Pharmacokinetic study of meropenem in healthy beagle dogs receiving intermittent hemodialysis.

Meropenem, a second carbapenem antimicrobial agent with a broad spectrum of activity, is used to treat sepsis and resistant-bacterial infections in veterinary medicine. The objective of this study was to identify the pharmacokinetics of meropenem in dogs receiving intermittent hemodialysis (IHD) and to determine the proper dosing in renal failure patients receiving IHD. Five healthy beagle dogs were given a single i.v. dose of 24 mg/kg of meropenem and received IHD. The blood flow rate, dialysate flow, and ultrafiltration rate were maintained at 40 mL/min, 300 mL/min, and 40 mL/h, respectively. Blood samples were collected for 24 h from the jugular vein and from the extracorporeal arterial and venous line. Urine samples and dialysate were also collected. The concentrations of meropenem were assayed using HPLC/MS/MS determination. The peak plasma concentration was 116 ± 37 µg/mL at 15 min. The systemic clearance was 347 ± 117 mL/h/kg, and the steady-state volume of distribution was 223 ± 67 mL/kg. Dialysis clearance was 71.1 ± 34.3 mL/h/kg, and the extraction ratio by hemodialysis was 0.455 ± 0.150. The half-life (T1/2 ) in dogs with IHD decreased compared with those without IHD, and the reduction in T1/2 was greater in renal failure patients than in normal patients. Sixty-nine percent and 21% of the administered drug were recovered by urine and dialysate in the unchanged form, respectively. In conclusion, additional dosing of 24 mg/kg of meropenem after dialysis could be necessary according to the residual renal function of the patient based on the simulated data.

Skin dryness in apparently healthy human skin is associated with decreased expression of bleomycin hydrolase in the stratum corneum.

BACKGROUND: Maintenance of water balance in the stratum corneum (SC) is determined by the content of intercellular lipids and natural moisturizing factors (NMFs) in corneocytes. AIM: To investigate the association between the NMFs and (pro)filaggrin and the proteases responsible for the processing of (pro)filaggrin to NMFs in the SC of hydrated and dry skin areas of healthy human subjects. METHODS: The SC hydration state and the transepidermal water loss (TEWL) were measured using a Corneometer and a Tewameter, respectively. Proteases, (pro)filaggrin and NMFs were extracted from SC samples obtained by tape-stripping of the tested skin. Expression levels of (pro)filaggrin were determined by dot blotting and western blotting, and total NMFs by ultra-high performance liquid chromatography. Expression of the proteases caspase-14, calpain-1 and bleomycin hydrolase was measured by western blotting. RESULTS: The levels of (pro)filaggrin were not significantly different between hydrated and dry skin, whereas the level of total NMFs was significantly reduced in dry skin. A negative correlation between (pro)filaggrin and NMFs was found in dry skin (Pearson correlation coefficient r = - 0.57, *P < 0.05). Bleomycin hydrolase expression was significantly decreased in the SC of dry skin. CONCLUSIONS: These results suggest that the low hydration state of dry skin may be due to the reduction in (pro)filaggrin degradation caused by decreased bleomycin hydrolase expression.

Cathepsin G inhibitor prevents ultraviolet B-induced photoaging in hairless mice via inhibition of fibronectin fragmentation.

BACKGROUND: Cathepsin G, a serine protease that is activated by ultraviolet (UV) radiation, increases matrix metalloproteinase-1 (MMP-1) expression in fibroblasts through fibronectin (Fn) fragmentation and promotes the conversion of proMMP-1 to active MMP-1. OBJECTIVES: This study investigated whether [2-[3-[[(1-benzoyl-4-piperidinyl)methylamino]carbonyl]-2-naphthalenyl]-1-(1-naphthalenyl)-2-oxoethyl]-phosphonic acid (KPA), a cathepsin G inhibitor, plays any role in extracellular matrix (ECM) damage in an in vitro 3D dermal equivalent (DE) and an in vivo ultraviolet B (UVB)-irradiated hairless mice. METHODS: We examined the potential ECM-protective effects of a cathepsin G inhibitor in an in vitro 3D DE model and an in vivo UVB-irradiated hairless mouse skin model. RESULTS: Among five known serine protease inhibitors, KPA showed the strongest potency and selectivity against cathepsin G. KPA inhibited the cathepsin G-mediated MMP-1 increase and alleviated the downregulation of mRNAs encoding collagen and tissue inhibitor of matrix metalloproteinase-1 in an in vitro 3D DE model. Most importantly, topical application of KPA (0.025%) to the dorsal skin of hairless mice enhanced collagen expression and attenuated UVB-induced Fn fragmentation and upregulation of MMP-2 and MMP-9 activities. CONCLUSIONS: Cathepsin G inhibitors may be useful for the prevention of UVB-induced photoaging through amelioration of ECM damage and MMP upregulation.

Pharmacodynamic comparison of two formulations of Acarbose 100-mg tablets.

