The advances in biotechnology and medicinal chemistry in 1980s made it possible to produce large amount of useful peptide/protein drugs. However, their clinical use is limited to parenteral route. Among them, we selected recombinant human granulocyte-colony stimulating factor (rhG-CSF) as a representative peptide/protein drug. For the sake of the QOL of patients, non-parenteral, especially oral, preparation is needed now. For the development of oral peptide/protein preparations, colon delivery system has attracted the interests of many scientists. The most important reason is the lower hydrolytic enzyme activities in the colon than in the small intestine. We have developed two colon delivery capsules (CDC). One is intestinal inner pressure-controlled CDC (PCDC) and the other is release time-controlled CDC. As PCDC does not receive the effect of food on the delivery efficiency of drugs to the colon, PCDC was used for the preparation of oral rhG-CSF. At first, the colon delivery ability of PCDC was ascertained by administering 5-aminosalicylic acid (5-ASA), a drug for inflammatory bowel disease, in PCDC. After oral administration of 5-ASA in PCDC to beagle dogs, plasma 5-ASA levels vs. time curves were analyzed. The first appearance time of 5-ASA into the systemic circulation was approximately 4hr which corresponds to the colon arrival time in the beagle dogs. Based on these results, rhG-CSF was formulated into the PCDC and was orally administered to beagle dogs, 25 μg/kg. Blood samples were collected consecutively for 96 hr and blood total leukocyte counts (BTLC) were measured. At 8 hr after administration, BTLC increased to 1.3 times higher than the pre-dose level and thereafter declined gradually to the normal level at 96 hr. These results support the usefulness of PCDC for designing the oral delivery system of peptide/protein drugs.

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Interaction of a hydroxypropylated polyrotaxane with the stratum corneum of hairless rat skin and its increased permeation of indomethacin through the full-thickness skin were examined. Polyrotaxanes are well known as a supramolecular assembly in which many cyclic compounds are threaded onto a liner polymeric chain capped with bulky end-groups. The synthesis of biodegradable polyrotaxanes consists of three steps : the preparation of an inclusion complex consisting of α-cyclodextrins (αCDs) and amino-terminated poly(ethylene glycol) (PEG), the introduction of L-phenylalanine (L-Phe) at each complex terminal via peptide linkages, and the hydroxypropylation of αCDs in the polyrotaxanes. The hydroxypropylation of αCDs improved the solubility of the polyrotaxanes in PBS, pH7.4. A decrease in the bound water content was observed at the stratum corneum treated by hydroxypropylated (HP-) polyrotaxanes. Further, enhanced permeation of indomethacin through the skin was observed by the treatment of HP-polyrotaxanes. These results suggest that a supramolecular structure of the polyrotaxane caused the exchange of water in polar lipids or some extraction of polar lipids from the stratum corneum to enhance indomethacin permeation. Further, such enhanced effect of the polyrotaxane on indomethacin permeation was also observed when the skin was treated from dermis side. This result suggests a possibility that the HP-polyrotaxane penetrates into the stratum corneum to enhance indomethacin permeation. The polyrotaxane can be dissociated into PEG and αCDs by degradation of the terminal moiety. Therefore, it is concluded that a feasible design of polyrotaxane terminals degradable at subcutaneous tissues provides excellent properties as an enhancer with a passive safety system.

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[in Japanese]

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[in Japanese]

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The controlled release of biologically active molecules by the living cells, which have various functions including regulation by sensor, biosynthesis and secretion of active proteins, is the ideal of drug delivery systems (DDS). The implantation of the living cells without graft rejection would enable delivery of the bioactive molecules produced by the cells for a long time in vivo. We have developed to novel DDS “cytomedicine” using living cells entrapped in alginate-poly(L)lysine-alginate (APA) microcapsules which has a selective semipermeable characteristic. Because the APA membrane allows small molecules such as glucose and nutrients to diffuse freely but prevents the passage of large molecules and cells, entrapped cells are isolated from the host's immune system. In this study, we examined the effects of molecular weight of poly(L)lysine on the properties of APA microcapsules and viability of entrapped cells in vitro. Moreover, cytomedical therapeutic effects of APA-microencapsulated SK2 hybridoma cells (APA-SK2 cells), which secrete the anti-human interleukin 6 (hIL-6) antibody, were examined using hIL-6 transgenic mice (hIL-6 Tgm). Single i. p. injection of APA-SK2 cells improved IgG1 plasmacytosis and mesangio-proliferative glomerulonephritis in hIL-6 Tgm. This indicated that the cytomedicine is very effective for long-term delivery of bioactive molecules in vivo.

