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Preservative Efficacy
The preservative efficacy of Apacider AW-N, C, and phenoxyethanol, which is a commonly used preservative, was microbiologically evaluated and compared using the following test method.
【Test Method】
Test microorganisms were deliberately inoculated into a solution containing the test substance,
and microbial viability was monitored over time.
Testing Institution: Marusan Pharmaceutical Biotech Co., Ltd.
| Test Bacteria Species | Abbreviation | Number of Inoculated Bacteria (cfu / g) |
|---|---|---|
| Escherichia coli | E. coli | 1.4 × 10⁶ |
| Pseudomonas aeruginosa | P. aeruginosa | 8.3 × 10⁵ | Staphylococcus aureus | S. aureus | 7.3 × 10⁵ | Candida albicans | C. albicans | 5.7 × 10⁴ | Aspergillus brasiliensis | A. brasiliensis | 5.9 × 10⁴ |
| Composition of Test Solutions | Concentration (%) |
|---|---|
| Apacider AW-N / Apacider C or Phenoxyethanol | 0.1 / 0.01 respectively |
| Thickener * | 0.2 |
| Water | Balance |
*A thickening agent was added to homogenize the formulation.
【Evaluation Criteria】
The evaluation criteria for various microorganisms, based on the Japanese Pharmacopoeia,
are shown below.
| Microorganism | Acceptance Criteria (Day 14) |
|---|---|
| Bacteria | Less than or equal to one percent of the initial inoculum |
| Fungi (yeasts/molds) | Count equal to or lower than the initial inoculum |
【Evaluation Results】
Compared with the commonly used preservative phenoxyethanol, Apacider AW-N and C each
demonstrated superior preservative efficacy at both 0.1% and 0.01% concentrations,
against all tested microorganisms except in the case of A. brasiliensis at a concentration of 0.1%,
where the efficacy was equal for all three substances.
Legend : ◎ Strong preservative efficacy / ○ Adequate preservative efficacy /
× Insufficient preservative efficacy
| Antibacterial Agent | Bacterial Species | ||||
|---|---|---|---|---|---|
| E. coli | P. aeruginosa | S. aureus | C. albicans | A. brasiliensis | |
| AW-N 0.1% | ○ | ◎ | ○ | ◎ | ○ |
| AW-N 0.01% | ○ | ◎ | ○ | ◎ | ○ |
| C 0.1% | ○ | ◎ | ○ | ◎ | ○ |
| C 0.01% | ○ | ◎ | ○ | ◎ | ○ |
| Phenoxyethanol 0.1% | × | × | × | × | ○ |
Based on the above test results, Apacider AW-N and C demonstrated the following advantages in preservative efficacy compared to phenoxyethanol.
1. Over 100 times greater preservative efficacy than phenoxyethanol against E. coli,
P. aeruginosa, S. aureus, C. albicans, A. brasiliensis (i.e. achieving equivalent or
superior efficacy with a concentration of 0.01% or one-tenth the concentration
of phenoxyethanol, which was 0.1%.)
2. Adequate preservative efficacy against E. coli, S. aureus, and A. brasiliensis at a low
concentration of 0.01%.
3. Even stronger preservative efficacy against P. aeruginosa and C. albicans at the same
low concentration 0.01%.
Preservative Efficacy Tests Against Each Microorganism
| Test Substance | E. coli |
|---|---|
 |  |
| P. aeruginosa | S. aureus |
|---|---|
 |  |
| C. albicans | A. brasiliensis |
|---|---|
 |  |