In vitro disintegration studies of weekly generic and branded risedronate sodium formulations available in Canada

Beyond Antiresorptive Activity: Risedronate-Based Coordination Complexes To Potentially Treat Osteolytic Metastases

Coordination of clinically employed bisphosphonate, risedronate (RISE), to bioactive metals, Ca²⁺, Mg²⁺, and Zn²⁺, allowed the formation of bisphosphonate-based coordination complexes (BPCCs). Three RISE-based BPCCs, RISE-Ca, RISE-Mg, and RISE-Zn, were produced, and their structures were elucidated by single crystal X-ray diffraction. Interestingly, the addition of an auxiliary ligand, etidronic acid (HEDP), resulted in the recrystallized protonated form of the ligand, H-RISE. The pH-dependent structural stability of the RISE-based BPCCs was measured by means of dissolution profiles under neutral and acidic simulated physiological conditions (PBS and FaSSGF, respectively). In comparison to RISE (Actonel), the complexes showed a lower equilibrium solubility (∼70-85% in 18-24 h) in PBS, while a higher equilibrium solubility (∼100% in 3 h) in acidic media. The results point to the capacity to release this BP in a pH-dependent manner from the RISE-based BPCCs. Subsequently, the particle size of RISE-Ca was reduced, from 300 μm to ∼350 d.nm, employing the phase inversion temperature (PIT)-nanoemulsion method, resulting in nano-Ca@RISE. Aggregation measurements of nano-Ca@RISE in 1% fetal bovine serum (FBS):H₂O was monitored after 24, 48, and 72 h to study the particle size longevity in physiological media, showing that the suspended material has the potential to maintain its particle size over time. Furthermore, binding assays were performed to determine the potential binding of nano-Ca@RISE to the bone, where results show higher binding (∼1.7×) for the material to hydroxyapatite (HA, 30%) when compared to RISE (17%) in 1 d. The cytotoxicity effects of nano-Ca@RISE were compared to those of RISE against the human breast cancer MDA-MB-231 and normal osteoblast-like hFOB 1.19 cell lines by dose-response curves and relative cell viability assays in an in vitro setting. The results demonstrate that nano-Ca@RISE significantly decreases the viability of MDA-MB-231 with high specificity, at concentrations ∼2-3× lower than the ones reported employing other third-generation BPs. This is supported by the fact that when normal osteoblast cells (hFOB 1.19), which are part of the tissue microenvironment at metastatic sites, were treated with nano-Ca@RISE no significant decrease in viability was observed. This study expands on the therapeutic potential of RISE beyond its antiresorptive activity through the design of BPCCs, specifically nano-Ca@RISE, that bind to the bone and degrade in a pH-dependent manner under acidic conditions.

Retrospective evaluation of persistence in osteoporosis therapy with oral bisphosphonates in Italy: the TOBI study

The patients' persistence with osteoporosis treatments is low. This retrospective, multicenter survey showed that almost 30% of osteoporotic patients discontinued the treatment within the first 6 months and that those taking drinkable bisphosphonates were less likely to interrupt the therapy; instead, the use of generic bisphosphonates was associated to a more precocious interruption.

PURPOSE

Low persistence with osteoporosis medications is associated with higher fracture risk. This study aimed to assess the persistence to treatment with oral bisphosphonates among Italian osteoporotic patients under treatment for at least 6 months and to evaluate whether the different oral formulations of bisphosphonates may influence the interruption of the therapy.

METHODS

723 consecutive osteoporotic patients, aged 50 years or over, referred as outpatients for a follow-up visit after receiving a prescription of an oral bisphosphonate for the first time for at least 6 months were enrolled in this retrospective, multicenter survey carried out under conditions of usual clinical practice. All the patients enrolled were submitted to a standardized interview.

RESULTS

191 patients turned out to have discontinued treatment (28.7%), the more common causes for interruption being the adverse events (43.9%), fear of adverse events (23.3%) and perceived absence of efficacy of the treatment (15.8%). The osteoporotic patients taking drinkable bisphosphonate or on treatment with aromatase inhibitors or under the age of 70 years were less likely to interrupt the treatment. However, these associations were no longer significant when the pharmaceutical formulation (generic vs branded) was included into the multivariate logistic regression model.

CONCLUSION

This study suggests that the new drinkable formulations of bisphosphonates could be an interesting option able to reduce upper GI adverse events, thus increasing persistence; whereas the generic formulations of bisphosphonates were associated to a premature discontinuation.

Differences in In Vitro Disintegration Time among Canadian Brand and Generic Bisphosphonates

The objective of this study was to compare the disintegration times among Canadian-marketed brand (alendronate 70 mg, alendronate 70 mg plus vitamin D 5600 IU, and risedronate 35 mg) and generic (Novo-alendronate 70 mg and Apo-alendronate 70 mg) once-weekly dosed bisphosphonates. All disintegration tests were performed with a Vanderkamp Disintegration Tester. Disintegration was deemed to have occurred when no residue of the tablet, except fragments of insoluble coating or capsule shell, was visible. Eighteen to 20 samples were tested for each bisphosphonate group. The mean (±standard deviation) disintegration times were significantly (P < 0.05) faster for Apo-alendronate (26 ± 5.6 seconds) and Novo-alendronate (13 ± 1.1 seconds) as compared to brand alendronate (147 ± 50.5 seconds), brand alendronate plus vitamin D (378 ± 60.5 seconds), or brand risedronate (101 ± 20.6 seconds). The significantly faster disintegration of the generic tablets as compared to the brand bisphosphonates may have concerning safety and effectiveness implications for patients administering these therapies.