Cancer drug costs continue to rise as demand increases across the globe. In public health care, searching for ways to save money and reduce waste is critical to maintaining a sustainable system. A recent study published in the Journal of Oncology Pharmacy Practice conducted by BC Cancer pharmacists and pharmacy technicians reviewed pembrolizumab, a newer drug for the treatment of non-small cell lung cancer and melanoma.
“We chose to review pembrolizumab because we noted that our cost of wastage was high and we were looking for options to help with minimizing that cost,” says Dr. Lynne Nakashima, BC Cancer provincial pharmacy director and co-author of the study. “When drugs are given by injection, dosing is based on the weight or body surface area of the patient - in other words, the dose is individualized to the patient. In that situation, the dose can vary widely, but if the drug only comes in one size, then there is the potential for wastage.”
Pembrolizumab was previously available in two sizes, but recently was switched to one size; 100 mg.
This study was a collaboration of all the pharmacies across the six BC Cancer regional centres evaluating a total of 202 non-small cell lung cancer and 182 melanoma patients with 2,948 doses dispensed. Provincial Pharmacy coordinated the data and looked at the differences between smaller and larger regional centres.
“Not unexpectedly, it is easier to reduce wastage if there are more patients being treated with the same drug on the same day,” says Dr. Nakashima. This is because of the ability to share vials of medication in the pharmacy. “If there is leftover from one container, or one vial, then there may the possibility that it can be used when preparing the next dose of the same medication.”
If there are two patients with a dose of 150 mg, pharmacists would require two vials of 100 mg for the first dose. For the second dose, with vial sharing, pharmacists could use the leftover 50 mg from the first dose to make up the second dose, using three vials in total. Without sharing, pharmacists would need four vials to make two doses and 50 mg of drug would be wasted.
Making the most of remaining medications can lead to big cost savings. By sharing vials of pembrolizumab, BC Cancer pharmacists learned they could save approximately $3.2 million in one fiscal year.
Overall, the study led to important recommendations, including using smaller vial sizes, practicing vial sharing and using weight-based dosing to improve cost savings. These changes have already been implemented at BC Cancer.