Effects of a Combination Therapy of Sclerostin Antibody III and Raloxifene on Bone Formation Markers in Ovariectomized Rats

Objective: To determine the systemic effect of sclerostin monoclonal antibody (Scl-AbIII) administration on markers of bone formation and compare it with a combination of sclerostin antibody and raloxifene. Study Design: Experimental study. Place and Duration of Study: Medical College Animal House at King Khaled University Hospital, Riyadh, Saudi Arabia, from January to November 2014. Methodology: Forty-five female rats were divided into 5 groups equally; 1 control group and 4 groups of ovariectomized (OVX) rats: control OVX rats and OVX rats treated by Scl-AbIII, raloxifene or Scl-AbIII+raloxifene one month after ovariectomy, continued for 4 weeks. At the end of treatment, serum levels of Bone Specific Alkaline Phosphatase (BSAP), alkaline phosphatase, osteocalcin, Insulin-like Growth Factor-1 (IGF-1), Parathyroid Hormone (PTH), Ca2+ and phosphorus were measured. Uterus was weighed and body weight change was calculated. Results: Scl-AbIII or raloxifene treatment produced significant increase of serum BSAP, osteocalcin, IGF-1, PTH and Ca2+ levels. Raloxifene, either alone or combined with Scl-AbIII attenuated the decrease in uterus wet weight, and the increase in body weight seen in OVX rats. Combination therapy of Scl-AbIII, and raloxifene produced significant increase of serum alkaline phosphatase, osteocalcin and IGF-1 levels than treatment with either Scl-AbIII or raloxifene alone. Conclusion: Combination therapy of Scl-AbIII and raloxifene is an attractive strategy to enhance bone formation and can offer better gain over treatment with either one of them alone. Confirmation of these preliminary observations must await careful long-term studies.