Teriparatide
Fosamax Interactions
Absorption of alendronate is very poor; oral bioavailability is less than 1%. Because of this, food interactions can be very significant. Alendronate oral absorption becomes almost negligible if alendronate is taken within 2 hours of breakfast. Even orange juice or coffee can reduce bioavailability by about 60%. To achieve maximum possible bioavailability alendronate must be taken in the fasting state and at least 2 hours before a standard breakfast.
Antacids are likely to interfere with the absorption of alendronate. At least 30 minutes should elapse after an alendronate dose before taking antacids or any other drugs. Concomitant administration of oral alendronate with vitamin supplements; mineral supplements; or other medications that contain calcium salts (e.g., calcium carbonate), iron salts such as ferrous sulfate or polysaccharide-iron complex, aluminum salts (i.e., aluminum hydroxide), or magnesium salts may interfere with the absorption of alendronate. Even though calcium salts are not to be administered with alendronate, patients need to maintain an adequate intake of calcium and vitamin D to avoid hypocalcemia. Due to the action of alendronate on bone, hypocalcemia and associated adverse effects can develop. The ingestion of high-calcium foods can interfere with the absorption of alendronate, and should not be eaten before, or for at least 30 minutes after, administration of alendronate.
Although the clinical significance has not been determined, the bioavailability of oral alendronate is doubled by concomitant administration of intravenous ranitidine. Investigations have not been undertaken to determine if other H2-antagonists have a similar effect on bioavailability. Patients should be closely monitored when antiulcer medications, such as proton pump inhibitors (PPIs), gastric mucosal agents, and H2-blockers, or other medications for GI disorders, are coadministered as they may affect the bioavailability of alendronate, leading to a higher likelihood of developing GI adverse effects while taking alendronate.
Aspirin, ASA should be used with caution in patients who are taking alendronate. In clinical trials, the incidence of upper gastrointestinal adverse events was increased in patients that received aspirin-containing medicines with alendronate 10 mg daily or higher. One patient with a history of peptic ulcer disease and gastrectomy that received alendronate 10 mg daily and aspirin got an anastomotic ulcer with mild hemorrhage. The patient recovered upon alendronate and aspirin discontinuation. The use of other NSAIDs in combination with alendronate has also been noted as an independent risk factor for the development of GI adverse reactions with alendronate therapy.
The concurrent use of alendronate with hormone replacement therapy (estrogens) has been assessed in several clinical trials. In these studies, the safety and tolerability profile of the combination is consistent with those of the individual treatments; however, the degree of suppression of bone turnover (as assessed by mineralizing surface) was significantly greater with the combination than with either treatment alone. Significant increases or favorable trends for increases in bone mineral density of the lumbar spine, hip, neck and trochanter have been noted in patients treated with alendronate and hormone replacement therapy. The long-term effects of the combination therapy on fracture occurrence and fracture healing have not been studied.
Alendronate has been given to postmenopausal women concurrently taking a wide range of other medications. No clinical interactions have been observed with anticholinergics, benzodiazepines, beta-blockers, calcium channel blockers, diuretics, glucocorticoids, sedative hypnotics, thiazides, thyroid hormones, vasoconstrictors, and vasodilators. However, specific studies have not been undertaken to determine the validity of these observations.
While the use of bisphosphonates usually follows treatment with teriparatide to help maintain bone density and is an appropriate clinical approach, the concurrent use of bisphosphonates and teriparatide may not be beneficial; the use of teriparatide alone may result in the greater accumulation of bone density than combined treatment. The concurrent use of alendronate and parathyroid hormone (PTH) or human PTH 1-34 (e.g., teriparatide) has been assessed in clinical trials. These studies show that alendronate impairs the anabolic activity of PTH/ teriparatide in trabecular bone and reduces the beneficial effects of PTH/ teriparatide on cortical bone. While the combined treatment was superior to treatment with alendronate alone, the use of PTH/ teriparatide alone was superior to the combination.
When the intravenous formulation of alendronate is used for the treatment of hypercalcemia of malignancy, combination therapy with loop diuretics should be used with caution in order to avoid hypocalcemia. In patients with hypercalcemia of malignancy, the initial treatment typically includes the use of loop diuretics, in combination with saline hydration, however, diuretic therapy should not be employed prior to correction of hypovolemia and dehydration. NOTE: The IV formulation is not available in the US.
[ Last revised: 8/25/2005 11:25:00 AM ]
References
. Black DM, Greenspan SL, Ensrud KE, et al. The effects of parathyroid hormone and alendronate alone or in combination in postmenopausal osteoporosis. N Engl J Med 2003;349:1207 - 15.
. Finkelstein JS, Hayes A, Hunzelman JL, et al. The effects of parathyroid hormone, alendronate or both in men with osteoporosis. N Engl J Med 2003;349:1216 - 26.
. Lasix® (furosemide) package insert. Bridgewater, NJ: Aventis Pharmaceuticals; 2004 Jan.
. Fosamax® (alendronate) package insert. Whitehouse Station, NJ: Merck and Co., Inc; 2004 Feb.
. Zometa® (zoledronic acid) package insert. East Hanover, NJ: Novartis Pharma Stein AG; 2004 Mar.
Related entries
Syndicate
