Tablet Technology Flashcards
What are the advantages of tablets?
Provide the greatest dose precision and the least content of variability
Least costly of all dosage forms.
Easiest and cheapest for product identification and to package and ship.
Easy to swallow
Potential for special release product such as enteric or delayed release
Best combination of properties in terms of chemical, mechanical and microbiological stability of all oral forms.
Better suited for large scale production
What is a tablet?
A unit form of solid medicament prepared by compression.
Most consist of mixtures of powders compacted in a die to produce a single rigid body
What are the disadvantages of tablets?
Some drugs resist compression into dense compacts due to their amorphous nature or low density
Drugs with poor wetting, slow dissolution properties may be difficult or impossible to formulate and manufacture as a tablet that will provide adequate or full drug bioavailability
Bitter tasting drugs, drugs with objectionable odour or drugs sensitive to oxygen or atmospheric moisture may require encapsulation or entrapment prior to compression or may require coating
What are the different classes of tablets?
Multiple compressed tablets
Standard compressed tablets
What are examples of multiple compressed tablets?
Layered tablets
Dry coated or compressed coated tablets
What are multiple compressed tablets?
Prepared by more than one compression cycle
What are layered tablets?
A type of multiple compressed tablet
Prepared by compressing additional tablet granulation over a previously compressed granulation to make tablets of 2 or 3 layers
What are dry coated or compressed coated tablets?
Tablets prepared by compressing a coat over a core
Why are multiple compressed tablets prepared?
To separate physically of chemically incompatible ingredients
To produce repeated action or prolonged action products
What are examples of different standard compressed tablets?
Prolonged action tablets including repeated action tablets, delayed action tablets, sustained release tablets,
Coated tablets including single coated tablets, film coated tablets, enteric coated tablets
Chewable tablets
Tablets used in the oral cavity
Tablets administered by other routes
Tablets designed to prepare solutions
What is a repeated action tablet?
Tablets which periodically release complete dose of drug in the GIT
What is a delayed release tablet?
Tablet which the release of drug is prevented for an interval of it mime or until certain physiological condition exists
What is a sustained release tablet?
…
What are sugar coated tablets?
Tablets covered by sugar coating
To produce elegant, glossy and easy to swallow dosage forms
To permit the separation of incompatible ingredients between coating and core
What is a Film coated tablet?
Tablet coated by a water soluble polymer such as hydroxypolymethylcellulose??? Or water insoluble polymers such as ethyl cellulose
What are enteric coated tablets?
Tablets covered by a thin layer of film of polymer that does not dissolve in the gastric fluid but dissolves in the intestinal fluid.
What are the reasons for enteric coating?
To reduce or eliminate irritation from some drugs e.g. Aspirin.
To protect the drug from the environmental condition of the stomach like low pH, enzymes, e.g. Erythromycin
The desire to release the drug undiluted and in the highest concentration possible within the intestine e.g. Intestinal antibacterial and antiseptic agent
What are chewable tablets?
Tablets which are intended to be chewed in the mouth prior to swallowing e.g. Aspirin chewable tablet for children.
Which type of drugs are not good candidates to formulate as chewable tablets?
Bitter or foul tasting drugs
Why are antacids formulated as a chewable tablet?
The dose of most antacids is large so a typical antacid tablet would be too large to be swallowed.
The activity of an antacid is related to particle size (small is better)
Chewable tablets may achieve better acid neutralising
What are the main types of tablets used in the oral cavity?
Buccal and sublingual tablets
Troches and lozenges
What are buccal and sublingual tablets?
Tablets held in the mouth where they release their drug contents for absorption directly through the oral mucosa of the mouth.
They are not designed to be swallowed as they contain drugs inactivated or not absorbed or destroyed in the stomach,
E.g. nitrate glycerine used for angina as a sublingual tablet.
Hormones are usually incorporated in buccal tablets.
What are the differences between buccal and sublingual tablets?
Buccal tablets are placed between the cheek and teeth or in the cheek pouch
They have a long disintegration time
Sublingual tablets are placed under the tongue.
They have a short disintegration time
What are the advantages of buccal/sublingual tablets?
Drug absorption by oral cavity avoids first pass metabolism
Gastric environment of stomach is avoided
More rapid onset of action than from tablets that are swallowed
What are troches and lozenges?
Tablets designed not to disintegrate in the mouth but to slowly dissolve over a period of time (30min or less)
They are used in the oral cavity to exert local effect in the mouth or throat.
They contain local anaesthetics, antiseptics, demulcents, astringents and anti-tussives
What are the types of tablets administered by other routes?
Implantation tablets
Vaginal tablets
What are implantation tablets?
Tablets designed for subcutaneous implantation in animal or man
Their purpose is to provide a prolonged drug effect ranging from one month to a year
What are vaginal tablets?
Tablets designed to undergo slow dissolution and release drug in the vaginal cavity e.g. Nystatin
What are examples of tablets designed to prepare solutions?
Effervescent tablets
Dispensing tablets
Hypodermic tablets
What are effervescent tablets?
Tablets containing the drug and an organic acid like citric or tartaric acid and sodium bicarbonate,
When dropped in a glass of water a chemical reaction is initiated between the acid and base to form a sodium salt of the acid to produce CO2 (disintegrant)
Why are effervescent tablets designed?
To improve the rate of disintegration of tablets
To improve the taste of the drug
What is the equation of an effervescent tablet in the presence of water?
Drug + citric/tartaric acid + NaHCO3 –> Na-citrate/tartarate + CO2 (disintegrant)
What are dispensing tablets?
Tablets intended to be added to a given volume of water by a pharmacist or the customer to produce a solution of a given concentration
What are the examples of materials commonly incorporated into dispensing tablets?
Mild silver proteinate,
bichlroide of mercury
Ammonium chloride
What are hypodermic tablets?
Composed of one or more drugs with other readily water soluble ingredients intended to add to sterile water or water for injection
What do conventional oral tablets for ingestion usually contain?
Some classes of essential and non essential components in addition to the drug
What are the main types of essential components?
Diluents or bulking agents Binders Disintegrants Lubricants Glidants Antiadhesvies
What are diluents?
Fillers designed to make up the required bulk of the tablet when the drug dosage itself is inadequate to produce this bulk