| Pharmacotherapeutic group: Drugs for treatment of bone diseases, bisphosphonates, ATC code: M05BA06 Mechanism of action Ibandronic acid is a highly potent bisphosphonate belonging to the nitrogen-containing group of bisphosphonates, which act selectively on bone tissue and specifically inhibit osteoclast activity without directly affecting bone formation. It does not interfere with osteoclast recruitment. Ibandronic acid leads to progressive net gains in bone mass and a decreased incidence of fractures through the reduction of elevated bone turnover towards premenopausal levels in postmenopausal women.Pharmacodynamic effects The pharmacodynamic action of ibandronic acid is inhibition of bone resorption. In vivo, ibandronic acid prevents bone destruction experimentally induced by cessation of gonadal function, retinoids, tumours or tumour extracts. In young (fast growing) rats, the endogenous bone resorption is also inhibited, leading to increased normal bone mass compared with untreated animals.Animal models confirm that ibandronic acid is a highly potent inhibitor of osteoclastic activity. In growing rats, there was no evidence of impaired mineralisation even at doses greater than 5,000 times the dose required for osteoporosis treatment.Both daily and intermittent (with prolonged dose-free intervals) long-term administration in rats, dogs and monkeys was associated with formation of new bone of normal quality and maintained or increased mechanical strength even at doses in the toxic range. In humans, the efficacy of both daily and intermittent administration with a dose-free interval of 9 - 10 weeks of ibandronic acid was confirmed in a clinical trial (MF 4411), in which ibandronic acid demonstrated anti-fracture efficacy.In animal models ibandronic acid produced biochemical changes indicative of dose-dependent inhibition of bone resorption, including suppression of urinary biochemical markers of bone collagen degradation (such as deoxypyridinoline, and cross-linked N-telopeptides of type I collagen (NTX)).Both daily, intermittent (with a dose-free interval of 9 - 10 weeks per quarter) oral doses as well as intravenous doses of ibandronic acid in postmenopausal women produced biochemical changes indicative of dose-dependent inhibition of bone resorption.Bonviva intravenous injection decreased levels of serum C-telopeptide of the alpha chain of Type I collagen (CTX) within 3 - 7 days of starting treatment and decreased levels of osteocalcin within 3 months.Following treatment discontinuation, there is a reversion to the pathological pre-treatment rates of elevated bone resorption associated with postmenopausal osteoporosis.The histological analysis of bone biopsies after two and three years of treatment of postmenopausal women with doses of oral ibandronic acid 2.5 mg daily and intermittent intravenous doses of up to 1 mg every 3 months showed bone of normal quality and no indication of a mineralisation defect. An expected decrease in bone turnover, normal quality of bone and absence of defects in mineralization were also seen after two years of treatment with Bonviva 3 mg injection.Clinical efficacy Independent risk factors, for example, low BMD, age, the existence of previous fractures, a family history of fractures, high bone turnover and low body mass index should be considered in order to identify women at increased risk of osteoporotic fractures.Bonviva 3 mg injection every 3 months Bone mineral density (BMD) Bonviva 3 mg intravenous injection, administered every 3 months, was shown to be at least as effective as oral ibandronic acid 2.5 mg daily in a 2-year, randomised, double-blind, multicentre, non-inferiority study (BM16550) of postmenopausal women (1386 women aged 55 - 80) with osteoporosis (lumbar spine BMD T-score below -2.5 SD at baseline). This was demonstrated in both the primary analysis at one year and in the confirmatory analysis at two years endpoint (Table 2).The primary analysis of data from study BM16550 at one year and the confirmatory analysis at 2 years demonstrated the non-inferiority of 3 mg every 3 months injection dosing regimen compared to 2.5 mg oral daily dosing regimen, in terms of mean increases in BMD at lumbar spine, total hip, femoral neck and trochanter (Table 2).Table 2: Mean relative change from baseline of lumbar spine, total hip, femoral neck and trochanter BMD after one year (primary analysis) and two years of treatment (Per-Protocol Population) in study BM 16550.| | One year data in study BM 16550
