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Pharm 125 > Tablets > Flashcards

Tablets Flashcards

1
Q

What are tablets? How are they classified? which shape is most common?

A

-solid dosage forms in which the drug substance is generally blended with excipients and compressed into the final dosage

classified by:

  1. manufacturing method - compressed or molded tablets
  2. drug release rate: modified or immediate

shape: disk like is most common

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2
Q

What are the advantages of tablets?

A
  • simplicity and economy of preparation
  • stability
  • convenience in packaging, shipping and dispensing
  • accuracy of dosage
  • portable
  • compactness
  • blandness of taste
  • easy administration
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3
Q

What are the disadvantages of tablets?

A
  • poor bioavailability of poorly soluble/absorbable drugs
  • some drugs may not compact into tablets
  • some drugs may cause local irritation
  • compression changes physical properties, particle size, and crystal form
  • difficulty in swallowing in some patients
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4
Q

What are the classes of drugs?

A

Class I: high solubility and permeability
Class II: low solubility, high permeability (reduce PS, salt formation, complexations, lipid formulations, and solid dispersions)
Class III: high solubility, low permeability (permeation enhancers, prodrugs, bioadhesives)
Class IV: low solubility and permeability (combine methods or IV)

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5
Q

What are some BCS examples?

A

Class I - chloroquine phosphate
Class II - ibuprofen
class III - captopril
Class IV - furosemide

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6
Q

_________ of dose absorbed in humans = highly permeable

highest drug dose soluble in _______ of water over a pH of 1-7.5

A

> 85-90%

<250 mL

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7
Q

What are the compressed tablet types?

A

Uncoated tablets

Coated tablets

  • Sugar coated
  • Film coated (thin layer of film or polymeric substance)

Modified release tablets

  • delayed release (film coated tablets with polymers that resist dissolution in gastric fluid but disintegrate in the intestine)
  • extended release (drug is released over an extended period of time after ingestion)
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8
Q

What are multiple compressed tablets?

A
  • compressed tablets made by more than 1 compression cycle
  • they are used when API has to be separated for stability purposes or mixing is not adequate enough for uniform distribution of 2 or more API

Layered tablets:
- prepared by compressing additional tablet granulation on a previously compressed granulation

Press coated tablets:
- prepared by feeding previously compressed tablets into a special tableting machine and compressing another granulation layer around the preformed tablets

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9
Q

What are effervescent tablets?

A
  • contains drug + mixture of sodium bicarbonate and an organic acid
  • in presence of water, the additives react and release CO2 that acts as disintegrant and produces effervescence
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10
Q

What are chewable tablets?

A
  • doesn’t require disintegrant
  • disintegrate when chewed
  • chewed and then swallowed
  • hard tablets: compression
  • soft tablets: molding
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11
Q

What are rapidly dissolving tablets or orally disintegrating tablets?

A
  • disintegrates in 30 s or 3 min in the mouth
  • smooth, palatable and non-gritty
  • manufactured by freeze drying and compression molding, granulation following compression, modified direct compression
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12
Q

What are vaginal tablets and tablets for oral solution/suspension?

A

Vaginal tablets:

  • NOT to be swallowed
  • most common are local antibiotic therapy (canestan vaginal tabs)

Oral sol/suspension tablets:
- solubilized or dispersed in a liquid before administration

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13
Q

What are buccal/sublingual tablets?

A
  • buccal tablets on side of cheeks and dissolve slowly
  • sublingual tablets under the tongue and dissolves fast
  • rapid systemic effect without first pass
  • absorption through oral mucosa
  • drug can be swallowed and available for absorption
  • excipients are water soluble and provide very fast dissolution
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14
Q

What are tablet triturates or molded tablets?

A
  • made by molding instead of compression
  • compounding pharmacy
  • soft and soluble for rapid dissolution
  • do not contain disintegrants, lubricants, or coatings
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15
Q

What are the group 1 and group 2 excipients?

A

Group 1: imparts satisfactory processing and compression characteristics to the tablet (diluents, glidants, binders, lubricants)

Group 2: helps to give additional desirable physical characteristics to the finished tablet (disintegrants, surfactants, colours, flavours, sweetening agents, polymers)

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16
Q

What are diluents?

A

They are added to increase the bulk of the tablet to make it practical for compression

Properties:

  • acceptable taste
  • non hygroscopic
  • chemically inert
  • good biopharmaceutical properties
  • good compactibility
  • compatible
  • cheap
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17
Q

What are examples of some diluents?

A

Lactose, Microcrystalline cellulose (Avicel), Dicalcium phosphate dihydrate, Calcium and sodium carbonate, starch, dextrose, sucrose, mannitol and sorbitol

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18
Q

What are binders?

