Small-Dosing Clinical Study: Pharmacokinetic, Pharmacogenomic (SLCO2B1 and ABCG2), and Interaction (Atorvastatin and Grapefruit Juice) Profiles of 5 Probes for OATP2B1 and BCRP.

The aims of this study were (1) to investigate the effects of atorvastatin (10 mg, therapeutic dose) and grapefruit juice (GFJ), inhibitors of OATP2B1, on the pharmacokinetics of substrates for OATP2B1 and BCRP under oral small-dosing conditions (300 µg sulfasalazine, 250 µg rosuvastatin, 300 µg glibenclamide, 1200 µg celiprolol, and 600 µg sumatriptan), and (2) to evaluate the contribution of SLCO2B1*3 and ABCG2 c.421C>A polymorphisms to the pharmacokinetics of the 5 test drugs in 23 healthy volunteers. In the 3 phases, the test drugs were administered to volunteers with either water (control phase), atorvastatin, or GFJ. GFJ but not atorvastatin reduced the exposure of the test drugs significantly more than the control phase, suggesting that all 5 test drugs are substrates for OATP2B1. The SLCO2B1*3 genotype had no effect on the pharmacokinetics of the test drugs. In contrast, the exposure of sulfasalazine and rosuvastatin was significantly higher in ABCG2 421C/A than in ABCG2 421C/C individuals at all 3 phases, even under small-dosing conditions.

Determination of celiprolol in human plasma using high performance liquid chromatography with fluorescence detection for clinical application.

A new method of analysis has been developed and validated for the determination of plasma celiprolol concentration. Plasma samples (1 ml) were pre-purified by solid-phase extraction with Bond Elut C18. The separation was achieved with XBridge C18 column (150 mm × 3.0mm i.d., 3.5 µm) at 35 °C using a mixture of acetonitrile and 10mM ammonium acetate buffer (pH 10.5) (34:66, v/v) under isocratic conditions at a flow rate of 0.4 ml/min. The peak was detected using a fluorescence detector at excitation 250 nm and emission 482 nm. Retention times for the internal standard (acebutolol) and celiprolol were 4.2 min and 6.3 min, respectively. Calibration curves were linear over the range of 1.0-1000 ng/ml (r>0.999), with a limit of quantification at 1.0 ng/ml. Intra- and inter-assay precision (relative standard deviation) were less than 13.3% and the accuracy (relative error) was -5.1% to 11.5% at four different concentrations. This proposed method was successfully applied to a study of pharmacokinetic interactions between celiprolol and apple juice in humans.

Thermodynamics of non-stoichiometric pharmaceutical hydrates.

Different physical and mathematical models of non-stoichiometric hydrates derived form previous work in inorganic hydrates are reviewed. A theoretical link between the order of water molecules in the hydrate and the shape of the isotherm is outlined. The comparison of the models with sorption isotherms and structural data of well-known cases from the literature and one in-house case shows that the model can fit many experimental situations and is in good agreement with qualitative assessments of the order in the hydrates.

[Separation of celiprolol enantiomer by high performance liquid chromatography with urea derivative as chiral stationary phase].

Celiprolol enantiomer was resolved directly by using normal-phase HPLC with urea derivative as chiral stationary phase (CSP). The resolution condition was optimized by varying the content of ethanol and 1, 2-dichloroethane in the mobile phase. The effects of the two components on stereoselectivity factor (alpha) and stereochemical resolution factor (Rs) are demonstrated. The higher the 1,2-dichloroethane content the faster the elution of solute is, but the lower the values of alpha and Rs are. For a suitable content of ethanol in mobile phase, the maximum resolution factor (Rs) can be obtained. Ethanol is a strong proton-donor and proton-acceptor. Its strong hydrogen bond interaction with solute and CSP is important for the direct resolution. In order to obtain both the low retention time and a high Rs, we chose the mobile phase with n-hexane:1,2-dichloroethane:ethanol (V/V/V) = 77:21:2. Other organic modifiers such as methanol, iso-propanol, n-butanol and acetonitrile were also used. Iso-propanol, methanol and n-butanol showed longer retention time and lower values of alpha and Rs than ethanol. Acetonitrile is only a proton-acceptor and has weak hydrogen bond interaction with solute and CSP, so resolution wasn't obtained. The elution order of enantiomer was also discussed. We thought that the hydrogen bond interaction between solute and the (S)-val component of CSP may mainly control the chiral recognition. The interaction strength is different between (R)- and (S)-celiprolol, so the celiprolol enantiomer was resolved. And the elution order is S, R.

Thin-layer chromatographic analysis of some beta-blocking drugs in plasma.

beta-receptor blockers--atenolol, celiprolol, metoprolol, propafenone, propranolol and talinolol--extracted from plasma, were separated by TLC method on silica gel by ascending technique. Isolation of drugs was performed by using liquid-liquid extraction after alkalization of blood plasma. Suitable conditions for separation were established using ethyl acetate-acetone-ammonia (5:4:1) as the mobile phase. The substances were identified by UV irradiation (254 nm) or by reactions with a variety of reagents. The visual limits of determination of named beta-blockers, after reaction with indicators, are between 100-300 ng; celiprolol and talinolol are the most sensitively detectable of investigated substances.

Liquid chromatographic determination of total celiprolol or (S)-celiprolol and (R)-celiprolol simultaneously in human plasma.

A method has been developed for the determination of total celiprolol (sum of enantiomers) or the enantiomers (R)-celiprolol and (S)-celiprolol in plasma by high-performance liquid chromatography with UV and fluorescence detection. After extraction from alkalinized plasma with methyl-tert.-butyl ether and back-extraction into 0.01 M HCl (for total celiprolol determination) or after evaporation of the organic phase and derivatisation with R(-)-1-(1-naphthyl)ethyl isocyanate (enantiomer determination), total celiprolol or its diastereomeric derivatives were chromatographed on a reversed-phase HPLC column with a mixture of acetonitrile and phosphate buffer pH 3.5 (+0.05% triethylamine). Acebutolol was used as internal standard. Linearity was obtained in the range of 5 to 2000 ng/ml for total and 2.5 to 500 ng/ml for enantiomer determination. Intra-day and inter-day variation was lower than 10%. The method can be applied for analysis of plasma samples obtained from patients treated with oral racemic celiprolol doses.