Absorption characteristics of compounds with different molecular weights after application to the unilateral kidney surface in rats

The aim of the present study is to clarify the absorption mechanism of a drug from the kidney surface membrane in rats. We studied the absorption characteristics of phenolsulfonphthalein (PSP) and other compounds with different molecular weights after their application to the rat kidney surface in vivo, employing a cylindrical diffusion cell (i.d. 6 mm, area 0.28 cm2). The time course of free PSP amounts remaining in the diffusion cell obeyed first-order kinetics at a dose of 1 mg, and its rate constant ka was calculated to be 0.0137 min?1. Absorption ratios of PSP in 4 h were calculated (from the amount recovered from the diffusion cell) to be 91.4, 96.4 and 97.7% at doses of 0.5, 1 and 1.5 mg, respectively. The area under the curve for the plasma concentration profile of free PSP was proportional to the application dose. It is thus suggested that the absorption process of PSP from the rat kidney surface does not approach saturation at a dose of 1.5 mg. Also, no significant difference was seen in the ka values within the dose range of 0.5?1.5 mg, which were estimated by curve-fitting the plasma concentration profiles of free PSP in a two-compartment model with first-order absorption. Furthermore, we examined the importance of molecular weight on the absorption from the kidney surface using fluorescein isothiocyanate-dextrans (FDs) with molecular weights of 4400 (FD-4), 11,000 (FD-10), 40,500 (FD-40) or 69,000 (FD-70), including the organic anions bromphenol blue and bromosulfonphthalein. The absorption ratios of FDs from the rat kidney surface in 6 h decreased with an increase in the molecular weight (76.1% for FD-4, 54.4% for FD-10, 11.5% for FD-40 and 3.9% for FD-70). A linear relationship was observed between ka and the reciprocal value of z the square root of the molecular weight of these compounds. The limit of absorption from the rat kidney surface was extrapolated to be at a molecular weight of approximately 130,000

Absorption characteristics of model compounds from the small intestinal serosal surface and a comparison with other organ surfaces

We examined the absorption of phenolsulfonphthalein (PSP) and fluorescein isothiocyanate dextrans (FD-4, MW 4,400; FD-10, MW 9,500; FD-40, MW 40,500) as model compounds through the small intestinal serosal surface. After application to the rat small intestinal serosal surface using a cylindrical diffusion cell, each compound was absorbed at different rates. The absorption ratios in 6 h after PSP, FD-4, FD-10 and FD-40 application were calculated to be 89.2, 34.6, 14.9 and 2.1 % of dose, respectively. Elimination profiles of PSP, FD-4 and FD-10 from the small intestinal serosal surface obeyed first-order kinetics. Moreover, we calculated the apparent permeability coefficient Papp for comparison to other organ surfaces. The kidney had the highest absorption efficiency, as shown by having more than 1.5 times significantly higher Papp values of PSP, FD-4 and FD-10. Similar to the other organ surfaces, a correlation was observed between the Papp of small intestine and the molecular weight of these hydrophilic compounds. In addition, the small intestine is likely to contribute largely to hydrophilic compounds absorption from the peritoneal cavity, judging from absorption clearance CLa calculated by utilizing the peritoneal organ surface area

Absorption of phenolsulfonphthalein as a model across the mesenteric surface in rats to determine the drug absorption route after intraperitoneal administration

The purpose of this study is to clarify absorption characteristics of a drug across the mesenteric surface which occupies a large area of absorption in the peritoneal cavity in order to determine the drug absorption route after intraperitoneal administration. Absorption of phenolsulfonphthalein (PSP) as a model after application to the mesenteric surface was investigated in rats, by employing a cylindrical diffusion cell attached to the mesentery with or without blood vessels. PSP was absorbed from the rat mesenteric surface, followed by its appearance in the plasma and bile, regardless of blood vessel existence. The absorption ratios of PSP in 6 h were calculated to be 92.1 % and 83.6 % from the mesenteric surface with and without blood vessels, respectively. We then employed an experimental system by sticking a polyethylene cap (PE cap) on the surface of the other side to exclude the influence of absorption of the drug from the other organ surfaces that penetrated across the mesentery. The PE cap-sticking decreased the appearance of PSP in the plasma from the mesenteric surface with blood vessels and eliminated the PSP absorption completely from the mesenteric surface without blood vessels. Accordingly, blood vessels on the mesenteric surface actually play an important role in drug absorption, but the contribution of the mesenteric surface to drug absorption from the peritoneal cavity is unlikely to be significant due to there being a small effective area of blood vessels

