Question

Which of the following is commonly used as a broad-spectrum preservative in pharmaceutical formulations?

• A. Benzoic acid
• B. Benzalkonium chloride
• C. Ascorbic acid
• D. Vitamin C

Hint:

Benzalkonium chloride provides broad antimicrobial protection, especially useful in aqueous multi-dose formulations.

Answer 1

The Correct Option is B

Benzalkonium chloride is a quaternary ammonium compound widely used as a broad-spectrum antimicrobial preservative in various pharmaceutical formulations, including ophthalmic solutions, nasal sprays, and topical preparations. It is effective against bacteria, fungi, and some viruses, making it a preferred preservative for multi-dose formulations. Its mechanism of action involves disruption of microbial cell membranes, leading to leakage of cellular contents and cell death. In contrast: - Benzoic acid is used primarily as a preservative in acidic preparations such as syrups and beverages but has a narrower spectrum of activity.
- Ascorbic acid and Vitamin C are antioxidants, not primarily used as antimicrobial preservatives.
Due to its broad efficacy and relatively low toxicity at recommended concentrations, benzalkonium chloride remains a common choice for preservation in pharmaceutical products.