Potential of Fairy Chemicals as Functional Cosmetic Ingredients: Effect of 2-Aza-8-Oxohypoxanthine on Skin Lightness.

Among the "fairy chemicals" involved in forming the natural phenomenon of "fairy rings," we focused on 2-aza-8-oxohypoxanthine (AOH) as a candidate functional cosmetic ingredient. In previous studies, AOH was confirmed to be safe for use on human skin, and no adverse reactions were observed in any of the safety studies. In this study, we report the results of a clinical trial using a lotion containing AOH. Our analysis using the L* value for indices of skin lightness indicated that the AOH application significantly increased the L* value after 8 weeks. Since a previous DNA microarray study using normal human epidermal cells showed that AOH suppressed the expression of a group of genes that induce inflammatory cytokines (prostaglandin E synthase, prostaglandin-endoperoxide synthase 2 [cyclooxygenase-2], and interleukin-18), our results suggest that the AOH-induced suppression of inflammatory factors results in skin lightening.

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine (II): in vivo evaluation.

A novel sustained-release (SR) system, disintegration-controlled matrix tablet (DCMT), was developed for poorly water-soluble drugs. DCMT, consisting of wax and solid dispersion (SD) granules containing a disintegrant, could control the release of nilvadipine (NiD), a model compound, by its disintegration. In the present study, two DCMTs (DCMT-1 and DCMT-2) with different release rates of NiD were orally administered to beagle dogs, and in vivo absorption of NiD from DCMTs was compared with that from immediate-release (IR) tablets. DCMTs successfully sustained the absorption of NiD longer than IR tablets, while they did not decrease the bioavailability of NiD. DCMT-2, providing the slower release of NiD than DCMT-1, prolonged the absorption longer than DCMT-1. In vivo absorption profiles of NiD from DCMTs were significantly correlated with in vitro release profiles, suggesting that the release property from DCMTs would maintain regardless of the change in physiological condition through the gastrointestinal tract. Furthermore, the food intake did not affect the absorption of NiD after oral administration of DCMT-2. The present results strongly indicate that the DCMT system would be a promising SR system, which could improve the solubility and sustain the absorption of poorly water-soluble drugs.

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine.

The goal of this study is to develop a novel sustained-release (SR) system for poorly water-soluble drugs by applying solid dispersion (SD) technique for improving the solubility. The developed SR system, disintegration-controlled matrix tablet (DCMT), consists of hydrogenated soybean oil (HSO) as wax and SD granules containing low-substituted hydroxypropylcellulose (L-HPC) as a disintegrant. In this study, nilvadipine (NiD) was chosen as a model compound. Sustained-release profiles of NiD from DCMT were identically controlled in several dissolution mediums in spite of varying pH and agitation speed. The release of NiD from DCMT was sustained more effectively by increasing the amount of wax or by decreasing the amount of disintegrant, and supersaturation of NiD was achieved without any re-crystallization in dissolution medium. The release rate of NiD from DCMT was controlled by the disintegration rate of tablet. The release profile of NiD was described by the Hixson-Crowell's model better than zero-order kinetics, first-order kinetics and Higuchi's model, which supports that the release of NiD from DCMT is regulated by the disintegration of the tablet. From this study, it was clarified that DCMT was one of the promising SR systems applying SD for the poorly water-soluble drugs.

Formulation development of inhalation powders for FK888 using the E-haler to improve the inhalation performance at a high dose, and its absorption in healthy volunteers.

FK888 is a candidate selective NK1 receptor antagonist, and it exhibits poor absorption from the gastrointestinal tract in healthy volunteers. In a previous study, the optimized dry powder inhaler (DPI) formulation with carrier lactose using the Spinhaler was developed, although the maximum dose per capsule was only 5mg because the fine particle fraction (FPF) was reduced at doses over 5mg. The objective of this study was to develop an optimized DPI formulation for higher doses, such as 40 mg, with proportional systemic absorption. The Spinhaler and E-haler were used as the inhalation devices, and the in vitro deposition was evaluated using a multistage cascade impactor at different flow rates (28.3 and 60 l/min). When hydroxypropyl methylcellulose (HPMC) capsules were used as the container, and spherical soft agglomerates of fine FK888 particles (soft pellets) and the E-haler were used, the fraction of particles emitted from the inhalation system (Em) was significantly improved, to over 80% of the nominal dose, and no significant difference was found between the airflow rates (84.3+/-2.3% for 28.3 l/min, 88.1+/-3.6% for 60 l/min). It was also found that the E-haler was an extremely suitable device for obtaining the higher respirable particle percentage of emitted particles (RP) in the 40 mg formulation with the soft pellets contained in HPMC capsules (35.0+/-1.8% for 28.3 l/min and 42.5+/-3.5% for 60 l/min), compared with the Spinhaler (13.8+/-3.0% for 28.3 l/min and 28.9+/-1.0% for 60 l/min). Using the formulations with the E-haler, proportional systemic absorption was achieved up to 40 mg FK888 in healthy volunteers (62.91+/-27.58, 103.70+/-40.19 and 254.79+/-85.01 ngh/ml as AUCs for 10, 20 and 40 mg FK888, respectively; R(2)=0.9641). It is also expected that the E-haler will act as an efficient device when a higher dose, such as 40 mg, is required in clinical situations.

