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.

Purpose: Due to limited oral bioavailability of doxorubicin (Dox) many efforts during the last decades focused on the development of novel delivery systems to overcome these limitations. In the present study, Dox encapsulated chitosan nanoparticles were prepared to evaluate the intestinal permeation of Dox via oral administration. Methods: Nanoparticles were fabricated based on ionic gelation method using tripolyphosphate. Some physicochemical properties, such as nanoparticle size and morphology, loading efficiency and in vitro drug release in 3 different pH values (5. 0, 6. 8 & 7. 4) were evaluated. Intestinal permeations of free Dox and Dox loaded in nanoparticles were assessed using rat intestinal sac model. Results: The nanoparticles were spherical shape with average size of 150 ± 10 nm. The entrapment and loading efficiency of Dox were up to 40% and 23%, respectively. According to the release profiles, up to 30% of loaded drug was released within 6hrs and the remaining amount of Dox was released more gradually, but this pattern was related to pH of the medium. The amount of drug released at acidic condition (pH 5. 0) was greater than other pHs. The intestinal permeation of Dox increased nearly up to 90% by loading in chitosan nanoparticles. Conclusion: Using chitosan nanoparticles presents a potential safe drug delivery system for oral administration of Dox. In vivo studies and the determined pharmacokinetic and pharmacodynamic of Dox loaded chitosan nanoparticles after oral administration are planned for future studies.

A gas permeation model (Coupling Model) has been developed which has the flexibility to be used for different membrane module configurations. The aim of this work is to predict the performance of a single stage gas separation process using membranes and provide a comprehensive description of process parameters like flow rates, composition, stage cut and stream pressure. The significant feature of this work is the development of computational technique which combines the counter-current flow mode with co-current flow mode. In contrary to other counter-current models (reported in literature), the model reported in this work (Coupling Model) does not require initial conditions to start and also it is independent of any adjustment technique like shooting method. This model is based on real membrane operation and works by the coupling of co-current and counter-current methods. After each iteration, output values of co-current mode become the input values for counter-current mode. This model has the capability to take upto nine components, whereas model reported in literature can handle 4-5 components in a gas mixture to be separated. The results obtained are validated with the published data and will be discussed to elaborate the operation of a gas separation membrane.

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.

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.