Tablets Defects and Quality Control

Picking

A form of sticking when a small portion of the tablet or granulation sticks to the punch face and it grows with each revolution of the press, picking out a cavity on the tablet face.

Reasons for capping and lamination

Air entrapped during granulation compression expands when the pressure is released. Large amount of fine powder in the granulation Inadequate or insufficient binder or not enough cohesiveness. Too much or too little lubricant Not enough moisture or excessively dried granules Worn tooling (i.e. punches and dies are not clean and smooth) Aged tablets

Weight may vary because of

Bad granulation The volume and weight of the fill and diameter of the die Improper size and size distribution in granulation Poor flow of granules through the feed frame resulting in incomplete fill Poor mixing and worn punches

Types of faulty tablets

Capping Lamination Sticking Picking Chipping Cracking Mottling Weight variation Hardness variation

Lamination

Lamination is separation of tablet into two or more distinct layers Tablet splits and comes apart.

Dissolution test

Measure the amount of drug dissolved vitro. Predict products in vitro bioavailability. The tester is a cylindrical stainless steel basket or a paddle The drug is placed in the basket or in the dissolution flask depending on the apparatus used. The temperature is maintained at 37°C.

Friability test

Measure the resistance to abrasion or tendency of a tablet product to crumble Tablets roll and fall within a rotating tumbling apparatus, called friabilator You weigh tablets before and after a certain number of rotations The loss in weight, expressed in %, is a measure of tablet's friability.

Capping

Partial or complete separation of top or bottom of tablet from the main body The separated part comes off as a cap

Tablets may be faulty because of several reasons:

Poor formulation Bad tableting machine A combination of both

Sticking

Removal of material from tablet surface and its adherence to the punch face. Occurs when punch tips have engraving or embossing

Hardness variation

Tablet hardness tablet may vary because of: Density, porosity, particle size of granulation Applied compressional pressure Nature of drug + excipients

Chipping and cracking

Tablets pieces broken out or chipped, usually around the edges. Cracked tablets are usually cracked at the center of the top due to extension of the tablet

Tablet hardness test

Tablets should be hard enough to resist breaking during normal handling but soft enough to disintegrate in a timely fashion Lozenges, buccal, chewable tablets are made hard to dissolve slowly You evaluate tablet hardness by crushing the tablet with a load. A force of 4 kg is minimum for a satisfactory tablet. The hardness range for tablets range from 4-10 kg

Disintegration test

The time a tablet takes to break up into particles that can pass through #10 mesh screen is called disintegration time. A DT has a glass tube with a 10 mesh stainless steel wire screen at the bottom. You place the tablet in one of the tubes A motor moves the basket containing water up and down at 29 to 30 cycles per minute. Tablets should disintegrate in 30 minutes.

Reasons for sticking and picking:

Too much moisture in the granulation Not enough lubricant High humidity or temperature

Mottling

Unequal or uneven distribution of color on tablet surface, with light or dark areas standing out

reasons for mottling

Uneven mixing Dye migration during drying of granulations

Tablet thickness test

Use Micrometer Calipers, Thickness Gauge, or by Ames Dial Comparator to measure tablet thickness. Determine the average thickness of 10 tablets The average thickness of each tablet should be ± 5%

Content uniformity test

Use an analytical method to determine the drug content in each tablet. You crush and dissolve the tablets to analyze the drug content. The active ingredient in each tablet should be between 85-115% of the label claim

Tests for weight variation

Weigh 10 tablets of 4 separate batches and take average. The average weight of tablets should be within ± 5%.

Quality control for tablets

Weight Variation Content Uniformity Tablet Thickness Friability Hardness Disintegration Dissolution

Double impressions

When a lower punch with a monogram or imprint code produces a new but lighter impression on the bottom of tablet, that result in a double impression