📘 SOP vs STP: Understanding the Difference in Pharmaceutical Documentation
🔹 Introduction
In the pharmaceutical industry, documentation is the backbone of GMP compliance.
Among the most commonly used documents are SOPs (Standard Operating Procedures) and STPs (Standard Testing Procedures) — both essential, yet often confused.
Though they sound similar, they serve different purposes within the Quality Management System (QMS).
Let’s break them down simply 👇
🧾 What Is an SOP (Standard Operating Procedure)?
An SOP is a controlled document that provides written, step-by-step instructions to perform routine operations in a consistent, safe, and compliant manner.
🎯 Purpose of an SOP
The main goal of an SOP is to ensure:
- Operational consistency across departments
- Regulatory compliance with GMP and company policies
- Safety for personnel, equipment, and product
🔍 Scope of SOPs
SOPs cover a wide range of activities across manufacturing, quality, and administrative processes — not limited to testing.
Examples include:
- Batch manufacturing operations
- Equipment cleaning and maintenance
- Material receiving, sampling, and storage
- Employee training and qualification
- Document control and change control management
🧰 Example of an SOP
An SOP for batch manufacturing might include:
- Equipment setup and calibration
- Raw material verification
- Manufacturing sequence and in-process checks
- Packaging and labeling procedures
- Record-keeping requirements
SOPs act as the foundation of GMP operations, guiding staff to perform each task uniformly and safely.
🧪 What Is an STP (Standard Testing Procedure)?
An STP, also known as a Standard Test Method (STM) or Method of Analysis (MOA), is a specific type of SOP focused on testing and analytical methods used in quality control.
🎯 Purpose of an STP
The purpose of an STP is to ensure that laboratory testing is performed with:
- Accuracy – producing valid, precise results
- Consistency – following the same steps each time
- Reliability – ensuring reproducibility across analysts and labs
STPs help confirm that raw materials, in-process samples, and finished products meet established quality specifications.
🔍 Scope of STPs
Unlike SOPs, STPs are narrow in scope, focusing only on specific test methodologies.
Examples include:
- Assay by HPLC
- Dissolution testing
- Identification test by IR
- pH measurement
- Loss on drying (LOD) determination
🧰 Example of an STP
An STP for “Assay by HPLC” would describe:
- Equipment type and system suitability criteria
- Sample preparation steps
- Mobile phase composition
- Column specifications
- Injection parameters
- Calculation formula for % Assay
This ensures that every analyst performs the test in exactly the same way, achieving consistent, validated results.
Key Differences Between SOP and STP
| Feature | SOP (Standard Operating Procedure) | STP (Standard Testing Procedure) |
|---|---|---|
| Purpose | To standardize routine operations across departments | To standardize specific laboratory or analytical tests |
| Scope | Broad – includes manufacturing, training, maintenance, etc. | Narrow – focused only on testing methods |
| Audience | Operators, production staff, QA, warehouse, etc. | QC analysts and laboratory personnel |
| Content Type | Describes how to perform operational activities | Describes how to perform analytical tests |
| Example | SOP for Equipment Cleaning | STP for Assay by HPLC |
| Regulatory Role | Supports GMP compliance and operational control | Ensures data accuracy and test reliability |
In Simple Terms
SOP = Operational Guide
STP = Testing Method Guide
SOPs tell you “how to perform a process”,
while STPs tell you “how to test and verify product quality.”
Why the Difference Matters
Maintaining a clear distinction between SOPs and STPs ensures:
- Proper document classification and control
- Compliance with regulatory inspections (FDA, EMA, WHO)
- Traceability and reproducibility of data
- Clear accountability for operators and analysts
🧠 Key Takeaway
Both SOPs and STPs are vital pillars of documentation control in the pharmaceutical industry.
While SOPs ensure standardization of operational processes, STPs ensure consistency and validity in laboratory testing.
Together, they strengthen the pharmaceutical quality system, ensuring safe, effective, and compliant products for patients.