Noboru Yata

Phosphatidylserine as a determinant for the tissue distribution of weakly basic drugs in rats

Interorgan variation in tissue distribution of weakly basic drugs such as quinidine, propranolol, and imipramine was investigated as a function of binding to phosphatidylserine (PhS) in tissues. Tissue distributions of these drugs were determined using 10 different tissues at a steady-state plasma concentration and were expressed as tissue-to-plasma partition coefficients (Kp values). The concentration of PhS in the tissue was determined by two-dimensional thin-layer chromatography. Plotting of Kp values, except for brain, against the tissue PhS concentrations showed a linear relationship, indicating that PhS is a determinant in the interorgan variation of these tissue distributions. Further, differences in tissue distribution among the drugs was considered to be due to the difference in binding potency to PhS. Drug binding parameters to individual standard phospholipid were determined using a hexane-pH 4.0 buffer partition system. Binding was highest to PhS, and a linear relationship was found between the log nK [product of the number of binding sites (n) and the association constant (K) for PhS binding] obtained in vitro and Kp values of drugs in tissues in vivo. The empirically derived equation, Kp = 14.3 × (log nK) × (PhS cone.) − 8.09, was found to predict Kp values in vivo of weakly basic drugs. Thus, a determinant of interorgan variation in the tissue distribution of the weakly basic drugs studied was the tissue concentration of PhS and the drug binding affinity to PhS.

Acyclic sesquiterpene oligoglycosides from pericarps of Sapindus mukurossi

Abstract New acyclic sesquiterpene oligoglycosides named mukuroziosides Ia, Ib, IIa and IIb were isolated from the pericarp of Sapindus mukurossi and their structures were elucidated. These oligoglycosides showed a potent solubilizing effect on the co-occurring saponins (monodesmosides), which are sparingly soluble in water in the pure state.

Enhancement of Topical Delivery of a Lipophilic Drug from Charged Multilamellar Liposomes

To enhance the topical delivery of rhodamine B base (Rho), a model lipophilic compound, the electrostatic interaction between the positive and negative components incorporated in the liposomal bilayer was utilized. The higher in vitro permeability to Rho in rat skin was observed with positive and neutral multilamellar liposomal preparations, the former was prepared with phosphatidylcholine (PC) and stearylamine (SA) and the latter with PC alone, than that given as a solution. Negative liposome composed of PC and dicetyl phosphate (DCP) showed lower skin permeability to Rho. To enhance the Rho retention in the skin, the electrostatic interaction between SA and DCP, which was confirmed by in vitro partition study, was utilized. By pretreating the skin surface with SA solution or empty SA liposome, the skin distribution of Rho given as DCP liposome was substantially enhanced, with increase in the PC distribution into the skin. The pretreatment effect of empty SA liposome was also observed in rats in vivo. In conclusion, it was found that negative DCP liposome provides better drug retention in the skin with lower skin permeability, and the topical drug delivery from DCP liposome was further enhanced by the pretreatment of the skin surface with empty SA liposome.

In-vitro Permeability to Salicylic Acid of Human, Rodent, and Shed Snake Skin

Abstract— In‐vitro permeability to salicylic acid of human, rodent, and shed snake skin has been examined for the purpose of selecting model membranes for human skin corresponding to different anatomic sites, since a marked regional variation is suggested among the different sites. The greatest permeability to salicylic acid was observed in the scrotum, that of the sole was negligible. The cheek, neck, and inguinal skin seemed more permeable than the breast, back, thigh, lower leg, or foot skin. Shed snake and skin of hairless rat were found to show similar permeability to human breast and thigh skin. Wistar rat and nude mouse skin showed similar permeability to human cheek, neck, and inguinal skin.

Biopharmaceutics: Topical Delivery of Keloid Therapeutic Drug, Tranilast, by Combined Use of Oleic Acid and Propylene Glycol as a Penetration Enhancer: Evaluation by Skin Microdialysis in Rats

Topical delivery of tranilast (N‐(3,4‐dimethoxycinnamoyl)anthranic acid), an inhibitor of collagen synthesis and a therapeutic drug for keloid and hypertrophic scar, was examined, in rats, with oleic acid alone or a combination of oleic acid and propylene glycol as penetration enhancer. Evaluation was by measurement of the concentration of tranilast in plasma and in the dialysate from skin microdialysis.

