Subcutaneous Infusion of Pamidronate in a Hospice Patient with Hypercalcemia: A Case Report.

Abstract

Hypercalcemia is a complication of cancer, reported to affect between 10% and 40% of patients with cancer and occurring in those with both solid tumours and hematologic malignancies.1-4 Cancer is the most common cause of hypercalcemia in the inpatient setting, most frequently breast, renal, and lung cancer and multiple myeloma.1,2,5 Malignancy is usually clinically evident by the time it causes hypercalcemia, and patients with hypercalcemia of malignancy often have a poor prognosis.1 There are several mechanisms by which hypercalcemia of malignancy can occur. The major mechanism, associated with approximately 80% of cases, is secretion of parathyroid hormone–related protein by the tumour.1-4 Other mechanisms include local release of cytokines (including osteoclastactivating factors) from osteolytic metastatic lesions, tumour production of 1,25-dihydroxyvitamin D (calcitriol), and production or secretion of parathyroid hormone secondary to parathyroid carcinoma.1,2,4 For hypercalcemia and bone pain, IV administration of bisphosphonates is a recognized, first-line treatment option.2-4 In our health authority, Fraser Health (located in the Lower Mainland of British Columbia), IV pamidronate is one of the first-line bisphosphonates in the treatment of hypercalcemia. However, for patients receiving palliative care in hospice settings, Fraser Health policy stipulates that IV administration is not an option because hospice nursing staff are not trained to provide the higher level of monitoring required with this route of administration. Additionally, other risks and barriers to IV administration in the palliative care population have been reported, including thrombophlebitis, pain secondary to needle insertion, difficult venous access, and infection.6,7 The subcutaneous (SC) administration of bisphosphonates for patients receiving palliative care has been reported as an alternative to IV administration.6-8 To determine the feasibility of an alternative route of administration in our setting, we searched PubMed and Ovid MEDLINE using the terms “hypercalcemia”, “bisphosphonates”, and/or “injections, subcutaneous”. This search identified the same 3 reports of SC administration of bisphosphonates in the palliative setting of which we were already aware6-8; no additional reports were found. Clodronate, a first-generation bisphosphonate, has been used in the palliative care setting in Edmonton, Alberta, with reported safety and efficacy.7,8 Duncan6 reported the SC use of pamidronate in a UK hospital, where the drug was administered to 10 patients, of whom 7 had a biochemical response, with serum calcium decreasing to within normal limits. However, although there is reported evidence for SC administration of clodronate, this drug is unavailable for use in our health authority, and although Duncan6 reported biochemical response in 7 of 10 patients who received SC pamidronate, she did not discuss patients’ symptoms or their symptomatic response. As such, evidence for and timing of symptomatic efficacy to guide SC administration of pamidronate is lacking from the literature at this time. We report a case of hypercalcemia of malignancy in a patient who experienced biochemical and symptomatic response to pamidronate administered by the SC route.