Introduction

In pharmaceutical manufacturing, product quality cannot depend only on final testing. Quality must be monitored during manufacturing itself. This is where In-Process Checks (IPC) become critical.

IPC ensures that tablets, capsules, and other dosage forms remain within predefined limits during production. Proper IPC limits and acceptance criteria help prevent batch failure, deviations, and regulatory issues.

In real GMP environments, operators and IPQA teams perform IPC checks continuously to maintain process control and ensure consistent product quality.

Understanding IPC limits becomes easier when you first know how GMP monitoring works during manufacturing. Read our detailed guide on IPC basics here:

According to WHO GMP guidelines, in-process controls are essential to ensure consistent product quality during manufacturing.

What Are In-Process Checks (IPC)?

In-Process Checks (IPC) limits and acceptance criteria in pharmaceutical manufacturing showing tablet testing and GMP quality control process

In-Process Checks are quality control activities performed during manufacturing to verify that process parameters and product attributes meet predefined specifications.

Instead of waiting until the batch is completed, IPC identifies problems early so corrective actions can be taken immediately.

Simple Example:

During tablet compression, weight variation or hardness is checked every 30 minutes to confirm the machine is producing tablets within limits.

Purpose of IPC Limits and Acceptance Criteria

IPC limits are predefined numerical ranges or conditions that define acceptable product quality during manufacturing.

Key Objectives

Maintain product consistency
Prevent batch rejection
Ensure GMP compliance
Control process variability
Detect equipment or process issues early

Types of IPC Parameters in Pharma Production

1. Physical Parameters

Tablet weight
Thickness
Hardness
Friability
Appearance

2. Process Parameters

Compression force
Turret speed
Spray rate (coating)
Drying temperature
Granulation endpoint

3. Environmental Parameters

Temperature
Relative humidity
Differential pressure

Each parameter has defined acceptance criteria approved during product development and validation.

IPC Limits vs Acceptance Criteria (Simple Explanation)

IPC Limits

Operational ranges are used during manufacturing to maintain process stability.

Example:

Tablet weight: 495 mg – 505 mg

Acceptance Criteria

Final acceptable quality specification based on pharmacopeial or regulatory standards.

Example:

Weight variation within ±5%

IPC limits are often tighter than final specifications to prevent deviations.

Step-by-Step IPC Procedure in GMP Manufacturing

Step-by-step In-Process Checks (IPC) procedure in GMP manufacturing showing sampling, testing, recording and acceptance criteria decision process

Step 1 – Sampling

Production or IPQA collects samples at defined intervals according to BMR instructions.

Step 2 – Testing

Samples are checked using calibrated instruments like:

Hardness tester
Vernier caliper
Weighing balance

Step 3 – Recording

Results are documented in IPC log sheets or electronic systems.

Step 4 – Comparison with Limits

Results are compared with predefined IPC limits.

Step 5 – Decision Making

Within limits → Continue production
Outside limits → Adjustment or investigation required

Before defining acceptance criteria, make sure you understand how tablet compression parameters affect IPC results. See: Tablet Compression Machine: Working Principle & GMP Controls:

Equipment and Documents Used in IPC

Equipment

Digital weighing balance
Hardness tester
Thickness gauge
Friability tester
Temperature and humidity monitor

Documents

Batch Manufacturing Record (BMR)
IPC log sheets
SOP for IPC testing
Calibration records

Advantages of Proper IPC Limits

Prevents major deviations
Improves process control
Reduces batch rejection risk
Enhances regulatory compliance
Supports continuous improvement

Risks If IPC Limits Are Not Defined Properly

Over-adjustment of machine settings
Product variability
Increased rejection during QC testing
Regulatory observations during audits

In many inspections, regulators focus heavily on IPC trends to evaluate process robustness.

If IPC values go beyond limits, deviation and CAPA procedures must be followed according to GMP requirements: Deviation and CAPA in Pharmaceutical Industry:

Real-Life GMP Example

In a tablet compression line, operators observed hardness dropping below IPC limits. Instead of continuing production, the team stopped the machine and adjusted the compression force.

Because IPC limits were properly defined, the issue was corrected early, and the batch passed final QC testing without deviation.

Common IPC Acceptance Criteria Examples

Tablet Compression

Weight variation: ±5%
Hardness: 5–8 kp
Thickness: 4.2–4.5 mm

Coating Process

Weight gain: 2%–3%
Appearance: Smooth surface without defects

Capsule Filling

Fill weight within ±3%
Lock length within specification

Many IPC failures are linked with granulation and coating issues. Learn common troubleshooting here: Common Coating Problems and Troubleshooting in Pharma:

IPC Trending and Data Analysis

Trending IPC data helps identify process trends over time.

Benefits of Trending:

Detect gradual machine wear
Improve process capability
Support Annual Product Quality Review (APQR/PQR)

Many pharma companies use statistical charts to analyze IPC data.

Responsibilities in IPC Monitoring

Production Team

Perform routine IPC checks
Record results accurately
Inform QA in case of deviations

IPQA Team

Verify IPC activities
Review records
Approve adjustments if required

Quality Control

Provide testing support if needed

IPC vs Final Quality Control Testing

IPC	Final QC
Performed during manufacturing	Performed after batch completion
Preventive control	Confirmation testing
Quick checks	Detailed analytical testing

Both are essential parts of GMP manufacturing.

Conclusion

In-Process Checks (IPC) limits and acceptance criteria are the backbone of pharmaceutical manufacturing control. By monitoring critical parameters during production, companies ensure consistent quality, regulatory compliance, and reduced risk of batch failure.

A well-designed IPC program not only protects product quality but also strengthens overall GMP systems.

Rank Math FAQ

1. What are In-Process Checks (IPC) in pharmaceutical manufacturing?

In-Process Checks (IPC) are quality control activities performed during production to monitor critical parameters such as tablet weight, hardness, thickness, and environmental conditions. IPC helps maintain process control and ensures consistent product quality under GMP guidelines.

2. What is the difference between IPC limits and acceptance criteria?

IPC limits are operational ranges used during manufacturing to control the process, while acceptance criteria define the final allowable product specifications based on regulatory standards and pharmacopeial requirements.

3. Why are IPC limits important in GMP production?

IPC limits help detect problems early, prevent batch rejection, maintain product consistency, and ensure regulatory compliance. They allow production teams to adjust parameters before defects occur.

4. Who is responsible for IPC monitoring in pharma manufacturing?

Production operators perform routine IPC testing, IPQA verifies compliance and documentation, and Quality Control supports analytical testing when required.

5. How often should IPC checks be performed during manufacturing?

IPC frequency depends on SOPs and risk assessment, but commonly checks are performed every 15 to 60 minutes during processes like tablet compression, coating, and granulation.

6. What happens if IPC results are outside predefined limits?

If IPC results exceed limits, production should be paused, machine parameters adjusted, and QA informed. Investigation may be required to prevent deviations.