Drug Interactions between alendronate and dexamethasone / ketorolac / moxifloxacin

MONITOR CLOSELY: Concomitant administration of corticosteroids may potentiate the risk of tendinitis and tendon rupture associated with fluoroquinolone treatment. The mechanism is unknown. Tendinitis and tendon rupture have most frequently involved the Achilles tendon, although cases involving the rotator cuff (the shoulder), the hand, the biceps, and the thumb have also been reported. Some have required surgical repair or resulted in prolonged disability. Tendon rupture can occur during or up to several months after completion of fluoroquinolone therapy.

MANAGEMENT: Caution is recommended if fluoroquinolones are prescribed in combination with corticosteroids, particularly in patients with other concomitant risk factors (e.g., age over 60 years; recipient of kidney, heart, and/or lung transplant). Patients should be advised to stop taking the fluoroquinolone, avoid exercise and use of the affected area, and promptly contact their physician if they experience pain, swelling, or inflammation of a tendon. In general, fluoroquinolones should only be used to treat conditions that are proven or strongly suspected to be caused by bacteria and only if the benefits outweigh the risks.

MONITOR: The combined use of corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the potential for serious gastrointestinal (GI) toxicity, including inflammation, bleeding, ulceration, and perforation. In a large, case-control study of elderly patients, those who used corticosteroids and NSAIDs concurrently had an estimated relative risk (RR) for peptic ulcer disease and GI hemorrhage of 14.6 compared to those who used neither. Corticosteroid use was associated with a doubling of the risk (estimated RR = 2.0), but the risk was confined to those who also used NSAIDs. It is possible that both categories of agents are ulcerogenic and have additive effects on the GI mucosa during coadministration. Some investigators have also suggested that the primary effect of corticosteroids in this interaction is to delay healing of erosions caused by NSAIDs rather than cause de novo ulcerations.

MANAGEMENT: Caution is advised if corticosteroids and NSAIDs are used together, especially in patients with a prior history of peptic ulcer disease or GI bleeding and in elderly and debilitated patients. During concomitant therapy, patients should be advised to take the medications with food and to immediately report signs and symptoms of GI ulceration and bleeding such as severe abdominal pain, dizziness, lightheadedness, and the appearance of black, tarry stools. The selective use of prophylactic anti-ulcer therapy (e.g., antacids, H2-antagonists) may be considered.

MONITOR: Theoretical concerns exist regarding the potential for increased risk and severity of gastrointestinal toxicity during coadministration of oral bisphosphonates and nonsteroidal anti-inflammatory drugs (NSAIDs) due to additive or synergistic irritant effects on the gastrointestinal mucosa. Because NSAIDs reduce the rate of ulcer healing in the stomach and duodenum, it is also possible that NSAIDs may delay healing and exaggerate the mucosal injury caused by oral bisphosphonates. In a blinded, randomized, crossover study consisting of 26 healthy volunteers, investigators using endoscopic techniques reported a significantly higher incidence of gastric ulcers following combined treatment with alendronate 10 mg once a day and naproxen 500 mg twice a day for 14 days than after treatment with either alendronate or naproxen alone (38% vs. 8% and 12%, respectively). In contrast, a 3-year controlled clinical study found no significant difference in the incidence of upper gastrointestinal adverse events between alendronate 5 or 10 mg/day and placebo given to more than 2000 subjects, most of whom received concomitant NSAIDs. Likewise, the incidence of upper gastrointestinal adverse events was similar for risedronate (24.5%) and placebo (24.8%) among patients who were regular users (>= 3 days/week) of aspirin or NSAIDs in phase 3 osteoporosis studies, which enrolled a total of over 5700 patients. Aspirin use was reported by 31% of patients and NSAID use by 48% of patients, 24% and 21% of whom were regular users, respectively.

MONITOR: Theoretical concerns exist regarding the potential for increased risk and severity of renal impairment during coadministration of bisphosphonates with high dosages or chronic use of NSAIDs due to additive or synergistic nephrotoxic effects on the kidney. The use of bisphosphonates has been associated with nephrotoxicity manifested as deterioration of renal function and renal failure. Cases have primarily involved intravenous formulations of the drugs such as pamidronic acid and zoledronic acid, especially when they are administered too rapidly. The risk of hypocalcemia may also be increased, as drug-induced renal tubular damage can lead to renal loss of calcium and other electrolytes such as magnesium. Bisphosphonates alone often cause mild, asymptomatic hypocalcemia via inhibitive effects on bone resorption and possibly chelation of blood calcium. Chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) may be associated with renal toxicities including elevations in serum creatinine and BUN, tubular necrosis, glomerulitis, renal papillary necrosis, acute interstitial nephritis, nephrotic syndrome, and renal failure.

MANAGEMENT: Caution is advised if bisphosphonates are prescribed in combination with NSAIDs. Patients receiving oral bisphosphonates should be closely monitored for the development of gastrointestinal toxicity and advised to immediately report potential signs and symptoms such as severe abdominal pain, nausea, vomiting, diarrhea, loss of appetite, dizziness, lightheadedness, and/or black, tarry stools. Patients receiving intravenous formulations of bisphosphonates should have renal function and serum electrolytes closely monitored. Serum creatinine should be assessed prior to each treatment, and treatment should be withheld in the presence of renal deterioration. In patients treated for bone metastases, treatment should not be resumed until renal function returns to baseline.

MONITOR: Coadministration with nonsteroidal anti-inflammatory drugs (NSAIDs) may potentiate the risk of central nervous system toxicity sometimes associated with fluoroquinolone use. The interaction has been reported most often with enoxacin. It may occur with other fluoroquinolones as well, but is poorly documented. The exact mechanism of interaction is unknown. Some investigators suggest that the piperazine ring of fluoroquinolones may inhibit the binding of gamma-aminobutyric acid (GABA) to brain receptors and that NSAIDs may synergistically add to this effect. Patients with a history of seizures may be at greater risk.

MANAGEMENT: Clinical monitoring for signs of CNS stimulation such as tremors, involuntary muscle movements, hallucinations, or seizures is recommended if fluoroquinolone antibiotics are prescribed in combination with NSAIDs.