The Pharmaceutics and Compounding Laboratory
Pharmaceutical Solutions II:
Nonaqueous Solutions

Preservation

Examination of unofficial liquid pharmaceutical speciality products and similar official products indicates that a minimum of 15% alcohol is required to preserve the product from microbial growth if no other preservative agents are present. Industrial pharmacists usually regard 15% alcohol as adequate for the preservation of products with a pH of 5, while 18% has been considered adequate for neutral or slightly alkaline preparations. It is obvious that products such as tinctures, spirits, and fluid extracts possess alcohol in concentrations that far exceed these values and need no further preservative.