Pharmacokinetic Analysis of the Absorption Enhancing Action of Decanoic Acid and Its Derivatives in Rats

The enhancing action of decanoic acid (C1O) and its derivatives on mucosal absorption of phenolsulfonphthalein (PSP) in the jejunum or colon was analyzed using pharmacokinetics in rats. After administration of a solution containing PSP and an enhancer [C10, 2-hydroxydecanoic acid (2-OHC10), or 3-hydroxydecanoic acid (3-OHC10)] into the jejunal or colonic loop, the amounts of PSP and enhancer remaining in the loop and/or plasma PSP concentration were determined periodically. 2-OHC10 exhibited a greater absorption enhancing potency than C10, while 3-OHC10 was less effective. Disappearance of residual PSP from the loop ceased after complete absorption of the enhancer. The enhancer-induced disappearance rate constant of PSP correlated well with the product of the enhancer disappearance rate and its capacity to sequester calcium ions. In conclusion, the enhancement of PSP mucosal absorption by C10 and its derivatives is consistent with a pharmacokinetic model, assuming that the enhanced membrane permeability of PSP depends on the enhancer disappearance kinetics from the loop and its calcium ion sequestration capacity.

Role of Phosphatidylserine in the Cellular and Subcellular Lung Distribution of Quinidine in Rats

The role of phosphatidylserine in the cellular and subcellular lung distribution of quinidine was investigated in rats, since quinidine was found to bind preferentially to phosphatidylserine. The concentration of phosphatidylserine in the cellular and subcellular fractions was determined after separation by two-dimensional thin-layer chromatography. Selective accumulation of quinidine in vivo was observed in the alveolar macrophage at the cellular level and in the plasma membrane at the subcellular level. Both alveolar macrophages and plasma membranes were rich in phosphatidylserine compared to other fractions. When plasma levels were kept at steady state by i.v. infusion, the distribution of quinidine in the lung cellular and subcellular fractions was linearly correlated with the concentration of phosphatidylserine (r = 0.906). These results suggest that the concentration of phosphatidylserine is a dominant determinant of the cellular and subcellular lung distribution of quinidine.

Effects of low-dose phenytoin administered to newborn mice on developing cerebellum

To examine correlations between dose levels of phenytoin (PHT) and neurotoxic effects on cerebellar development, we administered 10, 17.5, 25, and 35 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-4 and determined plasma PHT concentrations during the administration period. Mortality rates were 12.5% and 35.2% in males and 15.3% and 33.3% in females for the 25 and 35 mg/kg PHT-treated groups during the PHT treatment, respectively. In the 25 and 35 mg/kg PHT-treated groups, total brain weight, the size of the cerebellum, and cerebellar weight were significantly reduced on postnatal day 21. However, in the 10 and 17.5 mg/kg PHT-treated groups, total brain weight and the size and weight of the cerebellum did not differ from those of the control group. Histologically, the number of pyknotic cells in the external granular layer (EGL) in the 25 and 35 mg/kg PHT-treated groups was increased on postnatal day 5, and the EGL was thicker than in the control group on postnatal day 14. Some of the Purkinje cells in the 35 mg/kg PHT-treated group showed degeneration. Plasma PHT levels were 10.7 +/- 2.2 and 24.6 +/- 2.6 micrograms/ml in the 25 and 35 mg/kg PHT groups on the third day of PHT treatment, respectively. In the 25 mg/kg PHT group, plasma PHT level was found to be in the therapeutic range for humans, 10-20 micrograms/ml. Accordingly, during pregnancy, epileptic women should be carefully given PHT at the lowest effective dose while plasma PHT levels are monitored properly. These findings emphasize the importance of pharmacokinetics in evaluating of phenytoin-induced developmental neurotoxicity.

Biopharmaceutics: Effect of Ointment Bases on Topical and Transdermal Delivery of Salicylic Acid in Rats: Evaluation by Skin Microdialysis

Microdialysis has been used to determine the concentration of salicylic acid in skin tissue and plasma periodically for 4 h to evaluate the effect of ointment bases on topical and transdermal delivery of salicylic acid. The ointment bases examined were solbase (water‐soluble), poloid and white petrolatum (oleaginous), hydrophilic poloid (water in oil (w/o) type emulsion lacking water) and absorptive ointment (w/o‐type emulsion containing water). The ointments (0.1 g) containing 25 μmol salicylic acid were applied for 2 h to the surface of rat skin (1 cm2) with (intact) or without the stratum corneum.

Skin Microdialysis: Detection of in vivo Histamine Release in Cutaneous Allergic Reactions

In vivo histamine release in cutaneous allergic reactions was chronologically examined using the skin microdialysis technique. Antigen challenge was made in ovalbumin-sensitized guinea pigs 1 h after the implantation of the microdialysis probe. A marked histamine release after intradermal injection of ovalbumin solution was observed in the early phase (up to 40 min). No isolated delayed histamine release was observed thereafter over 8 h. Also, in an atopic volunteer, a marked release of histamine after intradermal injection of mite extract was observed only in the early phase, although erythema and induration at the site of injection were continuously observed in the late phase (up to 4 h). These findings suggest that the skin microdialysis technique is a useful, simple technique for chronological determination of chemical mediators released in the allergic skin in vivo.