Compressed Tablets and Coating Flashcards
Describe chewable tablets.
- disintegration in mouth via swallowing
- dissolution in GIT
- useful for paeds, veterinary use, adults with swallowing difficulties
- no disintegrants (happens via chewing)
- diluent such as sorbitol (sweetener) preferred
- same flow specs as compressed tablets
- hardness must be adjusted
Describe oromucosal tablets.
- disintegrate in oral cavity where drug dissolves and is absorbed
- buccal and sublingual: smaller and porous
- compressed lozenges: no disintegrant, limited porosity but increased strength, dissolve slowly in mouth, water soluble diluent and binders
Descrive multiple compression tablets.
- separation of two or more imcompatible APIs
- APIs released at different rates
- drug free layer keeps APIs separated
- first powder compressed, second powder added
- tablet in a tablet - moved to a bigger die
Whats the advantages and disadvantages of orodispersible tablets?
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- quick drug release
- good patient acceptability
- convenient
- useful for paeds, geriatric patients, and patients with dysphagia
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- high hygroscopicity
- low strength
- taste masking required
- stability issues
What quality tests are performed on orodispersible tablets?
- wetting time
- moisture uptake tests
How are orodispersible tablets prepared?
- moulding
- spray drying
- compression/compaction
- lyophilisation
Describe scored tablets.
help tablet spliiting
can affect:
- uniformity of dosing, if API not homogeneously split
- disintegration of drugs from fragments
- stability as API and excipients become exposed to environment
Why is coating beneficial?
- protects API from light and moisture
- masks bad taste
- makes larger doses easier to swallow
- controls where drug is released (enteric coating)
- standardises appearance and aids branding
- allows quick identification of a product
- reduces risk of dusting
What are the types of coating?
- sugar coating
- film coating
- spray coating
- compression coating
Describe the use of sugar coating (adv vs disadv)?
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- low upfront material cost
- simple
- visually pleasing
- taste
- easier to swallow
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- multiple steps
- time
- harder to add markings
- training required
- increases weight and size
- batch variability
- limited to tablets
What are the steps for sugar coating?
- sealinf cores - made waterproof by adding hydroxylpropylcellulose
- subcoating - smooths edges, addition of bulking agent, antiadherent and binders
- smoothing - sucrose coating
- colouring
- polishing - beeswax
- printing - branding via edible inks
What issues are associated with sugar coating?
- chips - enough polymer and filler must be added
- cracks - apply sealing coat and wait longer between compression and coating
- coating doesnt dry - caused by excess of invert sugar
- surface not uniform in colour - limit risk of colour migration before drying, ensure surface is smooth, ensure enough coating is used
- sweating - excess moisture in coating, optimise drying steps
- marbled colour - uneven coating surface, make sure its smooth
Whats the difference between film coated tablets and sugar coated?
film coated are more dull and still have visible edges
film coated have a minimal weight change (2-3%)
sugar coated have (30-50%)
Describe the coating for immediate release tablets.
- water soluble coating
- cellulose derivatives HPMC
- vinyl derivatives copovidone
Describe the coating for modified release tablets.
- coating is water insoluble or solubility depends on pH
- cellulose derivatives ethyl cellulose
- methyl methacrylate
- methacrylic acid insoluble at low pH