Effect of experimental acute renal and hepatic failure on absorption of tacrolimus in rat small intestine.

The objective of this study is to evaluate the effect of acute renal or hepatic failure on the intestinal absorption of tacrolimus. Simultaneous perfusion study in rat small intestine revealed that the extent of absorption into blood vessels was decreased in the jejunum and the ileum of rat of acute renal failure due to the decrease in the uptake of tacrolimus into enterocytes. In contrast, there observed no significant changes in tacrolimus absorption in rat of acute hepatic failure. Since it has been reported that tacrolimus absorption is regulated mainly by Cytochrome P-450 (CYP) mediated metabolism in the jejunum, but by P-glycoprotein (P-gp) mediated efflux in the ileum, these factors might contribute to the changes in intestinal absorption of tacrolimus in rat of acute renal failure. Enzyme inhibitor, ketoconazole, was co-perfused with tacrolimus to specify the effect of CYP and P-gp. However, since ketoconazole failed to recover the permeability in the jejunum and ileum of rat of acute renal failure, it is considered that the changes in CYP or P-gp functions might not be involved in the decreased uptake of tacrolimus. This type of kinetic study in rats should be valuable to identify the precise mechanisms of drug absorption and the effects of various diseases on it, such as acute renal or hepatic failure.

Applicability of (SBE)7m-beta-CD in controlled-porosity osmotic pump tablets (OPTs).

The purpose of this study was to investigate the general application of a controlled-porosity osmotic pump tablet (OPT) utilizing (SBE)7m-beta-CD as both a solubilizer and an osmotic agent for drugs with varying physical properties. OPTs utilizing (SBE)7m-beta-CD were prepared for five poorly soluble and two highly water-soluble drugs. The Japanese Pharmacopoeia dissolution method was used to study the drug and (SBE)7m-beta-CD release from the OPTs. The drug concentration in the OPT core after the OPT was placed in the release medium for two hours was assayed gravimetrically and by HPLC. An appropriate composition ratio (ACR) of (SBE)7m-beta-CD to drug at which drug release from the OPT was complete and pH-independent within the physiological pH range of the GI tract was determined for each drug. The ACR values correlate to the drug concentration in the OPT core when the OPTs were placed in the release medium for two hours. The release profiles of prednisolone (a poorly water-soluble drug) and sodium chloride (a water-soluble compound) from the OPTs were almost the same as that of (SBE)7m-beta-CD. Also, the release rate of each drug per unit membrane surface area from the OPTs was similar, regardless of the differences in drug solubility. The present results confirmed that (SBE)7m-beta-CD serves as both a solubility modulator and as an osmotic pumping agent for OPTs, from which the release rate of both water-soluble and poorly water-soluble drugs can be controlled.

Formulation development of inhalation powders for FK888 with carrier lactose using Spinhaler and its absorption in healthy volunteers.

(4R)-4-Hydroxy-l-[(l-methyl-lH-indol-3-yl)carbonyl]-L-prolyl-N-benzyl-N-methyl-3-(2-naphthyl)-L-alaninamide (FK888) is a candidate selective NK1 receptor antagonist, and it exhibits poor absorption from the gastrointestinal (GI) tract in healthy volunteers. The objective of this study was to develop an optimized DPI formulation with carrier lactose using a Spinhaler, and thereby improve the systemic absorption of FK888. The fine particles of FK888 were blended with various carrier lactoses, and in vitro deposition properties were investigated using a twin impinger. The mixture using 100 M and 325 M lactoses [Sieved lactoses (SLs)] exhibited a higher emitted dose (Em) than 200 M, 450 M and micronized lactoses [Milled lactoses (MLs)]. The flowability of carrier lactose had an influence on the Em. On the other hand, the respirable particle (RP) fraction in the formulations with MLs was much higher than that of SLs, in spite of the blended ratios of lactose. It was also observed that the mixture of 325 M with the micronized lactose particles had the same RP as 200 M, although the 325 M alone had a low RP. Considering the Em and RP obtained, we chose 200 M for FK888 dry powder inhaler (DPI). The proportional absorption was found up to the 12.5% of the FK888 ratio (5 mg as unit dose) for the Cmax and AUC in healthy volunteers. In conclusion, 200 M, which has fine lactose particles and a better flowability than other MLs, is an extremely suitable carrier for maximizing the fine particle dose as far as FK888 is concerned. Furthermore, an improvement in the systemic absorption of FK888 was achieved using the dry powder formulations.

