Effectiveness and safety of the simulation-based first-dose design of voriconazole.

BACKGROUND: We investigated whether the initial voriconazole (VRCZ) dosing design, as determined using simulation software with a population pharmacokinetic model of Japanese patients, impacts the effectiveness and safety when compared with VRCZ initiation according to the package insert. METHODS: In this single-center retrospective observational study, we employed records from Tosei General Hospital (a 633-bed hospital), dated April 2017 to September 2023. Eligible patients were divided into the software-based simulation group, comprising patients administered initial VRCZ dosage adjustment by pharmacists using software-based simulation, and the standard therapy group, whose dosage was administered by a physician following the package insert recommendations without simulation. The primary objective of this study was to determine the efficacy of VRCZ first-dose design in reducing the incidence of hepatotoxicity and visual symptoms. RESULTS: The median ages of enrolled participants (n = 93) were 75 (68-79) and 72 (65-78) years in the software-based simulation and standard therapy groups, respectively. Regardless of formulation, initial trough concentrations were lower in the VRCZ software-based first dosage adjustment group and higher rate within the appropriate range (1-4 µg/mL). The incidence of all-grade hepatotoxicity or visual symptoms was significantly lower in the software-based simulation group. The log-rank test revealed a significant impact on the occurrence of ≥grade 2 hepatotoxicity in the software-based first dosage adjustment group compared to that in the standard therapy group. CONCLUSIONS: The initial VRCZ dosing design using simulation software improved the achievement of appropriate initial trough concentrations and resulted in fewer occurrences of hepatotoxicity (≥grade 2) when compared with the standard therapy.

Biochemistry of fish stomach chitinase.

Fish are reported to exhibit chitinase activity in the stomach. Analyses of fish stomach chitinases have shown that these enzymes have the physiological function of degrading chitinous substances ingested as diets. Osteichthyes, a group that includes most of the fishes, have several chitinases in their stomachs. From a phylogenetic analysis of the chitinases of vertebrates, these particular molecules were classified into a fish-specific group and have different substrate specificities, suggesting that they can degrade ingested chitinous substances efficiently. On the other hand, it has been suggested that coelacanth (Sarcopterygii) and shark (Chondrichthyes) have a single chitinase enzyme in their stomachs, which shows multiple functions. This review focuses on recent research on the biochemistry of fish stomach chitinases.

Stomach Chitinase from Japanese Sardine Sardinops melanostictus: Purification, Characterization, and Molecular Cloning of Chitinase Isozymes with a Long Linker.

Fish express two different chitinases, acidic fish chitinase-1 (AFCase-1) and acidic fish chitinase-2 (AFCase-2), in the stomach. AFCase-1 and AFCase-2 have different degradation patterns, as fish efficiently degrade chitin ingested as food. For a comparison with the enzymatic properties and the primary structures of chitinase isozymes obtained previously from the stomach of demersal fish, in this study, we purified chitinase isozymes from the stomach of Japanese sardine Sardinops melanostictus, a surface fish that feeds on plankton, characterized the properties of these isozymes, and cloned the cDNAs encoding chitinases. We also predicted 3D structure models using the primary structures of S. melanostictus stomach chitinases. Two chitinase isozymes, SmeChiA (45 kDa) and SmeChiB (56 kDa), were purified from the stomach of S. melanostictus. Moreover, two cDNAs, SmeChi-1 encoding SmeChiA, and SmeChi-2 encoding SmeChiB were cloned. The linker regions of the deduced amino acid sequences of SmeChi-1 and SmeChi-2 (SmeChi-1 and SmeChi-2) are the longest among the fish stomach chitinases. In the cleavage pattern groups toward short substrates and the phylogenetic tree analysis, SmeChi-1 and SmeChi-2 were classified into AFCase-1 and AFCase-2, respectively. SmeChi-1 and SmeChi-2 had catalytic domains that consisted of a TIM-barrel (ß/α)8-fold structure and a deep substrate-binding cleft. This is the first study showing the 3D structure models of fish stomach chitinases.