フォルスコリン水溶性誘導体である急性心不全治療薬NKH477の体内動態を調べるために，ラットおよびイヌに¹⁴C-NKH477および非標識NKH477を単回静脈内投与したときの血中濃度，分布および排泄について検討した．
1．ラットに¹⁴C-NKH477を0.011～0.3mg/kg静脈内投与したとき，血液中放射能濃度は二相性で減衰し，そのときの消失半減期t_1/2βは70.67～118.23時間であった．血液中放射能濃度は血漿中放射能濃度に比べその消失は緩やかであり，その理由は放射能の赤血球への結合によるものと考えられた．
2．ラットにNKH477を静脈内投与したとき，未変化体NKH477および活性代謝物M-1の血漿中濃度は速やかに消失し，そのときの半減期はそれぞれ0.23および0.25時間であった．M-1のAUC_0-∞は未変化体のAUC_0-∞に比べ低かった．
3．イヌに静脈内投与後，血液および血漿中放射能濃度は二相性で減少した．血液中放射能濃度は血漿中放射能濃度に比べ緩やかに消失した．血液からの消失はラット投与時に比べ速やかであった．
4．麻酔下のイヌにNKH477を0.15～0.60μg/kg/minの投与量で2時間静脈内持続投与したとき，血漿中未変化体とM-1の消失半減期は1.57～2.36時間であった．M-1のAUCは未変化体NKH477の約1/2であった．
5．ラットに静脈内投与後，放射能は中枢神経系を除いて速やかに組織に広く分布した．特に肝臓中放射能濃度は他の組織に比べ高かった．心臓，血液，脾臓および副腎を除き多くの組織中放射能は速やかに減衰した．
6．ラットに静脈内投与したとき，投与後144時間までに尿および糞中に放射能はそれぞれ6.4%および90.2%排泄された．胆管カニューレ処置したラットでは投与後72時間までに胆汁および尿中にそれぞれ77.1%および7.8%が排泄された．このことより，主排泄経路は胆汁を介した糞中であることが明らかとなった．
7．イヌに静脈内投与したとき，投与後144時間までに投与量の78.2%が糞中に排泄された．

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雄性ラットに¹⁴C-NKH477を21日間反復静脈内投与したときの血液中放射能濃度，分布および排泄について検討した．また，非標識NKH477を用いて肝薬物代謝酵素系への影響も検討した．
1．毎日投与後24時間における血液中放射能濃度は投与日数に伴い増加し，最終投与後の血液からの放射能の消失は単回投与時に比べ緩慢であった．
2．反復投与により，ほとんどの組織に蓄積性が認められ，特に脾臓，血液，腎臓および腸間膜リンパ節に高い蓄積性が認められた．最終投与後，ほとんどの組織は単回投与時に比べて緩慢な消失を示した．
3．21日問反復投与したとき，最終投与後168時間までに尿に7.8%，糞に88.9%の放射能が排泄された．尿，糞中排泄率は単回投与群とほとんど相違は認められなかった．
4．0.3mg/kgおよび1.0mg/kgで7日間反復投与したとき肝重量，チトクロームP-450含量および肝薬物代謝酵素系への影響は認められなかった．

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妊娠ラットおよび授乳中ラットに¹⁴C-NKH477を単回静脈内投与したときの胎盤通過性および乳汁中移行性について検討した．
1．妊娠17日目のラットに¹⁴C-NKH477を単回静脈内投与したときの全身オートラジオグラムより，投与後6時間まで胎盤および羊膜に母獣血液とほぼ同程度の放射能が認められたが，24時間後には痕跡程度まで減衰した．胎仔および羊水には放射能は認められなかった．
2．妊娠14日目および18日目のラットに¹⁴C-NKH477を単回静脈内投与したとき，羊水，胎仔および胎仔肝臓中の放射能濃度は羊膜および胎盤中の放射能濃度よりも低値であった．また，投与後5分および1時間の胎仔の放射能は母獣血液の1/3～1/9であった．妊娠14日目および18日目でともに胎盤を通過する放射能はわずかであり，同様であった．胎仔に分布したわずかな放射能は速やかに消失した．
3．分娩後11日目の授乳中ラットに¹⁴C-NKH477を単回静脈内投与したときの乳汁中には放射能が認められ，乳汁/血漿中放射能濃度比は投与後24時間まで1.0～2.2であった．

