Biopharmaceutics: Topical Delivery of Keloid Therapeutic Drug,Tranilast, by Combined Use of Oleic Acid and Propylene Glycol as a Penetration Enhancer: Evaluation by Skin Microdialysis in Rats

Topical delivery of tranilast (N-(3,4-dimethoxycinnamoyl)anthranic acid), an inhibitor of collagen synthesis and a therapeutic drug for keloid and hypertrophic scar, was examined, in rats, with oleic acid alone or a combination of oleic acid and propylene glycol as penetration enhancer. Evaluation was by measurement of the concentration of tranilast in plasma and in the dialysate from skin microdialysis. When tranilast at a dose of 1.5 mg was applied topically as an ethanol solution containing 5% polyvinylpyrrolidone on a dorsal skin surface (2.25 cm²), the maximum concentration of tranilast in skin dialysate was approximately 2 μM. When 10 or 20% oleic acid was added to the same ethanol solution the maximum concentration of tranilast in the dialysate increased to 10–20 μM, and this value was further increased to 60 μM by the addition of a combination of oleic acid (10 or 20%) and propylene glycol (10%) to the solution. With the combination of oleic acid and propylene glycol the area under the plot of the concentration of tranilast in skin dialysate against time between 0 and 4 h (AUC_0–4) was more than 400-fold that after intravenous administration. The transdermal bioavailability of tranilast as assessed by the AUC_0–4 of tranilast in plasma, was 0.2% of the dose applied in the ethanol solution, 3–5% of that applied in the ethanol solution containing oleic acid, and 14–16% of that applied in the ethanol solution containing both oleic acid and propylene glycol. These results suggest that the topical delivery of tranilast with an absorption enhancer such as a mixture of oleic acid and propylene glycol might be a more effective medication than oral administration of tranilast for the treatment of keloid and hypertrophic scar.     

Evaluation of creams and ointments as suitable formulations for peldesine

In-vitro studies were conducted to study the efficacy of mixed and self-emulsifying creams and hydrophobic ointment formulations in delivering peldesine (BCX-34) into and across cryopreserved human cadaver skin (HCS). Oil-in-water cream formulations, containing 1% w/w of radiolabeled C(14) BCX-34 and propylene glycol (PG), glycerin (GLY), isopropyl myristate (IPM), oleic acid (OA) and capric-caprylic esters (CE) were prepared. Petrolatum and lanolin based ointments were also prepared with PG. Sections of the HCS, 250 microm thick, were fitted to vertical Franz diffusion chambers containing a receptor medium of pH 7.4 phosphate buffer solution maintained at 37 degrees C. Using the finite dose technique, 4-6 mg of a formulation sample was applied to the epidermal surface of each section and drug diffusion was permitted for 12 and 24 h periods. The distribution of drug into the HCS epidermis, dermis and into the receptor medium was measured by scintillation spectroscopy. The results show good correlation of the calculated in-vitro values for flux and skin-vehicle partition coefficients against the observed amounts of drug detected in the HCS. The mixed emulsion cream formulation containing PG delivered higher amounts of drug into the skin when compared to the same formulation containing GLY cream. The self-emulsifying cream formulation containing IPM had a higher skin-vehicle partition coefficient and delivered more drug into the dermis when compared to those formulations that contained OA and CE. The petrolatum ointment delivered six times more drug into the epidermis than the lanolin ointment, and had higher skin-vehicle partition values. In conclusion, creams containing PG and petrolatum-base formulations would be suitable for BCX-34 dermal delivery.     

不同促渗剂对盐酸氨酮戊酸原位凝胶体外透皮吸收的影响

目的：研究不同透皮促渗剂对盐酸氨酮戊酸原位凝胶体外透皮吸收的影响,为筛选最佳透皮促渗剂提供实验依据。方法：采用Franz扩散池法,以离体大鼠皮肤为模型,选择3种常用透皮促渗剂月桂氮芯卓酮（azone,AZ）、丙二醇（propylene glycol,PG）、二甲亚砜（dimethyl sulfoxide,DMSO）,分别考察单一促渗剂及二元促渗剂对盐酸氨酮戊酸原位凝胶体外透皮吸收的影响。结果：含促渗剂盐酸氨酮戊酸原位凝胶体外透皮吸收显著高于未添加促渗剂盐酸氨酮戊酸原位凝胶及市售制剂;采用单一促渗剂时,1% PG促渗效果最好;采用二元促渗剂时,3% AZ+1% PG促渗效果最好;3% AZ+1% PG促渗效果优于1% PG,含促渗剂3% AZ+1% PG的盐酸氨酮戊酸原位凝胶透皮性优于市售制剂艾拉。结论：添加促渗剂的方法能够显著改善盐酸氨酮戊酸的体外透皮吸收性,3% AZ+1% PG构成的二元促渗剂用于盐酸氨酮戊酸原位凝胶促渗效果最佳;本研究为设计优良的盐酸氨酮戊酸经皮给药系统药物奠定了重要基础。     

