Tablets

Define a tablet and describe key characteristics of its structure and administration.

A tablet is a solid preparation formed by compressing set volumes of particles containing a single dose of one or more active ingredients and excipients.

It is intended for oral use and is typically a cylindrical unit that may be coated or marked.

what are Tablet Advantages ? (5)

•Good patient compliance

•Convenient—easy to handle, take and store

•Accurate dosing

•Chemical, physical and microbial stability

•Generally cheap, robust and elegant

What are Tablet disadvsntages ? (6)

•Generally systemic delivery

•Poor bioavailability

e.g., poor solubility, absorption

•Must be swallowed

•First-pass metabolism

• GI instability and irritation

•Extensive developmental work

Differentiate between immediate-release and modified-release tablets

• Immediate release: a medication design that rapidly disintegrates upon ingestion into bloodstream

• Modified release: Altered release profile (prolonged, delayed, or pulsatile)

Describe the mechanisms of drug release in disintegrating tablets.

Disintegration → dissolution → absorption

•Disintegration rate: dependant on several formulation and production factors.

• Dissolution rate: limited by solubility and particle size.

• Absorption rate: lipophilicity dictates a drug’s ability to pass from the site of administration into the bloodstream. Optimal lipophilicity allows a drug to diffuse through the fatty cell membranes of the body, while too much limits absorption by rendering the drug insoluble in water.

Explain why chewable tablets do not require disintegrants.

They undergo mechanical disintegration in the mouth, eliminating the need for disintegrants.

Drug dissolves in stomach

Describe the mechanism of effervescent tablets and its impact on drug release.

Reaction between carbonate/bicarbonate and acid produces CO₂, enhancing disintegration and dissolution → rapid drug action.

Compare compressed lozenges with conventional tablets in terms of formulation and drug release. (4)

• No disintegrant

• Dissolve slowly in saliva

• Provide local/systemic delivery

• High hardness, low porosity due to high compression

Explain how sublingual and buccal tablets bypass first-pass metabolism.

Drug is absorbed directly into systemic circulation via oral mucosa, avoiding hepatic metabolism.

Describe the properties of an ideal powder blend for tablet manufacture. (4)

• Homogeneous (no segregation)

• Free-flowing (fills dies reproducibly)

• Cohesive/adhesive forces as the balance of these forces determines whether a tablet holds its shape

• Non-adherent to tooling

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Justify the use of excipients in tablet formulations.

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Excipients ensure efficient manufacturing and achieve desired tablet properties (e.g., flow, compressibility, stability), grouped by functional roles.

Explain why granulation improves powder flow and compactability

It forms larger, denser granules, reducing interparticle friction and improving packing and compression.

Describe the stages of powder compression.

Particles are forced into close proximity under pressure, reducing volume and forming a coherent, porous solid.

Compare single-punch and rotary tablet presses.

• Single-punch: One tooling set, low output (~200 tablets/min), used for small batches

• Rotary: Multiple tooling sets (3–60), high output (>10,000 tablets/min), used in large-scale production

Differentiate between capping and lamination.

and in what scenarios are these words used to describe

• Capping: Top of tablet separates

• Lamination: Tablet splits into multiple horizontal layers

capping and lamination refer to structural defects in pharmaceutical tablets

These terms are used to describe failed batches during R&D, scale-up, and quality control

Explain the causes and implications of sticking and picking.

• Sticking: Powder adheres to punch surface

• Picking: a specific type of sticking in which particles stick within the letters and logos of the punches.

Identify critical parameters that must be controlled during tablet compression.

Homogeneity, segregation, flowability, compression, compactability, friction, adhesion

Justify the need for tablet coating. (5)

• Protect drug

• Mask taste

• Improve swallowing and appearance

• Aid identification

• Modify drug release

Compare film coating and sugar coating. (4)

Film Coating:

• common

• sprayed onto rotating tablets

• immediate release—water soluble

• modified-pH 5-6

Sugar Coating:

• Traditional

• Sucrose-based syrup

• Immediate release-water soluble

List the essential quality attributes needed in a tablet. (6)

• Correct dose

• Consistent weight/size

• Controlled drug release

• Mechanical strength

• Stability

• Patient acceptability

Outline the BP test for uniformity of weight.

20 tablets weighed individually;

a max of 2 deviate beyond limits, none beyond double deviation.

Describe the friability test and acceptance criteria.

• To ensure dose and appearance is maintained.

process:

• 100 rotations in friabilator

• Fail if tablets crack/break or >1% weight loss

Explain fracture resistance testing and its significance.

•The resistance to crush tablet - measured by force.

• Tablet placed against platen, load applied along diameter by movable platen. Tablet cracks along diameter into two pieces of similar size and force recorded.

Describe the disintegration test and its limitations. (4)

•To determine if tablets disintegrate within the prescribed time.

• 6 tablets tested at 37°C for 15 min

• 16/18 must pass if retested

• Does not guarantee drug release or absorption

Outline the dissolution test and acceptance criteria.

• Tablet in stirred medium at ~37°C

• Measures drug release over time

• ≥70–75% released at 45 min

Explain why disintegration does not guarantee dissolution or bioavailability.

Drug release depends on solubility, particle size, and formulation factors beyond simple tablet breakup.