Tablet Film Coating

  • Created by: LBCW0502
  • Created on: 21-10-18 16:01
What are coated tablets? (1)
Tablets covered with one or more layers of a mixture of various substances (natural/synthetic resins, gums, inactive/insoluble fillers, sugars, plasticizers, polyhydric alcohols, waxes, authorised colouring material, flavouring material)
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What are coated tablets? (2)
Coating can be active ingredient, substances used for coating are applied as solution/suspension under conditions where vehicle evaporates (origin of coated tablets - Rhazes)
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What are coated tablets? (3)
Tablets can be sugar coated, film coated, enteric coated or coated to modify how drug is released into body (modified release)
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What are the therapeutic reasons for coating tablets?
Avoid irritation of oesophagus/stomach, avoids bad taste, avoids inactivation of drug in stomach, improves drug effectiveness, prolongs/improves dosing interval, improve patient compliance
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What are the technological reasons for coating tablets?
Reduces influence of moisture, avoids dust formation, reduces influence of atmosphere, improves drug stability, prolongs shelf life
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What are the patient/marketing reasons for coating tablets?
Avoid bad taste, improve product identity, improve appearance and acceptability
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What are the types of coating?
Sugar coating, film coating (conventional/functional), controlled release coating, other coating methods: compression, electrostatic, dip coating, vacuum film coating
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Describe features of sugar coating
Not common in PI, superseded by polymer film coating. Thick hard coating of sugar, used for ibuprofen/quinine (bitter). Prevent light/moisture entering tablet, smooth/rounded/polished to high gloss, 6 stages
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Describe the process of sugar coating (1)
Sealing tablet core (prevent contact with water, strengthen, polymers used). Subcoating (addition of layers to get desired shape, use gum/sucrose solution and powder dusting, apply suspension of dry powder in gum/sucrose solution and drying)
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Describe the process of sugar coating (2)
Smoothing (application of dilute syrup). Colouring (water-soluble dyes or water-insoluble pigments). Polishing (application of wax surface). Printing (aid identification)
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What are the disadvantages of sugar coating?
Process if tedious and time consuming. Requires expertise of highly skilled technician. Tablet size and weight almost doubled. Batch to batch variability. Cariogenic
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Describe features of film coating
Shape indicated by contour or original core. Single stage process. Spray a coating solution (polymer/solvent/plasticizer/colourant)
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When is film coating applied to a tablet?
To mask taste/colour/odour. Control drug release. Tablet properties constrain developmental design (e.g. size, shape, colour)
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Describe the film coating process (drum coating)
Coating liquid (solution/suspension) containing polymer in medium together with other ingredients (pigments/plasticizers). Coating liquid sprayed onto rotating tablet bed or fluidised bed. Drying (removal of solvent) to leave thin film around core
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What is Wurster film coating?
Polymeric solution sprayed from bottom into a fluidised bed of tablets. Coating and drying are combined in one process
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What are the main components in a tablet film?
Film formers (immediate release/functional), solvents, plasticizers, colourants and opaque-extenders
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Describe features of immediate release film formers
Immediate release coatings do not affect tablet disintegration, drug dissolution or drug bioavailability. Reasons for use: therapeutic/technological/marketing/patient (HMPC)
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Describe features of functional coatings: enteric film formers
Resists dissolution or disruption in the stomach but not in the intestines. Reasons for use: prevent degradation of active sensitive API, prevent irritation in stomach (sodium salicylate), delivery of API to SI, delayed release (PVAP, eudragits)
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Describe features of functional coatings: sustained release film formers
Sustained release coatings resist dissolution/disruption at all pH values, drug release is diffusion controlled. Reasons for use - control release rate of drug over specific period of time, reduce dose frequency, increase patient compliance (EC)
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What are the ideal properties for a film former? (1)
Inert/non-toxic, soluble in solvent, solubility requirement for intended use, low viscosity for spraying, high stability against heat/light/moisture/air/tablet components. Form smooth film. No taste/colour/odour. Compatible with excipients
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What are the ideal properties for a film former? (2)
High resistance to cracking, no bridging or filling of tablet embossments, compatible with printing procedures
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Describe features of film additives: plasticizers
Class of low mwt non-volatile compounds used in polymer industries as additives. Improve flexibility and handling of films (e.g. PEG, organic esters, oil/glycerides)
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Describe features of film additives: colourants
Permitted colourants in a film coat formulation are water-insoluble colours (pigments). Advantages over waters soluble colours - chemically stable towards light, better opacity/covering power, enhance, impermeability of given film to water vapour
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Give examples of colourants
Iron oxide pigments, titanium dioxide, Al
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Describe reasons why colourants are used
