Clyde N. Carducci

Bile acid profiles by capillary electrophoresis in intrahepatic cholestasis of pregnancy

ICP (intrahepatic cholestasis of pregnancy) is characterized by pruritus and biochemical cholestasis, including raised SBAs (serum bile acids) and, usually, elevated aminotransferases levels. However, AHP (asymptomatic hypercholanaemia of pregnancy) is defined as the presence of total SBA levels above the cut-off value (11 microM) in healthy pregnant women, thus elevation of total SBAs do not necessarily reflect an ICP condition. The aim of the present study was to describe clinical, obstetric, perinatal and biochemical findings, as well as the SBA profile, in pregnant women studied in the third trimester of pregnancy in order to define characteristic patterns of individual bile acids that enable women with ICP to be distinguished from AHP and healthy pregnancies. Free and conjugated ursodeoxycholic (UDCA), cholic (CA), lithocholic (LCA), deoxycholic (DCA) and chenodeoxycholic (CDCA) acids were evaluated by CE (capillary electrophoresis) in 41 patients (15 of them simultaneously by HPLC), in 30 healthy pregnant women and in 10 non-pregnant women. A highly significant correlation between CE and HPLC for total SBAs (r=0.990) and for individual SBAs was found. Normal pregnant women had higher total SBA levels than non-pregnant women (due to an increase in taurine-conjugated dihydroxy SBAs). Women with ICP had higher levels of total SBAs, the free/conjugated ratio, LCA, CA, CDCA and DCA than normal pregnant women. Newborns from women with ICP had lower birth weight and gestational age. Women with AHP had higher levels of conjugated dihydroxy SBAs than normocholanaemic patients, without any evidence of a clinical difference. In conclusion, the present study has shown a clear difference in SBA profiles between ICP and normal pregnancies (including AHP), involving a shift towards a characteristic hydrophobic composition in women with ICP.

Analysis of cis-trans isomers and enantiomers of sertraline by cyclodextrin-modified micellar electrokinetic chromatography

In this work development, optimization and validation of a cyclodextrin-modified micellar electrokinetic chromatography (CD-modified MEKC) method is proposed to resolve separation of the sertraline hydrochloride and synthesis-related substances. Sertraline hydrochloride, the cis-(1S,4S) enantiomer form, is used as an antidepressant therapeutic agent. A buffer concentration composed of 20 mM sodium borate, pH 9.0 with 50 mM sodium cholate, 15 mM sulfated beta-cyclodextrin and 5 mM hydroxypropyl-beta-cyclodextrin was found to be the most suitable background electrolyte. Quantitation of the impurities at levels of 0.1% in different samples of the bulk drug was determined. A comparison of the results with those obtained by HPLC methodology was also accomplished. The method proved appropriate for testing the purity of sertraline hydrochloride in bulk drug.

Determination of bile acids in pharmaceutical formulations using micellar electrokinetic chromatography

A micellar electrokinetic chromatography method (MEKC) has been developed and validated for the determination of bile acids (BA) such as ursodeoxycholic acid (UDCA), dehydrocholic acid (DHCA) and deoxycholic acid (DCA) in pharmaceuticals for quality control purpose. The background electrolyte consisted of 20 mM borate-phosphate buffer containing 50 mM sodium dodecylsulfate (SDS), and acetonitrile as additive. UV detection was set at 185 nm. Selectivity, linearity, range, repeatability, intermediate precision and accuracy showed good results. Comparison of the values obtained by MEKC and HPLC methods were in close agreement.

Application of extraction disks in dissolution tests of clenbuterol and levothyroxine tablets by capillary electrophoresis

Sample preparation procedures using octadecyl (C18) extraction disks were developed to obtain accurate and reproducible results for determinations of clenbuterol(20 micrograms per dose) and levothyroxine (100 micrograms per dose) in dissolution media of solid oral dosage forms. Preconcentration of samples allowed final concentrations of 1.1 micrograms/ml of clenbuterol and 4.0 micrograms/ml of levothyroxine to be reached prior to CE analysis. The results obtained by CE were in good agreement with those of HPLC. The precision of the migration time, peak area, peak height and accuracy were determined in both intra-day (n = 6) and inter-day (n = 18) assays. Linearity was demonstrated over the ranges 0.5-80.0 micrograms/ml of clenbuterol and 1.0-30.0 micrograms/ml of levothyroxine. The mean recoveries were higher than 94.0%, ranging from 50 to 125% levels with respect to dose potencies. The proposed methodology may be generally applied to determine drugs at ng/ml concentrations.

Adsorption of drugs in high-performance liquid chromatography injector loops

Abstract The effect of solvent injection on the area and peak-height responses of some drugs (ergotamine tartrate, astemizole, terfenadine, bromhexine hydrochloride, caffeine, ambroxol hydrochloride, phenylephrine hydrochloride, enalapril maleate and betamethasone) was evaluated. Reversed-phase chromatographic systems were employed and loops of different sizes and various overfill volumes were assayed. When injection solvents weaker than the mobile phases were used, significant variation in the area responses was observed for astemizole, bromhexine, ergotamine and terfenadine. Adsorption on the internal surface of the injection loops produced this anomalous behaviour depending on the chemical nature of the analyte injected.

Silanophilic Interaction in the Retention Mechanism of Pharmaceutical Drugs on a Cyanopropyl Bonded Silica Column

Abstract The mechanism of retention of several pharmaceutical drugs with basic, neutral and acidic properties have been examined on a cyano bonded silica stationary phases (Ultrasphere cyano). Clenbuterol, bromhexine, terphenadine, pirenzepine, astemizol, betamethasone, acetaminophen, indomethacin, diclofenac and nimesulide were chosen for this study. Methanol-phosphate buffer mixtures with low water levels were used as mobile phases. Different pH values and ionic strengths were considered. Under experimental conditions, the chromatographic behavior of basic drugs is more complex than the behavior of acidic and neutral ones. The predominant silanophilic interactions observed for drugs of basic characteristics may become quite useful in optimizing selectivity.

CAPILLARY ION ELECTROPHORESIS OF INORGANIC CATIONS IN STANDARD REFERENCE MATERIALS FROM VEGETABLE SOURCE

Taking into account the growing interest in applying capillary ion electrophoresis (CIE) for the determination of inorganic ions in real samples, this work focuses on CIE analysis of K+, Na+, Ca2+, Mg2+, and Mn2+ in botanical and food reference materials. Microwave-Assisted Digestion for sample preparation has been chosen ensuring a rapid, accurate, and reproducible treatment. A fused-silica capillary, 75 μm × 60 cm, a background electrolyte consisting of 6 mM imidazole and 10 mM α-hydroxy-isobutyric acid (HIBA). and indirect UV detection at 214 nm were used. Certified reference materials as Apple leaves SRM 1515 (NIST, USA), Beech leaves CRM 100, Rye flour CRM 381, Haricot beans CRM 383, and the green algae Ulva lactuca CRM 279 (BCR, Belgium) were selected. The optimal experimental conditions for microwave digestion and operational parameters in the electrophoresis system were studied. The calibration curves for K, Ca, Mg, and Mn ions were linear over the range of 0.6 ppm to 120 ppm and the detection lim...