Lecutre 13- Tablet Coating

Question 1

Tablet coating

Answer 1

Leads to;

Protecting drug from environment
Improve taste/ feel
Hide colour variations in raw materials
Improve appearance
Aid with brand identification/ marketing
Help patient with identification/ compliance
Improve handleability/ friability during packaging
Tailor the release of drug

Question 2

Film coating process

Answer 2

Requires; polymer- usually water-soluble e.g. cellulose derivatives

Plasticiser= improves polymer properties e.g. polyols

Colourants= water-insoluble pigments -> enhanced impermeability to water vapour

Solvent= preferably water; safety, cost environment + reduced residue

Question 3

Film coating process requirement

Answer 3

Slide 6

Film coated tablets must have;

Even coverage of film + colour, no abrasion of tablet edges, logos+ break lines should be distinct and not filled in + tablet should have the required finished specs

Question 4

Coating faults
Non- optimised coating formulation

Answer 4

Orange peel; texturised coating surface resembling an orange peel. Cause= too high spray pressure, fast spray rate- uneven coating- use mild drying conditions

Picking; tablets stick to each other. Cause= tabs too wet- insufficient drying/ atomization product movement- increase inlet temp/air volume

Cracking, bridging of logo, colour variation, film chipping, logo attrition, twinning + cratering= slide 9

Question 5

Press coating

Answer 5

Sugar coating; slide 11

Press coating; compaction of granular material around a preformed core using compressing equipment

Requirement= core material has reasonable strength at low compression

Uses; core shell properties, dual release profiles + incompatible drugs

Question 6

Functional coatings
Controlled release; film coated particles applied to a multi-particulate system

Answer 6

Easy access to GI tract- small in size

Problem= tabs stay in one place in GI tract -> ulcerative damage to the gastric mucosa as the drug solution is leaking out the tab

Solution= micro-particulates reduce the risk of drug poisoning. If fails and leaks out tab= no risk of patient being exposed to a high drug amount

Question 7

Multi-particulates

Answer 7

Extruded/ spheronised granulates= produced in modified granulating equipment

Non-pareils= sucrose spheres coated with drug + an adhesive water-soluble polymer. Coated with controlled release coating

Question 8

Microparticulates drug release MOA
3 main mechanisms

Answer 8

Diffusion; water enters the interior of the particle, dissolves the drug + the drug solution will diffuse across the polymeric coating

Erosion; coating erodes gradually with the time releasing the drug contained in the pellet

Osmosis; osmotic pressure can be built up within the interior of the pellet

Question 9

Enteric coating

Answer 9

-Protect unstable active constituents from the acidic pH

-Protect the stomach from the irritant effect of certain drugs

-Facilitate the absorption of drugs that are absorbed better from parts of GI other than stomach

Work by;
They have free -COOH groups on the polymer backbone. Ionisation INC at a pH of 5.2 + solubility. Coat dissolves in the small intestine and stays intact in the stomach

Question 10

Standards for coating tablets

Answer 10

1. Film-coated tabs must comply with the uniformity if mass test unless otherwise justified and authorised
2. Film-coated tabs comply with the disintegration test for uncoated tabs except that the operating time of the apparatus; 60 min inst of 30min
   ^test must be repeated using 0.1 N HCI in the event that any tabs fail to disintegrate in the presence of water