Gastric damage in the rat with nitrogen-containing bisphosphonates depends on pH

Symptoms and Upper Gastrointestinal Mucosal Injury Associated with Bisphosphonate Therapy

Objective The incidence of osteoporosis is increasing with the rapid aging of the Japanese population. Bisphosphonates are first-line agents used for the treatment of osteoporosis, but they can cause upper gastrointestinal mucosal injury. This study investigated symptoms and upper gastrointestinal mucosal injury associated with oral bisphosphonates. Methods Symptoms were evaluated using the F-scale questionnaire, and esophageal mucosal injury and gastroduodenal ulceration were assessed by endoscopy. Patients were stratified by the type of bisphosphonate (alendronate, risedronate, or minodronate), treatment schedule (once weekly or every four weeks), and the concomitant use of other medications [antithrombotic agents, nonsteroidal anti-inflammatory drugs (NSAIDs), or acid suppressants]. Patients The subjects included 221 patients treated with oral bisphosphonates for at least one month. Results The median F-scale total score was 4 (0-34), reflux score was 2 (0-20), and the mean dyspepsia score was 2 (0-16). Endoscopy showed esophageal mucosal injury of Grade A or worse (Los Angeles classification) in 22/221 patients (10.0%) and gastroduodenal ulcers in 9 patients (4.1%). The dyspepsia score in patients who took minodronate every four weeks was significantly lower (p<0.05) in comparison to patients who took other bisphosphonates. The dyspepsia score was significantly higher (p<0.05) and mucosal injury was significantly more frequent in patients who also used antithrombotic agents and NSAIDs. Conclusion Symptoms and upper gastrointestinal mucosal damage were not necessarily frequent or severe in patients treated with bisphosphonates. However, the concomitant use of bisphosphonates with antithrombotic agents and NSAIDs increased both symptoms and mucosal injury. The symptoms were milder in patients using minodronate once monthly.

Hydrogen Sulfide and Carbon Monoxide Protect Gastric Mucosa Compromised by Mild Stress Against Alendronate Injury

BACKGROUND

Alendronate is an inhibitor of osteoclast-mediated bone resorption, but its clinical utility is limited due to gastrointestinal complications including bleeding erosions.

AIMS

We studied whether potent vasodilators hydrogen sulfide (H₂S) and carbon monoxide (CO) can protect against alendronate-induced gastric lesions in rats exposed to mild stress.

METHODS

Three series (A, B, and C) of Wistar rats received alendronate (150-700 mg/kg i.g., series A) with or without NaHS (5 mg/kg), H₂S donor or CORM-2 (5 mg/kg) releasing CO administered i.g. 30 min before alendronate administration (series B) in rats exposed for 3 days before alendronate administration to mild stress (series C). The area of gastric lesions was assessed by planimetry, the gastric blood flow (GBF) was determined by H₂-gas clearance technique, and H₂S production via CSE/CBS/3-MST activity and the gastric expression of HO-1, HO-2, HIF-1α, NF-κB, iNOS, COX-2, IL-1β, TNF-α, GPx-1 and SOD-2 were analyzed by qPCR or Western blot.

RESULTS

Alendronate dose-dependently produced gastric mucosal lesions and significantly decreased GBF, and these effects were exacerbated by mild stress. NaHS and CORM-2 significantly reduced the alendronate-induced gastric lesions in non-stressed and stressed animals, but only NaHS but not CORM-2 raised H₂S production. NaHS and CORM-2 inhibited gastric expression of HIF-1α protein and HO-1, HIF-1α, NF-κB, COX-2, iNOS, IL-1β, TNF-α mRNAs but failed to affect those of HO-2, GPx-1, and SOD-2.

CONCLUSION

Both H₂S and CO released from their donors, NaHS and CORM-2, protect gastric mucosa compromised by stress against alendronate-induced gastric damage via mechanism involving downregulation of HIF-1α, NF-κB and proinflammatory factors COX-2, iNOS, IL-1β, and TNF-α.

