Nephrol Dial Transplant (2002) 17: 37-40
© 2002 European Renal Association-European Dialysis and Transplant Association
A comparison between daily and thrice-weekly i.v. administration of 1,25-dihydroxy-22-oxavitamin D3 regarding suppression of parathyroid hormone secretion and calcaemic action in uraemic rats
1 Fuji Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd, Gotemba, Shizuoka, Japan, 2 Department of Internal Medicine, Renal Division, Washington University School of Medicine, St Louis, Missouri, USA, 3 Tokai University School of Medicine, Isehara, Japan and 4 Division of Nephrology and Dialysis Center, Kobe University School of Medicine, Kobe, Japan
Abstract
Background. 1,25-Dihydroxy-22-oxavitamin D3 (22-oxacalcitriol, OCT) is an analogue of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3, calcitriol) with less calcaemic activity, thus more suitable than 1,25(OH)2D3 for the control of parathyroid hormone (PTH) secretion in chronic dialysis patients. As the low-calcaemic action of OCT has been mainly attributed to its short half-life in the blood stream, the number of doses per week is the key factor to effective OCT therapy toward suppression of PTH secretion and hypercalcaemia. Thus, we investigated a comparison between daily and thrice-weekly i.v. administration of OCT regarding suppression of PTH secretion and calcaemic action in 5/6 nephrectomized rats as a model for chronic renal failure.
Methods. Model rats of chronic renal failure were made by 5/6 nephrectomy. At 3 months after surgery, they were administered either vehicle or OCT intravenously, daily (0.125 or 0.625 µg/kg) or thrice-weekly (0.6 or 3.0 µg/kg) for 2 weeks.
Results. The data show that 0.625 µg/kg/day (=4.375 µg/kg/week) suppresses PTH secretion with significant increase in calcium levels at 24 h after the final administration, on the other hand, 3.0 µg/kg/ thrice-weekly (=9.0 µg/kg/week) suppresses PTH secretion, although moderate compared with 0.625 µg/kg/day, with a slight (not significant) increase in calcium.
Conclusions. The current clinical mode of OCT therapy, i.v. thrice-weekly administration, is a practically recommendable protocol.
Keywords: calcaemic action; OCT; parathyroid hormone; secondary hyperparathyroidism; uraemia; vitamin D analogue
Notes
Correspondence and offprint requests to: Michinori Hirata, PhD, Fuji Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd, 1-135 Gotemba, Shizuoka 412-8513, Japan. Email: hiratamcn{at}chugai\|[hyphen]\|pharm.co.jp