PAMIDRONATE Drug Interactions: What You Need to Know

INTERACTIONS

• Nephrotoxic drugs: Use with caution. ( 7.1 )
• Thalidomide: Increased risk of renal dysfunction in patients with multiple myeloma. ( 7.2 )

7.1 Nephrotoxic Drugs Caution is indicated when pamidronate disodium is used with other potentially nephrotoxic drugs.

7.2 Thalidomide In multiple myeloma patients, the risk of renal deterioration may be increased when pamidronate disodium is used in combination with thalidomide.

7.3 Loop Diuretics Concomitant administration of a loop diuretic had no effect on the calcium-lowering action of pamidronate disodium.

Pamidronate disodium is contraindicated in patients with hypersensitivity to pamidronate disodium, other bisphosphonates, or mannitol. Reactions to pamidronate disodium injection and to mannitol have included anaphylaxis. Hypersensitivity to pamidronate, other bisphosphonates, or mannitol ( 4 )

AND PRECAUTIONS

• Renal failure: Do not exceed single doses of 90 mg pamidronate disodium. Assess renal function before each treatment. In patients with bone metastases with severe renal impairment, use of pamidronate disodium is not recommended. ( 5.1 )
• Embryo-Fetal Toxicity: Can cause fetal harm. Advise females of reproductive potential of the potential risk to a fetus and to use effective contraception. ( 5.2 , 8.1 , 8.3 )
• Electrolyte disorders (e.g., hypophosphatemia, hypokalemia, hypomagnesemia, hypocalcemia): Monitor phosphorus, potassium, magnesium, calcium and vitamin D and adequately supplement as appropriate. ( 5.3 )
• Osteonecrosis of the jaw: Perform preventive dental procedures prior to initiating pamidronate disodium. Avoid invasive procedures if possible in patients receiving pamidronate disodium. ( 5.4 )
• Atypical fractures of the femur can occur after minimal or no trauma. Evaluate patients with thigh or groin pain for possible fracture. ( 5.5 )

5.1 Deterioration in Renal Function, Use in Patients with Renal Impairment Bisphosphonates, such as pamidronate disodium, have been associated with renal toxicity, including focal segmental glomerulosclerosis. This toxicity has been manifested as nephritic syndrome, deterioration of renal function, and renal failure. Renal failure has been reported in patients after a single dose of pamidronate disodium. Some patients had gradual improvement in renal status after pamidronate disodium was discontinued. Do not administer single doses of pamidronate disodium in excess of 90 mg due to the risk of clinically significant deterioration in renal function, <span class="opacity-50 text-xs">[see Dosage and Administration (2.5) ]</span> . Assess serum creatinine prior to each treatment. Withhold treatment until renal function returns to baseline in patients who show evidence of deterioration in renal function. Do not administer pamidronate in patients with severe renal impairment for the treatment of bone metastases <span class="opacity-50 text-xs">[see Dosage and Administration (2.1 , 2.2 , 2.3) ]</span> .

5.2 Embryo-Fetal Toxicity Based on findings in animals and its mechanism of action, pamidronate disodium can cause fetal harm when administered to a pregnant woman <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.1) ]</span> . In reproductive studies, administration of pamidronate to pregnant rats and rabbits at doses equivalent to 0.6 to 8.3 times the highest human recommended dose resulted in maternal toxicity and embryo-fetal effects. Bisphosphonates, such as pamidronate disodium, are incorporated into the bone matrix, from where they are gradually released over periods of weeks to years. There may be a risk of fetal harm (e.g., skeletal and other abnormalities) if a woman becomes pregnant after completing a course of bisphosphonate therapy. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during and after pamidronate disodium treatment <span class="opacity-50 text-xs">[see Use in Specific Populations (8.1 , 8.3) ]</span> .

5.3 Electrolyte Disorders Cases of asymptomatic hypophosphatemia (12%), hypokalemia (7%), hypomagnesemia (11%), and hypocalcemia (5% to 17%), were reported in pamidronate disodium-treated patients. Cases of symptomatic hypocalcemia (including tetany) have been reported in association with pamidronate disodium therapy. Monitor serum levels of calcium, phosphate, magnesium, and potassium, following initiation of therapy with pamidronate disodium. If hypocalcemia occurs, short-term calcium therapy may be necessary. In the absence of hypercalcemia, supplement with oral calcium and vitamin D in order to minimize the risk of hypocalcemia.

5.4 Osteonecrosis of the Jaw Osteonecrosis of the jaw (ONJ) has been reported predominantly in cancer patients treated with intravenous bisphosphonates, including pamidronate disodium. Many of these patients were also receiving chemotherapy and corticosteroids, which may be risk factors for ONJ. Postmarketing experience and the literature suggest a greater frequency of ONJ with certain tumor type (advanced breast cancer, multiple myeloma), and dental status (dental extraction, periodontal disease, local trauma including poorly fitting dentures). Local infection including osteomyelitis has been reported with ONJ. Patients receiving pamidronate should maintain good oral hygiene and have a dental examination with preventive dentistry prior to initiation of treatment. While on treatment, avoid invasive dental procedures if possible. For patients who develop ONJ while on bisphosphonate therapy, dental surgery may exacerbate the condition. For patients requiring dental procedures, there are no data available to suggest whether discontinuation of bisphosphonate treatment reduces the risk of ONJ. Clinical judgment of the treating physician should guide the management plan of each patient based on individual benefit/risk assessment <span class="opacity-50 text-xs">[see Adverse Reactions (6.2) ]</span> .

5.5 Atypical Fractures of the Femur Atypical subtrochanteric and diaphyseal femoral fractures have been reported in patients receiving bisphosphonate therapy, including pamidronate disodium. These fractures can occur anywhere in the femoral shaft from just below the lesser trochanter to just above the supracondylar flare and are transverse or short oblique in orientation without evidence of comminution. These fractures may occur after minimal or no trauma. Patients may experience thigh or groin pain weeks to months before presenting with a completed femoral fracture. Fractures are often bilateral; therefore, the contralateral femur should be examined in bisphosphonate-treated patients who have sustained a femoral shaft fracture. Poor healing of these fractures also has been reported. A number of case reports noted that patients were receiving treatment also with glucocorticoids (such as prednisone or dexamethasone) at the time of fracture. Causality with bisphosphonate therapy has not been established. Any patient with a history of bisphosphonate exposure who presents with thigh or groin pain in the absence of trauma should be evaluated for an atypical fracture. Consider discontinuation of pamidronate disodium therapy in patients suspected to have an atypical femur fracture pending evaluation of the patient, based on an individual benefit risk assessment. It is unknown whether the risk of atypical femur fracture continues after stopping therapy.