What Are The Causes of Tablet Defects

The core reasons for the physical defects of tablets are three categories: unsuitable material properties, improper process parameters and abnormal equipment status. Different defects (such as loose tablets, cracked tablets, sticking and so on) can be attributed to the problems in specific links.

I. Material-related causes: root causes of physical defects

The inherent properties of the material and the quality of the pretreatment are the basis for determining whether the tablet can be formed smoothly, and directly affect the subsequent tabletting process.

00001. Poor material fluidity: uneven particle size and excessive fine powder content will lead to unstable filling amount of mold holes, cause weight difference to exceed the standard, and indirectly lead to loose tablets due to insufficient filling amount.

00002. Poor compressibility of materials: the plasticity of raw materials or excipients themselves is low (such as crystalline drugs), and the bonding force between particles is weak under pressure, which is easy to produce loose tablets and excessive brittleness.

00003. Inappropriate selection or dosage of adjuvant:

· Insufficient amount or low concentration of adhesive will result in poor viscosity of particles and easy loosening after tabletting; excessive amount may lead to slow disintegration.

· Insufficient disintegrant dosage may cause tablets to exceed the disintegration time limit, while excessive dosage may affect tablet hardness.

· Excessive lubricant dosage will form an isolation layer on the particle surface, reduce the bonding force between particles, and lead to loose tablets or slow dissolution.

II. Process-related reasons: direct impact of the production process

Improper control of parameters in key processes such as granulation, drying and tabletting is the main direct cause of physical defects.

00001. Granulation process defects:

· During wet granulation, uneven amount of binder or excessive granulation will lead to too hard or too soft granules. Too hard granules are easy to crack when compressed, and too soft granules are easy to stick to the punch.

· During dry granulation, insufficient roller pressure results in low particle density and loose tablets after compression; excessive pressure leads to hard particles, affecting disintegration.

00002. Drying process defects:

· The granules are not completely dried, the moisture content is too high, and the tablets are easy to stick and rush during tabletting, and the tablets are easy to absorb moisture and change color during storage.

· If the drying temperature is too high or the time is too long, the particles are too dry and brittle, and fine powder is easily produced during tabletting, resulting in crack or weight difference.

00003. Inappropriate tabletting process parameters:

· As previously discussed, excessive tabletting speed may result in insufficient filling and delayed degassing, potentially causing tablet cracking or loosening. Conversely, insufficient pressure may lead to tablet loosening, while excessive pressure could cause top cracking or tablet hardening.

· Improper control of environmental temperature and humidity during tabletting, high humidity will make the particles absorb moisture, resulting in sticking; low humidity is easy to produce static electricity, affecting fluidity.

III. Equipment-related reasons: key variables of production assurance

An abnormal device status or improper debugging will directly cause defects in the appearance or physical properties of the tablets.

00001. Tablet press component problem:

· The wear, deformation or incomplete cleaning of the punch will lead to the surface of the tablet to appear pitted, spots, indistinct engraving, and even the fracture of the tablet caused by the uneven gap of the punch.

· The mixing device in the hopper of the tablet press is faulty, and the particle mixing is uneven, resulting in fluctuation of filling amount, weight difference or loose tablet.

00002. Improper device configuration:

· The deviation of the position adjustment of the upper punch and lower punch on the tablet press will lead to insufficient filling amount or excessive compression of the die hole, resulting in loose tablet or cracking.

· The tablet press feeding mechanism is malfunctioning, causing the particle conveying speed to mismatch the tablet pressing speed, resulting in unstable filling and weight variations.