| Two year data in study BM 16550
| | Mean relative changes from baseline % [95% CI]
| ibandronic acid 2.5 mg daily
(N=377)
| Bonviva 3 mg injection every 3 months
(N=365) | ibandronic acid 2.5 mg daily
(N=334)
| Bonviva 3 mg injection every 3 months
(N=334) | | Lumbar spine L2-L4 BMD
| 3.8 [3.4, 4.2]
| 4.8 [4.5, 5.2]
| 4.8 [4.3, 5.4]
| 6.3 [5.7, 6.8]
| | Total hip BMD
| 1.8 [1.5, 2.1]
| 2.4 [2.0, 2.7]
| 2.2 [1.8, 2.6]
| 3.1 [2.6, 3.6]
| | Femoral neck BMD
| 1.6 [1.2, 2.0]
| 2.3 [1.9, 2.7]
| 2.2 [1.8, 2.7]
| 2.8 [2.3, 3.3]
| | Trochanter BMD
| 3.0 [2.6, 3.4]
| 3.8 [3.2, 4.4]
| 3.5 [3.0, 4.0]
| 4.9 [4.1, 5.7]
| Furthermore, Bonviva 3 mg injection every 3 months was proven superior to oral ibandronic acid 2.5 mg daily for increases in lumbar spine BMD in a prospectively planned analysis at one year, p<0.001, and at two years, p<0.001. For lumbar spine BMD, 92.1 % of patients receiving 3 mg injection every 3 months increased or maintained their BMD after 1 year of treatment (i.e. were responders) compared with 84.9 % of patients receiving oral 2.5 mg daily (p=0.002). After 2 years of treatment, 92.8 % of patients receiving 3 mg injections and 84.7 % of patient receiving 2.5 mg oral therapy had increased or maintained lumbar spine BMD (p=0.001).For total hip BMD, 82.3 % of patients receiving 3 mg injection every 3 months were responders at one year, compared with 75.1 % of patients receiving 2.5 mg daily orally (p=0.02). After 2 years of treatment, 85.6 % of patients receiving 3 mg injections and 77.0 % of patient receiving 2.5 mg oral therapy had increased or maintained total hip BMD (p=0.004).The proportion of patients who increased or maintained their BMD at one year at both lumbar spine and total hip was 76.2 % in the 3 mg injection every 3 months arm and 67.2 % in the 2.5 mg daily orally arm (p=0.007). At two years, 80.1 % and 68.8 % of patients met this criterion in the 3 mg every 3 months injection arm and the 2.5 mg daily arm (p=0.001).Biochemical markers of bone turn-over Clinically meaningful reductions in serum CTX levels were observed at all time points measured. At 12 months median relative changes from baseline were 58.6 % for the intravenous injection of 3 mg every 3 months regimen and 62.6 % for oral 2.5 mg daily regimen. In addition, 64.8 % of patients receiving 3 mg every 3 months injection were identified as responders (defined as a decrease 50 % from baseline), compared with 64.9 % of patients receiving 2.5 mg daily orally. Serum CTX reduction was maintained over the 2 years, with more than half of the patients identified as responders in both treatment groups.Based on the results of study BM 16550, Bonviva 3 mg intravenous injection, administered every 3 months is expected to be at least as effective in preventing fractures as the oral regimen of ibandronic acid 2.5 mg daily.Ibandronic acid 2.5 mg daily tablets In the initial three-year, randomised, double-blind, placebo-controlled, fracture study (MF 4411), a statistically significant and medically relevant decrease in the incidence of new radiographic morphometric and clinical vertebral fractures was demonstrated (table 3). In this study, ibandronic acid was evaluated at oral doses of 2.5 mg daily and 20 mg intermittently as an exploratory regimen. Ibandronic acid was taken 60 minutes before the first food or drink of the day (post-dose fasting period). The study enrolled women aged 55 to 80 years, who were at least 5 years postmenopausal, who had a BMD at the lumbar spine of -2 to -5 SD below the