Nephrology Dialysis Transplantation, Vol 13, Issue 90003 68-72, Copyright © 1998 by Oxford University Press
J Frazao, R Chesney and J Coburn
Calcitriol and alfacalcidol are useful in suppressing parathyroid hormone
(PTH) in haemodialysis patients, but hypercalcaemia and hyperphosphataemia
are frequent. The vitamin D analogue, 1&agr;-hydroxy-vitamin D2
(1&agr;D2), has a higher therapeutic index in animal models.
Previously, 1&agr;D2, 4 &mgr;g/day or 4 &mgr;g/haemodialysis,
lowered iPTH to the target range in 87.5% of 24 haemodialysis patients with
moderate to severe secondary hyperparathyroidism (plasma iPTH, 359-1521
pg/ml). The incidences of hypercalcaemia (serum Ca>2.8 mM) or
hyperphosphataemia (serum P>2.23 mM) were low. Later, 10 of these
patients were re-treated with 1&agr;D2, initial dose, 10 &mgr;g,
thrice weekly with haemodialysis. The iPTH was suppressed as readily, and
there was no greater incidence of hypercalcaemia and hyperphosphataemia.
Based on these data, a large, multicentre study is ongoing in California
and Tennessee/Mississippi, using 1&agr;D2 in haemodialysis patients
with iPTH >400 pg/ml. In this and the earlier studies, only
calcium-based phosphate binders were used to control serum phosphorus. The
initial dose, 10 &mgr;g thrice weekly with haemodialysis is adjusted to
maintain a target iPTH within the range of 150-300 &mgr;g/ml; the final
dose range is 2.5-20 &mgr;g per haemodialysis. The protocol includes 8
weeks of randomized double blinded treatment with either continued
1&agr;D2 or placebo. Forty two patients from California and 38 from
Tennessee/Mississippi have completed 16 weeks of open label treatment. In
California, iPTH declined from 832±95 pg/ml at baseline to
222±71 pg/ml at the nadir and to 477±117 pg/ml at
week 16 of the treatment. In Tennessee/Mississippi, the iPTH declined from
977±65 pg/ml to 286±42 pg/ml at the lowest point and
to 493±79 at the end of the treatment. Plasma iPTH reached or
fell below the target range in 84% of the 80 patients completing open
treatment. Asymptomatic hypercalcaemia (serum Ca >2.8 mM) increased
from 0.3 episodes/100 weeks during wash-out to 3.6 episodes/100 treated
weeks in California and from 0 to 3.7 episodes in Tennessee/Mississippi. In
California and Tennessee, the episodes of hyperphosphataemia (serum P
>2.2 mM) increased from 5.0 and 5.0 episodes per 100 patient/week
during wash-out to 10.1 and 10.9 episodes/100 treatment weeks,
respectively, with 1&agr;D2 treatment. There were no adverse events in
association with 1&agr;D2 treatment. Thus, oral 1&agr;D2 is safe
and highly effective for the treatment of secondary
hyperparathyroidism.Keywords: haemodialysis;
1&agr;-hydroxyvitamin D2; intact PTH; secondary hyperparathyroidism;
therapeutic trial; vitamin
ORIGINAL ARTICLES
Intermittent oral 1&agr;-hydroxyvitamin D2 is effective and safe for the suppression of secondary hyperparathyroidism in haemodialysis patients
The Medical and Research Services, West Los Angeles Veterans Affairs Medical Center (Wadsworth Division), Los Angeles, CA, USA; The Department of Medicine, UCLA School of Medicine, Los Angeles, CA, USA; The Department of Pediatrics, College of Medicine, University of Tennessee, Memphis, TN, USA; Bone Care International, Inc., Madison, WI, USA; Corresponding author address: Nephrology Section (W111L), West Los Angeles VA Medical Center, 11301 Wilshire Blvd, Los Angeles, CA 90073, USA
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