Oral antiresorptive therapy

A roadmap to the brittle bones of cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder which despite advances in medical care continues to be a life-limiting and often fatal disease. With increase in life expectancy of the CF population, bone disease has emerged as a common complication. Unlike the osteoporosis seen in postmenopausal population, bone disease in CF begins at a young age and is associated with significant morbidity due to fractures, kyphosis, increased pain, and decreased lung function. The maintenance of bone health is essential for the CF population during their lives to prevent pain and fractures but also as they approach lung transplantation since severe bone disease can lead to exclusion from lung transplantation. Early recognition, prevention, and treatment are key to maintaining optimal bone health in CF patients and often require a multidisciplinary approach. This article will review the pathophysiology, current clinical practice guidelines, and potential future therapies for treating CF-related bone disease.

Effect of teriparatide [rhPTH(1,34)] and calcitonin on intertransverse process fusion in a rabbit model

STUDY DESIGN

Randomized, double-blinded, placebo controlled animal study.

OBJECTIVE

To evaluate the effect of teriparatide and calcitonin after an intertransverse process spinal fusion in a rabbit model.

SUMMARY OF BACKGROUND DATA

It is widely recognized that some osteoporosis medications, including bisphosphonates, can interfere with bone healing. Although prescribed frequently in the treatment of osteoporosis, the effect of teriparatide and calcitonin on spinal fusion has not been fully elucidated. We hypothesized that teriparatide, being the only anabolic medication for osteoporosis treatment, would have a beneficial effect on spine fusion.

METHODS

Fifty-one New Zealand white rabbits underwent a posterolateral L5-L6 intertransverse process arthrodesis using autogenous iliac crest bone graft. The rabbits were randomly divided into 3 groups. All animals received daily subcutaneous injections of group I (n = 17) 1 mL of saline placebo; group II (n = 17) 10 microg/kg/day of teriparatide; group III (n = 17) 14 IU/animal of calcitonin during the 8-week postoperative period. Postmortem analyses included manual palpation, radiographic, biomechanical, and histologic assessment. Three random 10x fields were examined/graded within the cephalad, middle, and caudal regions of each section (810 fields). Fusion quality was graded using the Emery histologic scale (0-7 based on fibrous/bone content of the fusion mass).

RESULTS

Histologic fusion rates for teriparatide averaged 86.7% and was significantly greater than the autograft control group (50%) (P = 0.033). Radiographically, there was a strong trend towards teriparatide being superior to the calcitonin group (85.7% vs. 56.3%, respectively; P = 0.07). The average Emery grading score was 5.99 +/- 1.46 SD for the autologous group and 6.26 +/- 0.93 SD for the teriparatide group (P = 0.031). Although not significant, the teriparatide group showed less motion in flexion/extension, lateral bending, and axial rotation.

CONCLUSION

Our results suggest that teriparatide enhances spinal fusion while calcitonin has a neutral effect. The teriparatide group had the best histologic fusion rate and Emery scores, while the calcitonin group was similar to the saline controls. Although not significant, the teriparatide group had a strong trend towards superior radiographic fusion over the calcitonin group.

Risedronate did not block the maximal anabolic effect of PTH in aged rats

The study was designed to investigate if pre-treating rats with a therapeutic equivalent dose of risedronate blunted the anabolic effects of PTH, and whether a withdrawal period prior to PTH treatment would alter any effect of risedronate on PTH treatment. Skeletally mature rats were treated for 18 weeks with vehicle, risedronate, or risedronate for 8 weeks followed by vehicle for 10 weeks (withdrawal period). At the end of this period, animals were treated for a further 12 weeks with PTH or PTH vehicle. Trabecular and cortical bone mass were monitored by serial pQCT, or by DXA and microCT. Bone histomorphometry was performed on the proximal tibiae and tibial shafts for bone turnover parameters at week 40. Risedronate alone moderately increased while PTH alone markedly increased trabecular bone mass at the proximal tibial (35% and 200%, respectively) and lumbar vertebral body (14% and 36%, respectively). The maximum bone gains were similar with and without pretreatment with risedronate as compared to the PTH alone. Continuous administration of risedronate for 18 weeks prior to PTH treatment had lower percentage increases in proximal tibial BMD during the first 8 weeks of PTH treatments, and had lower active bone forming surface and bone formation rates after being treated with PTH 12 weeks as compared to the PTH alone group. However, with the 10-week withdrawal period, risedronate did not blunt the stimulatory effect of PTH on osteoblast activity as shown by similar bone formation rates as with PTH alone. Our findings suggest that while risedronate pretreatment may slow the bone anabolic response to PTH, a withdrawal period prior to PTH treatment allows osteoblastic activity to respond normally to PTH stimulation.

