Tablets Flashcards
What are tablets?
Tablets are solid dosage forms and are prepared by compression (80-90%) and moulding (10-20%). Tablets also contain one or more medicinal substances in addition to diluent
What are some basic components of a tablet?
Drug
Diluent
Disintegrants
Binders
Colourants
Coatings
How are compressed tablets formed?
These tablets are prepared with machines capable of exerting great pressure in compacting the powdered or granulated material.
Compressed tablets are the most basic type of tablets in terms of functionality
Are all powders good candidates for compression into tablets?
No, some powders may have poor flow and compression characteristics. They require tremendous pressure and the resulting tablet may lack in desired physical qualities
These powders can be modified in a way that allows for better compression
What is granulation?
The process of particle size enlargement of powdered ingredients (agglomeration)
Common methods of granulation:
Wet granulation
Dry granulation
Describe the process of dry granulation
The powder blend is squeezed through a set of rollers. This turns the powder into flakes, a form that is further milled and sized into larger granules.
Describe the process of wet granulation
Dry powder is placed into a machine called the granulation and it is mixed with other ingredients like binder, water (need some type of liquid to act as the granulating fluid).
This results in the formation of a paste and is known as the wet granular mass.
The paste is dried and results in the dry granular mass. This mass can be broken into dry granules
What is the utility of binders in tablets?
Binders are a critical component because the increase durability, a quality especially important during shipping.
Binders impart cohesiveness to powders, therefore providing the necessary bonding to form granules, which are then compacted into tablets
Too little binder=fragile tablets
Too much binder = excessive hardness (slow disintegration)
Ex. Starch, gelatin, sugars, etc
Do excipients in drugs have more than one purpose?
Yes, many tablet excipients may perform more than one function
Ex. Starch has binding and disintegration properties while also adding to the softness
What is the purpose of lubricants in tablets?
- Provide glidant effect by coating and lubricating particle surfaces —> improves flow properties of tablet granulation
- Provide anti-adhesive effects —> prevents adhesion of materials to punches and fixes during tablet compression
- Act as a lubricant between walls of die cavity and tablet —> facilitating tablet ejection
What are the two main types of lubricant?
Water insoluble:
Magnesium stearate
Calcium
Stearic acid
Talcum
Hydrogenated vegetable oils
Water soluble:
Sodium stearate
Polyethylene glycol
Sodium benzoate
What percentage of a tablet is comprised of lubricants?
Less than 1%
Lubricants are usually the last item to be added
What are some disintegrants used in tablets?
Starch
Cellulose
Clays (bentonite)
Gums (acacia)
Why do effervescent tablets fizz when exposed to water?
They contain sodium bicarbonate and citric acid. When these two are exposed to water, CO2 is released
What is the purpose of colouring agents in tablets?
To enhance aesthetic quality
Product identification
Can drug manufacturers choose any colourant for tablets?
No, colourants must be approved by regulatory bodies and are subject to rigid toxicity standards
Ex. FD&C Red No. 3
What types of tablets need flavouring agents?
Sweeteners and flavouring agents are required for chewable and effervescent tablets.
They are not required for standard compressed tablets, which are intended to be swallowed
What are molded tablets?
They make soft, easily disintegrating tablets. They are designed for rapid dissolution
Are all excipients compatible with other tablet ingredients?
Unfortunately not all excipients are compatible.
Avoid combining calcium salts with tetracycline (interferes with absorption)
Bentonite and kaolin are highly adsorbent, which could inactivate certain drugs
Are tablets the most popular and frequently used dosage form?
Yes, largely due to its ease and economy of preparation, packaging and shipping, accuracy of doses stability, and patient acceptability
What is the purpose of tablet coatings?
Smooth surface (product quality)
Product identification
Mask drug taste
Improve drug stability
What are the two functional tablet coatings?
Enteric-coating (EC)
Controlled/sustained release
Why do some tablets have a line down the middle?
These tablets are designed to be easily split.
What are the different types of tablet coatings?
Sugar coating
Film coating
Functional coating