Information on the use of oral bisphosphonate agents to treat pediatric osteogenesis imperfecta (OI) is limited.

The objective of the investigation was to study the efficacy and safety of daily oral alendronate (ALN) in children with OI.

We conducted a multicenter, double-blind, randomized, placebo-controlled study. One hundred thirty-nine children (aged 4–19 yr) with type I, III, or IV OI were randomized to either placebo (n = 30) or ALN (n = 109) for 2 yr. ALN doses were 5 mg/d in children less than 40 kg and 10 mg/d for those 40 kg and greater.

Spine areal bone mineral density (BMD) z-score, urinary N-telopeptide of collagen type I, extremity fracture incidence, vertebral area, iliac cortical width, bone pain, physical activity, and safety parameters were measured.

ALN increased spine areal BMD by 51% vs. a 12% increase with placebo (P < 0.001); the mean spine areal BMD z-score increased significantly from −4.6 to −3.3 (P < 0.001) with ALN, whereas the change in the placebo group (from −4.6 to −4.5) was insignificant. Urinary N-telopeptide of collagen type I decreased by 62% in the ALN-treated group, compared with 32% with placebo (P < 0.001). Long-bone fracture incidence, average midline vertebral height, iliac cortical width, bone pain, and physical activity were similar between groups. The incidences of clinical and laboratory adverse experiences were also similar between the treatment and placebo groups.

Oral ALN for 2 yr in pediatric patients with OI significantly decreased bone turnover and increased spine areal BMD but was not associated with improved fracture outcomes.