Tablet Hardness Testing


What is Hardness Test and Why it so important?

Tablet Hardness Testing is also known as the “Crushing Strength Test“. 

Tablets must have a specific level of strength or hardness in order to withstand mechanical shocks during manufacturing, packaging, and shipping.

The force required to break a tablet in a diametric compression test is known as tablet hardness.

What are the Factors affecting hardness?

  1. Concentration of binder
  2. Moisture content
  3. Compression Force

What are the Equipment used in Tablets Hardness Test?

  1. Monsanto hardness tester
  2. Pfizer hardness tester
  3. Strong cobb hardness tester
  4. Erweka hardness tester
  5. Schleuniger tester

Out of the above equipment, Monsanto hardness tester and Pfizer are commonly used to determine the hardness of tablets.

A. Monsanto Hardness Tester:

  • Here, the tablet is put between the moving jaw and the fixed jaw. Moving jaw is moved and pressure is applied to the tablet by means of a screw knob.
  • Adjust to Zero by moving the knob and the point where the tablet gets to break down is recorded by means of scale.
  • The hardness is measured in Kg/cm2.
Monsanto Hardness Tester for Tablets Hardness Test

B. Pfizer Hardness Tester:

  • The Pfizer tester compresses the tablet between a holding anvil and a piston connected to a force-reading gauge when its plier-like handles are gripped.
  • The point where the tablet gets broken down, is noted by reading gauze.
 Tablet Hardness Testing-Pfizer Hardness Tester

C. Strong Cobb Hardness Tester:

  • The anvil is pressed against a stationary platform using the Strong-Cobb tester. A hydraulic gauge is used to view the results.
  • The outcomes resemble those of the Monsanto tester quite closely.
  • It consists of a plunger that is operated by pumping a lever arm and uses hydraulic pressure to push an anvil up against a stationary platform.
  • A hydraulic gauge is used to determine the amount of force needed to break the tablet.
Tablet Hardness Testing- Strong Cobb Hardness Tester

D. Erweka Hardness Tester:

  • The lower anvil is used to support the tablet, which is then raised until it just touches the upper test anvil.
  • A motor-driven suspended weight moves slowly and consistently along a rail while it applies pressure to the tablet.
  • The breaking strength in kilogrammes (Kgs) can be determined by following a pointer along a scale.
Tablet Hardness Testing- Erweka Hardness Teste

E. Schleuniger Tester:

  • It moves horizontally as it operates. An electrically powered anvil smashes a tablet against a stationary anvil at a consistent load rate until the tablet breaks.
  • The breaking strength value is indicated by a pointer moving along a scale indicator.
  • Both kg and strong-cobb units are displayed by the instruments.
Tablet Hardness Testing- Schleuniger Tester

Official standards for Hardness:

5-8 kg/cm2Standard compressed tablet Except for Effervescent tablet, Dispersible tablet, Orodispersible tablet, Chewable tablet, etc.
More than 8-12 kg/cm2Sustain Released (SR) Tablet and Controlled Release (CR) Tablet

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