Phase behaviour of transkarbam 12

Enhanced transdermal delivery of lornoxicam by nanostructured lipid carrier gels modified with polyarginine peptide for treatment of carrageenan-induced rat paw edema

Background: Nanostructured lipid carriers (NLCs) are emerging as attractive drug carriers in transdermal drug delivery. The surface modification of NLCs with cell-penetrating peptides (CPPs) can enhance the skin permeation of drugs.

Purpose: The objective of the current study was to evaluate the ability of the cell-penetrating peptide (CPP) polyarginine to translocate NLCs loaded with lornoxicam (LN) into the skin layers and to evaluate its anti-inflammatory effect.

Methods: The NLCs were prepared using an emulsion evaporation and low temperature solidification technique using glyceryl monostearates, triglycerides, DOGS-NTA-Ni lipids and surfactants, and then six histidine-tagged polyarginine containing 11 arginine (R11) peptides was modified on the surface of NLCs.

Results: The developed NLCs formulated with LN and R11 (LN-NLC-R11) were incorporated into 2% HPMC gels. NLCs were prepared with a particle size of (121.81±3.61)–(145.72±4.78) nm, and the zeta potential decreased from (−30.30±2.07) to (−14.66±0.74) mV after the modification of R11 peptides. The encapsulation efficiency and drug loading were (74.61±1.13) % and (7.92±0.33) %, respectively, regardless of the surface modification. Cellular uptake assays using HaCaT cells suggested that the NLC modified with R11 (0.02%, w/w) significantly enhanced the cell internalization of nanoparticles relative to unmodified NLCs (P<0.05 or P<0.01). An in vitro skin permeation study showed better permeation-enhancing ability of R11 (0.02%, w/w) than that of other content (0.01% or 0.04%). In carrageenan-induced rat paw edema models, LN-NLC-R11 gels inhibited rat paw edema and the production of inflammatory cytokines compared with LN-NLC gels and LN gels (P<0.01).

Conclusion: In our investigation, it was strongly demonstrated that the surface modification of NLC with R11 enhanced the translocation of LN across the skin, thereby alleviating inflammation.

Probing the interactions among sphingosine and phytosphingosine ceramides with non- and alpha-hydroxylated acyl chains in skin lipid model membranes

Ceramides (Cers) are significant constituents of the stratum corneum (SC), the uppermost skin layer responsible for skin barrier properties. Cers are a heterogeneous group of lipids whose mutual interactions are still unclear. To better understand these interactions, we characterized model membranes containing stearic acid, cholesterol, cholesterol sulfate and one or more of the following ceramides: N-stearoyl-sphingosine (CerNS), N-stearoyl-phytosphingosine (CerNP) and N-(2-hydroxy)stearoyl-phytosphingosine (CerAP). Small angle X-ray scattering and FTIR spectroscopy were used to study lipid arrangement, phase separation and thermotropic behaviour. In the one-Cer systems, the membranes with CerNP showed strong hydrogen bonding and significant phase separation, even after phase transition, while the systems containing CerAP and CerNS had increased lipid miscibility. The multi-Cer systems exhibited different behaviour. In particular, the membrane containing all three Cers was a highly miscible system with narrow one-step phase transition, which, of all the studied samples, occurred at the lowest temperatures. Our results show that even a small variation in Cer structure results in substantially different phase behaviour, which is further affected by the presence of other Cer subclasses. Interestingly, the phase behaviour of the most complex three-Cer system was simpler than that of the others, highlighting the importance of lipid diversity in real SC.