The potential impact of new effervescent alendronate formulation on compliance and persistence in osteoporosis treatment

Osteoporotic fractures are a public health problem and their incidence and subsequent economic and social costs are expected to rise in the next future. Different drugs have been developed to reduce osteoporosis and the risk of osteoporotic fractures, and among them, antiresorptive agents, and in particular oral alendronate, are the most widely utilized. However, one of the most common problems with antiresorptive drugs is poor adherence to treatment, which is associated with a high fracture incidence and with an increase in hospitalization costs. One of the main reasons of poor adherence to these treatments is the occurrence of adverse events, mainly at gastrointestinal (GI) level, including dyspepsia, dysphagia, and esophageal ulcers. In light of these considerations the aim of this paper is to perform a literature review to show the pathophysiologic bases of GI alendronate-induced adverse events and how new bisphosphonate formulations like effervescent alendronate can improve compliance and persistence to treatment and decrease the fracture rate incidence in osteoporotic patients.

Considerations regarding adherence of anti-osteoporosis therapy

Osteoporosis remains a challenging disease to treat due to a number of barriers including patient adherence to therapies. One of the most recent advances has been the development of the Fracture Risk Assessment Tool, which is helpful in conveying fracture risk to patients and providing treatment guidance to clinicians. The decision to use an anti-osteoporosis therapy must be tailored to the patient's specific clinical scenario. The bisphosphonates are first-line agents in the treatment of osteoporosis and are efficacious in substantially reducing fracture risk between 25% and 70% on average depending on fracture site. Compliance with oral bisphosphonate pills can be poor, resulting in a significant deterrent to the proper management of osteoporosis. Non-pill forms of bisphosphonate and nonbisphosphonate therapy are available for the treatment of osteoporosis and may increase compliance. Among these is Binosto, a new formulation of weekly effervescent alendronate, as well as intravenous bisphosphonates, teriparatide, and subcutaneously administered denosumab, which are all costly medications and are unlikely to become the mainstay of treatment over the oral bisphosphonate pills. Having a detailed conversation between the patient and physician is essential to the development of a tailored treatment plan that will decrease fracture risk.

Oral bisphosphonates and the risk of Barrett's esophagus: case-control analysis of US veterans

OBJECTIVES

This study examined Barrett's esophagus (BE) risk factors in veterans to determine the association between risk of BE and use of oral bisphosphonates.

METHODS

We conducted a case-control study among eligible patients scheduled for an elective esophagogastroduodenoscopy (EGD) and a sample of patients eligible for screening colonoscopy recruited from primary care clinics from a single VA Medical Center. Cases with definitive BE were compared with controls; all underwent study EGD. Use of oral bisphosphonates was ascertained by reviewing filled prescriptions in electronic pharmacy records. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs), using multivariate logistic regression modeling while adjusting for sex, age, race, proton-pump inhibitor use, hiatal hernia, waist-to-hip ratio, Helicobacter pylori infection, and gastroesophageal reflux disorder (GERD) symptoms.

RESULTS

There were 285 BE cases, 1,122 endoscopy controls, and 496 primary care controls. Alendronate and risedronate were the only oral bisphosphonates prescribed. The proportion of BE cases with filled prescription of oral bisphosphonates (4.6%) was greater than in endoscopy controls (1.6%) or primary care controls (2.9%). In the adjusted analysis, oral bisphosphonate use was significantly associated with BE risk (OR=2.33; 95% CI: 1.11-4.88) compared with the combined control groups. This association remained significant when BE cases were compared with endoscopy controls only (OR=2.74; 95% CI: 1.28-5.87) but was attenuated when compared with primary care controls only (OR=2.60; 95% CI: 0.99-6.84). The association was observed in patients with GERD symptoms (OR=3.29; 95% CI: 1.36-7.97) but not in those without GERD symptoms.

CONCLUSION

Oral bisphosphonate use may increase the risk for BE, especially among patients with GERD.