不同透皮促进剂对双氯芬酸钾凝胶体外透皮效果的影响研究

目的:考察氮酮(Azone)、丙二醇(PG)、油酸(OA)3种透皮促进剂一元、二元、三元联合对双氯芬酸钾凝胶的体外促透作用。方法:配制以下13种含不同透皮促进剂的双氯芬酸钾凝胶处方:空白,3%Azone,5%OA,12%PG,6%PG+2.5%OA,12%PG+5%OA,1.5%Azone+2.5%OA,1.5%Azone+6%PG+5%OA,1.5%Azone+12%PG,3%Azone+5%OA,3%Azone+6%PG,3%Azone+6%PG+5%OA,3%Azone+12%PG,以透皮速率J等为指标,采用改良的Franz扩散池,以离体人皮肤为透皮屏障,测定并计算双氯芬酸钾凝胶加入上述不同透皮促进剂处理后药物的透皮性能。结果:与空白组比较,其它各组J值均升高,其中以3%Azone+12%PG组的J值最高,达10.253 0μg.cm-2.h-1。结论:3种透皮促进剂对双氯芬酸钾凝胶均有不同程度促透效果,但以Azone和PG二元联用效果最佳。     

Bioavailability and metabolism of isosorbide dinitrate from a transdermal spray.

The plasma pharmacokinetics of isosorbide dinitrate (ISDN), isosorbide-2-nitrate (IS-2-N) and isosorbide-5-nitrate (IS-5-N) were investigated in 12 healthy volunteers after a single cutaneous administration of 60 mg ISDN (CAS 87-33-2) in the form of a solution sprayed onto the skin (TD Spray Iso Mack), in comparison with an intravenous infusion of 5 mg ISDN. After the intravenous dose, the apparent steady state volume of ISDN distribution came to 179.9 l, total body clearance was 3.14 l min-1, and terminal half-life was 79 min, on average. The transdermal absorption resulted in an average peak plasma concentration of 6.9 ng ISDN ml-1 at 5 h after the administration. ISDN concentrations between 1 and 5 ng ml-1 were maintained over at least 15 h. On average, 16.5% of the topically applied ISDN reached the systemic circulation. Total variations in Cmax (CV = 47.9%) and AUC (CV = 36.0%) of transdermal ISDN were similar to those usually observed after oral ISDN.     

The effects of fatty acids in propylene glycol on the percutaneous absorption of alendronate across the excised hairless mouse skin

The effects of fatty acids at various concentrations in propylene glycol (PG) on the in vitro permeation of alendronate from solution formulations and formulated pressure-sensitive adhesive (PSA) transdermal delivery systems through excised hairless mouse skin were investigated. Caprylic acid, capric acid, lauric acid, oleic acid and linoleic acid at concentrations of 3, 6 and 10% were employed as a fatty acid. The highest maximum permeation flux was obtained with 3% capric acid in PG followed by 6% capric acid and 3% oleic acid from solution formulations; the enhancement factor by the addition of 3% capric acid to PG was 20.5 compared to PG alone. On the contrary, from PSA transdermal delivery systems, the highest enhancement factor of 2.9 was attained with 6% caprylic acid in PG compared to PG alone. The maximum permeation flux and lag time from PSA transdermal delivery systems by the addition of 6% caprylic acid to PG were 195.68 ± 26.6 ng/cm²/h and 0.6 ± 0.3 h whereas PG without fatty acids showed 67.3 ± 5.8 ng/cm²/h and 0.5 ± 0.4 h, respectively. The PSA transdermal delivery systems initially provided very high permeation rate followed by a gradual decrease regardless of the fatty acids. The highest release rate was also obtained with the formulation containing 6% caprylic acid in PG although release rates were not matched with permeation rates perfectly. In conclusion, for effective transdermal delivery system of alendronate, 6% caprylic acid in PG could be employed.     

