Data suggest that following after bisphosphonate exposure of 3 to 5 years in postmenopausal women with osteoporosis:
- the protection from fractures persists for an unknown interval of time in selected patients when therapy is withdrawn; that the protection wanes within 3 to 5 years of discontinuation; and that the risk of atypical femoral fractures increases with the duration of therapy but may decrease upon withdrawal of treatment
- bisphosphonates is analogs of pyrophosphate having a three-dimensional structure capable of chelating divalent cations such as Ca2+
- bisphosphonates have a strong affinity for bone, targeting especially bone surfaces undergoing remodelingand binds strongly to hydroxyapatite and remains inactive until the bone containing BP are reabsorbed half-life after incorporation into mineralized bone nearly 10 years (1)
A. Determination of the duration for bisphosphonate therapy (2,3)
- i. Drug holiday from alendronate and risedronate may be considered after 5 years
- ii. Drug holiday from zoledronic acid may be considered after 3 years
B. Selection of the appropriate candidates for the drug holiday
- i. Consider a drug holiday after 5 years of alendronate and risedronate treatment, and after 3 years of zoledronic acid, in individuals without high risk.
- ii. Consider the continued treatment in individuals with high risk.
- 1) T-score at any site still <=-2.5 after bisphosphonate therapy (5 years for alendronate and risedronate, and 3 years for zoledronic acid).
- 2) Previous fracture of the hip or spine.
- 3) High risk of fracture because of secondary osteoporosis from chronic diseases or medication.
- iii. Alternative therapy may be used for individuals with high risk
- iv. Factors guiding the determination of a drug holiday are the variable anti-resorptive potency and binding affinity of each bisphosphonate, as well as a demonstration of compliance with the therapy
Duration and Monitoring during a drug holiday (2,3,4)
Duration of treatment and the length of the 'holiday' should be tailored to individual patient circumstances and based on individual assessments of risk and benefit
- it has been stated that "..a drug holiday of 1-2 years should be considered after 3-5 years of bisphosphonate therapy except in those patients who remain at very high fracture risk.." (4)
A. Parameter for monitoring during a drug holiday
- i. Consider the annual measurement of BMD using dual energy X-ray absorptiometry.
B. Restart therapy after a drug holiday
- i. Consider re-treatment if there is a significant decrease in BMD.
- ii. Consider re-treatment if T-score reaches <= -2.5 or a new osteoporotic fracture occurs
Reference:
- Friedman PA. Agents affecting mineral ion homeostasis and bone turnover. In: Brunton LL, Lazo JS, Parker KL, editors. Goodman & Gilman's the Pharmacological Basis of Therapeutics. 11th ed. New York: McGraw-Hill; 2006. Ch 16.
- Lee SH et al. Position Statement: Drug Holiday in Osteoporosis Treatment with Bisphosphonates in South Korea. J Bone Metab. 2015 Nov;22(4):167-74
- Diab DL, Watts NB. Bisphosphonate drug holiday: who, when and how long.Ther Adv Musculoskel Dis. 2013;5(3):107-111
- McClung M, Harris ST, Miller PD, Bauer DC, Davison KS, Dian L, et al. Bisphosphonate therapy for osteoporosis: Benefits, risks, and drug holiday. Am J Med. 2013;126:13-20.