Going on a drug holiday?

Bisphosphonates-much more than only drugs for bone diseases

α,α-Bisphosphonates (BPs) are well established in the treatment of bone diseases such as osteoporosis and Paget's disease. Their successful application originates from their high affinity to hydroxyapatite. While the initially appreciated features of BPs are already beneficial to many patients, recent developments have further expanded their pleiotropic applications. This review describes the background of the interactions of BPs with bone cells that form the basis of the classical treatment. A better understanding of the mechanism behind their interactions allows for the parallel application of BPs against bone cancer and metastases followed by palliative pain relief. Targeted therapy with bone-seeking BPs coupled with a diagnostic agent in one particle resulted in theranostics which is also described here. For example, in such a system, BP moieties are bound to contrast agents used in magnetic resonance imaging or radionuclides used in positron emission tomography. In addition, another example of the pleiotropic function of BPs which involves targeting the imaging agents to bone tissues accompanied by pain reduction is presented in this work.

The Prevention of Medication-related Osteonecrosis of the Jaw

BACKGROUND

Medication-related osteonecrosis of the jaw (MRONJ) is a preventable complication of antiresorptive treatment. It arises in 1-20% of patients with bone metastases of solid tumors and hematologic malignancies and in 0.1-2% of patients being treated for osteoporosis with bisphosphonates. Depending on the underlying disease and medication dosage, the risk of MRONJ can be elevated even in the first year of antiresorptive treatment. The treatment of MRONJ is difficult and often involves surgery of the jaw.

METHODS

We systematically reviewed publications retrieved by a selective search for literature on the prevention of MRONJ in the PubMed and Cochrane Library databases and with the aid of the Google Scholar search engine.

RESULTS

15 of 559 retrieved publications were included in the analysis. The quality of the evidence in the studies was generally moderate to low, with most of them being case series. In one case series of over 1200 patients with multiple myeloma, the incidence of MRONJ was lowered from 4.6% to 0.8% through regular dental checkups and improved oral hygiene. Tooth extraction, in particular, is associated with a high risk of MRONJ. In a retrospective study, 57% of patients who underwent tooth extraction without antibiotic prophylaxis developed MRONJ, compared to 0% with antibiotic prophylaxis.

CONCLUSION

Before antiresorptive medication is begun, oral hygiene should be improved. Moreover, it seems that perioperative antibiotic prophylaxis and adequate plastic wound closure can often prevent MRONJ. In view of the fact that bisphosphonates can persist in bone for more than 15 years, patients should be thoroughly informed of the risk that antiresorptive treatment can cause MRONJ, and the measures discussed should be initiated.

Atypical periprosthetic acetabular fracture in long-term alendronate therapy

Bisphosphonates have been commonly used in the treatment of osteoporosis, demonstrating its efficacy in fracture risk reduction. However, even if are generally safe and well tolerated, concerns have emerged about atypical fractures related to its prolonged use. Although atypical femoral fracture are more common, case reports demonstrated that even other skeletal areas can be involved by unusual pattern of fracture. We report a atypical acetabular periprosthetic fracture in a 83-year-old female patient after prolonged alendronate treatment for osteoporosis and isolated acetabular revision surgery. The patient underwent to clinical, bioumoral and radiological evaluation and all the history cases were fully reported. We believe this periprosthetic fracture, according to the available data, may have similar underlying pathology to atypical femoral fractures. Awareness of symptoms, in addition to a regular radiographic survey may facilitate early diagnosis and possible prevention of spontaneous periprosthetic fractures, in patients receiving bisphosphonate therapy beyond 5 years. The treatment of this atypical periprosthetic fracture should include both surgical than pharmacological therapy to obtained bone healing.

Position Statement: Drug Holiday in Osteoporosis Treatment with Bisphosphonates in South Korea

Bisphosphonates have been widely used in the treatment of osteoporosis with robust data from many placebo-controlled trials demonstrating its efficacy in fracture risk reduction over 3 to 5 years of treatment. Although bisphosphonates are generally safe and well tolerated, concerns have emerged about the adverse effects related to its long-term use, including osteonecrosis of the jaw and atypical femur fractures. Because bisphosphonates are incorporated into the skeleton and continue to exert an anti-resorptive effect for a period of time after the discontinuation of drugs, the concept of a "drug holiday" has emerged, whereby the risk of adverse effects might be decreased while the patient still benefits from anti-fracture efficacy. As randomized clinical trial evidence is not yet available on who may qualify for a drug holiday, there is considerable controversy regarding the selection of candidates for the drug holiday and monitoring during a drug holiday, both of which should be based on individual assessments of risk and benefit. This statement will provide suggestions for clinicians in South Korea on the identification of possible candidates and monitoring during a bisphosphonate drug holiday.

