In pharmaceutical manufacturing, the physical integrity of a tablet is just as important as its chemical composition. Tablet hardness testing, also known as tablet breaking force testing, measures the mechanical strength of a tablet—a parameter crucial for the final product quality.
Why Do We Test Hardness?
Resistance to Mechanical Stress
Tablets must be strong enough to withstand the rigors of packaging, shipping, and handling by consumers without chipping or breaking.
Disintegration and Dissolution
There is a direct relationship between hardness and how fast a tablet breaks down. If a tablet is too hard, it may not disintegrate or dissolve properly in the stomach, leading to reduced therapeutic efficacy.
Manufacturing Consistency
Hardness testing helps monitor the compression force of the tablet press. Consistent hardness indicates a stable manufacturing process.
Measuring Tablet Hardness
Modern Digital Tablet Hardness Testers provide high precision and ease of use. The test involves placing a tablet between two jaws—one jaw moves to apply pressure until the tablet fractures. The force required to break the tablet is recorded, typically in Newtons (N), Kiloponds (kp), or Strong-Cobb (Sc) units.
Load Cell Technology
Load cell technology revolutionized tablet hardness testing by replacing mechanical systems with electronic sensors capable of measuring force with precision and accuracy. Load cells utilize strain gauges to convert mechanical force into electrical signals, providing real-time data on tablet hardness.
Key Advantages
- Precise and repeatable hardness measurements
- Reduced variability ensuring consistency in quality control
- Less frequent calibration compared to mechanical testers
- Features including multi-point testing, data logging, and customizable test protocols
Factors Affecting Tablet Hardness
Several variables influence tablet hardness during production:
- Compression Force: Higher pressure usually results in harder tablets
- Excipient Selection: Certain binders and fillers increase bonding strength
- Moisture Content: Excessive moisture can interfere with particle bonding
- Dwell Time: Time under maximum pressure in the press
Tablet hardness is a vital parameter ensuring therapeutic delivery and physical durability.