A
  • granulating or binding agents
  • gives cohesive qualities to the powdered material and tablet formulation
  • ensures the tablet remains intact after compression

Too much: Tablet won;t disintegrate
Too little: tablet falls apart

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19
Q

What are the two types of binders?

A

Solution binders

  • act as granulation fluid
  • starch mucilage, sucrose solution, cellulose derivatives, gelatins, polyvinylpyrrolidone

Dry binders

  • added before wet granulation or mixed with other ingredients before compaction
  • microcrystalline cellulose, polyvinylpyrrolidone, pregelatinized starch
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20
Q

What are lubricants? What are some examples?

A
  • They prevent the adhesion of tablet material to the surface of the dies and punches
  • Facilitate the ejection of tablets from the die cavity

Insoluble lubricants: Mg stearate, Ca stearate, stearic acid, light mineral oil
Soluble lubricants: sodium benzoate, sodium lauryl sulfate, PEG 4000 and 6000

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21
Q

Which type of lubricant is better? When are lubricants added?

A

Hydrophobic is better

Lubricants are added after all ingredients have been mixed

  • it should be passed through a 60-100 mesh size onto the granulation
  • the granulation is mixed gently so that the particles are not coated too well or breaking them to finer particles
22
Q

What are glidants? some examples?

A
  • They improve the flow characteristics of a powder mixture by reducing interparticle friction
  • Added in the dry state just before compression (during lubrication step)
  • examples include colloidal silicon dioxide, talc, calcium silicate, mg carbonate
23
Q

What are disintegrants? what are the mechanisms?

A
  • a substance or a mixture of substances added to a tablet to facilitate its breakup or disintegration after administration
  1. facilitated water uptake - disintegrant facilitates the uptake of water into the pores of the tablets (eg. microcrystalline cellulose, starch)
  2. swelling on contact with water (eg, sodium starch glycolate, crospovidone, croscarmellose sodium)
  3. gas production in effervescent tablets
24
Q

What is extragranular and intragranular addition?

A

Extragranular - addition of disintegrant during the disintegration process (tablet to granules)

Intragranular - during the deaggregation process (granules to drug particles)

25
Q

What are the colouring agents? When are they added?

A
  • added for product identification or appearance
  • approved and certified by FDA, Health Canada
  • most common: iron oxide (yellow, red, black) and indigo carmine (FD&C Blue 2)

Added:

  • during the coating step for uniform colour
  • to the formulation (mixing an insoluble powder before compression or dissolving the dye in the binding solution prior to granulation)
26
Q

What are the flavours/sweeteners? wetting and solubizing agents? sorbents?

A

flavours/sweeteners are added to chewable tablets

wetting and solubilizing agents are added to water insoluble drugs and hydrophobhic tablets (sodium lauryl sulfate, poloxamer, docusate sodium, lecithin, polysorbate 80)

sorbents sorb oils or oil-drug solutions into a powder mixture during granulation and compaction (microcrystalline cellulose, fumed silica, mg carbonate, kaolin)

27
Q

What are the two types of granulation?

A

Wet

  • most common
  • convective mixing using a high shear mixer
  • more steps involved, including milling and screening

Dry

  • slugging (large tablet which is milled)
  • roller compaction: powder is pressed between rollers then ground
28
Q

What are the pros and cons of granulation?

A
  • prevents segragation
  • improves powder flow
  • improves compression
  • prevents clumping of hygroscopic powder
  • reduces dust

cons:

  • many steps involved
  • longer time, labor
29
Q

What is the wet granulation process?

A

Blend powders —> add binder solution —-> moist mass (granulator) —-> screening —-> moist agglomerates —-> dry granules —–> pass through screen —-> properly sized dry granules —–> add lubricant —–> compression

30
Q

What are the types of granulators?

A
  • Low shear mixers
  • High shear mixers
  • Fluidized bed granulators
  • spray dryers
  • extruders and spheronizers
31
Q

What are fluidized bed granulators?

A
  • Granulation and drying of the powders is continuous in the same vessel
  • requires proper balance of air flow rate, air temp, bed load, binder solvent, and temp of granulating solution
  • more control than high shear mixers
32
Q

What are extruders and spheronizers? What are the steps?

A

forms dense, spherical pellets with even smooth surface and a narrow size distribution, more expensive and labour intensive, controlled release DF

steps:

  1. dry mixing
  2. wet massing
  3. extrusion
  4. spheronization
  5. drying
  6. screening
33
Q

When is dry granulation used?

A
  • used for moisture or thermal sensitive drugs
  • drugs that do not compress by direct compression
  • slugging or roller compaction (more common)

Roller compaction —-> fine powder compressed into sheets then granulated into uniform sized granules

34
Q

What are the pros and cons of direct compression?