Potential therapeutic effects of oral bisphosphonates on the intestine

Bisphosphonates are the principal drugs prescribed for the prevention of osteoporotic fractures. They are bone specific but poorly absorbed. In oral formulations, almost 99% of the administered dose remains within the intestinal tract and reaches the small and large bowel. Although the nitrogen-containing bisphosphonates can irritate the distal esophageal/gastric mucosa, they improve drug-induced colitis in animal models and exhibit antitumor properties on intestinal cells in vitro. Several recent epidemiological studies provide evidence of a reduced risk of colorectal cancer in osteoporotic patients treated with oral bisphosphonates, notably alendronate. In this review, we will explore the possible mechanisms of action underlying these effects and raise the question of whether these agents might be used in the chemoprophylaxis against colorectal cancer.

Esophageal and gastric cancer incidence and mortality in alendronate users

Recent studies have reached conflicting conclusions regarding the risk of esophageal cancer with oral bisphosphonates. Prior studies did not record the number of cancer deaths or endoscopy rates, which could be higher in bisphosphonate users and lead to more cancers being diagnosed at a stage when their esophageal or gastric location could be accurately distinguished. We conducted a register-based, open cohort study using national healthcare data for Denmark. Upper endoscopy frequency, cancer incidence and mortality was examined in 30,606 alendronate users (female, age 50+) and 122,424 matched controls. Primary outcomes were esophageal cancer incidence and death because of esophageal cancer. The analysis showed that alendronate users were more likely to have undergone recent upper endoscopy (4.1 versus 1.7%, p < 0.001). Alendronate users had a lower risk of incident gastric cancer [odds ratio (OR) 0.61; 95% confidence interval (CI): 0.39-0.97) and no increased risk of esophageal cancer (OR 0.71; 95% CI: 0.43-1.19). Risk reductions were greater in users with 10+ prescriptions. The risk of dying of esophageal cancer was significantly reduced in alendronate users after 3 years OR 0.45 (95% CI: 0.22-0.92) but not after 9 years (OR 1.01; 95% CI: 0.52-1.95). An additional comparison with etidronate users revealed no statistically significant difference in outcomes. In conclusion, we found no excess in esophageal cancer deaths or incidence. The early decrease in esophageal cancer rates may relate to the greater use of endoscopy before starting alendronate. Longer term observations also indicated no excess risk of esophageal cancer death and a significantly decreased risk of gastric cancer death.

Safety of long-term bisphosphonate therapy for the management of osteoporosis

Drugs in the bisphosphonate class are the most commonly prescribed therapeutic agents for the treatment of osteoporosis. Prospective, randomized, placebo-controlled clinical trials have demonstrated efficacy in reducing fracture risk, with favourable safety profiles, in women with postmenopausal osteoporosis. However, long-term use in clinical practice has been associated with reports of undesirable events not previously recognized. These have included gastrointestinal intolerance, osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer, atrial fibrillation and chronic musculoskeletal pain. Physicians must be alert to newly recognized safety concerns, understand the level of evidence supporting them and be able to effectively communicate the balance of expected benefit and potential risk to patients. Usually, post-marketing adverse events are first presented as case reports or observational studies with variable levels of supporting evidence for plausibility, pathophysiology and causality. Widespread coverage in the news media, which can be alarming to patients and their physicians, may not present a balanced view of the proven benefits, the uncertain risks of therapy and the relative magnitude of these events. There may be confusion about the risks associated with bisphosphonate use for the treatment of osteoporosis versus treatment of other conditions, such as cancer, which typically involves a very different patient population and different doses or frequency of drug administration. Often reports of possible adverse events do not provide information on the number of patients exposed to the drug in proportion to the reported adverse event, or do not describe the incidence of the adverse event in a comparator population not exposed to the drug. Gastrointestinal intolerance with oral bisphosphonates, and hypocalcaemia, acute phase reactions and renal toxicity with intravenous bisphosphonates are characterized by biological plausibility and demonstration of causality. Safety concerns with uncertain biological plausibility and unproven causality include osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer and ocular inflammation. Suspected concerns that are unlikely to be causally related include atrial fibrillation and hepatotoxicity. When making the decision to use a bisphosphonate for the treatment of osteoporosis, the balance between benefit and potential risks according to clinical circumstances of each patient should be considered.

