Standard Operating Procedure for Culture Age Verification Prior to Inoculation in Biosimilar Manufacturing

Department	Biosimilars
SOP No.	SOP/BS/147/2025
Supersedes	SOP/BS/147/2022
Page No.	Page 1 of 9
Issue Date	04/05/2025
Effective Date	06/05/2025
Review Date	04/05/2026

1. Purpose

To define the procedure for verifying the age of cell cultures before inoculating production-scale or pilot bioreactors in biosimilar manufacturing, ensuring that culture age falls within validated specifications to maintain viability, productivity, and process consistency.

2. Scope

This SOP is applicable to all inoculation operations using mammalian or microbial seed cultures during upstream manufacturing of biosimilar drug substances in GMP environments.

3. Responsibilities

• Production: Monitor culture age from thaw or subculture point and verify prior to inoculation.
• QA: Review inoculation checklist and approve culture age documentation.
• Process Development: Define acceptable culture age range during tech transfer and validation.

4. Accountability

The Upstream Manufacturing Manager is accountable for ensuring that only cultures within the defined age range are used for inoculating GMP batches.

5. Procedure

5.1 Recording Start Time

1. At the time of WCB vial thaw or subculture initiation, record the time and date on Annexure-1: Culture Age Log.
2. Assign a unique seed culture ID and link to corresponding production batch number.

5.2 Monitoring Culture Growth

1. Monitor VCD, viability, and morphology at regular intervals (e.g., every 12 hours).
2. Document time of each sampling and result in culture monitoring sheet (Annexure-2).
3. Verify that growth curve aligns with expected doubling time as per validation report.

5.3 Determining Culture Age

1. Calculate culture age using formula:
   
   Culture Age (hrs) = Inoculation Time – Culture Start Time
2. Confirm that culture age is within acceptable range (e.g., 60–72 hours for CHO cells).
3. Document in Annexure-3: Inoculation Readiness Checklist.

5.4 QA Review and Approval

1. QA reviews completed logbooks and inoculation checklist for approval.
2. Only upon QA clearance shall the production team proceed with inoculation.

5.5 Deviation Management

1. If culture age is outside validated range, inform QA immediately.
2. Do not proceed with inoculation without approved deviation or waiver form.

6. Abbreviations

• VCD: Viable Cell Density
• QA: Quality Assurance
• WCB: Working Cell Bank
• GMP: Good Manufacturing Practice

7. Documents

1. Culture Age Log – Annexure-1
2. Culture Monitoring Sheet – Annexure-2
3. Inoculation Readiness Checklist – Annexure-3

8. References

• ICH Q8 – Pharmaceutical Development
• EU GMP Annex 2 – Manufacture of Biological Medicinal Products
• WHO TRS 999 – GMP for Biotherapeutic Products

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Culture Age Log

Seed ID	Start Date	Start Time	Recorded By
SC-CHO-110	01/05/2025	10:00	Ajay Verma

Annexure-2: Culture Monitoring Sheet

Time	VCD (x10⁶/mL)	Viability (%)	Comments	Analyst
02/05/2025 – 10:00	3.2	96.5	Healthy	Sunita Reddy

Annexure-3: Inoculation Readiness Checklist

Parameter	Observed	Spec Limit	Status	Reviewed By
Culture Age	64 hrs	60–72 hrs	Pass	QA Officer

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
04/05/2025	2.0	Updated template with readiness checklist and deviation procedure	GMP enhancement