Patient identification, brand identification, quality perception (increase aesthetic value), counterfeit prevention
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Summarise features of film coating
Retain core contours, not shiny, increase 2-3% in weight, possible to have logo/break lines, automated process/less skills, easy to adapt GMP, single stage process, easily adaptable for controlled release
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Summarise features of sugar coating
Rounded with high degree of polish. Increase 30-50% weight. No logo/break lines, skills required, difficult to adapt to GMP, multistage process, not possible for functional coatings accept EC
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What is compression coating?
Uses compression to form a coat of material around a pre-formed core. Used mainly to separate chemically incompatible. Dry process
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What is electrostatic coating?
Based on photocopying technology. Used to create tablet coatings with highly distinctive patterns important to brand identification. Load very low dose drugs onto tablet
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What is vacuum film coating?
Sealed container containing tablets heated by water bath/placed under vacuum. Coating solution sprayed into container/evaporated solvent removed using vacuum pump. Low energy requirements, high coating efficiency, organic solvents (safety)
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What is picking?
Tablets stick together. Solution - decrease spraying application rate, increase inlet air temperature
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What is pitting?
Occurs when temperature of the tablet core exceeds mp of material (pinholing)
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What is chipping?
Film becomes chipped and dented, usually at edges of tablet
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What is roughness or orange peel?
Film is rough with surface appearance similar to that of an orange. Uneven spreading of coating before drying
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What is mottling?
An uneven distribution of colour within the film coating
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What is cracking?
A result of post-compaction stress relaxation in tablet or stress incurred during drying
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Which assumptions have been made when looking at tableting?
Make tablets for oral delivery, assumed only humans use tablets, assumed all patients are the same
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Describe features of mini-tablets
Flat/slightly curved tablets with a diameter between 1-3 mm. Can be used in capsules, compressed into larger tablets, placed in sachets for easy administration. Age-appropriate dosage form e.g. geriatrics, paediatric patients
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What are the advantages of mini-tablets? (1)
Manufactured easily, offer flexibility during formulation development. Good size uniformity, regular shape/smooth surface/acts as good coating substrate. Less risk of dose dumping
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What are the advantages of mini-tablets? (2)
Less inter and intra-subject variability. High degree of dispersion in GIT, minimise risk of high local drug concentrations. Offer high drug loading, wide range of release rate patterns, fine tune release rates
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What are the other routes for tablets?
Vaginal tablets and ocular mini-tablets
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Describe features of taste sensation
Humans - large number of taste buds. Issue with sub-therapeutic dosing (e.g. mix medication with yoghurt). Taste masking - make it sweeter, add flavour, hide drug
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Describe features of colour
Used for branding, identification, aesthetically better, more patient compliance
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Which factors impact acceptability of vet. medicine?
Administration, taste, duration of efficacy, price, appearance
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Describe features of companion animals
Family member, high status. Challenge - pet stays in infant status regarding medical treatments. Palatability is a key factor for all over acceptability - describes voluntarily uptake and acceptance of treatments by animal
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What are the common ways of administering medicines to animals?
Solids (tablets/chewables), topicals (spot-ons), gels (local administration)
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Describe features of taste sensation in animals
Cats can taste sour/bitter/salty and proteins but not sweet. Dog taste buds are less sensitive
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What are the key pharmaceutical issues?
Patients don't take medication as prescribed. Patients are not always given medication as manufacturer intended
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Outline the key pharmaceutical issues for younger and older people and state strategies in practice (1)
Polypharmacy (medicine optimisation). Patient compliance/immediate release formulations (change to modified release formulations). Dysphagia/nil by mouth (crush/split solid dosage form). Impaired memory - take medication (medicine compliance)
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Outline the key pharmaceutical issues for younger and older people and state strategies in practice (2)
Inclusion of older people in clinical trials (PPI initiatives) - altered dosage form - use of thickening agents/drug administration via enteral feeding tubes/MCAs
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Other cards in this set

Card 2

Front

What are coated tablets? (2)

Back

Coating can be active ingredient, substances used for coating are applied as solution/suspension under conditions where vehicle evaporates (origin of coated tablets - Rhazes)

Card 3

Front

What are coated tablets? (3)

Back

Preview of the front of card 3

Card 4

Front

What are the therapeutic reasons for coating tablets?

Back

Preview of the front of card 4

Card 5

Front

What are the technological reasons for coating tablets?

Back

Preview of the front of card 5
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