The effects of topical calcipotriol on systemic calcium homeostasis in patients with chronic plaque psoriasis.
BACKGROUND
Calcipotriol is an effective treatment of chronic plaque psoriasis. We have previously demonstrated that it has a small effect on systemic calcium homeostasis even at recommended doses.


OBJECTIVE
We attempted to determine the mechanism of the effect of calcipotriol on systemic calcium homeostasis so we could assess the possible consequences of long-term use.


METHODS
Sixteen patients with extensive chronic plaque psoriasis were hospitalized and treated with high-dose topical calcipotriol. Up to 360 gm of calcipotriol (50 micrograms/gm) ointment was applied per week for 2 weeks under controlled conditions.


RESULTS
There was a dose-dependent rise in intestinal absorption of calcium. No effect on bone turnover was demonstrated over this short period. Five patients became hypercalcemic, and there was a dose-dependent rise in serum total adjusted calcium, serum ionized calcium, serum phosphate, urine calcium, and urine phosphate. There was a dose-dependent fall in serum parathyroid hormone and serum 1,25 dihydroxyvitamin D3.


CONCLUSIONS
Calcipotriol exerts its effects on systemic calcium homeostasis by increasing intestinal absorption of calcium and probably phosphate. This results in suppression of parathyroid hormone and 1,25 dihydroxyvitamin D3.
Bourke
J F
JF
Department of Dermatology, Leicester Royal Infirmary, United Kingdom.
Mumford
R
R
Whittaker
P
P
Iqbal
S J
SJ
Le Van
L W
LW
Trevellyan
A
A
Hutchinson
P E
PE
D000279:Administration, Cutaneous; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002117:Calcitriol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D002118:Calcium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002908:Chronic Disease; D003879:Dermatologic Agents / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006706:Homeostasis / Q000187:drug effects*; D006760:Hospitalization; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced; D007408:Intestinal Absorption / Q000187:drug effects; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009824:Ointments; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood / Q000378:metabolism / Q000652:urine; D011565:Psoriasis / Q000188:drug therapy* / Q000378:metabolism
D003879:Dermatologic Agents; D009824:Ointments; D010281:Parathyroid Hormone; D010710:Phosphates; C055085:calcipotriene; D002117:Calcitriol; D002118:Calcium