Influence of isosorbide dinitrate concentration on its skin permeability from adhesive matrix devices

Use of Silicone Membrane Permeation to Assess Thermodynamic Activities of Ionic Liquids and Their Component Cation and Anion

Ionic liquid (IL) was prepared by mixing lidocaine and ibuprofen as a cation and anion, respectively, at various ratios. We determined the permeation of both compounds from the IL through a silicone membrane selected as a model biological membrane, and mathematically analyzed the permeation data from the viewpoint of the thermodynamic activities of lidocaine, ibuprofen, and the IL. As a result, IL and ibuprofen diffusely permeated through the membrane in the case of applying IL preparations with a molar fraction of ibuprofen of 0.5 or higher. The IL was thought to separate into lidocaine and ibuprofen in the receiver. On the other hand, when applying IL preparations with a molar fraction of lidocaine of 0.5 or higher, IL and lidocaine permeated. The permeation rate of IL itself was maximized when the applied IL was prepared using equimolar amounts of lidocaine and ibuprofen, and it decreased when the fraction of lidocaine or ibuprofen increased by more than 0.5. Their membrane permeation rates increased with an increase in their activity, and no more increase was found when the drugs were saturated in the IL. These membrane permeation profiles reflected well the mathematically calculated ones according to the concept of activity.

Formulation and evaluation of ethylene-vinyl acetate copolymer matrix patches containing formoterol fumarate

The skin permeability and stability of formoterol fumarate (FF) in matrix patches containing l-menthol as an enhancer and N-methyl-2-pyrrolidone (NMP) as the solvent were investigated. Using a total of 28 matrix patches having a similar composition, containing ethylene-vinyl acetate (EVA) as the forming polymer and hydrogenated rosin glycerol ester (Ester Gum H) as the adhesive, the skin permeation of FF was found to increase with increasing l-menthol and NMP contents. FF in the matrix patches containing NMP in the range of 4.8-7.2% was stable, but stability decreased at higher values. With a standard matrix patch containing FF, the Cmax and AUC(0-24) values were found to be 1.93 ng/ml after 4 h percutaneous application to rats and 25.6 ng x h/ml. The bioavailability after percutaneous exposure was equivalent to 15.2% of the AUC(0-24) after intravenous administration. Percutaneous application proved efficacious with regard to control of simulated asthma at dose levels lower than those with which side effects occurred. Thus an optimized matrix patch containing FF was prepared with potential advantages for control of asthma.

Potential usefulness of solubility index for prediction of the skin permeation rate of 5-ISMN from pressure-sensitive adhesive tape

Skin permeation of 5-ISMN from pressure sensitive adhesive (PSA) tape was evaluated using thermodynamic activity of the drug in PSA. Three acrylic adhesives (Gelva 737, Gelva 1430 and Gelva 1753) were used as PSA. Since the drug activity in PSA is difficult to determine, however, a solubility index was defined. Several PSA tapes containing different amounts of 5-ISMN were prepared, and heat of fusion at the dissolution of 5-ISMN in each PSA was determined by DSC. No exothermic peak was found when the drug concentration was less than the solubility in PSA, whereas the heat of fusion increased proportionally with amount of solid drug in the PSA when the drug concentration was above the solubility. The bending point in the profile of heat of fusion versus 5-ISMN content in PSA was defined as the solubility index. In vitro skin permeation was determined using excised hairless rat skin from 5-ISMN-saturated PSA tapes. The obtained skin permeation of the drug decreased with increases in the solubility index. These profiles were confirmed by a theoretical approach using the differential equation corresponding to Fick's second law of diffusion. These results suggested that the solubility index can be utilized for prediction of the skin permeability of drugs from PSA tape.

Transdermal testing: practical aspects and methods

Interest in transdermal drug delivery has increased in recent years owing to its many advantages over other routes of administration. In order to evaluate a transdermal product effectively, three main issues need to be addressed: (1) the kind of skin model that will be used to evaluate the drug permeation; (2) the mathematical model that will be used to characterize the permeation of the drug across the skin; and (3) the diffusion apparatus that will be used to conduct the permeation study.

The chemistry of gamete attraction: chemical structures, biosynthesis, and (a)biotic degradation of algal pheromones

Female gametes of marine brown algae release and/or attract their conspecific males by chemical signals. The majority of these compounds are unsaturated, nonfunctionalized acyclic, and/or alicyclic C11 hydrocarbons. Threshold concentrations for release and attraction are generally observed in the range of 1-1000 pmol. The blends may contain various configurational isomers of the genuine pheromones as well as mixtures of enantiomers. Higher plants produce the C11 hydrocarbons from dodeca-3,6,9-trienoic acid; brown algae exploit the family of icosanoids for biosynthesis of the same compounds. The biosynthetic routes comprise several spontaneously occurring pericyclic reactions such as [3.3]-sigmatropic rearrangements, [1.7]-hydrogen shifts, and electrocyclic ring closures. All pheromones are (a)biotically degraded by ubiquitous oxidative pathways involving singlet oxygen or hydroxyl radicals, which may be produced through the agency of heavy metals, huminic acids, or light.