In recent years, plasma treatments have presented good results since they offer high-tech efficiency with low waste generation. One of the most important characteristics of plasma methods is their action only on a thin surface layer, whereas the bulk of sample remains unchanged and the modified material keeps its chemical and mechanical properties. In this research, polyurethane membrane surface was modified by low-frequency plasma grafting with methacrylic acid and acrylamide monomers to alter solution-diffusion mechanism. We chose different parameters of plasma treatment and studied their effects toward maximum solubility, permeation, and selectivity. The grafting on the surfaces was characterized by water contact angle measurement and atomic force microscopy. After confirming a successful grafting, we studied the effect of surface modification on permeation of CH4 and CO2. Significant increase in CO2 permeation and about 32 percent increase in CO2/CH4 selectivity were observed. Better results were obtained for low powers and acrylamide grafted surface.

Transdermal drug delivery (TDD) is a non-invasive, topical administration method for therapeutic agents. Transdermal delivery also has advantages including providing release for long periods of time, improving patient compliance, and generally being inexpensive. Despite these advantages, the use of TDD has been limited by innate barrier functions of the skin. Only small (<500 Da), lipophilic molecules can passively diffuse through the skin. As a result of the barrier function of the skin, passive transdermal delivery has primarily been limited to small molecules. The skin, which consists of several layers including the stratum corneum, other epidermal layers, and dermis, is the primary defense system of the body. The main barrier to therapeutic delivery is the outermost layer of the skin, the stratum corneum. As a result, various methods of skin permeabilization have been explored for their ability to enhance the transport of drugs across the stratum corneum. Scientists evaluated new drug delivery systems such as nano-carriers and drug delivery systems and enhancer methods such as penetration enhancers.The purpose of drug delivery systems are to deliver sufficient drug molecules into the skin with maximum stability and minimal toxicity. To guarantee successful transdermal drug delivery, a drug delivery system must exhibit several essential properties including drug protection, targeted drug delivery, biocompatibility and biodegradability.This paper reviews transdermal drug delivery systems, recent enhancement techniques to optimize drug delivery such as microneedles and especially vesicular systems. Herein, we focus on the differences in their composition, physicochemical properties and applications of those drug delivery systems. We hope recent innovations can work as a foundation for further research and development in transdermal drug delivery system.

Minoxidil, a pyrimidine derivative (2, 4-diamino-6-piperidinopyrimidine-3-oxide) is the only topical medical treatment with proven efficacy for the treatment of androgenic alopecia that showed low skin penetration and bioavailability. The main aim of this research was to investigate the effect of some permeation enhancers on the in vitro skin permeability of minoxidil. Minoxidil permeability experiments through rat skin pretreated with some of permeation enhancers namely, Urea, Eucalyptus oil and Menthol were performed in fabricated Franz diffusion cells and compared with hydrated rat skin as control. The permeability parameters evaluated include steady-state flux (Jss), permeability coefficient (Kp), and diffusion coefficient (D). The penetration enhancer’ s permeability enhancement mechanisms were investigated by comparing of changes in peak position and their intensities of asymmetric (Asy) and symmetric (Sym) C-H stretching, C=O stretching, C=O stretching (Amide I) and C-N stretching of keratin (Amide II) absorbance using Fourier transform infrared spectroscopy (FTIR), as well as by comparing mean transition temperature (Tm) and their enthalpies (Δ H) using differential scanning calorimetry (DSC). Minoxidil permeability parameters through rat skin, were evaluated with and without chemical enhancers such as Eucalyptus oil, menthol, and urea. The skin showed barrier for minoxidil permeability through whole skin and that diffusion into the skin was the rate-limiting step for drug flux. Urea, Eucalyptus oil, and Menthol were the most effective enhancers as they increased flux 1. 86, 2. 16, and 1. 75 times and diffusion coefficient 3. 25, 1. 34 and 2. 16 folds in comparison with hydrated skin, respectively. FTIR and DSC results showed lipid fluidization, extraction, disruption of lipid structure and irreversible denaturation of proteins in the SC layer of skin by permeation enhancers.

Objective(s): In this study, a kind of pH sensitive composite membrane was prepared and drug permeation through it was investigated in terms of pH. Rationale of this study originated from the fact that a pH change which may be a result of a disease state in the body can trigger drug release.Materials and Methods: Here, a kind of pH sensitive composite membrane containing different nanoparticle [1: 1 n-isopropyl acrylamide (Nipam): metacrylic acid (Maa)] contents in ethylcellulose was prepared by a casting method.Swelling ratios of these nanoparticles and composite membranes with different particle loadings were determined. Permeation of two different drug models with different hydrophilicity and molecular weights, vitamin B12 (vit B12) and paracetamol, through these membranes was studied in terms of pH. Results: It was seen that swelling ratios of nanoparticles and the composite membranes went up as the particle content increased at each pH. Vit B12 and paracetamol permeation through the membranes in pH value below the pKa was much higher than that at pHs above it, but this difference was much more pronounced for vit B12 compared to paracetamol.Conclusion: Permeation through these membranes showed a sharp sensitivity to pH changes. Nanoparticles in the composite membranes could act as nanovalves due to their sharp swelling/shrinkage around the pKa of Maa. These membranes could be considered as an ideal stimuli-sensitive barrier for modulating drug release with a small change in pH.

Background: A novel liposomal pilocarpine formulation as an ophthalmic drug delivery system has been designed to treat patients with glaucoma. The purpose of the present study was to formulate and evaluate liposomes loaded with pilocarpine and to evaluate permeation through rabbit cornea. Method: Liposomes containing pilocarpine were prepared using thin film method. The quantities of soya lecithin and cholesterol were changed to enhance the encapsulation of the drug. The physicochemical properties of the prepared liposomes were evaluated according to their viscosity, pH, particle size, in vitro drug release, and transcorneal rabbit permeation. Dialysis membrane method was utilized to assess drug release profile. Results: The results indicated that the mean particle sizes of liposomes were 120. 5-212 nm and the pH and viscosity of formulations were in the range of 6. 30-6. 63 and 43. 85-80. 1 cps, respectively. According to the release study results, maximumally 60% of the drug released from liposomal formulations after 24 hours of the experiment. Also, the cumulative percentage of the drug permeated through rabbit cornea was differing from 3. 86 to 14. 9%. Irrespective from the composition and characteristics of the different liposomal formulations, they significantly increased the drug partitioning, permeability coefficient and flux of pilocarpine in rabbit cornea ex vivo model in comparison to control drug solution. Conclusion: The present study proved that any alteration in composition and nature of pilocarpine liposomal formulations may affect the drug permeability parameters through corneal membrane and also physico-chemical properties. It is probably due to the change in corneal structure in the presence of different liposomes composition.