A high-performance liquid chromatography was developed to assay levofloxacin and vancomycin. Fluorescence polarization immunoassay was to assay amikacin. The oseltamivir carboxylate and telavancin concentrations were assayed by high-performance liquid chromatography coupled with tandem mass spectrometry. / An in vitro model was utilized to examine adsorption of antibiotics onto haemofilters. In order to test antibiotics from a range of classes, levofloxacin, amikacin, vancomycin, telavancin, and oseltamivir carboxylate were studied. / In summary, the antibiotic adsorption by haemofilters is a complex process. Both characteristics of antibiotics and haemofilters may determine adsorption. Among the studied antibiotics, in vitro adsorption of amikacin by PAN filters may have clinical significance, thus the routine monitoring of amikacin peak concentration in vivo during CRRT is recommended. / In the in vitro model, blood was pumped from an agitated, glass mixing chamber (heated using an automatic water bath), around a circuit and returned to the mixing chamber using a haemofiltration machine. Ultrafiltrate was also returned to the mixing chamber to constitute a closed circuit. As a result any decrease in drug concentration could only be due to adsorption to the filter and extracorporeal circuit, spontaneous degradation or metabolism by red cells. / The main findings were: (1) low adsorption of levofloxacin and vancomycin by haemofilters at clinically relevant concentrations; (2) significant absolute adsorption of amikacin by polyacrylonitrile haemofilters; (3) the adsorption of antibiotics was membrane-material dependent with greater adsorption by polyacrylonitrile filters; (4) lack of relationship between membrane surface area and amikacin adsorption; (5) the adsorption of levofloxacin is reversible, contrary to irreversibility of vancomycin and amikacin; (6) sieving coefficient of oseltamivir is very near to 1.0. / This thesis investigated: (1) the extent of antibiotic adsorption (levofloxacin, vancomycin, amikacin, telavancin and oseltamivir carboxylate) by haemofilters; (2) the time course of antibiotic adsorption by haemofilters; (3) the effects of plasma albumin concentration, initial dosage, pH, filter membrane material, filter membrane surface area and repeated dosing on adsorption; (4) the reversibility or irreversibility of adsorption; (5) clearance of oseltamivir carboxylate and telavancin by ultrafiltration. / Up to 25% of critically ill patients develop acute renal failure with sepsis being the most common cause. Outside of North and South America, these patients usually receive continuous renal replacement therapy (CRRT) which utilizes high flux haemofilter membranes. Thus it is common for these patients to be concurrently receiving antibiotics and CRRT. However, information about the adsorptive capacity of various haemofilters for most drugs is lacking. / "September 2007." / Advisers: Charles Gomersall; Tony Gin. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4659. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 147-164). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.