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ラット肝9000×g上清を用いてNKH477の代謝を検討した．また，ラット，イヌおよびヒトに静脈内投与したときの血漿，組織，尿，糞および胆汁中代謝物を検索した．
1．ラット肝9000×g上清によるNKH477の代謝をLC/FRIT-FAB-MSを用いて合成標品と比較することで確認した．NKH477はN-脱メチル化，水酸化および分子内環化により代謝された．
2．ラットに¹⁴C-NKH477を単回静脈内投与したときの組織内代謝物を検索した．投与後5および30分では血漿，心臓および腎臓で未変化体とN-脱メチル体のM-1が主であった。また，肝臓は投与後5分で種々の代謝物が検出されており，主要な代謝部位であることが示唆された．
3．ラットに¹⁴C-NKH477を単回静脈内投与したときの尿，糞および胆汁中代謝物を検索した．24時間までの尿中にNKH477，M-1，M-3とM-4を含む画分(画分D)およびM-5とM-6を含む画分(画分C)が投与後それぞれ0.8%，2.2%，1.7%および1.7%が排泄された．尿中主代謝物はM-1であった．投与後48時間までの糞中に画分D，画分CおよびM-7とM-8を含む画分(画分B)がそれぞれ20.9%，15.8%および14.6%が排泄された．NKH477および尿中の主代謝物であるM-1は少なかった．投与後6時間までの胆汁中に画分D，画分Cおよび画分Bがそれぞれ13.4%，14.4%および11.8%が排泄され，そのプロフィールは糞中代謝物のプロフィールと同様であった．
4．イヌに¹⁴C-NKH477を単回静脈内投与したときの尿および糞中代謝物を検索した．投与後24時間までの尿中にNKH477，M-1および含む画分Dがそれぞれ2.8%，5.9%および1.3%が排泄された．尿中主代謝物はM-1であった．投与後72時間までの糞中に画分D，画分Cおよび画分Bがそれぞれ20.9%，9.9%および6.0%が排泄され，ラットの尿および糞中代謝物のプロフィールと同様であった．
5．ヒトにNKH477を単回静脈内持続投与したときの尿中代謝物を検索した．投与後24時間までの尿中には未変化体およびM-1がほとんどで，ほかの代謝物はわずかであった．

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ラットに[¹⁴C]-Alendronate(MK-217/GTH-42)を経口投与し，血漿中濃度，分布および排泄を検討した．
1．雄ラットに5mg/kgを単回投与後168時間までの放射能尿中排泄は投与量の0.46%であった．残りの放射能は糞中に定量的に回収された．
2．雌雄ラットに5mg/kgを単回経口投与した後30分に，骨，気管および腎臓中の放射能は血漿中の3～6倍高値を示した．骨および気管中の放射能は4時間まで上昇し，その後の消失はきわめて緩やかであった．胃腸管中にも高い放射能が検出されたが，これは未吸収の薬剤の影響と考えられた．その他の軟組織の放射能濃度は血漿中と同程度かより低く，投与後24時間にはほぼ検出限界以下にまで減衰した．[¹⁴C]-Alendronateのラットの組織内分布に性差は認められなかった．
3．雌ラットに5mg/kgを1日1回7日間連続投与すると，気管および骨中の放射能は単回投与に比べ著しく上昇した．しかし，その他の臓器および組織の放射能分布は単回投与時と同様の推移を示した．
以上の結果から本試験におけるAlendronateの経口吸収率は低く(1%程度)，雌雄にかかわらず吸収後に薬物は速やかに薬効発現部位である骨へと選択的に分布し，そこに蓄積されることが明らかとなった．

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The absorption, distribution, metabolism and excretion of tacrolimus (FK506) were studied in the rat after intravenous (i.v.) and oral administration of ¹⁴C-labeled FK506 (¹⁴C-FK506).
1. After i.v. injection at a dose level of 1.0 mg/kg, the pharmacokinetic parameters of FK506 in the whole blood were as follows: elimination half life, 6.4 hours; total body clearance, 1.59 l/h ·kg; and volume of distribution at steady state, 11.8 l/kg. After oral administration at a dose level of 3.2 mg/kg, the parameters in the whole blood were as follows: maximal blood concentration (C_max), 41 ng/ml; time to reach C_max, 0.25 hour; and area under the concentration-time curve (AUC_0-24h), 255 ng·h/ml. Absorption of radioactivity and FK506 was 37 and 14%, respectively, calculated from the values of AUC0-24 h in the whole blood. Distribution of FK506 in the blood changed depending on its levels. The ratio of whole blood to plasma levels was more than 2.5 at less than the whole blood levels of 50 ng/ml but decreased above these levels.
2. Radioactivity was distributed throughout the body after i.v. injection of ¹⁴C-FK506 at a dose of 0.32 mg/kg. Radioactivity was highest in most of tissues at 5 minutes after injection, the first sampling point after injection, and the levels were higher than those in the plasma except that in the white fat, testis, cerebellum and cerebrum. At 72 hours after injection, radioactivity in most tissues decreased to less than 10% of the maximal concentrations except that in the cerebrum, testis and urinary bladder, in which about half of the concentration was detected. After oral administration at a dose of 1.0 mg/kg, radioactivity was distributed mainly in the gut and liver and was hardly detected in the other tissues.
3. During 72 hours after administration of ¹⁴C_ FK506 at a dose of 1.0 mg/kg, 8 and 95%of the dosed radioactivity were respectively excreted to the urine and feces after i.v. injection and 4 and 96% after oral administration. During 48 hours after i.v. injection to the bile duct-cannulated rats, 3, 8 and 82% of the dosed radioactivity were recovered in the urine, feces and bile, respectively, and 3, 6 and 35% during the same period after oral administration.
4. Less than 0.4% of the dosed radioactivity was excreted as unchanged FK506 in the urine, feces and bile, and the elution pattern of excreted radioactivity was very complex on high performance liquid chromatography and no major but many small radioactive peaks were observed. The major in vitro metabolite, 13-O-mono-demethylated metabolite, was detected in the urine, feces and bile but its portion to total radioactivity was very small.

