Standard Operating Procedure for Preservative Efficacy Testing in Transdermal Patches

1) Purpose

The purpose of this SOP is to establish procedures for evaluating the effectiveness of preservatives used in transdermal patches to prevent microbial growth.

2) Scope

This SOP applies to preservative efficacy testing conducted during the formulation and quality control of transdermal patches within the facility.

3) Responsibilities

The Microbiology Laboratory is responsible for executing preservative efficacy testing as per this SOP. Quality Control (QC) and Production personnel provide samples and facilitate testing activities.

4) Procedure

4.1 Sample Preparation

• 4.1.1 Obtain representative samples of transdermal patches containing preservatives from production batches according to approved sampling procedures.
• 4.1.2 Ensure samples are prepared aseptically and in quantities suitable for testing multiple time points.

4.2 Inoculum Preparation

• 4.2.1 Prepare microbial inoculum using specified test organisms, such as Staphylococcus aureus and Pseudomonas aeruginosa, in accordance with compendial methods.
• 4.2.2 Verify the viability and concentration of the inoculum to ensure consistency and accuracy of test results.

4.3 Test Method

• 4.3.1 Inoculate transdermal patch samples with the prepared microbial suspension at specified concentrations.
• 4.3.2 Incubate inoculated samples under controlled conditions that mimic storage or in-use conditions.

4.4 Sampling and Analysis

• 4.4.1 Collect samples at defined time intervals during the incubation period to assess microbial growth and