premenopausal mean (T-score) in at least one vertebra [L1-L4], and who had one to four prevalent vertebral fractures. All patients received 500 mg calcium and 400 IU vitamin D daily. Efficacy was evaluated in 2,928 patients. Ibandronic acid 2.5 mg administered daily, showed a statistically significant and medically relevant reduction in the incidence of new vertebral fractures. This regimen reduced the occurrence of new radiographic vertebral fractures by 62 % (p=0.0001) over the three year duration of the study. A relative risk reduction of 61 % was observed after 2 years (p=0.0006). No statistically significant difference was attained after 1 year of treatment (p=0.056). The anti-fracture effect was consistent over the duration of the study. There was no indication of a waning of the effect over time. The incidence of clinical vertebral fractures was also significantly reduced by 49 % after 3 years (p=0.011). The strong effect on vertebral fractures was furthermore reflected by a statistically significant reduction of height loss compared to placebo (p<0.0001).Table 3: Results from 3 years fracture study MF 4411 (%, 95 % CI)| | Placebo
(N=974)
| ibandronic acid 2.5 mg daily
(N=977)
| | Relative risk reduction
New morphometric vertebral fractures
| | 62% (40.9, 75.1)
| | Incidence of new morphometric vertebral fractures
| 9.56% (7.5, 11.7)
| 4.68% (3.2, 6.2)
| | Relative risk reduction of clinical vertebral fracture
| | 49% (14.03, 69.49)
| | Incidence of clinical vertebral fracture
| 5.33% (3.73, 6.92)
| 2.75% (1.61, 3.89)
| | BMD mean change relative to baseline lumbar spine at year 3
| 1.26% (0.8, 1.7)
| 6.54% (6.1, 7.0)
| | BMD mean change relative to baseline total hip at year 3
| -0.69%
(-1.0, -0.4)
| 3.36%
(3.0, 3.7)
| The treatment effect of ibandronic acid was further assessed in an analysis of the subpopulation of patients who, at baseline, had a lumbar spine BMD T-score below 2.5 (table 4). The vertebral fracture risk reduction was very consistent with that seen in the overall population.Table 4: Results from 3 years fracture study MF 4411 (%, 95 % CI) for patients with lumbar spine BMD T-score below 2.5 at baseline| | Placebo
(N=587)
| ibandronic acid 2.5 mg daily
(N=575)
| | Relative Risk Reduction
New morphometric vertebral fractures
| | 59% (34.5, 74.3)
| | Incidence of new morphometric vertebral fractures
| 12.54% (9.53, 15.55)
| 5.36% (3.31, 7.41)
| | Relative risk reduction of clinical vertebral fracture
| | 50% (9.49, 71.91)
| | Incidence of clinical vertebral fracture
| 6.97% (4.67, 9.27)
| 3.57% (1.89, 5.24)
| | BMD mean change relative to baseline lumbar spine at year 3
| 1.13% (0.6, 1.7)
| 7.01% (6.5, 7.6)
| | BMD mean change relative to baseline total hip at year 3
| -0.70% (-1.1, -0.2)
| 3.59% (3.1, 4.1)
| In the overall patient population of the study MF4411, no reduction was observed for non-vertebral fractures, however daily ibandronic acid appeared to be effective in a high-risk subpopulation (femoral neck BMD T-score < -3.0), where a non-vertebral fracture risk reduction of 69% was observed.Daily oral treatment with ibandronic acid 2.5 mg tablets resulted in progressive increases in BMD at vertebral and nonvertebral sites of the skeleton. Three-year lumbar spine BMD increase compared to placebo was 5.3 % and 6.5 % compared to baseline. Increases at the hip compared to baseline were 2.8 % at the femoral neck, 3.4 % at the total hip, and 5.5 % at the trochanter.Biochemical markers of bone turnover (such as urinary CTX and serum Osteocalcin) showed the expected pattern of suppression to premenopausal levels and reached maximum suppression within a period of 3 - 6 months of using 2.5 mg ibandronic acid daily.A clinically meaningful reduction of 50 % of biochemical markers of bone resorption was observed as early as one month after starting treatment with ibandronic acid 2.5 mg.Paediatric population Bonviva was not studied in the paediatric population, therefore no efficacy or safety data are available for this patient population. | |