Bisphosphonate increases risk of gastroduodenal ulcer in rheumatoid arthritis patients on long-term nonsteroidal antiinflammatory drug therapy

BACKGROUND

Rheumatoid arthritis (RA) patients are at increased risk of peptic ulcers (PU) induced by nonsteroidal antiinflammatory drugs (NSAIDs). However, the impact of potential drug interactions on the development of PU has yet to be determined in a daily clinical setting. The aim was to estimate the clinical important interactions for PU presented by comedication in Japanese RA outpatients on long-term NSAID treatment.

METHODS

This retrospective cohort study enrolled 196 consecutive RA outpatients on NSAID medication for at least 3 months. Potential risk factors for endoscopic PU were analyzed in RA outpatients on longterm NSAID treatment.

RESULTS

PU incidence was 31% with bisphosphonate co-therapy and 17% without the co-therapy. PU incidence was only 5% in subjects with proton pump inhibitors (PPI) or prostaglandin E1 analogues (PG) co-therapy, 14% with histamine-H(2) receptor antagonists(H2RA) co-therapy, and 27% without anti-ulcer agents. In multivariate logistic regression analysis, bisphosphonate co-therapy remained a significant risk factor for PU (OR, 2.29; 95% CI, 1.09-4.81). Other risk factors for ulcer development were advanced age (greater than 60 years) and smoking (OR, 2.58; 95% CI, 1.03-6.49 and OR, 2.71; 95% CI, 1.13-5.53, respectively.) Factors that significantly reduced the incidence of PU were H2RA or PPI/PG cotherapies (OR, 0.29; 95% CI, 0.12-0.68.).

CONCLUSIONS

Bisphosphonate co-therapy as well as advanced age and smoking was found to be a significant risk factor in PU, while co-therapies of standard-dose H2RA or PPI/PG proved effective in preventing PU in Japanese RA patients on long-term NSAID treatment.

Safety of bisphosphonates in the treatment of osteoporosis

In this review 4 experts consider the major safety concerns relating to bisphosphonate therapy for osteoporosis. Specific topics covered are skeletal safety (particularly with respect to atypical fractures and delayed healing), gastrointestinal intolerance, hypocalcemia, acute-phase (i.e., postdose) reactions, chronic musculoskeletal pain, renal safety, and cardiovascular safety (specifically, atrial fibrillation).

Risedronate for prevention and treatment of osteoporosis in postmenopausal women

Risedronate sodium is an N-containing bisphosphonate that has been approved for the prevention and treatment of osteoporosis in postmenopausal women. An increase in the rate of bone remodelling is a regular feature of oestrogen withdrawal during the menopausal transition, but excessive remodelling leads to bone fragility. Risedronate and similar compounds reduce the rate of bone remodelling by suppressing the action of osteoclasts. The antifracture efficacy of risedronate is impressive. In large clinical trials of postmenopausal women with osteoporosis-related fracture(s) at entry, the risk of incident vertebral and non-vertebral fractures was reduced by approximately 40%. In older women at risk for hip fracture, incident hip fractures were also reduced by approximately 40%. Antifracture efficacy develops within the first 6 months, and treatment has been followed for as long as 5 years without deleterious effects on bone. We await reports of experience with risedronate in 'real-world' cases of greater complexity (i.e., in patients with co-morbidities and medications that would have excluded them from published clinical trials).

