Sustained-release formulations of controlled substances are commonly used to provide analgesia in research animals.These formulations represent refinements that offer the advantage of prolonged, multiday pain relief with a single injection, thereby decreasing handling stress in animals and saving time for scientists. Compounding pharmacies produce sustained-release buprenorphine for veterinary use (i.e., buprenorphine SR-LAB); one of these pharmacies has shortened the original 6-mo shelf-life to 28 d to comply with United States Pharmacopeia standards for ensuring sterility. This limitation risks increasing the waste of controlled substances, which require an expensive destruction process that is legally enforced in our state. To assess whether the sterility of buprenorphine SR-LAB is preserved for at least 6 mo in a general laboratory setting, we tested 5 bottles for the presence of endotoxin and bacterial and fungal contamination monthly for 6 mo. Overall, results of the study showed that the bottles remained sterile over the 6-mo duration as no endotoxin was detected and the bottles did not become contaminated with bacteria or fungi. In conclusion, when stored securely and used with aseptic handling techniques, buprenorphine SR-LAB can be maintained in a sterile state for 6 mo in a general laboratory setting.