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Keloids and hypertrophic scars, especially keloids, are clinically intractable scars caused by an abnormal proliferation of fibroblasts and excessive production of collagen. The present clinical therapy for such scars is described briefly, and the feasibility of iontophoretic therapy with tranilast was examined in hairless rats and patients with scars. A drug electrode containing 12 mg tranilast, which was dissolved in 1.5 ml of ethanol/water (8 : 2 v/v) mixture, was placed on the dorsal skin surface of anesthetized rats or the affected parts of patients, and connected to the negative pole. An electric current was pulsed through at one min intervals. The in vivo current density was almost comparable between intact skin surfaces of healthy volunteers and keloids/hypertrophic scars of patients. Tranilast given iontophoretically (2 mA) a period of 30 min a week reduced the patients' complaints of pain and itching after only one or two treatments. Thus, the transdermal iontophoretic delivery of tranilast may be a useful treatment for keloid and hypertrophic scars, particularly for relieving pain and itching, and is more beneficial than tranilast given orally. Some discussions were also made in the present report.

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Doxorubicin hydrochloride (ADR) is an antineoplastic substance which has a wide therapeutic range against human solid tumors, lymphomas, and acute leukemias. However ADR has the risk of cardiotoxicity and marrow dipression as side effects. Acrylic bone cement conteining ADR (ADR-bone cement) has been used for filling the bony defect and for controlling local recurrences after excision of malignant tumors in our hospital. We investigate the release of ADR from ADR-bone cement in vitro and in vivo elution studies for assessing usefullness of ADR-bone cement as drug delivery system. The release of ADR from ADR-bone cement has two phases. First phase of the release was supposed to occur a very high discharge from the external-surface of the cement, and secondary from the pores of the cement. In vitro elution studies, the release of ADR from ADR-bone cement was eluted slowly during over 12 weeks. 50 percentage of the total released ADR was eluted within 1 hour, 90 percentage within 1 week. During 12 weeks 0.6-1.6 percentage of the total ADR implanted was released. The concentration of ADR in drain fluid of the patient implanted ADR-bone cement is higher than the serum concentration of ADR of the patient dosed 30 mg ADR intravenously. However, the patient implanted ADR-bone cement has no symptoms like general side effects, necrosis, dead spase fluid and infection by local high concentration of ADR. Our studies show the possibility of long and local administration of ADR by ADR-bone cement. This topical administration decrease general side effects and is a useful drug delivery system.

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3-l-menthoxypropan-1, 2-diol (MPD), which is a derivative of l-menthol, and l-menthol enhance the penetration of indomethacin (IM) through hairless rat (HR) skin. It is well known that degree of enhancement differs with skin type, so we studied the enhancement of MPD and l-menthol on the penetration of IM through Yucatan micropig (YMP) skin. Ethanol (40%) containing 0.5% IM and 3% enhancer was applied to the donor phase of a modified Franz-type cell. The permeation rate of IM through YMP skin without enhancer was 1.7 μg/cm²/hr, which was about 1/3 that through HR skin. In the presence of MPD or l-menthol the rate of IM permeation through YMP skin were 2.5 and 5.6 μg/cm²/hr, respectively, much lower than through HR skin, 90 and 144 μg/cm²/hr. IM concentration in the skin without enhancer was 240 μg/g, with MPD, 380 μg/g and with l-menthol, 490 μg/g. MPD and l-menthol concentrations in the skin were 2.9 and 2.2 mg/g, respectively. It was considered that each enhancer was partitioned in the skin so that the partition coefficient of IM in the skin increased, though the increasing factor was smaller than that in the case of HR skin. The rate of IM permeation through epidermal membrane and stripped YMP skin were also determined.

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