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Biomedical subjects

I Fakhry

Publications and source records attributed to I Fakhry.

11 recordsLinked to original sources
PubMed1998

Simple method for determination of hydrochlorothiazide in human urine by high performance liquid chromatography utilizing narrowbore chromatography.

A simple high performance liquid chromatographic (HPLC) method utilizing narrowbore chromatography was developed for the determination of hydrochlorothiazide in human urine. A mobile phase of 0.1% aqueous acetic acid--acetonitrile (93:7, v/v) pH 3 was used with a C18 analytical column and ultraviolet detection (UV). The method demonstrated linearity from 2 to 50 micrograms ml-1 using 50 microliters of urine with a detection limit of 1 microgram ml-1. The method was utilized in a study evaluating if racial differences are present in the pharmacokinetic and pharmacodynamic effects of hydrochlorothiazide.

Black People↗
PubMed1997

Simple high-performance liquid chromatographic method for determination of losartan and E-3174 metabolite in human plasma, urine and dialysate.

A simple high-performance liquid chromatographic (HPLC) method was developed for the determination of losartan and its E-3174 metabolite in human plasma, urine and dialysate. For plasma, a gradient mobile phase consisting of 25 mM potassium phosphate and acetonitrile pH 2.2 was used with a phenyl analytical column and fluorescence detection. For urine and dialysate, an isocratic mobile phase consisting of 25 mM potassium phosphate and acetonitrile (60:40, v/v) pH 2.2 was used. The method demonstrated linearity from 10 to 1000 ng/ml with a detection limit of 1 ng/ml for losartan and E-3174 using 10 microl of prepared plasma, urine or dialysate. The method was utilized in a study evaluating the pharmacokinetic and pharmacodynamic effects of losartan in patients with kidney failure undergoing continuous ambulatory peritoneal dialysis (CAPD).

Antihypertensive Agents↗
PubMed1997

Solid-phase extraction and determination of ranitidine in human plasma by a high-performance liquid chromatographic method utilizing midbore chromatography.

An improved high-performance liquid chromatographic (HPLC) method utilizing solid-phase extraction (SPE) and midbore chromatography was developed for the determination of ranitidine in human plasma. A mobile phase of 20 mM K2HPO4-acetonitrile-triethylamine (87.9:12.0:0.1, v/v) pH 6.0 was used with a phenyl analytical column and ultraviolet detection (UV). The method demonstrated linearity from 25 to 1000 ng/ml in 500 microliters of plasma with a detection limit of 10 ng/ml. The method was utilized in a pharmacokinetic study evaluating the effects of pancreatico-biliary secretions on ranitidine absorption.

Anti-Ulcer Agents↗
PubMed1994

Novel high-performance liquid chromatographic method using solid-phase on-line elution for determination of metolazone in plasma and whole blood.

A novel solid-phase on-line elution HPLC method employing fluorescence detection to measure metolazone in plasma and whole blood has been developed. The method is sensitive and selective for metolazone and linear over a dynamic range of 1-50 ng/ml with a sample requirement of 250 microliters. The limit of quantitation for the method is 1 ng/ml and combined intra- and inter-day accuracy and precision had an error and coefficient of variation of 2.9 and 5.5%, respectively.

Chromatography, High Pressure Liquid↗
PubMed1992

External-standard high-performance liquid chromatographic method for quantitative determination of furosemide in plasma by using solid-phase extraction and on-line elution.

A rapid and simple external-standard high-performance liquid chromatographic (HPLC) method has been developed for the determination of the concentration of furosemide in plasma. The analyte is extracted with a C-2 ethyl sorbent. On-line elution of the analyte into the HPLC system is accomplished with an advanced automated sample processor (Varian). Furosemide is quantified by fluorescence detection within a linear range of 25 to 1000 ng/mL (average correlation coefficient, 0.9998), with a limit of detection of 1.8 ng/mL. Both internal- and external-standard procedures were evaluated, and the external-standard procedure demonstrated superior characteristics. The external-standard procedure was precise to within a relative standard deviation of 8% and accurate with less than 3% error throughout the concentration range studied. The external-standard HPLC method was used to analyze the concentration of furosemide in greater than 1000 plasma samples obtained from patients with either normal kidney function or renal failure who had received furosemide either orally or intravenously in an experimental setting.

