancers increased the flux in the following order: lauryl alcohol>glycerol monooleate>Azone >cineole>oleyl alcohol>1-methyl-2-pyrrolidinone. Moreover, the concentration of the penetration enhancer and the type of the skin were proved to significantly affect the permeation rate of ondansetron through human epidermis. From the results obtained, it was shown that the formulations containing lauric acid or oleic acid at 5% or 10% could increase sufficiently the permeation of ondansetron. Therefore, the transdermal administration of ondansetron seems feasible.     

Transdermal Drug Delivery Using Low-Frequency Sonophoresis

Purpose. Application of therapeutic ultrasound (frequency: 1–3 MHz and intensity: 0–2 W/cm²) enhances transdermal drug transport, although typically by a factor of less than 10. In this paper, we show that application of ultrasound at 20 KHz induces transdermal transport enhancements of up to 1000 times higher than those induced by therapeutic ultrasound. Methods. In vitro (human cadaver epidermis) as well as in vivo (hairless rat skin) permeation experiments were performed to assess the effect of low-frequency ultrasound on transdermal transport. Results. Application of low-frequency ultrasound (20 KHz, 125 mW/cm², 100 msec pulses applied every second) enhanced transdermal transport of several permeants, including estradiol, salicylic acid, corticosterone, sucrose, aldosterone, water, and butanol, across human cadaver skin by a factor in the range of 3 to 3000 and that of salicylic acid across hairless rat skin in vivo by a factor of up to 300. Low-frequency ultrasound did not induce a long-term loss of the barrier properties of the skin (in vitro) or damage to living skin of hairless rats. At a mechanistic level, it is hypothesized that application of low-frequency ultrasound enhances transdermal transport through aqueous channels in the SC generated by cavitation-induced bilayer disordering. Support for this hypothesis is provided using experimental and theoretical analyses of low-frequency sonophoresis. Conclusions. Low-frequency ultrasound enhances transdermal transport of drugs more effectively than that induced by therapeutic ultrasound.     

Nanosized ethosomes bearing ketoprofen for improved transdermal delivery

The potential of ethosomes for delivering ketoprofen via skin was evaluated. The ethosomes were prepared, optimized and characterized. Vesicular shape, size and entrapment efficiency were determined by transmission electron microscopy, dynamic light scattering and minicolumn centrifugation technique, respectively. Vesicle sizes varied from 120.3±6.1 to 410.2±21.8 nm depending on the concentrations of soya phosphatidyl choline (SPC) and ethanol. Entrapment efficiency increased with concentrations of SPC and ethanol. The formulations exhibited entrapment efficiencies of 42–78%. In vitro release through cellophane membrane showed sustained release of drug from ethosomal formulations in contrast to hydroalcoholic drug solution (HA), which released most of the drug within 2–3 h. In vitro drug permeation across human skin revealed improved drug permeation and higher transdermal flux with ethosomal formulations compared to hydroethanolic drug solution. Kinetics of in vitro skin permeation showed zero order drug release from formulations. Based on in vitro transdermal flux, the estimated steady state in vivo plasma concentration from ethosomes attained therapeutic drug levels whereas hydroalcoholic drug solution exhibited sub therapeutic drug concentration with a patch size of 50 cm². Skin permeation of ethosomal formulations assessed by confocal microscopy revealed enhanced permeation of Rhodamine 123 loaded formulation in comparison to the hydroalcoholic solution.     

Transdermal Delivery of Cytochrome C—A 12.4 kDa Protein—Across Intact Skin by Constant–Current Iontophoresis

Purpose To demonstrate the transdermal iontophoretic delivery of a small (12.4 kDa) protein across intact skin. Materials and Methods The iontophoretic transport of Cytochrome c (Cyt c) across porcine ear skin in vitro was investigated and quantified by HPLC. The effect of protein concentration (0.35 and 0.7 mM), current density (0.15, 0.3 or 0.5 mA.cm⁻² applied for 8 h) and competing ions was evaluated. Co-iontophoresis of acetaminophen was employed to quantify the respective contributions of electromigration (EM) and electroosmosis (EO). Results The data confirmed the transdermal iontophoretic delivery of intact Cyt c. Electromigration was the principal transport mechanism, accounting for ∼90% of delivery; correlation between EM flux and electrophoretic mobility was consistent with earlier results using small molecules. Modest EO inhibition was observed at 0.5 mA.cm⁻². Cumulative permeation at 0.3 and 0.5 mA.cm⁻² was significantly greater than that at 0.15 mA.cm⁻²; fluxes using 0.35 and 0.7 mM Cyt c in the absence of competing ions (J _tot  = 182.8 ± 56.8 and 265.2 ± 149.1 μg.cm⁻².h⁻¹, respectively) were statistically equivalent. Formulation in PBS (pH 8.2) confirmed the impact of competing charge carriers; inclusion of ∼170 mM Na⁺ resulted in a 3.9-fold decrease in total flux. Conclusions Significant amounts (∼0.9 mg.cm⁻² over 8 h) of Cyt c were delivered non-invasively across intact skin by transdermal electrotransport.     

Percutaneous permeation comparison of repellents picaridin and DEET in concurrent use with sunscreen oxybenzone from commercially available preparations

Concurrent application of insect repellent picaridin or DEET with sunscreens has become prevalent due to concerns on West Nile virus and skin cancer. The objectives of this study were to characterize the percutaneous permeation of picaridin and sunscreen oxybenzone from commercially available preparations and to compare the differences in permeability between picaridin and DEET in association with oxybenzone. In vitro diffusion studies were carried out to measure transdermal permeation of picaridin and oxybenzone from four different products, using various application concentrations and sequences. Results were then compared to those of repellent DEET and sunscreen oxybenzone under identical conditions. Transdermal permeation of picaridin across human epidermis was significantly lower than that of DEET, both alone and in combination with oxybenzone. Concurrent use resulted in either no changes or suppression of transdermal permeation of picaridin and oxybenzone. This finding was different from concurrent use of DEET and oxybenzone in which a synergistic permeation enhancement was observed. In addition, permeation of picaridin, DEET and oxybenzone across human epidermis was dependent on application concentration, use sequence, and preparation type. It was concluded from this comparative study that picaridin would be a better candidate for concurrent use with sunscreen preparations in terms of minimizing percutaneous permeation of the chemicals.     

维A酸维生素C棕榈酸酯泡囊的体外释放、经皮渗透和皮肤贮留研究

目的研究维生素C棕榈酸酯泡囊作为维A酸载体时,主药的体外释放、经皮渗透和皮肤贮留情况。方法采用Franz扩散池测定维A酸从载体中的释放速度,扩散池与供给池之间为纤维素膜（截留分子量8000～14000）,扩散池面积为2.92cm^2。体外透皮试验用小鼠、大鼠或兔子背部皮肤替代半透膜。在体外透皮试验完结后,取下皮肤,剪碎匀浆,用50%异丙醇-生理盐水提取,提取液处理后用HPLC测定药物浓度。结果结果表明维A酸释放速率和累积经皮渗透量大于市售乳膏,同时具有较高的皮肤贮留量。结论维生素C棕榈酸酯泡囊作为维A酸载体有助于增加局部药物浓度。