Cytotoxicity and enhancement activity of essential oil from Zanthoxylum bungeanum Maxim. as a natural transdermal penetration enhancer

The aim of this present study is to investigate the effect of Zanthoxylum bungeanum oil (essential oil from Z. bungeanum Maxim.) on cytotoxicity and the transdermal permeation of 5-fluorouracil and indomethacin. The cytotoxicity of Z. bungeanum oil on dermal fibroblasts and epidermal keratinocytes was studied using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The rat skin was employed to determine the percutaneous penetration enhancement effect of Z. bungeanum oil on hydrophilic and lipophilic model drugs, i.e., 5-fluorouracil and indomethacin. The secondary structure changes of the rat stratum corneum (SC) were determined using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and saturated solubilities and SC/vehicle partition coefficients of two model drugs with and without Z. bungeanum oil were also measured to understand its related mechanisms of action. It was found that the half maximal inhibitory concentration (IC50) values of Z. bungeanum oil were significantly lower in HaCaT and CCC-ESF-1 cell lines compared to the well-established and standard penetration enhancer Azone. The Z. bungeanum oil at various concentrations effectively facilitated the percutaneous penetration of two model drugs across the rat skin. In addition, the mechanisms of permeation enhancement by Z. bungeanum oil could be explained with saturated solubility, SC/vehicle partition coefficient, and secondary structure changes of SC.

Study on the mechanisms of chitosan and its derivatives used as transdermal penetration enhancers

The efficacy of chitosan (CS) and its derivatives used as transdermal penetration enhancers has been confirmed in our previous research. This study investigated the mechanisms of penetration enhancement by CS and its derivatives, i.e., N-trimethyl chitosan (TMC) with different degree of quaternization (DQ) and mono-N-carboxylmethyl chitosan (MCC). After treatment with CS, TMCs or MCC, the secondary structure changes of keratin in stratum corneum (SC) from mice were examined by an Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) combined with the application of the second-order derivative, deconvolution and curve-fitting. The water content in the SC was also studied by ATR-FTIR. HaCaT cell lines were employed as the cell models in the study. HaCaT cells were first treated with blank D-Hanks solution, CS or its derivatives, and were then fluorescent labeled with DiBAC(4) (3). The change of membrane potential was measured by a flow cytometer (FCM). Alternatively, the treated HaCaT cells were labeled with NBD-C(6)-HPC and the change of membrane fluidity was examined under a Confocal Laser Scanning Microscope (CLSM). It was found that CS, TMCs and MCC could significantly affect the secondary structure of keratin in SC in different ways. Although the amide II absorption peak of keratin moved to a lower wave number following treatment with CS, TMCs, or MCC, the beta-turning structure of keratin was converted to beta-sheeting and random coiling after treatment with TMCs and was converted to beta-sheeting and alpha-helix following treatment with MCC and CS. At the same time, CS and its derivatives all could increase the water content of SC, decrease HaCaT cells membrane potentials and enhance HaCaT cells membrane fluidity significantly. The effect of TMCs appeared to be independent of their DQ. The results suggest that the mechanisms of transdermal enhancement of CS, TMCs and MCC are closely related to their effects on the secondary structure of keratin and water content in SC, cell membrane potential and fluidity.

Synthesis and transdermal permeation-enhancing activity of carbonate and carbamate analogs of Transkarbam 12

Transkarbam 12 (5-(dodecyloxycarbonyl)pentylammonium-5-(dodecyloxycarbonyl)pentylcarbamate, T12) is a highly effective skin permeation enhancer. In this study, ester groups in the molecule of T12 were replaced by carbonate and carbamate ones, respectively. The in vitro permeation-enhancing activities were evaluated using porcine skin and compared with those of T12 and previously prepared series of amide, ketone, and alkyl analogs. According to the activities and behavior of the compounds in donor samples, ester group is essential for the activity of T12; its replacement not only decreases the enhancing potency, but is likely to change the mechanism of action.

Preliminary pharmaceutico-analytical evaluation of Transkarbam 12 using liquid chromatography

This paper deals with the search for optimal conditions for the identification of Transkarbam 12 (T 12) as a substance used for acceleration of transdermal penetration. Such substances are used in cases when drugs do not pass through the skin barrier under normal conditions. Other advantages are that they do not irritate the digestive system, provide continuous administration to an organism, and reduce fluctuations of drug concentration in blood. TLC and HPLC were used for identification. In the case of TLC, Silufol UV254 was used as stationary phase and the mobile phase consisted of chloroform, ethanol, and acetic acid. Detection was performed with iodine vapour. In the case of HPLC, the following three chromatographic columns were tested for the analysis of T 12: Silasorb SPH C 18, Silasorb SPH nitrile, and LiChrosorb Si-60. Because of the absence of any chromophore in the structure of T 12, work was performed on the derivatized compound. Detection was carried out at 230 nm. Quantification was studied on LiChrosorb Si-60 and the linearity, precision, and accuracy were evaluated.