Percutaneous absorption of piroxicam from ointment bases in rabbits

In order to investigate the process of percutaneous absorption from various ointment bases, the blood levels of piroxicam were determined at optimal intervals after the ointment application in rabbits.After the oral and intravenous administrations, the plasma levels of piroxicam were described by the two-compartment model. A pharmacokinetic model similar to the percutaneous absorption of indomethacin was developed to test the concepts regarding the percutaneous absorption of piroxicam from topical ointment bases.A reasonably good fit between experimental and calculated values was obtained by taking into account identical absorption rate constant (K_a) and the changes in drug release constant (K_r) and the fraction of drug absorbed (F).We found that piroxicam in the o/w ointment base (UCH ointment containing 12% propylene glycol) had a better percutaneous absorption effect than the other three different kinds of ointment bases which were a simple ointment, PEG ointment and petrolatum rosewater ointment.The pH value of the water phase in UCH ointment containing 12% propylene glycol was adjusted to pH 9.2 by the sodium bicarbonate-buffered solution, then the percutaneous absorption of piroxicam could be increased. The effect of the amount of piroxicam on the percutaneous absorption was also investigated.The optimal effect with the additives in the ointment was finally attained with an addition of 5% urea.     

不同促渗剂对氨氯地平凝胶透皮作用的比较

目的 :考察十二烷基硫酸钠 (SLS)、丙二醇 (PG)作为单一促渗剂和二元促渗剂对氨氯地平体外透皮作用的影响。方法 :用两室扩散池体外实验装置 ,以鼠皮为屏障 ,选用 1%SLS、2 %PG和 1%SLS +2 %PG为促渗剂 ,在各时间下测定氨氯地平的单位面积累积渗透量。结果 :1%SLS、2 %PG和 1%SLS +2 %PG均可促进氨氯地平的透皮吸收 (P <0 .0 1) ,其促渗效果顺序为 1%SLS +2 %PG >2 %PG >1%SLS。结论 :1%SLS和 2 %PG均可不同程度地促进氨氯地平凝胶的透皮吸收效果 ,且二者联用效果更佳。     

Evaluation of in vitro percutaneous absorption of lorazepam and clonazepam from hydro-alcoholic gel formulations

Clonazepam and lorazepam are two anxiolytics, antidepressant agents, having suitable features for transdermal delivery. The objectives of this study were to evaluate the in vitro percutaneous absorption of these drugs through excised human skin (stratum corneum and epidermis, SCE) and to determine their in vitro permeation behavior from a series of hydro-alcoholic gel formulations containing various enhancing agents. The best permeation profile was obtained for both drugs applying them together with Azone in combination with propylene glycol (PG): these enhancers were able to increase the clonazepam and lorazepam percutaneous fluxes at steady-state about threefold, compared to the free enhancer formulations (Control). To explain the mechanism of the used promoters, the benzodiazepine diffusion and partitioning coefficients from the gel containing the enhancers were calculated. The results indicated that the Azone in combination with PG could act by increasing the benzodiazepine diffusion coefficients, Transcutol increased only the SC/vehicle partition coefficients, limonene in combination with PG appeared to increase both partition and diffusion coefficients moderately, while PG did not increase both the parameters. Furthermore, to evaluate the potential application of tested benzodiazepine formulations containing Azone in combination with PG using the flux values from the in vitro experiments, the corresponding steady-state plasma concentrations (C(SS)) were calculated. The obtained calculated C(SS) values are within the lorazepam therapeutic range and suggest that transdermal delivery of this drug could be regarded as feasible.     

Transdermal bioavailability and first-pass skin metabolism: a preliminary evaluation with nitroglycerin

A model comprising six compartments, a systemic and presystemic compartment for nitroglycerin and each of its two dinitrate metabolites is presented to describe the interrelationships between plasma concentrations of the two metabolites and metabolism in skin after intravenous and transdermal ointment administration of nitroglycerin. Using a perfusion-limited pharmacokinetic model, the equation for the calculation of the fraction (F) of the dose of nitroglycerin systemically available from skin was derived independent of nitroglycerin plasma concentrations. Estimated F values (0.68-0.76) are comparable to values reported in Rhesus monkeys (0.80-0.84). Simulated plasma concentration-time profiles were reasonably fitted to the observed concentrations of nitroglycerin and its two metabolites after transdermal administration. This preliminary model suggests that transdermal bioavailability for a drug metabolized in the skin can be reasonably estimated.     