In Vivo Ocular Pharmacokinetic Model for Designing Dosage Schedules and Formulations of Ophthalmic Drugs in Human

The purpose of this study was to develop an in vivo pharmacokinetic model and parameters for predicting the concentrations of ophthalmic drugs in the anterior chamber after instillation into human eyes. We have already reported the usefulness of mathematical model including a diffusion process in rabbits 1). Timolol was used as a model ophthalmic drug. The concentrations of timolol and fluorescein in the tear fluid were determined after instillation into the eyes of human volunteers. The in vivo pharmacokinetic parameters in the tear fluid were estimated by the elimination profile according to a one-compartment model. The concentrations of timolol in the aqueous humor were obtained from the data previously reported 2),3). Other parameters of timolol were estimated from the concentration profiles of timolol in the aqueous humor according to a pharmacokinetic model including a corneal diffusion process. The parameters for human were almost equal to those for rabbits reported previously 1). This mathematical model and in vivo parameters will be effective to estimate the adequate regimen for ophthalmic chemotherapy and develop the ocular drug delivery systems

Effect of instillation method on the absorption of phenolsulphonphthalein as a model drug from the liver and small intestinal serosal surface in rats

The aim of this study is to examine the effect of the instillation method on absorption of a drug from the liver and small intestinal serosal surface in rats. We performed continuous microinstillation via an infusion pump and bolus instillation via a syringe. Phenol red as a model was absorbed after continuous microinstillation of 2.35 mg in 235 ?L for 5 min on the liver and small intestinal serosal surface in rats with a significantly higher AUC of the plasma concentration profile until 60 min, compared with that after bolus instillation. A similar trend was observed after continuous microinstillation of 2.35 mg in 117.5 ?L for 2.5 min. The calculated absorption rate constants Ka after continuous microinstillation of phenol red based on a two-compartment model with first-order absorption were higher than those after bolus instillation on the liver and small intestinal serosal surface at either instillation concentration. Moreover, Ka was increased after continuous microinstillation of 2.35 mg in 117.5 ?L on either instillation site. In the comparison between instillation sites, instillation of phenol red on the liver surface resulted in 1.2 to 2.3-fold higher Ka, compared to small intestinal serosal surface. This tendency was marked after continuous microinstillation of 2.35 mg in 117.5 ?L. In conclusion, absorption could be enhanced by instilling a small amount of drug solution on the liver surface gradually and continuously, suggesting a promising approach for instillation site-selective drug delivery in the peritoneal cavity

Highly stomach-selective gene transfer following gastric serosal surface instillation of naked plasmid DNA in rats.

BACKGROUND: The purpose of this study was to achieve stomach-selective gene transfer in rats by our simple and novel administration method, which is gastric serosal surface instillation of naked plasmid DNA (pDNA). METHODS: Naked pDNA encoding firefly luciferase as a reporter gene was instilled onto the gastric serosal surface in male Wistar rats. As controls, we performed intraperitoneal, intragastric and intravenous administration of naked pDNA. At appropriate time intervals, we measured luciferase activities in the stomach and other tissues. RESULTS: Gene expression in the stomach 6 h after gastric serosal surface instillation of naked pDNA (5 microg) was significantly higher than that after using other administration methods. The present study is the first report on stomach-selective gene transfer following instillation of naked pDNA onto the gastric serosal surface in rats. Also, the gene expression level in the stomach 6 h after gastric serosal surface instillation of naked pDNA was markedly higher than that in other tissues. In a dose-dependent study, the gene expression level was saturated over 5 microg. Gene expression in the stomach was detected 3 h after gastric serosal surface instillation of naked pDNA. The gene expression level peaked 12-24 h after instillation of naked pDNA, then decreased to a level similar to 3 h at 48 h. CONCLUSIONS: Gastric serosal surface in stillation of naked pDNA can be a highly stomach-selective gene transfer method in rats

Absorption characteristics of model compounds with different molecular weights from the serosal caecal surface in rats

