PubMed · 15795682
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2005-03-28. Elidel and protopic.. https://pubmed.ncbi.nlm.nih.gov/15795682/
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The goal was to explore whether the incorporation of antinucleant polymers into a testosterone spray formulation could stabilize a putative supersaturated state and improve the delivery of the drug across the skin. Several antinucleants were screened using differential scanning calorimetry (DSC) and two candidates showed particular promise: a cyclodextrin derivative (RAMEB) and a vinylpyrrolidone/vinyl acetate copolymer (Kollidon VA64). These agents also improved significantly the long-term stability of saturated solutions of the drug. Further, using the method of mixed cosolvents, it was possible to create, in the presence of 5% w/v antinucleant polymer, supersaturated ethanol/propylene glycol/water (4:1:1 v/v) solutions of the drug with degrees of saturation between 1.4 and 2.6; however, these metastable systems existed only transiently under carefully controlled conditions and had reverted back to equilibrium solubilities of the drug within 6 h. When the same solutions were administered to hairless rat skin in vitro from mechanical sprays, no improvement in testosterone delivery, relative to a nonstabilized control, was observed. It appears, therefore, that the in situ crystallization process of the drug is more complex and incompletely understood (and cannot be predicted from DSC experiments). The complicated evaporation/volatilization process, which takes place when a spray is pulverized, requires better characterization before the use of supersaturation for testosterone delivery can be optimized.
One major problem encountered in transdermal drug delivery is the low permeability of drugs through the skin barrier. In the present investigation ultradeformable lipid vesicles, that is, elastic liposomes were prepared incorporating propranolol hydrochloride for enhanced transdermal delivery. Elastic liposomes bearing propranolol hydrochloride were prepared by conventional rotary evaporation method and characterized for various parameters including vesicles shape and surface morphology, size and size distribution, entrapment efficiency, elasticity, turbidity, and in vitro drug release. In vitro flux, enhancement ratio (ER), and release pattern of propranolol hydrochloride were calculated for transdermal delivery. In vivo study conducted on male albino rats (Sprague Dawley) was also taken as a measure of performance of elastic liposomal, liposomal, and plain drug solution. The better permeation through the skin was confirmed by confocal laser scanning microscopy (CLSM). Results indicate that the elastic liposomal formulation for transdermal delivery of propranolol hydrochloride provides better transdermal flux, higher entrapment efficiency, ability as a self-penetration enhancer and effectiveness for transdermal delivery as compared to liposomes.
PURPOSE: In clinical practice heparin has to be administered by injection with obvious disadvantages; thus, transdermal delivery by electrically assisted methods have been studied. In this study we evaluated the efficacy of a Food and Drug Administration-approved pulsed current iontophoresis system in delivering heparin through living rat skin. METHODS: Fluorescent and radioactive heparin as well as a commercial heparin preparation were delivered through rat skin via a pulsed current iontophoresis system. RESULTS: Pulsed current iontophoresis allowed fluorescent heparin to cross the stratum corneum localizing in epidermis and dermis. Unfractionated, high-, and low molecular weight fraction pools, obtained by fractionating [35S]-unfractionated heparin on a molecular weight sieve, were then separately tested. Pulsed current iontophoresis elicited the transdermal delivery of low molecular weight heparin, but not that of high molecular weight heparin. Finally, pulsed current iontophoresis of an unfractionated pharmaceutical heparin preparation significantly decreased plasmatic factor Xa activity. CONCLUSIONS: We hypothesize that this technique could be used to administer low molecular weight heparin in a cost-efficient and safe manner without the need for syringes and needles.