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Molecular genetic studies of familial adenomatous polyposis (FAP) kindreds led to the discovery of the APC (adenomatous polyposis coli) gene on human chromosome 5q21. Mutations in APC appear to be responsible for not only FAP but also many sporadic cancers of the colorectal axis, stomach, and esophagus. The APC protein contains regions that may form an α-helical coiled-coil structure, and a subdomain of the first 55 as form a stable, parallel helical dimer. Antibody studies showed that the wild-type, but not mutant, APC protein is associated with the microtubule cytoskeleton. The predicted structure of APC, its localization, and its interaction with β-catenin suggested its involvement in cell adhesion. In fact, recent studies demonstrated that APC is localized to plasma membrane sites involved in active cell migration. At the same time, β-catenin interacts with hTcf-4 and Lef transcription factors. hTcf-4 transactivates transcription only when associated with β-catenin. We recently constructed a gene knockout mouse strain in which the mouse homolog of the human APC was inactivated by homologous recombination. Using this mouse strain, we elucidated the mechanism how the polyp adenomas are formed in both morphological and genetic aspects. At the same time, we investigated the effects of carcinogens and anticancer agents on the polyposis. Accumulating evidence indicates that nonsteroidal antiinflammatory drugs (NSAIDs) reduce the incidence of colorectal cancers in human and experimental animals, and reduce the polyp number and size in FAP patients. Recently, evidence has been presented that COX-2 is induced in human colorectal cancers, and in the polyps of mouse FAP models. Accordingly, we inactivated the COX-2 gene in our FAP model mice, and demonstrated that both the number and size of polyps are reduced dramatically. In addition, a COX-2 selective inhibitor caused similar results to COX-2 gene knockout mutations. These genetic and pharmacological data open the possibility of effectively treating human FAP and various cancers with COX-2 selective inhibitors, a new class of NSAIDs.

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Discussions on the hepatic uptake mechanisms for Pravastatin and Temocaprilat were made. The uptake of Pravastatin by primary cultured rat hepatocytes was temperature-dependent, saturated at high substrate concentrations, and inhibited by metabolic inhibitors such as rotenone, indicating an involvement of carrier-mediated active transport system. The hepatic uptake of Pravastatin was also inhibited competitively by various organic anions such as dibromosulfophthalein and bile acids, and was dependent neither on Na⁺ ion nor on Cl^- ion. Pravastatin competitively inhibited the uptake of Na⁺-independent bile acids, indicating that Pravastatin serves as the substrate of the Na⁺-independent bile acids transporter. Therefore, the organic anion transporting polypeptide (oatp) was strongly suggested to be involved in the hepatic uptake of Pravastatin, while the expression system of oatpl in COS-7 cells failed to transport Pravastatin, suggesting that the uptake of Pravastatin is mediated either by other isoforms of oatp, or by bilitranslocase or by organic anion binding protein. The hepatic uptake of Temocaprilat, the active metabolite of Temocapril, was also found to be the carrier-mediated active transport according to the observations obtained in the similar uptake experiments as described above. Oatpl accounted for most part of the hepatic uptake of Temocaprilat.

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The rates and routes of the metabolism of a compound, as well as its potential to interfere with the metabolism of other, co-administered compounds, can often be the major factors that determine the clinical usefulness of a drug. There are, therefore, obvious economic advantages in being able to make predictions of these factors in drug discovery, thus enabling informed choices to be made between candidate molecules in a discovery series. Many of the major drug-drug interactions recognised to date occur at the level of liver cytochromes P450. All of the major human cytochromes P450 involved in drug metabolism have been cloned and expressed in transformed cell lines. These are commercially available, either as the original cell lines, or as microsomes or purified enzyme prepared from them. In these formats, the P450s can be used to determine the enzymology of a compound's metabolism and its potential for inhibition-based interactions. Current adaptations of the methods used in these types of study are enabling expressed P450s to be used in high throughput metabolism screens. It is possible that, in the future, they will also be incorporated into novel techniques, such as hyphenated screening systems. Thus, the expressed P450s will continue to be an important tool for drug discovery in the pharmaceutical industry.

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