Reduced bone mineral density and radial bone growth in young rabbits treated with dexamethasone eye drops.
OBJECTIVE
To investigate the effect of dexamethasone eye drops on bone metabolism in newborn rabbits.


METHODS
Thirty-four 3-week-old rabbits had unilateral clear lens extraction and were randomized into three groups. Postoperatively, group 1 received high-dose and group 2 low-dose dexamethasone eye drops (average doses 0.27 and 0.10 mg/kg body weight/day, respectively). These rabbits also received a postoperative subconjunctival injection of betamethasone. Group 3 (control) received vehicle eye drops only. After 8 weeks of treatment, all animals were killed and the left femurs were isolated and subjected to peripheral quantitative computerized tomography (pQCT) and dual X-ray absorptiometry (DXA) analyses.


RESULTS
DXA showed that rabbits treated with either a high or low dose of dexamethasone eye drops had significantly reduced areal bone mineral density (BMD), area and total bone mineral content (BMC) of the femur. Measurements with pQCT demonstrated a dose-dependent reduction in cortical BMC, cortical volumetric BMD and cortical area. These effects were associated with an inhibition of radial femur growth, cortical thickness and periosteal and endosteal circumferences.


CONCLUSIONS
Dexamethasone eye drops have systemic effects affecting several bone parameters in young rabbits. Any long-term systemic effects of ocular glucocorticoids need to be further studied.
Kugelberg
Maria
M
St. Erik's Eye Hospital, Stockholm, Sweden. m.kugelberg@sankterik.se
Ohlsson
Claes
C
Sävendahl
Lars
L
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000009:adverse effects*; D015519:Bone Density / Q000187:drug effects*; D001846:Bone Development / Q000187:drug effects*; D003907:Dexamethasone / Q000008:administration & dosage / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D007279:Injections, Subcutaneous; D011817:Rabbits
D000893:Anti-Inflammatory Agents; D003907:Dexamethasone