The study was performed to evaluate the percutaneous penetration of ketoprofen after transdermal administration using a microdialysis technique in pigs, in comparison with rats. Ketoprofen release from patches was determined by analysis of the remaining drug content after application to hairless rats and pigs. Skin and knee joint penetration of ketoprofen was tested by microdialysis, and recovery was determined by retrodialysis. Residual rates in hairless rats and pigs were 68.1 ± 1.6% and 81.7 ± 4.4%, respectively, at 10h. The average recoveries of ketoprofen over 480 min in the skin and knee joint cases were 72.0 ± 3.4% and 9.8 ± 6.2% in rats and 72.3 ± 2.5% and 57.6 ± 3.1% in pigs, respectively. In rats, ketoprofen was rapidly absorbed with transdermal administration, with C(max) values of 191.7 ± 76.2 and 35.5 ± 21.7 ng/mL and AUC(0-8h) values of 918.2 ± 577.5 and 195.9 ± 137.1 ngh/mL, respectively, for the skin and knee joint. The C(max) values for the pig were 20.9 ± 18.5 and 3.7 ± 3.0 ng/mL, with AUC(0-8h) values of 73.1 ± 69.2 and 16.1 ± 16.1 ngh/mL. Ketoprofen concentrations within skin and knee joint of non-application sites in rats and pigs were less than 0.8 ng/mL. Transdermal administration of ketoprofen significantly reduced prostaglandin E2 levels in the skin of the application site and showed a tendency for inhibition in the knee joint. We thus demonstrated that topical patches containing ketoprofen can deliver the drug through the skin and knee joint of pigs and rats via direct diffusion, and microdialysis data with the pig may be useful for the prediction of human tissue penetration of drugs with transdermal administration.
Oligoarginines, which are known as cell-penetrating peptides, enhance the cellular uptake of poorly membrane-permeable bioactive molecules that are chemically conjugated to them. We designed a novel polymer: oligoarginine-linked poly(N-vinylacetamide-co-acrylic acid), with the expectation that the polymers will enhance the cellular uptake of the bioactive molecules that are physically mixed with them. Oligoarginines were grafted onto the polymer backbone through the chemical reaction with acrylic acid functional groups. The changes in the blood glucose concentration after nasal administration of insulin with and without the polymer were monitored in mice. The blood glucose concentration was slightly reduced when insulin was given solely at a dose of 10IU/kg. A D-octaarginine-linked poly(N-vinylacetamide-co-acrylic acid) with a grafting degree of 2% significantly enhanced the insulin-induced hypoglycemic effect. A similar enhancement was not observed when the polymer was substituted with intact D-octaarginine. The penetration-enhancing function of D-octaarginine-linked poly(N-vinylacetamide-co-acrylic acid) increased dramatically with an increase in the grafting degree of D-octaarginine. Substitution of D-octaarginine with the corresponding optical isomer and an increase in the number of arginine residues rather reduced the penetration-enhancing function. In vitro cell studies also indicated that a D-octaarginine-linked poly(N-vinylacetamide-co-acrylic acid) with a grafting degree of 17% enabled fluorescein isothiocyanate-dextran to effectively penetrate the cell membrane. Results demonstrated that our oligoarginine-linked polymer has a potential to provide a new class of penetration enhancers.
The androgen receptor (AR) is the main therapeutic target for treatment of metastatic prostate cancers. The present study demonstrates that the topoisomerase I inhibitor camptothecin selectively inhibits androgen-responsive growth of prostate cancer cells. Camptothecin strikingly inhibited mutated and wild-type AR protein expression in LNCaP and PC-3/AR cells. This inhibition coincided with decreased androgen-mediated AR phosphorylation at Ser(81) and reduced androgen-mediated AR transcriptional activity in a dose-dependent manner. Additionally, camptothecin disrupted the association between AR and heat shock protein 90 and impeded binding of the synthetic androgen [3H]R1881 to AR in LNCaP cells. Camptothecin also blocked androgen-induced AR nuclear translocation, leading to downregulation of the AR target gene PSA. In addition to decreasing the intracellular and secreted prostate-specific antigen (PSA) levels, camptothecin markedly inhibited androgen-stimulated PSA promoter activity. Collectively, our data reveal that camptothecin not only serves as a traditional genotoxic agent but, by virtue of its ability to target and disrupt AR, may also be a novel candidate for the treatment of prostate cancer.
