A new, highly slective high-performance liquid-chromatographic (HPLC) assay for theophylline and its major metabolites in urine is described. The method utilizes an ion-pair extraction followed by separation and quantitation by reversed-phase ion-pair gradient-elution HPLC. Comparison with several other methods showed that interferences were present in too many blank urine samples to allow for the accurate quantitation of the metabolites of theophylline by direct injection--isocratic HPLC assays. Sample processing involving ion-pair complexing and extraction together with gradient-elution systems is recommended for accurate pharmacokinetic studies.
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http://dx.doi.org/10.1016/s0378-4347(00)81010-5 | DOI Listing |
NPJ Prim Care Respir Med
January 2025
Department of Pulmonary and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China.
This survey aimed to investigate the availability of drugs for stable chronic obstructive pulmonary disease (COPD) treatment in Chinese hospitals and to determine whether drug availability significantly varied among hospitals with different characteristics. A well-constructed questionnaire was designed according to the Chinese Guidelines for the Diagnosis and Management of COPD (revised version 2021). Both inhaled drugs (monotherapy, double therapy and triple therapy) and oral drugs (expectorants, theophylline, antibiotics, and bacterial lysates) were included in this survey.
View Article and Find Full Text PDFBMC Pediatr
October 2024
Department of Pharmacy, College of Medicine and Health Sciences, Adigrat University, P.O. Box 50, Adigrat, Tigrai, Ethiopia.
Front Cardiovasc Med
August 2024
Division of Cardiology, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
Phys Chem Chem Phys
September 2024
Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India.
The crystal habit of an organic crystalline material impacts its properties, processing, and performance, especially in pharmaceuticals. In solution crystallization, solvents play a crucial role in modulating the crystal habits by interacting with the different growing facets - either enhancing or inhibiting the growth of specific facets. Thus, an in-depth understanding of the role of the solvent in crystal shape selection is of paramount importance for the design and growth of crystals.
View Article and Find Full Text PDFAnal Biochem
January 2025
School of Pharmacy, Wannan Medical College, Wuhu, 241002, China. Electronic address:
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