The purpose of this study is to clarify the absorption characteristics of drugs across the serosal cecal surface membrane occupying a large absorption area in the peritoneal cavity in rats. Absorptions of phenolsulphonphthalein (PSP) and fluorescein isothiocyanate-dextrans (FDs) as model drugs after application to the rat serosal cecal surface were investigated in rats, employing a cylindrical diffusion cell. PSP was absorbed from the rat serosal cecal surface, followed by appearance in the plasma and bile. The time course of the remaining PSP amount in the diffusion cell obeyed first-order kinetics, and its rate constant Ka was calculated to be 8.01 x 10-3 min-1. No significant difference was seen in the absorption ratio of PSP which was approximately 90 % in 6 h among three doses (0.3, 0.5 and 1 mg), suggesting a linearity of absorption. Moreover, the absorption ratios of FDs from the rat serosal cecal surface at 3 h decreased with an increase in the molecular weight (24.7% for FD-4, 12.8% for FD-10 and 3.4% for FD-40)

Cationic liposomes-mediated plasmid DNA delivery in murine hepatitis induced by carbon tetrachloride.

In order to elucidate the influence of hepatic disease stage on cationic liposomes-mediated gene delivery, we investigated the cationic liposomes-mediated plasmid DNA delivery with time in murine hepatitis induced by subcutaneous injection of CCl(4). Liver injury after injection of CCl(4) was confirmed by the determination of serum aspartate aminotransferase and alanine aminotransferase activities. Two kinds of liposomes constructed with N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethlylammoniumchloride and dioleylphosphatidylethanolamine (DOTMA-DOPE) or DOTMA and cholesterol (DOTMA-CHOL) were used for the gene-delivery vector. We determined luciferase activities in various organs after the intravenous administration of the lipoplexes. The CCl(4)-treated mice administered with DOTMA-DOPE lipoplexes showed the more significant decreases of transgene expression in the liver and spleen at 18 hours after CCl(4) injection. On the other hand, the CCl(4)-treated mice administered with DOTMA-CHOL lipoplexes showed a significant increase in the liver at 48 hours. In conclusion, our findings demonstrate that murine hepatitis induced by CCl(4) can influence cationic liposomes-mediated plasmid DNA delivery. The extent of influences was also affected by lipid contents. These results indicate the necessity of considering the timing and the formulation for gene therapy according to the disease stage.This is an electronic version of an article published in Journal of liposome research, 19(2), pp.141-147; 2009. Journal of liposome research is available online at:http://dx.doi.org/10.1080/08982100802666514

Effects of Tissue Pressure on Transgene Expression Characteristics via Renal Local Administration Routes from Ureter or Renal Artery in the Rat Kidney

We previously developed a renal pressure-mediated transfection method (renal pressure method) as a kidney-specific in vivo gene delivery system. However, additional information on selecting other injection routes and applicable animals remains unclear. In this study, we selected renal arterial and ureteral injections as local administration routes and evaluated the characteristics of gene delivery such as efficacy, safety, and distribution in pressured kidney of rat. Immediately after the naked pDNA injection, via renal artery or ureter, the left kidney of the rat was pressured using a pressure controlling device. Transfection efficiency of the pressured kidney was about 100-fold higher than that of the injection only group in both administration routes. The optimal pressure intensity in the rat kidney was 1.2 N/cm2 for renal arterial injection and 0.9 N/cm2 for ureteral injection. We found that transgene expression site differs according to administration route: cortical fibroblasts and renal tubule in renal arterial injection and cortical and medullary tubule and medullary collecting duct in ureteral injection. This is the first report to demonstrate that the renal pressure method can also be effective, after renal arterial and ureteral injections, in rat kidney

Induction of mucosal immunity by pulmonary administration of a cell-targeting nanoparticle

We previously found that a nanoparticle constructed with an antigen, benzalkonium chloride (BK) and γ-polyglutamic acid (γ-PGA) showed high Th1 and Th2-type immune induction after subcutaneous administration. For prophylaxis of respiratory infections, however, mucosal immunity should be induced. In this study, we investigated the effect of pulmonary administration of a nanoparticle comprising ovalbumin (OVA) as a model antigen, BK, and γ-PGA on induction of mucosal immunity in the lungs and serum. The complex was strongly taken up by RAW264.7 and DC2.4cells. After pulmonary administration, lung retention was longer for the OVA/BK/γ-PGA complex than for OVA alone. OVA-specific serum immunoglobulin (Ig)G was highly induced by the complex. High IgG and IgA levels were also induced in the bronchoalveolar lavage fluid, and in vivo toxicities were not observed. In conclusion, we effectively and safely induced mucosal immunity by pulmonary administration of an OVA/BK/γ-PGA complex