Bisphosphonates are a class of drugs that prevent the loss of bone mass, used to treat osteoporosis and similar diseases. They are the most commonly prescribed drugs used to treat osteoporosis. They are called bisphosphonates because they have two phosphonate (PO(OH)
Bone undergoes constant turnover and is kept in balance (homeostasis) by osteoblasts creating bone and osteoclasts destroying bone. Bisphosphonates inhibit the digestion of bone by encouraging osteoclasts to undergo apoptosis, or cell death, thereby slowing bone loss.
The uses of bisphosphonates include the prevention and treatment of osteoporosis, Paget's disease of bone, bone metastasis (with or without hypercalcaemia), multiple myeloma, primary hyperparathyroidism, osteogenesis imperfecta, fibrous dysplasia, and other conditions that exhibit bone fragility.
Bisphosphonates are used to treat osteoporosis, osteitis deformans (Paget's disease of the bone), bone metastasis (with or without hypercalcaemia), multiple myeloma, and other conditions involving fragile, breakable bone.
In osteoporosis and Paget's, the most popular first-line bisphosphonate drugs are alendronate and risedronate. If these are ineffective or if the person develops digestive tract problems, intravenous pamidronate may be used. Strontium ranelate or teriparatide are used for refractory disease. The use of strontium ranelate is restricted because of increased risk of venous thromboembolism, pulmonary embolism and serious cardiovascular disorders, including myocardial infarction. In postmenopausal women, the selective estrogen receptor modulator raloxifene is occasionally administered instead of bisphosphonates. Bisphosphonates are beneficial in reducing the risk of vertebral fracture in steroid induced osteoporosis.
Long-term treatment with bisphosponates produces anti-fracture and bone mineral density effects that persist for 3–5 years after an initial 3–5 years of treatment. The bisphosphonate alendronate reduces the risk of hip, vertebral, and wrist fractures by 35-39%; zoledronate reduces the risk of hip fractures by 38% and of vertebral fractures by 62%. Risedronate has also been shown to reduce the risk of hip fractures.
After five years of medications by mouth or three years of intravenous medication among those at low risk, bisphosphonate treatment can be stopped. In those at higher risk ten years of medication by mouth or six years of intravenous treatment may be used.
Bisphosphonates reduce the risk of fracture and bone pain in people with breast, lung, and other metastatic cancers as well as in people with multiple myeloma. In breast cancer there is mixed evidence regarding whether bisphosphonates improve survival.
Bisphosphonates can also reduce mortality in those with multiple myeloma, breast and prostate cancer.
The risk of oesophageal cancer increases with 10 or more prescriptions for oral bisphosphonates over a five year period. In Europe and North America, the incidence of oesophageal cancer at age 60-79 is typically 1 per 1000 population over five years, and this is estimated to increase to about 2 per 1000 with five years’ use of oral bisphosphonates.
Evidence suggests that the use of bisphosphonates would be useful in the treatment of complex regional pain syndrome, a neuro-immune problem with high MPQ scores, low treatment efficacy and symptoms which can include regional osteoporosis. In 2009 bisphosphonates were "among the only class of medications that has survived placebo-controlled studies showing statistically significant improvement (in CRPS) with therapy."
Other bisphosphonates, including medronate (R
2=H) and oxidronate (R
2=OH), are mixed with radioactive technetium and injected, as a way to image bone and detect bone disease. Bisphosphonates have been used to reduce fracture rates in children with the disease osteogenesis imperfecta and to treat otosclerosis by minimizing bone loss.
Oral bisphosphonates can cause upset stomach and inflammation and erosions of the esophagus, which is the main problem of oral N-containing preparations. This can be prevented by remaining seated upright for 30 to 60 minutes after taking the medication. Intravenous bisphosphonates can give fever and flu-like symptoms after the first infusion, which is thought to occur because of their potential to activate human γδ T cells.
Bisphosphonates, when administered intravenously for the treatment of cancer, have been associated with osteonecrosis of the jaw (ONJ), with the mandible twice as frequently affected as the maxilla and most cases occurring following high-dose intravenous administration used for some cancer patients. Some 60% of cases are preceded by a dental surgical procedure (that involve the bone), and it has been suggested that bisphosphonate treatment should be postponed until after any dental work to eliminate potential sites of infection (the use of antibiotics may otherwise be indicated prior to any surgery).
A number of cases of severe bone, joint, or musculoskeletal pain have been reported, prompting labeling changes.
