Publications by authors named "Shunichi Kametani"

This study was conducted to investigate the possibility of performing nose-to-brain delivery of TS-002, which is an analog compound of prostaglandin D2 (PGD2) and thus would be a natural sleep inducer. The absolute bioavailability (BA) and sleep-inducing effect (SIE) following intranasal (IN) administration of TS-002 dry powder to cynomolgus monkeys were evaluated in comparison with intravenous (IV) administration. The SIE was evaluated as the accumulated time of sleeping-posture for 3 h.

View Article and Find Full Text PDF

A new type of S-protected thiol-type thiamines (prodrugs), which have a (5-methyl-2-oxo-1,3-dioxol-4-yl) methyl group recognized as a biologically safe promoiety, were designed, prepared, and confirmed to show higher serum thiamine levels after oral administration to rats than after that of thiamine itself and bisbentiamin as standards. Thus it was shown that the promoiety should be also used for improvement of poor oral absorption of drugs with a mercapto group, in addition to the absorption of drugs with carboxyl, amino, and hydroxyl groups.

View Article and Find Full Text PDF

The present study characterized the effects of TS-011 [N-(3-chloro-4-morpholin-4-yl) phenyl-N'-hydroxyimido formamide], a new selective inhibitor of the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE), on the metabolism of arachidonic acid by human and rat renal microsomes and the inhibitory effects of this compound on hepatic cytochrome P450 enzymes involved in drug metabolism. The effects of TS-011 on the fall in cerebral blood flow following subarachnoid hemorrhage (SAH) and in reducing infarct size in ischemic stroke models were also examined since 20-HETE may contribute to the development of cerebral vasospasm. TS-011 inhibited the synthesis of 20-HETE by human renal microsomes and recombinant CYP4A11 and 4F2, 4F3A, and 4F3B enzymes with IC50 values around 10 to 50 nM.

View Article and Find Full Text PDF

As a part of the studies conducted by the Pharma SNPs Consortium (PSC), the enzyme activities of CYP1A2, CYP2A6 and CYP2B6 variants with altered amino acids as a result of single nucleotide polymorphisms (SNPs) found among the Japanese population were analyzed under a unified protocol using the same lots of reagents by the laboratories participating in the PSC. Mutations in CYP1A2, CYP2A6 and CYP2B6 were introduced by site-directed mutagenesis and the wild type and mutated CYP molecules were expressed in Escherichia coli. The expressed cytochrome P450s were purified and the enzyme activities were measured in reconstitution systems.

View Article and Find Full Text PDF