Phosphate-binding capacities of calcium and aluminum formulations.

Calcium and aluminum phosphate binders are used to treat hyperphosphatemia which is responsible for the development of osteodystrophy commonly seen in patients with end-stage renal disease. The purpose of this study was to determine the phosphate binding capacities of several frequently used calcium and aluminum formulations. The effect of formulation types on phosphate binding was evaluated. Calcium and aluminum phosphate binders were administered to six healthy volunteers after phosphate load on separate study days. Total urine outflow was collected afterwards to determine the amount of phosphate recovered, which indicates the ability of the phosphate binder to reduce gastrointestinal phosphate absorption. The amounts of urinary phosphate recovered were different after administration of the phosphate binders. Calcium acetate resulted in the least amount of phosphate excreted. Calcium carbonate suspension, when compared with the tablet formulation, caused a smaller amount of phosphate excreted in the urine. Different phosphate binders formulations were found to have different phosphate binding capacities. Patients should therefore be closely monitored for efficacy after switching from one phosphate binder to another.

Gender effect on diuretic response to hydrochlorothiazide and furosemide.

Gender has been shown to elicit differences in drug disposition and response to therapeutic agents. We measured the diuretic response to oral hydrochlorothiazide, oral and intravenous furosemide in 6 male and 6 female normal volunteers. After fasting overnight, each subject received single doses of the individual diuretics or no treatment on 4 separate days. Total urine output was collected over the next 24 hours for volume measurement and determination of sodium and potassium concentrations. There was no statistically significant difference found between male and female subjects with respect to urine flow rate, sodium, and potassium excretion rates among the treatments. However, when natriuretic response was adjusted for mg/kg of the intravenous furosemide dose received, male subjects had a higher peak sodium excretion rate than the female subjects. Results of this study reveal a gender-related difference on the natriuretic response to diuretics. Further studies are necessary to identify if this gender-related difference is caused by differences in drug metabolism, disposition, or intrinsic diuretic responsiveness at the site of action.

Effect of diuretic drugs on creatinine clearance determination.

Diuretic drugs have been reported to alter the glomerular filtration rate and possibly the creatinine excretion by the kidneys. We evaluated the effects of single doses of diuretic drugs on creatinine clearance determination. Ten healthy volunteers were randomized to receive either oral hydrochlorothiazide, oral furosemide, intravenous furosemide, or no treatment in a cross-over fashion during four separate test days with 6-day washout periods. Urine and blood specimens were collected during 24 h after the treatments. Specimens were assayed for creatinine, and the creatinine clearance corresponding to the 4-, 6-, 12-, and 24-h urine collections were calculated. Analysis of variance did not show a statistically significant effect of the diuretic regimens on creatinine clearance over these periods. This study demonstrates that single doses of diuretic drugs do not have significant effect on creatinine clearance determination using urine collected during 4-24-h periods.