Recent studies have reported bisphosphonate use (specifically zoledronate and alendronate) as a risk factor for atrial fibrillation in women. The inflammatory response to bisphosphonates or fluctuations in calcium blood levels have been suggested as possible mechanisms. Until now, however, the benefits of bisphosphonates, in general, outweigh this risk, although care must be taken in certain populations at high risk of serious adverse effects from atrial fibrillation (such as patients with heart failure, coronary artery disease, or diabetes). FDA has not yet confirmed a causal relationship between bisphosphonates and atrial fibrillation.
In large studies, women taking bisphosphonates for osteoporosis have had unusual fractures ("bisphosphonate fractures") in the femur (thigh bone) in the shaft (diaphysis or sub-trochanteric region) of the bone, rather than at the femoral neck, which is the most common site of fracture. However, these unusual fractures are extremely rare (12 in 14,195 women) compared to the common hip fractures (272 in 14,195 women), and the overall reduction in hip fractures caused by bisphosphonate far outweighed the unusual shaft fractures. There are concerns that long-term bisphosphonate use can result in over-suppression of bone turnover. It is hypothesized that micro-cracks in the bone are unable to heal and eventually unite and propagate, resulting in atypical fractures. Such fractures tend to heal poorly and often require some form of bone stimulation, for example bone grafting as a secondary procedure. This complication is not common, and the benefit of overall fracture reduction still holds. In cases where there is concern of such fractures occurring, teriparatide is potentially a good alternative because it does not cause as much damage as a bisphosphonate does by suppressing bone turnover.
Three meta analyses have evaluated whether bisphosphonate use is associated with an increased risk of esophageal cancer. Two studies concluded that there was no evidence of increased risk.
Chemistry and classes
All bisphosphonate drugs share a common P-C-P "backbone":
The two PO
3 (phosphonate) groups covalently linked to carbon determine both the name "bisphosphonate" and the function of the drugs. Bis refers to the fact that there are two such groups in the molecule.
The long side-chain (R
2 in the diagram) determines the chemical properties, the mode of action and the strength of bisphosphonate drugs. The short side-chain (R
1), often called the 'hook', mainly influences chemical properties and pharmacokinetics.
Of the bisphosphonate that is resorbed (from oral preparation) or infused (for intravenous drugs), about 50% is excreted unchanged by the kidney. The remainder has a very high affinity for bone tissue, and is rapidly adsorbed onto the bone surface.
Mechanism of action
Bisphosphonates' mechanisms of action all stem from their structures' similarity to pyrophosphate (see figure above). A bisphosphonate group mimics pyrophosphate's structure, thereby inhibiting activation of enzymes that utilize pyrophosphate.
Bisphosphonate-based drugs' specificity comes from the two phosphonate groups (and possibly a hydroxyl at R
1) that work together to coordinate calcium ions. Bisphosphonate molecules preferentially "stick" to calcium and bind to it. The largest store of calcium in the human body is in bones, so bisphosphonates accumulate to a high concentration only in bones.
Bisphosphonates, when attached to bone tissue, are "ingested" by osteoclasts, the bone cells that break down bone tissue.
There are two classes of bisphosphonate: the N-containing and non-N-containing bisphosphonates. The two types of bisphosphonates work differently in killing osteoclast cells.
- Etidronate (Didronel) — 1 (potency relative to that of etidronate)
- Clodronate (Bonefos, Loron) — 10
- Tiludronate (Skelid) — 10
The non-nitrogenous bisphosphonates (disphosphonates) are metabolised in the cell to compounds that replace the terminal pyrophosphate moiety of ATP, forming a non-functional molecule that competes with adenosine triphosphate (ATP) in the cellular energy metabolism. The osteoclast initiates apoptosis and dies, leading to an overall decrease in the breakdown of bone. This type of bisphosphonate has overall more negative effects than the nitrogen containing group, and is prescribed far less often.
- Pamidronate (APD, Aredia) — 100
- Neridronate (Nerixia) — 100
- Olpadronate — 500
- Alendronate (Fosamax) — 500
- Ibandronate (Boniva) — 1000
- Risedronate (Actonel) — 2000
- Zoledronate (Zometa, Aclasta) — 10000
Disruption of the HMG CoA-reductase pathway at the level of FPPS prevents the formation of two metabolites (farnesol and geranylgeraniol) that are essential for connecting some small proteins to the cell membrane. This phenomenon is known as prenylation, and is important for proper sub-cellular protein trafficking (see "lipid-anchored protein" for the principles of this phenomenon).