Pharmacokinetics of pilsicainide transdermal patch and its electropharmacological effects were simultaneously assessed using chronic atrioventricular block dogs. After application of the patch (9.8 mg/kg), pilsicainide was continuously absorbed through the skin with a C(max) of 0.49 +/- 0.13 microg/ml, while its plasma concentration was kept above the clinically reported minimum effective plasma concentration for 2 - 8 h. Inter-atrial conduction time was significantly prolonged, whereas statistically significant prolongation was not detected in the atrial effective refractory period. Prolongation of the cycle length of atrial fibrillation and anti-fibrillatory action were confirmed. Thus, pilsicainide can be absorbed transdermally to exert long-lasting electropharmacological effects leading to anti-atrial fibrillatory action.
We evaluated the potential of poly(N-vinylacetamide-co-acrylic acid) modified with d-octaarginine, which is a typical cell-penetrating peptide, as a carrier for mucosal vaccine delivery. Mice were nasally inoculated four times every seventh day with PBS containing ovalbumin with or without the d-octaarginine-linked polymer. The polymer enhanced the production of ovalbumin-specific immunoglobulin G (IgG) and secreted immunoglobulin A (IgA) in the serum and the nasal cavity, respectively. Ovalbumin internalized into nasal epithelial cells appeared to stimulate IgA production. Ovalbumin transferred to systemic circulation possibly enhanced IgG production. An equivalent dose of the cholera toxin B subunit (CTB), which was used as a positive control, was superior to the polymer in enhancing antibody production; however, dose escalation of the polymer overcame this disadvantage. A similar immunization profile was also observed when ovalbumin was replaced with influenza virus HA vaccines. The polymer induced a vaccine-specific immune response identical to that induced by CTB, irrespective of the antibody type, when its dose was 10 times that of CTB. Our cell-penetrating peptide-linked polymer is a potential candidate for antigen carriers that induce humoral immunity on the mucosal surface and in systemic circulation when nasally coadministered with antigens.
We are investigating a new class of penetration enhancers that enable poorly membrane-permeable molecules physically mixed with them to effectively penetrate cell membranes without their concomitant cellular uptake. Since we previously revealed that poly(N-vinylacetamide-co-acrylic acid) modified with d-octaarginine, which is a typical cell-penetrating peptide, significantly enhanced the nasal absorption of insulin, we examined the performance of the polymers on cell membranes. When Caco-2 cells were incubated with 5(6)-carboxyfluorescein (CF) for 30 min, approximately 0.1% of applied CF was internalized into the cells. This poor membrane permeability was dramatically enhanced by d-octaarginine-linked polymers; a 25-fold increase in the cellular uptake of CF was observed when the polymer concentration was adjusted to 0.2mg/mL. None of the individual components, for example, d-octaarginine, had any influence on CF uptake, demonstrating that only d-octaarginine anchored chemically to the polymeric platform enhanced the membrane permeation of CF. The polymer-induced CF uptake was consistently high even when the incubation time was extended to 120 min. Confocal laser scanning microphotographs of cells incubated with d-octaarginine-linked polymers bearing rhodamine red demonstrated that the cell outline was stained with red fluorescence. The polymer-induced CF uptake was significantly suppressed by 5-(N-ethyl-N-isopropyl)amiloride, which is an inhibitor of macropinocytosis. Results indicated that d-octaarginine-linked polymers remained on the cell membrane and poorly membrane-permeable CF was continuously internalized into cells mainly via macropinocytosis repeated for the individual peptidyl branches in the polymer backbone.
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