Aged↗
PubMed1991

Fosinopril pharmacokinetics and pharmacodynamics in chronic ambulatory peritoneal dialysis patients.

The pharmacokinetics and pharmacodynamics of fosinoprilat, the diacid of fosinopril sodium, a new angiotensin-converting enzyme (ACE) inhibitor, were investigated after the oral administration of 10 mg of fosinopril sodium to 6 chronic ambulatory peritoneal dialysis (CAPD) patients. The results from 1 patient are reported separately because of the presence of concomitant liver dysfunction. The mean t1/2, Cmax, tmax, and AUC values for 5 of the CAPD patients were 19.5 h, 202 ng.ml-1, 4.8 h, and 3.19 micrograms.h.ml-1, respectively. Values for 1 CAPD patient with liver dysfunction were t1/2 of 65.4 h, Cmax of 182 ng.ml-1, tmax of 9 h, and AUC of 18.1 micrograms.h.ml-1. Peritoneal clearance of fosinoprilat was negligible, ranging from 0.07 to 0.23 ml.min-1. Serum ACE activity remained significantly suppressed at 24 and 48 h after fosinopril sodium administration with mean decreases from baseline of 94.2% and 70.6%, respectively. ACE activity was suppressed to an even greater degree in the patient with liver dysfunction, remaining 97% inhibited 72 h after drug administration. Plasma renin activity (PRA) increased and plasma aldosterone concentrations decreased following drug administration. Mean arterial pressure did not change appreciably throughout the study. Dosage reductions may not be necessary in the majority of dialysis patients.

Adult↗
PubMed1991

Metolazone pharmacokinetics and pharmacodynamics in renal transplantation.

Metolazone pharmacokinetics and pharmacodynamics were investigated in five renal transplant patients and five creatinine clearance matched controls. Whereas the time to peak metolazone excretion was similar in both groups (with the exception of one renal transplant patient who subsequently was found to have chronic rejection), the percent of the administered dose excreted over 48 h was significantly less in renal transplant patients (8% in renal transplant patients vs 24% in controls). Diminished bioavailability of metolazone or tubular secretion likely accounted for this disparity in metolazone excretion. Both groups developed diuretic tolerance as indicated by hysteresis in the dose response relationship. Cumulative sodium excretion over three successive 12-h time intervals did not differ between groups. Despite this comparable natriuresis, potassium excretion was significantly less in the renal transplant patients during the first day of the study. Accordingly, metolazone administration may provide a means to "unmask" subclinical, tubular secretory dysfunction in the transplanted kidney, as exemplified by defects in metolazone secretion and potassium excretion.

Adult↗
PubMed1988

Furosemide pharmacokinetics and pharmacodynamics in renal transplantation.

Furosemide was administered intravenously to four patients who had undergone renal transplantation in the past and four creatinine clearance--matched control subjects. Both patients who had undergone renal transplant and control subjects displayed similar pharmacokinetic and pharmacodynamic behavior, as assessed by drug delivery to the urine and sodium excretion, respectively. Despite similar degrees of natriuresis, patients who had undergone renal transplantation demonstrated a clear defect in urine potassium excretion. This defect in potassium excretion was not related to altered responsiveness of the renin-angiotensin-aldosterone axis because plasma renin activity increased in a normal fashion after furosemide in both control and transplant subjects. Although the plasma aldosterone response to increases in plasma renin activity was sluggish in patients undergoing renal transplantation, normal increases in plasma aldosterone levels were achieved in both groups, suggesting that there may be an intrinsic defect in distal tubular potassium secretion that can be unmasked by furosemide.

Adult↗
PubMedDate not supplied

Simple method for simultaneous determination of halothane, enflurane, and isoflurane in Krebs solution using capillary gas chromatography.

A simple gas chromatography (GC) method for the simultaneous determination of halothane, enflurane, and isoflurane in Krebs buffer solution has been developed. The method utilizes methylene chloride as the internal standard and liquid-liquid extraction using chloroform as the solvent. The method demonstrated excellent recovery (100%) of each component and a linear calibration range of 100-700, 100-800, and 300-1,400 micrograms/mL for halothane, isoflurane, and enflurane, respectively. Intra-day accuracy and precision had an error and coefficient of variation of less than 5.1% and 2.7%, respectively.

Anesthetics, Inhalation↗