COMPARISONS BETWEEN ORAL AND INTRAPERITONEAL 1,25-DIHYDROXYVITAMIN D-3 THERAPY IN CHILDREN TREATED WITH PERITONEAL-DIALYSIS

Recent studies in adults have suggested that parenteral 1,25-dihydroxy vitamin D-3 (1,25[OH]D-2(3)) may have advantages over oral therapy in the management of renal osteodystrophy. The purpose of this study was to determine whether there were clear differences between oral and IP 1,25(OH)(2)D-3 treatments in children who did not pose a treatment pro blem. Seven children (5 males, 2 females, aged 1.8 to 16 years, median 4.8 years) undergoing peritoneal dialysis were initially treated with oral 1,25(OH)(2)D-3 for a one month equilibration period They were ra ndomly assigned to 3 months of either oral or intraperitoneal (IP) the rapy with 1,25(OH)(2)D-3 followed by 3-months-treatment using the alte rnative route. No significant differences in serum creatinine, phospha te, or parathyroid hormone concentrations were found between the diffe rent routes of administration in the patients. No significant differen ces in height standard deviation scores or renal osteodystrophy scores were found over the six-month study. Paired oral and IP pharmacokinet ic studies were performed on these 7 patients and 2 other children who had been treated for at least 2 months using either oral or IP 1,25(O H)(2)D-3. Serum was taken prior to one of the usual 1,25(OH)(2)D-3 dos es and 0.5, 1.5, 3, 6, and 24 h afterward. The highest measured concen trations of 1,25(OH)(2)D-3 were found at 1.5 h for both oral and IP tr eatments (mean C-max [SD]: oral 116 [23] pmol/l, IP 121 [24] pmol/l, p >0.05). The AUC's for oral and IP therapy were similar(l701 [276] and 1645 [301] pmol/h/l, respectively). In the paired pharmacokinetic stu dies no significant differences were found between oral and IP treatme nts for the serum half life (27.4 [11.6] h and 19.2 [8.1] h, respectiv ely) and total body clearance (15.3 [2.1] h and 18.4 [3.3] h, respecti vely) of 1,25(OH),D,. In children who respond appropriately to oral 1, 25(OH)(2)D-3 there is no biological advantage to the use of IP 1,25(OP I)(2)D-3.