Comparative appraisal of clodronate, aspirin and dexamethasone as agents reducing alendronate-induced inflammation in a murine model

Among the bisphosphonates, the nitrogen-containing bisphosphonates have much stronger anti-bone-resorptive activities than bisphosphonates containing no nitrogen, but nitrogen-containing bisphosphonates mostly have inflammatory side effects. Our previous murine-model experiments with a single intraperitoneal bisphosphonate injection demonstrated that (i) nitrogen-containing bisphosphonates induce various inflammatory reactions via an IL-1-dependent mechanism, (ii) alendronate (an nitrogen-containing bisphosphonate) produces a clear sclerotic line in the tibia that is easily detectable by radiography a few weeks later (tentatively called the bisphosphonate line, a useful marker for the anti-bone-resorptive activities of bisphosphonates), and (iii) clodronate (a non-nitrogen-containing bisphosphonate) reduces the inflammatory reactions induced by alendronate but does not reduce the bisphosphonate line formation induced by alendronate. We compared the effects of clodronate, aspirin and dexamethasone on the inflammatory reactions induced by alendronate (40 micromol/kg) (induction of the histamine-forming enzyme, accumulation of pleural exudate and splenomegaly) and on the bisphosphonate line formation induced by alendronate (0.1 micromol/kg). The effects of aspirin (833 micromol/kg) were weak. However, like clodronate, dexamethasone (10 micromol/kg, injected 5 min. after alendronate), strongly inhibited the alendronate-induced inflammatory reactions but did not reduce the alendronate-induced bisphosphonate line formation. Alendronate produced normal bisphosphonate lines in IL-1-deficient mice, too. These results suggest that clodronate and/or dexamethasone may be suitable for preventing or reducing the inflammatory side effects of nitrogen-containing bisphosphonates while preserving their powerful anti-bone-resorptive activities (although in practice the known side effects of dexamethasone may limit its use), and that the anti-bone resorptive activities of nitrogen-containing bisphosphonates are not influenced by IL-1.

Drug injury in the upper gastrointestinal tract: effects of alendronate

Osteoporosis is a disease characterized by an increase in bone resorption and a decline in bone density, which leads to increased susceptibility to bone fractures. Long-term therapy is needed to increase bone mineral density and maintain bone strength. Safe and well-tolerated medical therapies are required for long-term maintenance. Alendronate, an oral bisphosphonate, has been used for treatment of osteoporosis since the mid 1990s; however, recent studies have suggested alendronate can have significant gastrointestinal side effects. Most data suggest that the risk of these effects is low and not significantly higher than with placebo but there are limited reports that suggest otherwise, in both clinical trials and animal studies. Alendronate continues to remain an important mainstay of osteoporosis therapy.

Prescription-event monitoring study on 13,164 patients prescribed risedronate in primary care in England

Risedronate sodium is indicated in postmenopausal women for the prevention and treatment of osteoporosis and for the treatment of Paget's disease. Our aim was to evaluate the safety of risedronate in a large cohort of patients prescribed risedronate by general practitioners (GPs) in England, soon after it was marketed. An observational cohort study was conducted using the technique of prescription-event monitoring (PEM). Exposure data were obtained from dispensed National Health Service prescriptions issued between September 2000 and June 2002. Outcome data were collected by sending questionnaires to prescribing GPs requesting them to report any events that had occurred since starting risedronate, demographic details, indication, start and stop dates, reasons for stopping, suspected adverse drug reactions (ADRs) and causes of death. Event rates calculated as incidence densities (IDs) separately, for Paget's disease group and all other patients (osteoporosis group) were ranked and the difference between IDs in month 1 and months 2-6 calculated. The osteoporosis cohort comprised 13,180 patients (10,934 [83.0%] female); median ages for female and male patients were 73 and 69 years, respectively. The most frequently reported event in the first month of treatment was dyspepsia, being also amongst the most frequently reported reasons for stopping risedronate and suspected ADR. Adverse events assessed as possibly or probably related to risedronate included, six of facial edema and one each of Stevens-Johnson syndrome, swollen tongue, palpitation and episcleritis. Risedronate was fairly well tolerated. Adverse events affecting skin, eye, cardiovascular and immunological systems were identified. Prescribing doctors should be aware of these and monitor their patients accordingly.

