• Alendronate
  

Small decreases in calcium and phosphate may occur with these medications, particularly in patients with Paget's disease (O'Doherty et al. 1992; PDR 1998). Bisphosphonates also cause symptomatic hypocalcemia in prostate cancer patients with diffuse metastatic invasion of the skeleton (Adami 1997).

Calcium: Osteoporosis is the primary disease associated with chronic calcium deficiency; it can result in pathologic fractures associated with bone pain, spinal deformity, and premature morbidity and mortality (Cashman and Flynn 1999; Covington 1999). Other signs and symptoms of depleted serum calcium levels include arrhythmias, neuromuscular irritability, and mental status changes such as depression and psychosis (Potts 1998).

Phosphorus: Although rare, suboptimal intake of phosphorus can lead to hypophosphatemia, which is associated with general debility characterized by muscle weakness, bone pain, paraesthesia, ataxia, acute respiratory failure, mental confusion, seizures, anorexia, anemia, increased susceptibility to infection, and even death (Cashman and Flynn 1999; Covington 1999). In chronic situations, patients with severely depleted phosphate levels below approximately 0.3 mmol/L may exhibit signs of rickets (children) or osteomalacia (adults) (Cashman and Flynn 1999).

Calcium: Daily calcium supplementation between 500 and 1000 mg has been used in clinical studies with alendronate (Fleisch 1997; Gonnelli et al. 1999; Pols et al. 1999). These values should be adjusted on an individual basis depending upon the patient's age, gender, clinical presentation, serum calcium levels, dietary habits, and medication regimen. Calcium replacement should be part of a comprehensive approach to the evaluation and treatment of osteoporosis.

Note: Calcium and other minerals should be taken at least two hours before or after alendronate administration to minimize interference with absorption of the drug (PDR 1998).

Phosphorus: The recommended dietary allowance (RDA) for phosphorus ranges from 100 to 1250 mg/day depending on age (Cashman and Flynn 1999; Covington 1999). Doses for replacement therapy should be adjusted to reflect individual circumstances, including the patient's age, gender, clinical presentation, serum phosphate levels, dietary habits, and medication regimen.

This information is intended to serve as a concise reference for healthcare professionals to identify substances that may be depleted by many commonly prescribed medications. Depletion of these substances depends upon a number of factors including medical history, lifestyle, dietary habits, and duration of treatment with a particular medication. The signs and symptoms associated with deficiency may be nonspecific and could be indicative of clinical conditions other than deficiency. The material presented in these monographs should not in any event be construed as specific instructions for individual patients.

Adami S. Bisphosphonates in prostate carcinoma. Cancer. 1997;80(8 Suppl):1674-1679.

Cashman K, Flynn A. Optimal nutrition: calcium, magnesium and phosphorus. Proc Nutr Soc. 1999;58:477-487.

Covington T, ed. Nonprescription Drug Therapy Guiding Patient Self-Care. St Louis, MO: Facts and Comparisons; 1999:467-545.

Fleisch HA. Bisphosphonates: preclinical aspects and use in osteoporosis. Ann Med. 1997;29(1):55-62.

Gonnelli S, Cepollaro C, Pondrelli C, et al. Bone turnover and the response to alendronate treatment in postmenopausal osteoporosis. Calcif Tissue Int. 1999;65(5):359-364.

O'Doherty DP, Gertz BJ, Tindale W, et al. Effects of five daily 1 h infusions of alendronate on Paget's disease of bone. J Bone Miner Res. 1992;7(1):81-87.

Physicians' Desk Reference, PDR. 52nd ed. Montvale, NJ: Medical Economics Company; 1998.

Pols HA, Felsenberg D, Hanley DA, et al. Multinational, placebo-controlled, randomized trial of the effects of alendronate on bone density and fracture risk in postmenopausal women with low bone mass: results of the FOSIT study. Foxamax International Trial Study Group. Osteoporos Int. 1999;9(5):461-468.

Potts JT. Diseases of the parathyroid gland and other hyper- and hypocalcemic disorders. In: Fauci AS, Braunwald E, Isselbacher KJ, et al, eds. Harrison's Principles of Internal Medicine. 14^th ed. New York: McGraw-Hill Companies Health Professional Division; 1998:2241.