喷昔洛韦凝胶中不同促渗剂对透皮作用的影响

目的:考察聚山梨酯80(Tw80)、丙二醇(PG)作为单一促渗剂和二元促渗剂对喷昔洛韦凝胶体外透皮作用的影响。方法:选用直立式Franz扩散池,以离体鼠皮为屏障,分别采用10％PG,10％PG 1％Tw80,20％PG 1％Tw80为促渗剂,HPLC测定接受液中喷昔洛韦的含量,计算药物累积渗透量。结果:Tw80可促进喷昔洛韦的透皮吸收,不同浓度PG对喷昔洛韦的透皮吸收影响较小。结论:促渗剂Tw80与PG联用效果更佳。     

The feasibility study of transdermal drug delivery systems for antidepressants possessing hydrophilicity or hydrophobicity

The feasibility studies on the transdermal drug delivery systems have been performed to avoid the systemic side-effects and gastric disorders that could be occurred due to the transient high blood concentration after oral administration of antidepressants such as venlafaxine HCl and citalopram. When surfactants of tween 80^? and plasticizer of diethyl phthalate were combined with citalopram?Cethylene vinyl acetate (EVA) matrix, the permeation of citalopram showed the best enhancement. As well as, venlafaxine HCl gels were prepared using carbomer, oleic acid and/or propylene glycol to enhance the skin permeation of venlafaxine HCl. The citalopram-EVA matrix containing tween 80^? and diethyl phthalate as permeation enhancers might be a good transdermal delivery system for providing sustained plasma concentrations of citalopram. Also, venlafaxine HCl showed the possibility to be enhanced skin permeation in the formulation of gels with carbomer including penetration enhancer, oleic acid and/or propylene glycol.     

Transdermal bioavailability and first-pass skin metabolism: A preliminary evaluation with nitroglycerin

A model comprising six compartments, a systemic and presystemic compartment for nitroglycerin and each of its two dinitrate metabolites is presented to describe the interrelationships between plasma concentrations of the two metabolites and metabolism in skin after intravenous and transdermal ointment administration of nitroglycerin. Using a perfusion-limited pharmacokinetic model, the equation for the calculation of the fraction (F)of the dose of nitroglycerin systemically available from skin was derived independent of nitroglycerin plasma concentrations. Estimated Fvalues (0.68–0.76) are comparable to values reported in Rhesus monkeys (0.80–0.84). Simulated plasma concentration-time profiles were reasonably fitted to the observed concentrations of nitroglycerin and its two metabolites after transdermal administration. This preliminary model suggests that transdermal bioavailability for a drug metabolized in the skin can be reasonably estimated.Supported in part by NIH Grant HL 32243.     

Formulation and in vitro/in vivo evaluation of levodopa transdermal delivery systems

This study aims to investigate the feasibility of Levodopa transdermal delivery systems (TDSs). Levodopa TDSs were formulated using various vehicles and permeation enhancers, and in vitro permeation and in vivo pharmacokinetic studies were carried out. In the in vitro study, ester-type vehicles showed relatively high enhancing effects; propylene glycol monocaprylate and propylene glycol monolaurate showed the highest permeation fluxes from both solution and pressure sensitive adhesive (PSA) TDS formulations. Lag time was dramatically shortened with PSA TDS formulations as compared with solution formulations. In the in vivo study, the addition of fatty acids increased blood drug concentrations regardless of the kind or concentration of fatty acid; the AUC_inf increased up to 8.7 times as compared with propylene glycol (PG) alone. PSA TDS containing 10% linoleic acid exhibited prolonged T_max as compared with oral form. Total clearance of L-dopa from PSA TDSs was significantly lower than from oral form (up to 86.8 times). Especially, PSA TDS containing 10% linoleic acid (LOA) revealed 76.2 fold higher AUC_inf than oral administration. Based on our results, the L-dopa PSA TDS containing PG with 10% LOA could be used as a good adjuvant therapy for Parkinson's disease patients who experience symptom fluctuation by L-dopa oral administration.     

透皮促进剂对白花前胡甲素体外经皮渗透的影响

目的:考察透皮促进剂对白花前胡甲素(dl-praeruptorin A,Pd-Ia)体外经皮渗透的影响。方法:采用改进的Franz扩散池,以大鼠离体皮肤为渗透屏障,用高效液相色谱法对Pd-Ia进行含量测定,考察月桂氮酮(Azone)及1%Azone与不同浓度丙二醇(PG)混合物对Pd-Ia透皮吸收的影响。结果:使用Azone对Pd-Ia有促透作用,1%Azone效果较好,平均渗透速率达到4.064μg.cm-2.h-1;1%Azone与15%PG合用促透效果最好,平均渗透速率达到4.889μg.cm-2.h-1,且与单用1%Azone有显著性差异(P<0.05)。结论:1%Azone与15%PG合用时,含0.5%Pd-Ia溶液体外渗透具有最大促透效果,体现出协同作用。     