Comparison of the lung absorption of FK224 inhaled from a pressurized metered dose inhaler and a dry powder inhaler by healthy volunteers.

FK224 is a cyclopeptide drug with poor oral absorption due to proteolysis in the gastrointestinal tract. The objectives of this study were to investigate the absorption of FK224 from the lung in healthy volunteers, and compare the pharmacokinetic profiles of FK224 after inhalation from a pressurized metered dose inhaler (pMDI) and dry powder inhaler (DPI). The pMDI (Suspension type, 1 mg as FK224/puff) and DPI (4 mg and 10 mg as FK224/capsule, using Spinhaler as the device) were developed by formulating the same micronized particles of FK224 which were premixed with beta-cyclodextrin (beta-CyD) to improve the solubility of FK224. In the case of pMDI, 1, 4 or 8 mg was inhaled by the corresponding number of puffs with the pMDI. In addition, the in vitro drug delivery characteristics of the inhalers were evaluated using a multistage liquid impinger. In both inhalers, it was observed that FK224 could be absorbed into the systemic circulation from the lungs of the healthy volunteers, and the AUC and C(max) were proportionally increased depending on the emitted dose after inhalation. However, the pharmacokinetic (PK) parameters for DPI were significantly higher than that of pMDI, in spite of usage of the same fine particles for the formulations in both inhalers. Based on the distribution from the in vitro examination, the fine particle dose, which is defined as the dose region delivered as particles <3.8 microm, was calculated from the emitted dose inhaled by the healthy volunteers. It was found that the PK parameters for both inhalers were proportionally increased depending on the predicted fine particle dose regardless of the type of inhaler. This suggests that the absorption from the lung is influenced by the fine particle dose. We concluded that DPI is a suitable inhaler for FK224, and the alveolus, which is generally known as the site of action of the fine particles, is a possible absorptive site for FK224.

Establishment of new preparation method for solid dispersion formulation of tacrolimus.

The aim of this study was to establish a new preparation method for solid dispersion formulation (SDF) of tacrolimus, a poorly water-soluble drug, without dichloromethane, because no use of dichloromethane is recommended by ICH harmonized tripartite guideline. To select the appropriate carrier, three different SDFs with polyethylene glycol 6000 (PEG 6000), polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC) were prepared by the conventional solvent method, in which tacrolimus and the carrier were completely dissolved in the mixture of dichloromethane and ethanol. Powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) patterns indicated that tacrolimus exists in an amorphous state in all three SDFs. The supersaturated dissolution profiles of tacrolimus were observed in all SDFs, and the highest level of supersaturation for tacrolimus was obtained and maintained for 24h from SDF with HPMC. On the other hand, the supersaturated level from SDF with PEG 6000 or PVP decreased rapidly. The in vivo oral absorption study in dogs showed that bioavailability of tacrolimus from SDF with HPMC was remarkably improved compared with the crystalline powder. It was clarified that HPMC is the most appropriate carrier for SDF of tacrolimus. Then, SDF of tacrolimus was prepared by the new method, which allows us to make SDF of tacrolimus by swelling HPMC with ethanol, in which tacrolimus was completely dissolved. This new method does not need dichloromethane. The physicochemical properties of SDF with HPMC prepared by the new method were the same as those of SDF prepared by the conventional solvent method. Furthermore, SDF with HPMC prepared by the new method was still stable after stored at 40 degrees C for 3 months. The pharmacokinetic parameters after oral administration in monkeys showed no significant difference (P>0.01) between SDFs with HPMC prepared by the two methods. In conclusion, we have established the new preparation method for SDF of tacrolimus with HPMC and the new method makes it possible to prepare SDF of tacroliumus without dichloromethane.

The site-specific transport and metabolism of tacrolimus in rat small intestine.

