use in screening assays.

Quality Assurance (QA): QA ensures that the compound library preparation and maintenance processes adhere to regulatory and internal standards. They monitor the quality of the compounds and ensure proper documentation is maintained.

Project Managers: Oversee the compound library preparation process, ensuring that timelines and budgetary constraints are met. They ensure the compound library is aligned with drug discovery goals and accessible to the screening teams.

Supply Chain Managers: Responsible for procuring compound libraries, ensuring that all necessary quantities are acquired, and that inventory levels are maintained according to the needs of the project.

4) Procedure

The following steps outline the detailed procedure for preparing and maintaining compound libraries:

1. Step 1: Compound Selection
   1. Select compounds based on the specific therapeutic area, biological target, and the desired diversity of chemical structures. Consider using commercially available compound libraries, in-house collections, or custom-designed libraries based on the project’s focus.
   2. Ensure that the compound library covers a wide range of chemical space, including small molecules, natural products, and known drug-like compounds, to increase the chances of finding hits during screening.
   3. Assess the diversity of the compound library by reviewing the chemical space it represents, using metrics such as molecular weight, logP (partition coefficient), and topological polar surface area (TPSA).
2. Step 2: Compound Acquisition
   1. Acquire compounds from trusted suppliers or chemical vendors. If acquiring compounds from commercial vendors, ensure that they are of high quality and meet the required purity standards (usually ≥95%).
   2. For in-house libraries, ensure that compounds are synthesized following appropriate protocols and are properly documented.
   3. Catalog compound sources and batch numbers for traceability, particularly if compounds are being sourced from multiple vendors or synthesized in-house.
3. Step 3: Compound Storage
   1. Store compounds in appropriate conditions, such as temperature-controlled storage rooms, freezers, or liquid nitrogen tanks, to ensure the stability and longevity of compounds.
   2. Ensure that compounds are stored in well-labeled, sealed containers to avoid contamination or degradation. Provide storage conditions based on the chemical nature of the compound (e.g., temperature, humidity, light exposure).
   3. For compounds that require special handling (e.g., light-sensitive compounds, volatile chemicals), ensure that appropriate safety measures are in place and that they are stored according to safety guidelines.
4. Step 4: Compound Cataloging and Database Management
   1. Create a compound inventory system, either in physical or digital format, to catalog compounds in the library. Use unique identifiers (e.g., compound ID numbers) for each compound and store data related to its molecular structure, purity, batch number, and acquisition details.
   2. Maintain an up-to-date digital database for easy tracking of compound availability, storage locations, and screening progress. This can include tools like ChemDraw, ChemAxon, or other commercial chemical databases.
   3. Ensure proper documentation for each compound, including batch records, certificate of analysis (CoA), and safety data sheets (SDS), when applicable.
5. Step 5: Quality Control and Validation
   1. Perform routine quality control checks on the compound library to ensure that compounds meet the required purity, identity, and stability standards.
   2. Periodically test a random sample of compounds from the library to confirm their integrity and ensure that no degradation has occurred during storage.
   3. Validate the chemical identity and purity of compounds upon receipt, especially for key compounds used in screening assays. Perform reanalysis if necessary.
6. Step 6: Library Maintenance and Updates
   1. Regularly update the compound library by adding new compounds and removing those that are outdated or degraded. This includes reviewing and purchasing new compounds based on emerging targets or therapeutic areas.
   2. Ensure that the compound library is reviewed and reorganized periodically to facilitate its use in screening assays. This may include grouping compounds by chemical properties, biological targets, or therapeutic relevance.
   3. Track and update the availability of compounds to ensure that screening teams have access to the necessary compounds when required.
7. Step 7: Documentation and Reporting
   1. Maintain accurate and up-to-date records for all compounds in the library, including acquisition details, purity tests, cataloging information, and storage conditions.
   2. Prepare regular reports on the status of the compound library, including information on new acquisitions, compound usage, inventory levels, and any issues with compound quality or availability.
   3. Ensure that all data is accurately recorded and accessible for regulatory compliance and future use in screening campaigns.

5) Abbreviations

• QC: Quality Control
• CoA: Certificate of Analysis
• SDS: Safety Data Sheets
• HTS: High-Throughput Screening

6) Documents

The following documents should be maintained throughout the compound library preparation and maintenance process:

1. Compound Catalog
2. Compound Acquisition Records
3. Quality Control Reports
4. Certificate of Analysis (CoA) and Safety Data Sheets (SDS)
5. Library Maintenance and Update Logs

7) Reference

References to regulatory guidelines and scientific literature that support this SOP:

• FDA Guidance for Industry on Drug Discovery and Screening
• Scientific literature on compound library management and maintenance

8) SOP Version

Version 1.0: Initial version of the SOP.