Transdermal Iontophoretic Delivery of Vapreotide Acetate AcrossPorcine Skin in Vitro

Abstract

Based on the observed transport rate of vapreotide across porcine epidermis and its clinical pharmacokinetics, therapeutic concentrations should be achievable using a 15-cm2 patch.

Transdermal Delivery of Cytochrome C—A 12.4 kDa Protein—Across Intact Skin by Constant–Current Iontophoresis

“…The impact of electrical current on the stability of Cyt c solutions was evaluated prior to the iontophoretic permeation studies. 5 ml of unbuffered protein solution (8.7 mg.ml j1 (0.7 mM), typical concentration for the permeation studies, pH 8.2) was subjected to a current density of 0.5 mA.cm j2 using salt bridges (20). Samples were collected and analysed every hour for a period of 8 h. Experiments were performed in triplicate.…”

“…Dermatomed skin was clamped in threecompartment vertical flow-through diffusion cells (area 0.85 cm 2 ). The anode (containing PBS buffer at pH 7.4) was isolated from the donor solution via a salt bridge (SB) assembly (3% agarose in 0.1 M NaCl) to minimize the effect of competing ions (20). After a 40 min equilibration period with PBS, 1 ml of unbuffered peptide solution containing Cyt c (0.7 mM, pH 8.2) and ACE (15 mM) was placed in the donor compartment.…”

Richard Guy and His Collaborators: ‘Crackling' the Skin Code

“…I particularly recommend the superb 5-fluorouracil series summarized in figure 5[106], the work on the 5-aminolevulinic acid esters [109], and that on the relative contribution of electro-osmosis and electrorepulsion [21]. Later, the group provided further insight into transport numbers during transdermal iontophoresis [110,111,112,113], an aspect which had been relatively neglected in the field, and into peptide iontophoretic transport [114,115,116,117,118,119,120,121] presenting new structure-transport relationships. On the whole, the extensive work by Guy and collaborators provided a better understanding of drug iontophoretic transport and its rational optimization.…”

The Pharmaceutical Biochemistry Group: Where Pharmaceutical Chemistry Meets Biology and Drug Delivery

“…herpes labialis [71] and the local delivery of anti-oxdiants [72] ) and for systemic effect (e.g. migraine [73,74] and chemotherapy-induced emesis [75][76][77] ), therapeutic peptides (triptorelin and vapreotide), [78,79] and conducted mechanistic studies that resulted in the first published reports on the non-invasive transdermal delivery of functional proteins across the skin. [80][81][82][83] Experiments with valaciclovir, a cleavable valine ester prodrug of aciclovir with superior oral bioavailability, showed that its transdermal iontophoresis resulted in several hundred-fold increases in aciclovir delivery due to the charged amino group.…”