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Simultaneous determination of atenolol and amiloride in pharmaceutical preparations by capillary zone electrophoresis with capacitively coupled contactless conductivity detection

Al Azzam KM, Saad B, Aboul-Enein HY

Biomed Chromatogr, 2010 Sep;24(9):948-53.
PMID: 20082285 DOI: 10.1002/bmc.1390

Capillary zone electrophoresis coupled with a capacitively coupled contactless conductivity detector (CE-C(4)D) has been employed for the determination of atenolol and amiloride in pharmaceutical formulations. Acetic acid (150 mm) was used as background electrolyte. The influence of several factors (detector excitation voltage and frequency, buffer concentration, applied voltage, capillary temperature and injection time) was studied. Non-UV-absorbing L-valine was used as internal standard; the analytes were all separated in less than 7 min. The separation was carried out in normal polarity mode at 28 degrees C, 25 kV and using hydrodynamic injection (25 s). The separation was effected in an uncoated fused-silica capillary (75 microm, i.d. x 52 cm). The CE-C(4)D method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 5-250 microg/mL for the studied analytes. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of atenolol and amiloride in different pharmaceutical tablet formulations.

Matched MeSH terms: Amiloride/analysis*
Simultaneous determination of atenolol and amiloride by capillary electrophoresis with capacitively coupled contactless conductivity detection (C4D)

AL Azzam KM, Aboul-Enein HY

Methods Mol Biol, 2013;919:67-78.
PMID: 22976091 DOI: 10.1007/978-1-62703-029-8_7

Capillary electrophoresis coupled with a capacitively coupled contactless conductivity detector (CE-C(4)D) has been employed for the determination of the β-blocker drugs (atenolol and amiloride) in pharmaceutical formulations. 150 mM acetic acid was used as background electrolyte. The influence of several factors (detector excitation voltage and frequency, buffer concentration, applied voltage, capillary temperature, and injection time) was studied. Non-UV absorbing L-valine was used as an internal standard; the analytes were all separated in less than 7 min. The separation was carried out in normal polarity mode at 28 °C, 25 kV, and using hydrodynamic injection (25 s). The separation was effected in a bare fused-silica capillary 75 μm × 52 cm. The CE-C(4)D method was validated with respect to linearity, limit of detection and quantification, accuracy, precision, and selectivity. Calibration curves were linear over the range 5-250 μg mL(-1) for the studied analytes. The relative standard deviations of intra- and inter-day precisions of migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of the β-blocker drugs in different pharmaceutical tablets.

Matched MeSH terms: Amiloride/analysis*; Amiloride/chemistry
Simultaneous determination of atenolol, chlorthalidone and amiloride in pharmaceutical preparations by capillary zone electrophoresis with ultraviolet detection

Al Azzam KM, Saad B, Aboul-Enein HY

Biomed Chromatogr, 2010 Sep;24(9):977-81.
PMID: 20066730 DOI: 10.1002/bmc.1395

Capillary zone electrophoresis methods for the simultaneous determination of the beta-blocker drugs, atenolol, chlorthalidone and amiloride, in pharmaceutical formulations have been developed. The influences of several factors (buffer pH, concentration, applied voltage, capillary temperature and injection time) were studied. Using phenobarbital as internal standard, the analytes were all separated in less than 4 min. The separation was carried out in normal polarity mode at 25 degrees C, 25 kV and using hydrodynamic injection (10 s). The separation was effected in an uncoated fused-silica capillary (75 mum i.d. x 52 cm) and a background electrolyte of 25 mm H(3)PO(4) adjusted with 1 m NaOH solution (pH 9.0) and detection at 198 nm. The method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 1-250 microg/mL for atenolol and chlorthalidone and from 2.5-250 microg/mL for amiloride. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of atenolol, chlorthalidone and amiloride in various pharmaceutical tablets formulations.

