EXAM 3 L6 Flashcards
Majority of tablets are made by
-Compression (Compaction)
-Very few made by molding
Types of tablets:
-Immediate-release tablet
-Extended release tablet
-Rapidly disintegrating/dissolving tablets
Immediate-Release tablets
Are designed to release their medication with no special rate-controlling features
Extended release tablets:
Are designed to release their medication in a predetermined manner over an extended period
Rapidly disintegrating or dissolving tablets:
Characterized by disintegrating or dissolving in the mouth within 1 minute, some within 10 seconds
Tablet manufacturing processes (1):
-Wet granulation
-Dry granulation
-Direct Compression
Less processing steps and does not require granulation
The powders should have very good flowability, content uniformity and compressibility
Tablet manufacturing processes (2):
- Die Filling
- Tablet compression
- Tablet ejection
Excipients for tablets: Diluents and Binders
-Diluents or fillers: add the necessary bulk to a formulation to prepare tablets of the desired size (lactose, mannitol, starch)
-Binders - promote adhesion of the particles of the formulation, allowing a granulation to be prepared and maintaining the integrity of the final tablet (water, alcohol, start paste, sucrose syrup, etc.)
More binder in the tablets may lead to HARDER tablet, SLOWER disintegration time, and SLOWER dissolution rate
More binder in the tablets may lead to
HARDER tablets, SLOWER disintegration time, and SLOWER dissolution rate
Excipients for tablets: Disintegrants and Glidants
-Disintegrants - promote breakup of tablets after admin to smaller particles for ready drug availability (Starch, cellulose derivatives)
-Glidants, enhance the flow of the material into the tablet dies (Colloidal silicone dioxide, talc)
Excipients for tablets: Lubricants
-Prevent fill material from sticking to the punches and dies
-Decrease adhesion to punch/die
-Decrease friction to punch/die and facilitate tablet ejection
-Reduce punch/die wear
(Mg stearate, talc, sodium stearyl fumarate)
Negative effects of over-lubriication with Mg stearate:
-Reduced tablet harness
-Retarded tablet dissolution due to hydrophobic nature of Mg stearate
-Some drugs are NOT compatible with Mg Stearate (sometimes caused by impurities such as magnesium oxide or MgO)
Tablet coating main purpose
To provide special characteristics of drug release (enteric coatings employed when drug substance is destroyed by gastric acid or is particularly irritating to the gastric mucosa or when bypass of the stomach substantially enhances drug absorp
Tablet coating other functions:
-To protect the medicinal agent against destructive exposure to air and/or humidity
-To mask the taste of the drug
-Improving the ease of swallowing
-Facilitating rapid identification of product
Type of coating
-Sugar coating
-Film coating
-Compression coating
Sugarcoating
-Tablets coated with a sugar layer (sucrose as the major coating material)
-The coating is water soluble and quickly dissolves after swallowing
-The sugarcoated tablets are usually round and smooth by polishing
Disadvantages of sugar coating:
-Multi-steps - sealing, subcoating, smoothing, color coating and polishing
-Time consuming (8 hrs and more)
-Need expertise
-Increase tablets size and weight (up to 50%)
Film coating
Thin, skin-tight film of polymeric materials
Film coating types:
-Immediate-release film coating (“non functional”) - soluble in water
-Modified release film coating (“functional”(, including delayed release (enteric) - soluble in water only when pH > 5 or 6 - and extended -release coatings - not soluble in water
Film coating properties:
-Deposition of a polymer formulation around each tablet core through spraying
-The coating formulation contains a polymer in a suitable liquid with other ingredients including pigments and plasticizers
-Drying of the liquid leaves a thin film of coating material around each tablet
Film coating formation:
-Initial solvent evaporation is rapid because of the deposit and spreading of coating liquid droplets onto the surface of tablets: the initial, rapid drying leads to a non-sticky residue
-The coating polymers become more viscous and less mobile as the solvent starts to evaporate
-Complete drying occurs slowly
Film Coating Requirement
- The coating liquid needs to be atomized into small droplets
-Tablets need adequate mixing and agitating - each tablet surface needs to pass through the spraying zone for a uniform coating
-Enough hot drying air to evaporate the solvent
-Effective exhaust to remove dust - and evaporated solvent
