A multi-capillary nozzle emitter consisting of one metal plate with capillary nozzles and a ring type counter electrode was used as a multi-electrospray atomizer. The number of capillary nozzles, flow rate of the liquid and the interval between the capillary nozzles were changed, and the droplet diameter and the voltage required for a steady cone-jet mode were measured. For the multi-capillary nozzle emitter, the interaction between the capillary nozzles is the important factor for obtaining fine droplets of uniform size. These fine droplets are obtained when there is only a small interaction between the capillary nozzles, and the equations obtained from the single capillary nozzle case are also applicable for the multicapillary nozzle emitter. When the number of capillary nozzles decreases (a situation which is not good for obtaining a large amount of droplets) or the interval between the capillary nozzles increases, the interaction between the capillary nozzles can be reduced. As the number of capillary nozzles increase, a higher voltage is required to obtain a fine droplet of uniform size.

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PURPOSE: Nivolumab dosage was initially selected on the basis of body weight, often resulting in leftover drug after sterile compounding. This study sought to investigate the real-world wastage of nivolumab and assess the long-term stability of leftover nivolumab within vials to facilitate drug vial optimization (DVO). METHODS: We collected all discarded vials after preparation from 17 regional hospitals in Japan over a 6-month period preceding the adoption of a fixed dose of 240 mg per administration. The actual amount of waste was measured for each preparation. Stability assessment was performed under different storage conditions. RESULTS: A total of 2,789 100-mg vials and 4,069 20-mg vials were collected. Overall, the drug cost associated with the expenditure of nivolumab alone was $12.1 million, whereas the total cost due to drug wastage was $0.735 million (rate of wastage, 6.1%). Furthermore, the immunoglobulin G concentrations of nivolumab remaining within vials, as well as binding activity to programmed death-1 protein, did not change significantly over 4 weeks of storage at either 4°C or room temperature. CONCLUSION: Significant drug wastage occurs during sterile preparation of nivolumab according to body weight–based dosing. Although nivolumab dosing has been changed to a fixed dose in Japan, body weight–based dosing is still applied in some other countries, as well as in combination therapy with ipilimumab. Our findings regarding the long-term stability of leftover nivolumab within the vials should motivate hospitals to implement DVO for cost savings.

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竹内 誠貴 1,2) 工藤 卓人 3) 藤田 拓 4) 石川 良太 5) 宇井 秀斗 6) 遠藤 沙紀 7) 小山 千賀穂 8) 佐藤 榛花 9) 鈴木 里沙子 10) 森岡 奏子 11) 渡辺 麻美 12) 久保 晃 13) 石坂 正大 13)