While inhibition of protein prenylation may affect many proteins found in an osteoclast, disruption to the lipid modification of Ras, Rho, Rac proteins has been speculated to underlie the effects of bisphosphonates. These proteins can affect both osteoclastogenesis, cell survival, and cytoskeletal dynamics. In particular, the cytoskeleton is vital for maintaining the "ruffled border" that is required for contact between a resorbing osteoclast and a bone surface.
Statins are another class of drugs that inhibit the HMG-CoA reductase pathway. Unlike bisphosphonates, statins do not bind to bone surfaces with high affinity, and thus are not specific for bone. Nevertheless, some studies have reported a decreased rate of fracture (an indicator of osteoporosis) and/or an increased bone mineral density in statin users. The overall efficacy of statins in the treatment of osteoporosis remains controversial.
Bisphosphonates were developed in the 19th century but were first investigated in the 1960s for use in disorders of bone metabolism. Their non-medical use was to soften water in irrigation systems used in orange groves. The initial rationale for their use in humans was their potential in preventing the dissolution of hydroxylapatite, the principal bone mineral, thus arresting bone loss. Only in the 1990s was their actual mechanism of action demonstrated with the initial launch of Fosamax (alendronate) by Merck & Co.
- National Osteoporosis Society. "Drug Treatment". U.K. National Osteoporosis Society. Retrieved 7 August 2012.
- Eriksen EF, Díez-Pérez A, Boonen S (January 2014). "Update on long-term treatment with bisphosphonates for postmenopausal osteoporosis: a systematic review". Bone. 58: 126–35. doi:10.1016/j.bone.2013.09.023. PMID 24120384.
- Serrano AJ, Begoña L, Anitua E, Cobos R, Orive G (December 2013). "Systematic review and meta-analysis of the efficacy and safety of alendronate and zoledronate for the treatment of postmenopausal osteoporosis". Gynecol. Endocrinol. 29 (12): 1005–14. doi:10.3109/09513590.2013.813468. PMID 24063695.
- Gauthier, K; Bai, A; Perras, C; Cunningham, J; Ahuja, T; Richter, T; Kovacs, C (February 2012). "Denosumab, Raloxifene, and Zoledronic Acid for the Treatment of Postmenopausal Osteoporosis: Clinical Effectiveness and Harms". Rapid Response Report: Systematic Review. Ottawa: Canadian Agency for Drugs and Technologies in Health. PMID 24278999.
- Watts NB, Bilezikian JP, Camacho PM, Greenspan SL, Harris ST, Hodgson SF, Kleerekoper M, Luckey MM, McClung MR, Pollack RP, Petak SM (2010). "American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for the diagnosis and treatment of postmenopausal osteoporosis". Endocr Pract. 16 Suppl 3: 1–37. doi:10.4158/ep.16.s3.1. PMC . PMID 21224201.
- Kanis JA, McCloskey EV, Johansson H, Cooper C, Rizzoli R, Reginster JY (January 2013). "European guidance for the diagnosis and management of osteoporosis in postmenopausal women". Osteoporos Int. 24 (1): 23–57. doi:10.1007/s00198-012-2074-y. PMC . PMID 23079689.
- Weinstein RS, Roberson PK, Manolagas SC (January 2009). "Giant osteoclast formation and long-term oral bisphosphonate therapy". N. Engl. J. Med. 360 (1): 53–62. doi:10.1056/NEJMoa0802633. PMC . PMID 19118304.
- "Strontium ranelate: cardiovascular risk—restricted indication and new monitoring requirements Article date: March 2014". MHRA.
- Allen, CS; Yeung, JH; Vandermeer, B; Homik, J (5 October 2016). "Bisphosphonates for steroid-induced osteoporosis.". The Cochrane database of systematic reviews. 10: CD001347. doi:10.1002/14651858.CD001347.pub2. PMID 27706804.
- "Management of osteoporosis in postmenopausal women: 2010 position statement of The North American Menopause Society". Menopause. 17 (1): 25–54; quiz 55–6. 2010. doi:10.1097/gme.0b013e3181c617e6. PMID 20061894.
- Hauk L (August 2013). "ACOG releases practice bulletin on osteoporosis". Am Fam Physician. 88 (4): 269–75. PMID 23944732.
- Compston J, Bowring C, Cooper A, et al. (August 2013). "Diagnosis and management of osteoporosis in postmenopausal women and older men in the UK: National Osteoporosis Guideline Group (NOGG) update 2013". Maturitas. 75 (4): 392–6. doi:10.1016/j.maturitas.2013.05.013. PMID 23810490.