A

Pros:

  • less steps (pre milling, mixing, compression)
  • cost effective
  • less time
  • higher dissolution rate for certain drugs
  • higher stability

Cons

  • special excipients required
  • higher doses of API not recommended
  • may have flow and segragation problems
  • tablets are softer which can cause problems during coating
35
Q

What do tablet machines consist of?

A

Hopper: stores materials for compressing
Feed frame: distributes materials to the dies
dies: control the shape and size of the tablet
punches: compress the materials within the dies

36
Q

What are the stages in formation of tablets?

A
  1. lower punch at the bottom and upper punch outside the die
  2. lower punch moves up to remove excess powder
  3. upper punch moves inside die to apply force and compress materials to form tablets
  4. the upper punch moves outside the die and lower punch moves up to the eject tablet
37
Q

What are the diff types of tablet machines?

A
  1. single punch machines - one die, one set of punches, 1 tab at a time, 200 tabs/min (automated ones)
  2. rotary tablet machine - rotating table of dies and punches, 10000 tabs/min, at a cost of control over compression pressure, main difficulty is the adequate filling of the dies
  3. multilayer rotatory press - multiple filling and compression steps
38
Q

What do the properties of compressed tablets depend on?

A
  1. Physical and mechanical properties
  2. manufacturing process parameters (compression pressure, speed, time)
  3. equipment and tooling design
  4. temp and humidity
  5. extent of lubrication
39
Q

What is the difference between powder compression and compaction?

A

powder compression - reduction of the volume of powders when a force is applied
powder compaction - formation of a solid specimen with defined geometry by powder compression (deforming particles)

40
Q

What are the powder compaction phases?

A
  1. loose packing
  2. dense packing
  3. elastic deformation
  4. plastic deformation
  5. brittle fracture
41
Q

What are the tablet compression characterizations?

A
  1. Punch displacement profile
  2. Tablet mechanical strength
  3. Tablet porosity
  • typical porosity values: 0.1 and 0.4
  • if porosity =0, solid fraction = 1
  • true density of organic: 1-1.7 g/ml and inorganic: 2-3 g/ml
    porosity = 1-solid fraction
  1. manufacturability profile - change in breaking strength of a compressed body with applied force
  2. tabletability profile - change in tensile strength of a compressed body with applied force
  3. compressibility profile - change in the solid fraction of a compressed body with applied force
  4. compactibility profile - change in the tensile strength of a compressed body with solid fraction
  5. Tablet compression profile - relationship between compression pressure, solid fraction and tensile strength
  6. machine speed sensitivity - comparison of a range of compression speeds and tablets properties
42
Q

What is the heckel equation?

A

Describes the densification of powders during compression

43
Q

What are the post compaction changes?

A

Reduced tablet strength:

  • condensation of water in tablet pores causes reduced intermolecular force
  • the dissolution of material in the condensed water changes tablet microstructure
  • softening of amorphous material due to water absorption

Increased tablet strength:

  • formation of bonds due to crystallization of material dissolved in condensed water
  • formation of bonds due to crystallization of amorphous material
  • change in tablet microstructure due to rearrangement of the solid material in the amorphous state and polymorphic transformations
44
Q

What are the common manufacturing problems?

A
  • Dose and weight variation
  • adhesion of the tablet to the punch tips (sticking/picking)
  • capping or lamination of tablets
  • high friction during tablet ejection
  • low mechanical strength of the tablets
45
Q

What are the tablet characteristics for quality control?

A
  • diameter size
  • shape
  • thickness
  • hardness
  • disintegration time
  • dissolution characteristics
  • uniformity of dosage units
46
Q

What defines the size, shape and thickness of tablets? how are they measured?

A
  • diameter of the die
  • amount of fill
  • compression parameters
  • tablet properties

micrometer, sliding caliper (+/- 5% variation of standard value)

47
Q

How do you ensure uniformity of weight and content?

A

uniformity of weight - measure weight of 10 tablets and take average
uniformity of content - ensure that each tablet contains the right amount of drug

Usual acceptance range: 85 to 115% of the label claim with

48
Q

What is the tablet breaking force?

A

force need to break or fracture a tablet along its diameter

target tensile strength should be greater than 2 MPa

49
Q

What is tablet friability?

A
  • tendency for a tablet to chip or crumble
  • tablets are rotated in drum at a set speed and revolutions
  • important to measure due to mechanical shocks
  • USP limit: less than 1% weight loss
50
Q

What is tablet dissolution? why is it important?

A
  • describes the overall rate of release of drug from a solid dosage form into a bioavailable form
  • formulation and drug development
  • monitoring during manufacturing for quality assurance
  • ensures bioequivalence from batch to batch
  • required test for all drugs

Pharm 125 (4 decks)

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