Evaluation of Tablet

 

GENERANL APPEARANCE

Size, shape and thickness

Size and shape:  Can be controlled by size and shape of punches and die of tablet compression machine.

Tablet thickness (dimensional variation) related to:

a)       Constant compression load:  Tablet Thickness varies with tab. weight, die fill and Particle Size distribution.

b)      Constant die fill: Thickness varies with compression load.

Tablet thickness can be measured by:

Micrometer: Measure individual tablet thickness (so accurate information on variation between tab.)

Holding tray: measure total tab. thickness of 5-10 tablet with a sliding caliper scale (not accurate information provider on variation between tabs but overall estimation) to give more rapid readings.

Shape:

Shape of tablet influence the choice of tablet machine used with special slotted punches that run at lower speed than conventional punches that produce round tablets.

Organoleptic properties (color uniformity, odor and taste)

Color uniformity:

To identify the product and give good impression to the consumer, while mottling (unequal distribution of the color on tablet) give bad idea to the manufacturer.

Odor:

Presence of odor in a batch of tablet could indicate stability problems like: odor of acetic acid in degrading aspirin tablet.

Taste:

It is important in chewable tab.

Non official tests:

A) Hardness (tablet crushing strength)

Tablet hardness: is the force required to break a tablet in a diametric compression test.

Tabs required a certain amount of strength or hardness and resistance to friability in order to:

1. Withstand mechanical shock of handling in manufacture, packaging and shipping.
2. In addition the tabs should be able to withstand reasonable abuse when in the hands of consumer.

Hardness of tab like its thickness is a function of:

•       (Die fill constant) then additional compression force result in more hardness and less thickness

•       (Compression force constant–fixed distance between upper and lower punches)  then hardness increase with increase in die fill and decrease with lower die fill.

•       Quantity and quality of binder (good binder result in appropriate tablet hardness and not hinder the release of drug from tablet).

•       Lubricant can affect tablet hardness (if too high conc. or long time mixing)

Hardness of different types of tablet

Ordinary tab. 4-8 kg

Chewable tab. 3 kg to prevent harmful effect on teeth

Lozenges (troches) and sustained release 10-20 kg

Non official tests:
B) Friability (abrasion and shock)

Friable tablet: tablet that tend to powder, chip and fragment when handled result in:

•       Lack elegance and consumer acceptance.

•       Create excessively dirty process in area of manufacturing as coating and packaging.

•       Tab’s weight variation or content uniformity problems

Factors affecting friability:

•       Addition of large amount of fine powder to the formula

•       Over drying of granules (moisture content).

•       Use of material that is not cohesive to the formula.