Evaluation of the stability of ceftazidime/avibactam in elastomeric infusion devices used for outpatient parenteral antimicrobial therapy utilizing a national stability protocol framework.

Objectives: To evaluate the stability of ceftazidime/avibactam in elastomeric infusers, utilizing the UK's Yellow Cover Document (YCD) stability testing framework, in conditions representative of OPAT practice.

Methods: Ceftazidime/avibactam was reconstituted with sodium chloride 0.9% (w/v) in two elastomeric infusers at concentrations (dose) levels of 1500/375, 3000/750 and 6000 mg/1500 mg in 240 mL. The infusers were exposed to a fridge storage (2°C-8°C) for 14 days followed by 24 h in-use temperature (32°C).

Results: After 14 days of fridge storage and subsequent 24 h exposure to 32°C, mean ± SD of ceftazidime percent remaining was 75.5% ± 1.8%, 79.9% ± 1.1%, 82.4% ± 0.6%, for Easypump, and 81.7% ± 1.2%, 82.5% ± 0.5%, 85.4% ± 1.1% for Dosi-Fuser devices at the high, intermediate and low doses tested, respectively. For avibactam, mean ± SD percent remaining was 83.2% ± 1.8%, 87.4% ± 2.0%, 93.1% ± 0.9% for Easypump, and 85.1% ± 2.0%, 86.7% ± 0.1%, 92.5% ± 0.1% for Dosi-Fuser devices. The cumulative amount of pyridine generated in the devices ranged from 10.4 mg at low dose to 76.9 mg at high dose. Regression-based simulation showed that the degradation of both ceftazidime and avibactam was <10% for at least 12 h of the running phase, if stored in a fridge for not more than 72 h prior to in-use temperature exposure.

Conclusions: Whilst not meeting the strict UK YCD criteria for ≤5% degradation, ceftazidime/avibactam may be acceptable to administer as a continuous 12 hourly infusion in those territories where degradation of ≤10% is deemed acceptable.