- Adler, Robert A; El-Hajj Fuleihan, Ghada; Bauer, Douglas C; Camacho, Pauline M; Clarke, Bart L; Clines, Gregory A; Compston, Juliet E; Drake, Matthew T; Edwards, Beatrice J; Favus, Murray J; Greenspan, Susan L; McKinney, Ross; Pignolo, Robert J; Sellmeyer, Deborah E (January 2016). "Managing Osteoporosis in Patients on Long-Term Bisphosphonate Treatment: Report of a Task Force of the American Society for Bone and Mineral Research". Journal of Bone and Mineral Research. 31 (1): 16–35. doi:10.1002/jbmr.2708.
- Zhu M, Liang R, Pan LH, et al. (February 2013). "Zoledronate for metastatic bone disease and pain: a meta-analysis of randomized clinical trials". Pain Med. 14 (2): 257–64. doi:10.1111/pme.12016. PMID 23279447.
- Wong MH, Stockler MR, Pavlakis N (2012). "Bisphosphonates and other bone agents for breast cancer". Cochrane Database Syst Rev. 2: CD003474. doi:10.1002/14651858.CD003474.pub3. PMID 22336790.
- Lopez-Olivo MA, Shah NA, Pratt G, Risser JM, Symanski E, Suarez-Almazor ME (November 2012). "Bisphosphonates in the treatment of patients with lung cancer and metastatic bone disease: a systematic review and meta-analysis". Support Care Cancer. 20 (11): 2985–98. doi:10.1007/s00520-012-1563-z. PMC . PMID 22956190.
- Mhaskar R, Redzepovic J, Wheatley K, et al. (2012). "Bisphosphonates in multiple myeloma: a network meta-analysis". Cochrane Database Syst Rev. 5: CD003188. doi:10.1002/14651858.CD003188.pub3. PMID 22592688.
- Ben-Aharon I, Vidal L, Rizel S, et al. (2013). "Bisphosphonates in the adjuvant setting of breast cancer therapy--effect on survival: a systematic review and meta-analysis". PLoS ONE. 8 (8): e70044. doi:10.1371/journal.pone.0070044. PMC . PMID 23990894.
- Zhu J, Zheng Y, Zhou Z (June 2013). "Oral adjuvant clodronate therapy could improve overall survival in early breast cancer: results from an updated systematic review and meta-analysis". Eur. J. Cancer. 49 (9): 2086–92. doi:10.1016/j.ejca.2013.01.021. PMID 23452992.
- Van Acker, HH; Anguille, S; Willemen, Y; Smits, EL; Van Tendeloo, VF (23 November 2015). "Bisphosphonates for cancer treatment: Mechanisms of action and lessons from clinical trials.". Pharmacology & therapeutics. 158: 24–40. doi:10.1016/j.pharmthera.2015.11.008. PMID 26617219.
- Jane Green; Gabriela Czanner; Gillian Reeves; Joanna Watson; Lesley Wise; Valerie Beral. 2010 Oral bisphosphonates and risk of cancer of oesophagus, stomach, and colorectum: case-control analysis within a UK primary care cohort.
- Pontell D (July 2008). "A clinical approach to complex regional pain syndrome". Clinics in Podiatric Medicine and Surgery. 25 (3): 361–80; vi. doi:10.1016/j.cpm.2008.02.011. PMID 18486850.
- Shapiro JR, Sponsellor PD (December 2009). "Osteogenesis imperfecta: questions and answers". Current Opinion in Pediatrics. 21 (6): 709–16. doi:10.1097/MOP.0b013e328332c68f. PMID 19907330.
- Brookler K (2008). "Medical treatment of otosclerosis: rationale for use of bisphosphonates". Int Tinnitus J. 14 (2): 92–6. PMID 19205157.
- Woo S, Hellstein J, Kalmar J (2006). "Narrative [corrected] review: bisphosphonates and osteonecrosis of the jaws". Ann Intern Med. 144 (10): 753–61. doi:10.7326/0003-4819-144-10-200605160-00009. PMID 16702591.
- Wysowski D, Chang J (2005). "Alendronate and risedronate: reports of severe bone, joint, and muscle pain". Arch Intern Med. 165 (3): 346–7. doi:10.1001/archinte.165.3.346-b. PMID 15710802.
- Black DM, Delmas PD, Eastell R, et al. (May 2007). "Once-yearly zoledronic acid for treatment of postmenopausal osteoporosis". N. Engl. J. Med. 356 (18): 1809–22. doi:10.1056/NEJMoa067312. PMID 17476007.
- Heckbert SR, Li G, Cummings SR, Smith NL, Psaty BM (April 2008). "Use of alendronate and risk of incident atrial fibrillation in women". Arch. Intern. Med. 168 (8): 826–31. doi:10.1001/archinte.168.8.826. PMID 18443257.