乙醇和丙二醇单用与联用对曲安奈德喷雾溶液透皮性能的影响

目的 对曲安奈德喷雾溶液进行体外透皮试验,考察乙醇和丙二醇单用与联用时对曲安奈德喷雾溶液体外透皮功能的影响。方法 选取新西兰白兔腹部皮肤,用Franz扩散池法对曲安奈德喷雾溶液进行体外透皮试验,用高效液相色谱法（HPLC）测定曲安奈德含量,用单因素方差分析法对各组间的透皮吸收速率进行对比分析。结果 乙醇和丙二醇联用时的透皮吸收速率均显著高于单用时的透皮吸收速率（P<0.05）,且乙醇和丙二醇联用时对曲安奈德喷雾溶液的促透作用顺序为10%乙醇+25%丙二醇>10%乙醇+20%丙二醇>15%乙醇+25%丙二醇>15%乙醇+20%丙二醇。结论 10%乙醇和25%丙二醇联用时可使曲安奈德喷雾溶液的透皮功能达到最佳化。     

Transdermal delivery of zidovudine: effect of vehicles on permeation across rat skin and their mechanism of action.

The purpose of this study was to investigate the effects of various solvent systems containing water, ethanol, propylene glycol (PG), and their binary combinations on the ex vivo permeation of zidovudine (AZT) across Sprague-Dawley rat skin using Franz diffusion cells at 37 degrees C. Further, saturation solubility and epidermis/vehicle partition coefficient of AZT in the solvent systems, and their effect on percentage hydration of epidermis using thermogravimetric analysis were determined to understand the mechanisms by which these solvent systems change drug permeability properties. All binary combinations of PG, ethanol and water significantly increased saturation solubility of AZT. Maximum AZT flux was observed with 66.6% ethanol among ethanol-water solvents, with 33.3% PG in PG-water solvents and with 100% ethanol among PG-ethanol combinations. PG-water and PG-ethanol solvents neither reduced the lag time nor increased AZT flux across rat skin. In addition, high concentrations of PG in both water and ethanol reduced steady state flux of AZT. Further, thermogravimetric studies revealed that solvents containing high PG concentrations dehydrate epidermis. Among all the solvent combinations, highest flux and short lag time were achieved with ethanol at 66.6% in water and hence is a suitable vehicle for transdermal delivery of AZT.     

Formulation and evaluation of a testosterone transdermal spray

The long-term goal is to develop a spray formulation for transdermal testosterone delivery, and to optimize the drug's skin permeability. Testosterone transport from a series of ethanol/propylene glycol (PG)/water formulations was assessed in vitro across hairless rat skin, and the optimal composition determined. The formulation was then modified for delivery from a mechanical spray, and from an aerosol containing a high percentage of propellant. Drug transport was greatest from a saturated solution in 1:1:1 ethanol/PG/water (1.7 +/- 0.2 microg/cm(2) . h); five spray formulations were then tested, but only 1:1 ethanol/PG achieved a comparable flux. Increasing the % ethanol in the mixture increased evaporation rate but did not alter testosterone delivery. Formulation as an aerosol produced primarily unstable vehicles (phase separation, crystallization). Only 3:1 ethanol/PG remained stable, but no significant improvement in drug transport was observed (testosterone precipitated rapidly at the skin surface). The 1:1:1 ethanol/PG/water saturated solution suggested that some penetration enhancement was possible. Eliminating water to improve sprayability identified 1:1 ethanol/PG as a vehicle, which might allow transient supersaturation (and improved delivery). However, this effect was not improved by using a pressurized aerosol due to instability. Finally, testosterone fluxes were 5 to 10-fold lower than those required for useful transdermal therapy.     

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.     

Percutaneous absorption of diclofenac sodium ointment

In order to allow a high concentration of the drug to reach the lesion, preventing disorders in the digestive tract as a result of the oral administration of an anti-inflammatory steroid-type agent and to attain a sufficient plasma concentration to obtain an effective systemic effect, we prepared ointments and studied the percutaneous absorption of the drug in rabbits. Diclofenac sodium was rarely absorbed precutaneously when given as a simple ointment, hydrophilic ointment, absorption ointment, macrogols ointment described in the Japanese Pharmacopoeia, and carboxyvinylpolymer as gel ointment were used as the ointment bases. Therefore, we used a gel ointment made with methylcellulose as the ointment base and added isopropyl myristate to it as a sorbefacient, obtaining a good plasma concentration. Using the values obtained by the intravenous injection of diclofenac sodium, the parmacokinetics of the plasma concentration obtained by the percutaneous absorption was studied by two-compartment models containing two first-order rate constants. In addition, the retention of this drug in skin and the test for the loss of water and ethanol from the ointment were studied.