Regarding your question about piperacillin/tazobactam BUD after reconstitution, first i think BUD is not the most accurate term to use we can say as its shelf life or stability after reconstitution as like Mariah demonstrated BUD is more related to microbial growth rather than the chemical and physical stability of the drug.
Best in this case i guess to get back to the leaflet of each specific product as based on each company test about their own product, even if general recommendations gave other extended time, it’s rather to use the product specific consideration when available
In the attachments you will find FDA specific leaflet for ZOSYN which states “ Discard unused portion after 24 hours if stored at room temperature (20°C to 25°C [68°F to 77°F]), or after 48 hours if stored at refrigerated temperature (2°C to 8°C [36°F to 46°F]).” Page 5 of the attachment.
There’s another package leaflet at https://www.medicines.org.uk/emc/files/pil.1267.pdf that is revised lately 1/2020 stating “Chemical and physical in-use stability has been demonstrated for up to 12 hours when stored in a refrigerator at 2-8°C, when reconstituted with one of the compatible solvents for reconstitution “ page 7 of the attachment from medicines.org.uk (emc).
Another source that mentioned after reconstitution stability is lexicomp.com which states “ Discard any unused portion after 24 hours if stored at 20°C to 25°C (68°F to 77°F) or after 48 hours if stored at 2°C to 8°C (36°F to 46°F). Do not freeze vials after reconstitution. Stability in D5W or NS has been demonstrated for up to 24 hours at room temperature and up to 1 week at refrigerated temperature. Stability in an ambulatory IV infusion pump has been demonstrated for a period of 12 hours at room temperature.”, you will find a screen shot attachment regarding lexicomp page.