Loss of Potency of Antibiotic Otic Solution (Sodium Ampicillin) during Storage

Abstract

We tested the stability in solution of sodium ampicllin by nephelometry using Bacillus subtilis natto at various concentrations and storage temperatures (which was available in a ordinary clinic). The results showed that the antibiotic in solution was more stable when the solution was kept at lower temperature and lower concentration. More than 50% of the initial potency was lost within 48 hrs at a high concentration (200 mg/ml) even at a lower temperature (4°C). However, the solution kept in a refrigerator at lower concentration (20 mg/ml) retained more than 75% of the initial potency even after 3 weeks.