Optimization of HPLC chromatographic conditions for determination of Transkarbam 12 and its degradation products

This paper deals with searching of HPLC chromatographic conditions for determination and separation of Transkarbam 12 (T 12) and its two main degradation products (omega-aminocaproic acid and dodecylalcohol). T 12 is a new substance which belongs to the group of accelerators of transdermal penetration. Chromatographic separation was achieved using Separon SGX C18 analytical column (150 mm x 3 mm i.d.; 5 microm). Mobile phase contained acetonitrile and sodium acetate buffer pH 4.5 at the flow rate of 1 ml/min. Separation was carried out under the conditions of gradient elution. After the modification of the structure by derivatization reagent (3,5-dinitrobenzoyl chloride) detection at wavelength 230 nm was realized. The aim of this study was not only the optimization of the separation of derivatization reagent and derivatized T 12, Ak and D but also optimal derivatization processes for all three substances.

Synthesis and Enhancing Effect of Transkarbam 12 on the Transdermal Delivery of Theophylline, Clotrimazole, Flobufen, and Griseofulvin

PURPOSE

Dodecyl-6-aminohexanoate (DDEAC) is a transdermal permeation enhancer with excellent activity, low toxicity, and no dermal irritation. We hypothesized that DDEAC reacts with air CO2 to form a two-chain ammonium carbamate--Transkarbam 12 (T12)--which is responsible for the enhancing effect.

METHODS

DDEAC and T12 were synthesized, their structures were confirmed by spectral methods, and their enhancing activity was studied using the Franz diffusion cell and human skin. A high-performance liquid chromatography method was developed for determination of T12, and its biodegradability was evaluated using porcine esterase.

RESULTS

Only the carbamate salt T12 was responsible for the high enhancing activity; DDEAC tested under argon to avoid reaction with CO2 was inactive. T12 enhanced transdermal permeation of drugs covering a wide range of physicochemical properties, including theophylline (enhancement ratio up to 55.6), clotrimazole (7.7), flobufen (5.0), and griseofulvin (24). The activity was pH-dependent, further confirming the importance of the carbamate structure. The metabolization of T12 followed a second-order kinetics with t(1/2) = 31 min.

CONCLUSION

Our results indicate that T12 is a promising biodegradable permeation enhancer for a wide range of drugs, and the structurally novel group of carbamate enhancers warrants further investigation.

Synthesis and transdermal permeation-enhancing activity of ketone, amide, and alkane analogs of Transkarbam 12

Transkarbam 12 (5-(dodecyloxycarbonyl)pentylammonium-5-(dodecyloxycarbonyl)pentylcarbamate, T12) is a highly active transdermal permeation enhancer. In this study, ketone, amide, and alkane analogs of T12 have been synthesized and evaluated for their permeation-enhancing activity using porcine skin and theophylline as a model drug. Replacement of ester by methylene and ketone, respectively, led to a significant decrease of activity. Amide analogs displayed lower activity in 60% propylene glycol and were comparable to T12 in isopropyl myristate. An intramolecular H-bond between ester and ammonium-carbamate group was suggested to be important for the permeation-enhancing activity of T12.

Synthesis and transdermal penetration-enhancing activity of carbonic and carbamic acid esters—Comparison with transkarbam 12

Transkarbam 12 (T12) is a novel transdermal penetration enhancer with high activity. Its polar head group is formed by carbamic acid salt that is unstable in acidic environment and releases CO(2). To find out whether this property influences its high activity, two series of compounds with CO(2) stronger bound in the polar head have been prepared-carbonic and carbamic acid esters. The carbamate salt in the polar head was found to be essential for the enhancing activity and its decomposition in an acidic environment suggested relating to the mode of action of T12.