- Cummings SR, Schwartz AV, Black DM (May 2007). "Alendronate and atrial fibrillation". N. Engl. J. Med. 356 (18): 1895–6. doi:10.1056/NEJMc076132. PMID 17476024.
- "Early Communication of an Ongoing Safety Review on Bisphosphonates: Alendronate (Fosamax, Fosamax Plus D), Etidronate (Didronel), Ibandronate (Boniva), Pamidronate (Aredia), Risedronate (Actonel, Actonel W/Calcium), Tiludronate (Skelid), and Zoledronic acid (Reclast, Zometa)". Postmarket Drug Safety Information for Patients and Providers. Food and Drug Administration (United States). 2007-10-01. Retrieved 2009-07-15.
- "Update of Safety Review Follow-up to the October 1, 2007 Early Communication about the Ongoing Safety Review of Bisphosphonates". Postmarket Drug Safety Information for Patients and Providers. Food and Drug Administration (United States). October 2008. Retrieved 2009-07-15.
- Shane E (May 2010). "Evolving data about subtrochanteric fractures and bisphosphonates". N. Engl. J. Med. 362 (19): 1825–7. doi:10.1056/NEJMe1003064. PMID 20335574.
- Lenart BA, Lorich DG, Lane JM (March 2008). "Atypical fractures of the femoral diaphysis in postmenopausal women taking alendronate". N. Engl. J. Med. 358 (12): 1304–6. doi:10.1056/NEJMc0707493. PMID 18354114.
- Arkan S Sayed-Noor; Bakir K Kadum; Göran O Sjödén (31 March 2010). "Bisphosphonate-induced femoral fragility fractures: What do we know?". Orthopedic Research and Reviews. 2 (1): 27–34. doi:10.2147/ORRS7521. Retrieved 26 April 2012.
- Andrici J, Tio M, Eslick GD (October 2012). "Meta-analysis: oral bisphosphonates and the risk of oesophageal cancer". Aliment. Pharmacol. Ther. 36 (8): 708–16. doi:10.1111/apt.12041. PMID 22966908.
- Sun K, Liu JM, Sun HX, Lu N, Ning G (January 2013). "Bisphosphonate treatment and risk of esophageal cancer: a meta-analysis of observational studies". Osteoporos Int. 24 (1): 279–86. doi:10.1007/s00198-012-2158-8. PMID 23052941.
- Oh YH, Yoon C, Park SM (October 2012). "Bisphosphonate use and gastrointestinal tract cancer risk: meta-analysis of observational studies". World J. Gastroenterol. 18 (40): 5779–88. doi:10.3748/wjg.v18.i40.5779. PMC . PMID 23155320.
- Frith J, Mönkkönen J, Blackburn G, Russell R, Rogers M (1997). "Clodronate and liposome-encapsulated clodronate are metabolized to a toxic ATP analog, adenosine 5'-(beta, gamma-dichloromethylene) triphosphate, by mammalian cells in vitro". J Bone Miner Res. 12 (9): 1358–67. doi:10.1359/jbmr.19184.108.40.2068. PMID 9286751.
- (not sold in the United States)
- van Beek E, Cohen L, Leroy I, Ebetino F, Löwik C, Papapoulos S (November 2003). "Differentiating the mechanisms of antiresorptive action of nitrogen containing bisphosphonates". Bone. 33 (5): 805–11. doi:10.1016/j.bone.2003.07.007. PMID 14623056.
- Wiemer, AJ; Wiemer, DF; Hohl, RJ (December 2011). "Geranylgeranyl diphosphate synthase: an emerging therapeutic target.". Clinical pharmacology and therapeutics. 90 (6): 804–12. doi:10.1038/clpt.2011.215. PMID 22048229.
- Van Beek E, Löwik C, van der Pluijm G, Papapoulos S (1999). "The role of geranylgeranylation in bone resorption and its suppression by bisphosphonates in fetal bone explants in vitro: A clue to the mechanism of action of nitrogen-containing bisphosphonates". J Bone Miner Res. 14 (5): 722–9. doi:10.1359/jbmr.19220.127.116.112. PMID 10320520.
- Uzzan, B; et al. (2007). "Effects of statins on bone mineral density: a meta-analysis of clinical studies". Bone. 40 (6): 1581–7. doi:10.1016/j.bone.2007.02.019. PMID 17409043. Retrieved 2012-07-13.
- Fleisch H (2002). "Development of bisphosphonates". Breast Cancer Res. 4 (1): 30–4. doi:10.1186/bcr414. PMC . PMID 11879557.