WHAT IS KNOWN AND OBJECTIVE: Acarbose, an α-glycosidase inhibitor, is used to treat diabetic patients. Pharmacokinetic evaluation of acarbose is difficult because <2% is absorbed systemically. The current investigation evaluated the bioequivalence of two formulations of acarbose through pharmacodynamic comparison. METHODS: This investigation consisted of a pilot study and a main study. The pilot study had an open, single-dose, single-sequence design. Subjects received placebo and then two tablets of reference formulation (Glucobay(®) 100 mg tablet; Bayer Healthcare) on two consecutive days with sucrose. The main study was an open, randomized, two-period, two-sequence crossover study. Subjects randomly received placebo and two tablets of either test formulation (generic acarbose 100-mg tablet) or reference formulation with sucrose on two consecutive days in the first period. In the second period, placebo and alternative formulation were administered. Serial blood samples for pharmacodynamic assessment were taken after each administration. The maximum serum glucose concentration (G(max)) and the area under the serum glucose concentration-time profile (AUC(gluc)) were determined and compared. RESULTS AND DISCUSSION: Five subjects completed the pilot study. The AUC(gluc) from dosing until 1 h post-dose (AUC(gluc,1 h)) was significantly different between the placebo and acarbose. A total of 33 subjects completed the main study. The mean differences in G(max) (ΔG(max)) and AUC(gluc,1 h) (ΔAUC(gluc,1 h)) for the reference formulation compared with placebo were 22·0 ± 18·3 mg/dL and 928·2 ± 756·0 mg min/dL, respectively. The corresponding values for the test formulation were 23·3 ± 21·2 mg/dL and 923·0 ± 991·4 0 mg min/dL, respectively. The geometric mean ratios (GMRs) of the test formulation to the reference formulation for ΔG(max) and ΔAUC(gluc, 1 h) were 1·06 and 1·00, respectively, and the 90% confidence intervals (CIs) corresponding values were 0·79-1·39 and 0·64-1·36, respectively. WHAT IS NEW AND CONCLUSION: The 90% CIs of GMRs for the pharmacodynamic parameters chosen for bioequivalence evaluation of two formulations of acarbose did not meet the commonly accepted regulatory criteria for bioequivalence (0·80-1·25).

Identification of an emulsifier and conditions for preparing stable nanoemulsions containing the antioxidant astaxanthin.

In this study, oil-in-water nanoemulsions of astaxanthin were prepared by high-pressure homogenization. The influence of emulsifying conditions including emulsifier type, concentration, passing time, astaxanthin concentration and coantioxidants were optimized. The stabilities of nanoemulsions were measured using zetasizer, FF-SEM, TEM, colorimeter and particle size analyzer. The mean diameter of the dispersed particles containing astaxanthin ranged from 160 to 190 nm. The size distribution was unimodal and extended from 100 to 200 nm. The nanoemulsions prepared with glyceryl citrate/lactate/linoleate/oleate (glyceryl ester) had smaller particle size and narrower size distribution than the emulsion prepared with hydrogenated lecithin. Stable incorporation of astaxanthin in nanoemulsion was performed and checked using HPLC, FF-SEM and TEM. The nanoemulsion was not significantly affected during storage under light and thermal condition for one month indicating that the nanoemulsion had a zeta potential of less than -41 mV, indicating a stable colloid.

Two-phase airlift fermentor operation with elicitation for the enhanced production of enzophenanthridine alkaloids in cell suspensions of Escherichia californica.

Approaches to increasing the productivity of benzophenanthridine alkaloids in suspension cultures in Escherichia californica were made in an airlift fermentor under different culture conditions. Elicitation with yeast extract elicitor reduced the time required to obtain a certain amount of alkaloid production. In a two-phase airlift fermentor with compounded silicone fluid, total alkaloid concentration in silicone fluid was 153.1 mg/L and that in the aqueous cellular phase was 8.2 mg/L at day 21 from inoculation. The large accumulation capacity of silicone fluid made it possible to store correspondingly large amounts of total alkaloid and increased the alkaloid production. Act day 21 from inoculation, the volumetric alkaloid productivity and the netproduction in a two-phase airlift fermentor were 1.4 and 1.5 times higher than those of normal airlift fermentor operation. This performance was furthermore enhanced by elicitation. Elicitation in two-phase airlift fermentor operation increased the volumetric productivity and the new production 3.3- and 3.5-fold compared to those of normal airlift fermentor operation.

Integrated bioprocessing for plant cell cultures.

Plant cell suspension culture has become the focus of much attention as a tool for the production of secondary metabolites including paclitaxel, a well-known anticancer agent. Recently, it has also been regarded as one of the host systems for the production of recombinant proteins. In order to produce phytochemicals using plant cell cultures, efficient processes must be developed with adequate bioreactor design. Most of the plant secondary metabolites are toxic to cells at the high concentrations required during culture. Therefore, if the product could be removed in situ during culture, productivity might be enhanced due to the alleviation of this toxicity. In situ removal or extractive bioconversion of such products can be performed by in situ extraction with various kinds of organic solvents. In situ adsorption using polymeric resins is another possibility. Using the fact that secondary metabolites are generally hydrophobic, various integrated bioprocessing techniques can be designed not only to lower toxicity, but also to enhance productivity. In this article, in situ extraction, in situ adsorption, utilization of cyclodextrins, and the application of aqueous two-phase systems in plant cell cultures are reviewed.