Once-monthly Ibandronate for postmenopausal Osteoporosis: Review of a new dosing regimen

BACKGROUND

Ibandronate, a nitrogen-containing bisphosphonate, was approved by the US Food and Drug Administration (FDA) in May 2003 as a daily oral regimen for the treatment and prevention of post-menopausal osteoporosis. In March 2005, the FDA approved once-monthly dosing with ibandronate for the same indications.

OBJECTIVE

The purpose of this article was to review the efficacy and tolerability of ibandronate 150 mg once monthly in the treatment and prevention of post-menopausal osteoporosis.

METHODS

A search of MEDLINE (1966-September 2005) and International Pharmaceutical Abstracts (1971-September 2005) for articles relating to the efficacy and tolerability of once-monthly ibandronate in the treatment of postmenopausal osteoporosis was conducted using the terms ibandronate and ibandronic acid. Additional searches were conducted to identify publications relevant to compliance and pharmacoeconomic considerations using the terms bispbospbonate, compliance, cost, and pharmacoeconomics. The reference lists of identified articles and presentations from recent scientific meetings also were reviewed. Selected safety information from the manufacturer was incorporated.

RESULTS

Ibandronate 2.5 mg/d and intermittent ibandronate (20 mg QOD for 12 doses every 3 months) have been shown to effectively reduce the incidence of vertebral fractures; after 3 years of therapy in a placebo-controlled clinical trial, the relative risk reductions for new vertebral fractures with daily and intermittent ibandronate were 62% and 50%, respectively (both, P<0.001 vs placebo). Once-monthly ibandronate has been evaluated in 2 clinical trials: a Phase I dose-ranging trial in 144 healthy postmenopausal women and a Phase III noninferiority trial in 1609 women with postmenopausal osteoporosis who were randomized to receive ibandronate 2.5 mg/d or 1 of 3 monthly ibandronate regimens: 50/50 mg (50 mg given on 2 consecutive days) once monthly; 100 mg once monthly; and 150 mg once monthly. The primary end point of the Phase III trial was the change from baseline in lumbar spine bone mineral density (BMD). After 1 year of therapy, patients who received ibandronate 150 mg once monthly had a significantly greater increase from baseline in lumbar spine BMD compared with those who received ibandronate 2.5 mg/d (4.9% vs 3.9%, respectively; P=0.002). The overall adverse-event profile was similar between the daily and monthly regimens. Drug-related adverse events were reported in 32.4% of patients receiving ibandronate 2.5 mg/d and 36.9% of patients receiving ibandronate 150 mg monthly. Upper gastrointestinal adverse events occurred in a respective 22.8% and 22.5% of the 2 groups. After 1 year of therapy, patients receiving ibandronate 150 mg monthly reported more flulike symptoms (8.3%) compared with those receiving ibandronate 2.5 mg/d (2.8%). In a crossover study comparing preference for and convenience of monthly ibandronate and weekly alendronate in 342 ambulatory women with postmenopausal osteoporosis, significantly more patients preferred the monthly ibandronate regimen to the weekly alendronate regimen (71.4% vs 28.5%, respectively; P<0.001).

CONCLUSION

Once-monthly ibandronate is an effective and well-tolerated treatment option for postmenopausal osteoporosis.