Scope

This SOP applies to formulation scientists, product development personnel, and QA teams involved in the development, documentation, and review of intradermal injection formulations in a sterile injectable facility.

3. Responsibilities

• Formulation Scientist: Conducts formulation design and risk assessments.
• R&D Chemist: Prepares lab-scale batches and supports analytical testing.
• QA Representative: Ensures compliance with GMP guidelines and documentation protocols.
• Head – R&D: Approves final formulation before scaling up.

4. Accountability

The Head of Formulation Development is accountable for ensuring the formulation development complies with pharmacopeial, regulatory, and internal quality standards.

5. Procedure

5.1 Pre-Formulation Studies

1. Evaluate the physicochemical properties of the API including solubility, stability, pKa, and molecular weight.
2. Assess dermal absorption potential and local irritation risk.
3. Target a final injection volume of 0.1 mL to 0.2 mL per site.

5.2 Excipient Selection

1. Use only injectable-grade excipients, suitable for dermal administration:
   • Buffers: Acetate, phosphate, or citrate to maintain pH
   • Isotonic agents: Sodium chloride, dextrose
   • Preservatives (if multidose): Phenol or benzyl alcohol (as permitted)
2. Justify excipient choice through toxicological assessment (Annexure-3).

5.3 Formulation Development

1. Target pH: 6.5 to 7.4 (dermal compatibility).
2. Osmolarity: 270–310 mOsm/kg to avoid irritation.
3. Ensure the formulation is non-viscous, sterile, and pyrogen-free.

5.4 Trial Batches

1. Prepare 3 pilot batches under aseptic conditions using WFI.
2. Sterilize using 0.22 µm filtration; fill in Type I glass vials.
3. Perform visual inspection for clarity and particles.

5.5 Stability Testing

1. Conduct stability testing as per ICH Q1A guidelines.
2. Test for:
   • Assay, degradation products, pH, clarity
   • Sterility and endotoxins
   • Color, particulate matter

5.6 Documentation

1. All batch records must be documented in the Formulation Development Report (Annexure-2).
2. Excipient selection and concentration justification must be provided (Annexure-3).

6. Abbreviations

• ID: Intradermal
• API: Active Pharmaceutical Ingredient
• ICH: International Council for Harmonisation
• GMP: Good Manufacturing Practices
• WFI: Water for Injection

7. Documents

1. Stability Protocol – Annexure-1
2. Formulation Development Report – Annexure-2
3. Excipient Justification Table – Annexure-3

8. References

• ICH Q8 (R2): Pharmaceutical Development
• ICH Q1A (R2): Stability Testing
• USP <71>: Sterility Tests

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation	Formulation Scientist	QA Officer	R&D Head
Department	Formulation Development	Quality Assurance	Research & Development

11. Annexures

Annexure-1: Stability Protocol

Batch No.	Storage Condition	Duration	Test Parameters	Analyst
ID-B-001	25°C / 60% RH	1M	Assay, Sterility	Sunita Reddy

Annexure-2: Formulation Development Report

Product Name	Intradermal Injection – API X
Batch Number	ID-FORM-002
Date of Preparation	12/06/2025
Prepared By	Rajesh Kumar

Annexure-3: Excipient Justification Table

Excipient	Function	Rationale
Phosphate Buffer	pH adjustment	Maintains physiological pH
Sodium Chloride	Isotonicity	Prevents irritation at site
Benzyl Alcohol	Preservative	Required for multidose stability

Revision History

Revision Date	Revision No.	Details	Reason	Approved By
15/01/2022	1.0	Initial version released	New formulation SOP	QA Manager
18/06/2025	2.0	pH and osmolarity sections updated	Regulatory alignment	QA Manager