Standard Operating Procedure for Preparation of API Solutions for Lyophilization

1) Purpose

This SOP outlines the procedures for preparing Active Pharmaceutical Ingredient (API) solutions to be used in lyophilized formulations, ensuring accurate concentration and uniformity prior to lyophilization.

2) Scope

This SOP applies to formulation scientists, production operators, and quality assurance teams involved in the preparation of API solutions for lyophilized products.

3) Responsibilities

• Formulation Scientists: Responsible for specifying the concentration and composition of the API solution.
• Operators: Responsible for preparing the API solution according to the Batch Manufacturing Record (BMR).
• QA: Responsible for verifying solution preparation and documentation.

4) Procedure

4.1 Preparation of API Solution

4.1.1 Equipment Setup

• 4.1.1.1 Ensure that all equipment used for solution preparation (stirrers, balances, etc.) is cleaned, sanitized, and calibrated.
• 4.1.1.2 Use sterilized containers for API solution preparation.

4.1.2 API Weighing and Solution Preparation

• 4.1.2.1 Weigh the required amount of API using a calibrated balance according to the formulation instructions.
• 4.1.2.2 Slowly add the weighed API to a designated volume of solvent (e.g., water for injection, WFI).
• 4.1.2.3 Stir the solution using a mechanical stirrer until the API is completely dissolved, ensuring no visible particulates remain.

4.1.3 pH Adjustment (if applicable)

• 4.1.3.1 Measure the pH of the solution using a calibrated pH meter.
• 4.1.3.2 Adjust the pH by adding a small amount of acid or base if specified in the formulation instructions.

4.2 Filtration and Storage

4.2.1 Filtration

• 4.2.1.1 Filter the prepared API solution using a sterile filtration system (e.g., 0.22-micron filter) to remove any particulates.

4.2.2 Storage

• 4.2.2.1 Transfer the filtered solution into sterilized, labeled containers.
• 4.2.2.2 Store the solution under conditions specified by the formulation (e.g., refrigerated or ambient temperature).

4.3 Documentation

All steps involved in API solution preparation, including API weight, solvent used, and pH readings, must be documented in the API Solution Preparation Logbook.

5) Abbreviations

• API: Active Pharmaceutical Ingredient
• BMR: Batch Manufacturing Record
• WFI: Water for Injection

6) Documents

• API Solution Preparation Logbook

7) References

• Pharmacopoeial guidelines for API solution preparation (e.g., USP, EP)

8) SOP Version

Version 1.0

Annexure

API Solution Preparation Logbook Template

Date	API Name	Batch No.	Concentration	pH	Operator Initials	QA Verification
DD/MM/YYYY	API Name	Batch Number	Concentration (mg/mL)	pH Value	Operator Name	QA Initials