Schiller L R, Santa Ana C A, Sheikh M S, Emmett M, Fordtran J S
Department of Internal Medicine, Baylor University Medical Center, Dallas, TX 75246.
N Engl J Med. 1989 Apr 27;320(17):1110-3. doi: 10.1056/NEJM198904273201703.
Phosphorus binders are given to patients with renal failure to increase gastrointestinal excretion of phosphorus. To determine the relative importance of the binding of dietary as compared with endogenous phosphorus and to determine the optimal dose schedule, we gave either 4.4 g of calcium acetate (25 mmol of calcium) or a placebo to six normal subjects on each of seven different schedules in a randomized sequence. The net gastrointestinal balance of phosphorus and calcium was determined by a one-day lavage technique. After a meal containing approximately 12 mmol of phosphorus, the mean phosphorus absorption (+/- SE) measured 9.17 +/- 0.36 mmol (78 percent) with placebo but decreased to 3.81 +/- 0.58 mmol (31 percent) when calcium acetate was given immediately before the meal (representing binding of 5.36 +/- 0.77 mmol of phosphorus). Similar binding was observed when calcium acetate was given immediately after the meal and when half the dose was given before and half after the meal. In contrast, when calcium acetate was given two hours after the meal or while the subject was fasting, phosphorus binding was reduced to 2.00 +/- 0.52 mmol and 1.81 +/- 0.84 mmol, respectively. Calcium absorption from calcium acetate averaged 21 +/- 1 percent when the binder was given with a meal; absorption from calcium acetate averaged 40 +/- 4 percent when the binder was given while the subject was fasting. We conclude that calcium acetate increases fecal excretion of phosphorus by binding both dietary and endogenous phosphorus, but the binding of dietary phosphorus is quantitatively much more important. For the most efficient phosphorus binding, calcium (and presumably other phosphorus-binding cations) should be given with meals.
给肾衰竭患者使用磷结合剂以增加胃肠道对磷的排泄。为了确定饮食中磷与内源性磷结合的相对重要性，并确定最佳给药方案，我们以随机顺序在七个不同方案中的每个方案下，给六名正常受试者分别服用4.4克醋酸钙（25毫摩尔钙）或安慰剂。通过一日灌洗技术测定磷和钙的胃肠道净平衡。在摄入含约12毫摩尔磷的一餐之后，服用安慰剂时测得的平均磷吸收量（±标准误）为9.17±0.36毫摩尔（78%），但在进餐前立即服用醋酸钙时降至3.81±0.58毫摩尔（31%）（相当于结合了5.36±0.77毫摩尔磷）。在餐后立即服用醋酸钙以及将剂量的一半在餐前服用、一半在餐后服用时，观察到了类似的结合情况。相比之下，当在餐后两小时或受试者禁食时服用醋酸钙，磷结合量分别降至2.00±0.52毫摩尔和1.81±0.84毫摩尔。当与餐同服结合剂时，醋酸钙的钙吸收平均为21±1%；当受试者禁食时服用结合剂，醋酸钙的钙吸收平均为40±4%。我们得出结论，醋酸钙通过结合饮食中的磷和内源性磷来增加粪便中磷的排泄，但饮食中磷的结合在数量上更为重要。为了最有效地结合磷，钙（可能还有其他磷结合阳离子）应与餐同服。