Bisphosphonates stimulate an endogenous nonselective cation channel in Xenopus oocytes: potential mechanism of action

The mechanisms of action of bisphosphonates (BPs) have been poorly determined. Besides their actions on osteoclasts, these agents exhibit gastrointestinal complications. They have also recently been described as affecting various preparations that express an epithelial Na+ channel (ENaC). To understand the effects of BP on ion channels and the ENaC in particular, we used the Xenopus oocyte expression system. Alendronate, and similarly risedronate, two aminobisphosphonates, caused a large stimulation of an endogenous nonselective cation conductance (NSCC). This stimulation averaged 63 ± 12 μS ( n = 18) 60 min after the addition of 2 mM alendronate. The effects on the endogenous NSCC were blocked by extracellular acidification to pH 6.4. On the other hand, alendronate caused a small inhibition of ENaC conductance at pH 7.4 and 6.4, but the effects at pH 6.4 were more readily observed in the absence of changes of the endogenous conductance. The effects on membrane capacitance were also markedly different, with a clear decrease at pH 6.4 and no consistent changes at pH 7.4. The effects on the endogenous channel were further augmented by genistein and were inhibited by a tyrosine phosphatase inhibitor, indicating the involvement of the tyrosine kinase pathway. Stimulation of NSCC with BP is expected to cause membrane depolarization and may explain, in part, its mechanisms of action in inhibiting osteoclasts.

Upper gastrointestinal tolerability of once weekly alendronate 70 mg with concomitant non-steroidal anti-inflammatory drug use

BACKGROUND

Both oral bisphosphonates and non-steroidal anti-inflammatory drugs have the potential to irritate the upper gastrointestinal mucosa, and are frequently used by the same patient population.

AIM

To determine the rate of upper gastrointestinal adverse events with once weekly alendronate 70 mg and concomitant non-steroidal anti-inflammatory drug use.

METHODS

A post hoc analysis was performed on 222 patients who received both medications concomitantly during a 3-month placebo-controlled study. A total of 450 (224 alendronate; 226 placebo) postmenopausal women and men with osteoporosis were randomized. Concomitant non-steroidal anti-inflammatory drug users were defined as patients who received > or =7 continuous days of any dose of a dual cyclo-oxygenase-1 and cyclo-oxygenase-2 inhibiting non-steroidal anti-inflammatory drug, a selective cyclo-oxygenase-2 inhibitor, or aspirin. A survival analysis was performed, and significance assessed. Logistic regression was used to assess consistency of treatment effect on rate of upper gastrointestinal adverse events across non-steroidal anti-inflammatory drug subgroups.

RESULTS

Similar percentages of alendronate (52.7%) and placebo (46.0%) patients used non-steroidal anti-inflammatory drugs regularly. Among concomitant non-steroidal anti-inflammatory drug users, 11 alendronate and 11 placebo patients experienced upper gastrointestinal adverse events (9.3% and 10.8%, respectively, P = 0.744). Logistic regression revealed no significant interaction (P = 0.722) between alendronate and concomitant non-steroidal anti-inflammatory drug use.

CONCLUSION

Based on this subgroup analysis, once weekly alendronate 70 mg used concomitantly with non-steroidal anti-inflammatory drugs, did not increase upper gastrointestinal adverse events relative to placebo over 3-months.

The gastrointestinal tolerability and safety of oral bisphosphonates

Oral bisphosphonates are effective for osteoporosis and other hyperresorptive bone disorders. Although well-tolerated in efficacy trials, some oral aminobisphosphonates have been associated with upper gastrointestinal intolerance and injury in postmarketing experience. Clinical trials often underestimate the rate of adverse events in clinical practice, and ethics prohibit direct evaluation of toxicity in high-risk patients. Accordingly, animal models and endoscopy studies of oral bisphosphonates provide valuable insight. It is unclear whether variation in ulcerogenic potential reflects differences in dosing, formulation or chemical structure. Furthermore, the clinical relevance of endoscopic lesions is uncertain. Ongoing postmarketing review will determine whether differences in endoscopic damage predict tolerability and safety in clinical practice. However, physicians and patients should consider risk factors for oesophageal injury when initiating therapy.