Matched MeSH terms: Amiloride/analysis*
Testosterone enhances expression and functional activity of epithelial sodium channel (ENaC), cystic fibrosis transmembrane regulator (CFTR) and sodium hydrogen exchanger (NHE) in vas deferens of sex-steroid deficient male rats

Khadijah Ramli NS, Giribabu N, Salleh N

Steroids, 2018 10;138:117-133.
PMID: 30003911 DOI: 10.1016/j.steroids.2018.06.012

Effects of testosterone on expression and functional activity of ENaC, CFTR and NHE in vas deferens were investigated.
METHODS: Orchidectomized, adult male rats were given 125 and 250 μg/kg/day testosterone subcutaneously, with or without flutamide and finasteride for seven consecutive days. At the end of the treatment, rats were anesthetized and vas deferens were perfused. Changes in vas deferens fluid secretion rate, pH, HCO3-, Cl- and Na+ concentrations were recorded in the presence of amiloride and Cftr inh-172. Rats were then sacrificed and vas deferens were harvested and subjected for molecular biological analysis.
RESULTS: Testosterone treatment caused the fluid pH and HCO3- concentrations to decrease but secretion rate, Cl- and Na+ concentrations to increase, where upon amiloride administration, the pH and HCO3- concentration increased but Cl- and Na+ concentrations further increased. In testosterone-treated rats, administration of Cftr inh-172 caused all fluid parameters to decrease. In testosterone-treated rats co-administered with flutamide or finasteride, pH and HCO3- concentration increased but fluid secretion rate, Cl- and Na+ concentrations decreased and these parameters were not affected by amiloride or Cftr inh-172 administration. Under testosterone influence, CFTR and γ-ENaC were highly expressed at the apical membrane while NHE-1 and 4 were highly expressed at the basolateral membrane of vas deferens epithelium. Meanwhile, NHE-2 and 3 were highly expressed at the apical membrane.
CONCLUSIONS: Differential expression of ENaC, CFTR and NHE in vas deferens under testosterone influence indicated the important role of these transporters in creating optimal fluid microenvironment that is essential for preserving male fertility.

Matched MeSH terms: Amiloride
Fulltext Annexin II Light Chain p11 Interacts With ENaC to Increase Functional Activity at the Membrane

Cheung TT, Ismail NAS, Moir R, Arora N, McDonald FJ, Condliffe SB

Front Physiol, 2019;10:7.
PMID: 30800070 DOI: 10.3389/fphys.2019.00007

The epithelial Na+ channel (ENaC) provides for Na+ absorption in various types of epithelia including the kidney, lung, and colon where ENaC is localized to the apical membrane to enable Na+ entry into the cell. The degree of Na+ entry via ENaC largely depends on the number of active channels localized to the cell membrane, and is tightly controlled by interactions with ubiquitin ligases, kinases, and G-proteins. While regulation of ENaC endocytosis has been well-studied, relatively little is understood of the proteins that govern ENaC exocytosis. We hypothesized that the annexin II light chain, p11, could participate in the transport of ENaC along the exocytic pathway. Our results demonstrate that all three ENaC channel subunits interacted with p11 in an in vitro binding assay. Furthermore, p11 was able to immunoprecipitate ENaC in epithelial cells. Quantitative mass spectrometry of affinity-purified ENaC-p11 complexes recovered several other trafficking proteins including HSP-90 and annexin A6. We also report that p11 exhibits a robust protein expression in cortical collecting duct epithelial cells. However, the expression of p11 in these cells was not influenced by either short-term or long-term exposure to aldosterone. To determine whether the p11 interaction affected ENaC function, we measured amiloride sensitive Na+ currents in Xenopus oocytes or mammalian epithelia co-expressing ENaC and p11 or a siRNA to p11. Results from these experiments showed that p11 significantly augmented ENaC current, whereas knockdown of p11 decreased current. Further, knockdown of p11 reduced ENaC cell surface population suggesting p11 promotes membrane insertion of ENaC. Overall, our findings reveal a novel protein interaction that controls the number of ENaC channels inserted at the membrane via the exocytic pathway.

Matched MeSH terms: Amiloride