The effect of prior bisphosphonate therapy on the subsequent therapeutic effects of strontium ranelate over 2 years

Abstract

Many osteoporotic women prescribed strontium ranelate have previously received bisphosphonates. Prior bisphosphonate use blunted the spinal bone mineral density (BMD) response for 6 months. Hip BMD was blunted to a degree for 2 years, although there was an overall increase in hip BMD in contrast to the heel where BMD did not increase.

Introduction: Many osteoporotic women commenced on strontium ranelate have already received treatment with bisphosphonates. This study investigates whether prior bisphosphonate use impairs the subsequent therapeutic response to strontium ranelate.

Methods: Women were recruited who were either bisphosphonate naïve or currently receiving a bisphosphonate. All women received strontium ranelate and were followed up for 2 years.

Results: One hundred and twenty women were recruited. After 2 years, the bisphosphonate-naïve group had significant BMD increases of 8.9%, 6.0% and 6.4% at the spine, hip and heel, respectively. In the prior bisphosphonate group, BMD increased significantly at the spine (4.0%) and hip (2.5%) but not at the heel. At all time points at all sites, the BMD increase was greater in the bisphosphonate-naïve group. BMD at the spine did not increase during the first 6 months in the prior bisphosphonate group but then increased in parallel with the bisphosphonate-naïve group. In contrast, the difference between the two groups in hip BMD continued to increase throughout the 2 years. P1NP was suppressed in the prior bisphosphonate group for the first 6 months.

Conclusions: After bisphosphonate exposure, the BMD response to strontium ranelate is blunted for only 6 months at the spine. At the hip, a degree of blunting was observed over 2 years, although there was an overall increase in hip BMD in contrast to the heel where no increase in BMD was observed.