Increase in the serum parathyroid hormone level during a bisphosphonate drug holiday

After discontinuation of bisphosphonate therapy, an antiresorptive effect and antifracture protection persist for an undefined period. Patients are encouraged to continue calcium and vitamin D supplementation, during a bisphosphonate drug holiday. However, assessment of adequate calcium intake during the bisphosphonate drug holiday is difficult. Therefore, we measured the serum intact parathyroid hormone (PTH) level as a surrogate marker. A premenopausal woman discontinued bisphosphonate therapy, after 7.5 years of treatment. Two months later, blood calcium and phosphorus levels were normal, serum 25-hydroxyvitamin D level was 31.3 ng/mL, but serum PTH level had increased to 94.9 pg/mL. The elemental calcium supplement dose was increased to 600 mg/day, with no change in the cholecalciferol dose (400 IU). Her serum PTH levels decreased to 49.1 after 4 months and 32.9 pg/mL after 5 months. The serum PTH level may be helpful in assessing adequate calcium intake during a bisphosphonate drug holiday.

Effect of prior oophorectomy on changes in bone mineral density and carotid artery intima-media thickness in postmenopausal women

OBJECTIVE

To determine the effect of prior oophorectomy in healthy postmenopausal women on the rate of loss of bone mineral density (BMD) and rate of increase in carotid artery intima-media thickness (CIMT).

DESIGN

Secondary analysis from a randomized controlled trial.

SETTING

University-based research clinic.

PATIENT(S)

Two hundred twenty-two healthy postmenopausal women in the Greater Los Angeles area.

INTERVENTION(S)

Baseline and annual screening of BMD and assessment of CIMT every 6 months for a total of 3 years.

MAIN OUTCOME MEASURE(S)

Changes in BMD and CIMT during postmenopausal years.

RESULT(S)

Among women who were menopausal for more than 10 years, the rate of CIMT progression was statistically significantly less in women with intact ovaries compared with those in women with prior oophorectomy. In women 5-10 years postmenopause, there was a trend toward a slower loss of BMD in those who retained their ovaries, and in women more than 10 years postmenopause there was significantly less BMD loss in those who retained their ovaries.

CONCLUSION(S)

As time from menopausal transition increases, retained ovaries are associated with a slower rate of bone loss and a slower rate of thickening of the carotid artery wall compared with rates in menopausal women with oophorectomy.

Treat-to-target for osteoporosis: is now the time?

OBJECTIVES

Current clinical practice guidelines identify patients at high risk for fracture who are likely to benefit from pharmacological therapy and suggest ways to monitor for effectiveness of therapy. However, there is no clear guidance on when fracture risk has been reduced to an acceptably low level. As a consequence, some patients at low risk for fracture may be treated for longer than necessary, whereas others at high risk for fracture may have treatment stopped when they might benefit from continuation of the same treatment or a change to a more potent therapeutic agent. The objective of this statement is to describe the potential clinical utility of developing a "treat-to-target" strategy for the management of patients with osteoporosis.

PARTICIPANTS

We recommend that a task force of clinicians, clinical investigators, and other stakeholders in the care of osteoporosis explore the options, review the evidence, and identify additional areas for investigation to establish osteoporosis treatment targets.

EVIDENCE

Data from large, prospective, randomized, placebo-controlled registration trials for currently available osteoporosis therapies should be analyzed for commonalities of correlations between easily measured endpoints and fracture risk.

CONSENSUS PROCESS

Osteoporosis experts, professional organizations, and patient care advocates should be involved in the process of developing consensus on easily measurable osteoporosis treatment targets that are supported by the best available evidence and likely to be accepted by clinicians and patients in the care of osteoporosis.

CONCLUSIONS

A treat-to-target strategy for osteoporosis offers the potential of improving osteoporosis care by reducing the burden of osteoporotic fractures and limiting adverse effects of therapy.

Bisphosphonate therapy for osteoporosis: benefits, risks, and drug holiday

The amino-bisphosphonates are first-line therapy for the treatment of most patients with osteoporosis, with proven efficacy to reduce fracture risk at the spine, hip, and other nonvertebral skeletal sites. Further, bisphosphonates have been associated with a significant decrease in morbidity and increase in survival. Following the use of bisphosphonates in millions of patients in clinical practice, some unexpected possible adverse effects have been reported, including osteonecrosis of the jaw, atypical femur fractures, atrial fibrillation, and esophageal cancer. Because bisphosphonates are incorporated into the skeleton and continue to exert an antiresorptive effect for a period of time after dosing is discontinued, the concept of a drug holiday has emerged, whereby the risk of adverse effects might be decreased while the patient still benefits from antifracture efficacy. Patients receiving bisphosphonates who are not at high risk for fracture are potential candidates for a drug holiday, while for those with bone mineral density in the osteoporosis range or previous history of fragility fracture, the benefits of continuing therapy probably far outweigh the risk of harm.