This item is not intended for injection and is not marketed for any medical, therapeutic, or clinical purpose
PMID 2137911 Subcutaneous injection-site pharmacokinetics FDA review
The preservative systems, delivery mechanisms, and packaging are all optimized for maximum stability
While they may appear interchangeable, the correct choice depends on how the medication will be used, how often it will be accessed, and the sensitivity of the tissue or patient involved
Note that benzyl alcohol is bacteriostatic, not bactericidal: it inhibits proliferation of organisms introduced at the septum during needle entry, it does not sterilise a solution that is already contaminated, and preservative-free sterile water remains the specified vehicle in certain clinical contexts where benzyl alcohol is contraindicated