The objective of this study was to evaluate the absorption of tacrolimus by means of simultaneous perfusion of intestinal lumen and blood vessels in rats. In our previous report, the permeability of tacrolimus was found to be higher in the jejunum than in the ileum or colon, suggesting the site-dependent absorption after oral administration. However, in this article, simultaneous perfusion technique revealed that the extent of absorption into blood vessels was similar in the jejunum and the ileum regardless of the site difference in permeability as the absorption rate. In addition to the multidrug resistance-associated protein-mediated efflux, cytochrome P450 (P450)-mediated metabolism could be a possible mechanism to explain the inconsistencies in the site dependence of tacrolimus absorption. Two enzyme inhibitors, ketoconazole and midazolam, were coperfused in rat intestinal lumen with tacrolimus to specify the effect of P-gp and P450. In the jejunum, both inhibitors significantly enhanced the absorbed amount of tacrolimus, whereas the permeability was not affected. It was suggested that both inhibitors mainly suppress P450-mediated metabolism in the upper region of the intestine. In contrast, in the ileum, ketoconazole significantly enhanced both the absorbed amount and the permeability of tacrolimus. However, midazolam failed to enhance the absorption of tacrolimus, indicating the dominant role of P-glycoprotein (P-gp)-mediated efflux in the lower region. From these findings, it is concluded that the site-dependent differences in P-gp and/or P450 activity could be the prime cause of large intra- and interindividual variability in the oral absorption of tacrolimus.

Improvement of pulmonary absorption of cyclopeptide FK224 in rats by co-formulating with beta-cyclodextrin.

FK224 is a cyclopeptide drug with a low aqueous solubility. Following oral administration to rats, poor absorption was observed due to proteolysis in the gastrointestinal tract. The objective of this study was to investigate the effect of the pulmonary route on the systemic absorption of FK224 in comparison with other administration routes, and to determine the bioavailability (BA) of FK224 following pulmonary administration in rats using various dosage forms. From absorption studies on the Polyethylene Glycol 400 solution given by various routes (intranasal, subcutaneous, intratracheal and intravenous as reference), it was shown that pulmonary administration was a potentially attractive route for FK224. In the pulmonary absorption studies, after administration of the aqueous suspension, the BA was reduced to 2.7% compared with 16.8% for the solution. However, beta-cyclodextrin (beta-CyD) was found to be an effective additive as far as improving the solubility of FK224 was concerned. The BA of the aqueous suspension containing beta-CyD was increased to 19.2%. Pressurized metered dose inhalers were prepared by formulating beta-CyD with various molar ratios of 1:0, 1:1 and 1:7 (FK224/beta-CyD), and the resulting BAs were 4.3%, 29.0% and 91.2%, respectively. It was observed that both the C(max) and AUC of FK224 were increased as the amount of beta-CyD increased. The plasma profiles showed sustained absorption. In conclusion, we have seen that the lung is a suitable route for absorption of FK224, and beta-CyD is an extremely effective additive as far as improving the pulmonary absorption of FK224 is concerned. beta-CyD or derivatives with various degrees of aqueous solubility are potential drug carriers for controlling pulmonary absorption.

Tacrolimus is a class II low-solubility high-permeability drug: the effect of P-glycoprotein efflux on regional permeability of tacrolimus in rats.

The objective of this study is to investigate the role of P-glycoprotein (P-gp), a membrane efflux pump associated with multidrug resistance (MDR) and a known substrate for tacrolimus, in determining the regional intestinal permeability of tacrolimus in rats. Thus, isolated segments of rat jejunum, ileum, or colon were perfused with tacrolimus solutions containing polyethoxylated hydrogenated castor oil 60 surfactant, and with or without verapamil, a P-gp substrate used to reverse the MDR phenotype. The results indicated that the intrinsic permeability of tacrolimus in the jejunum, calculated on the basis of the concentration of non-micellized free tacrolimus, was quite high ( approximately 1.4 x 10(-4) cm/s). The apparent permeability (P(app)) in the jejunum was unaffected by the presence of verapamil; however, the P(app) in the ileum and the colon increased significantly in the presence of verapamil and were similar to the values observed in the jejunum. The results suggest that systemic absorption of tacrolimus from the gastrointestinal tract could be significantly affected by P-gp efflux mechanisms. It is also possible that differences in P-gp function at various intestinal sites in a subject or at a given intestinal site in various subjects could lead to large intra- and interindividual variability in bioavailability of tacrolimus following oral administration.