Pharmaceutics III - Tablets Quiz

Pharmaceutics III/Pharmaceutical Dosage Forms III - PT 316/PTC 316 - Tablets - Fall 2024

• Course instructor: Prof. Dr. Amal Saber Mohammed Abu El-Enin, Head of Pharmaceutics Department
• Course grading: 100 marks total
  • Midterm: 15 marks
  • Practical: 25 marks
  • Final Exam: 50 marks
  • Oral Exam: 10 marks

Contents

• Introduction to Tablets and Tablet Excipients: 2 hours
• Tablet Types: 2 hours
• Manufacturing of Tablets: 2 hours
• Tablet Coating and Tablet Defects: 2 hours

Introduction to Tablets

• Tablets are solid pharmaceutical preparations holding a single or multiple active ingredients, formed by compressing uniform particle volumes.
• Used for local and systemic effects.
• Most commonly used for oral administration.
• Account for approximately 46% of all other dosage forms.

Advantages of Tablets

• Convenient and safe drug administration
• More physically and chemically stable than liquid dosage forms
• Easier to package and ship than liquids
• Enable more accurate dosing
• Mask bitter or unpleasant tastes
• Comparatively lower manufacturing costs
• Simple to identify

Disadvantages of Tablets

• Not suitable for poorly water-soluble or poorly absorbable drugs (poor bioavailability).
• Some drugs can cause gastrointestinal irritation or harm to the mucous membranes.
• Some drugs resist compression into tablets due to their nature
• Difficulty in swallowing for some patients.

Quality Attributes of Tablets

• Correct drug dose
• Elegant appearance, and consistent weight & size
• Controlled and reproducible drug release
• Biocompatible (no harmful excipients or contaminants)
• Enough hardness to withstand handling and prevent erosion

Tablet Components

• Active therapeutic agent (drug)
• Inactive materials (excipients)

Tablet Excipients

• Inert materials added to ensure quality and preparation.
• Help create satisfactory compression characteristics:
  • Diluents
  • Lubricants
  • Glidants
• Help to create additional physical characteristics:
  • Disintegrators
  • Colors
  • Flavors
  • Sweeteners

Fillers/Diluents

• Role: Increase the bulk volume of the powder to make it an acceptable size.
  • Not needed if the medication dose per tablet is high.
• Common Fillers:
  • Lactose
  • Sugar or sugar alcohols
  • Starch
  • Cellulose
  • Dicalciumphosphate dihydrate

Requirements for a Good Filler

• Chemically inert and biocompatible
• Non-hygroscopic
• Good biopharmaceutical properties (e.g., water-soluble or hydrophilic)
• Good technical properties (e.g., good compression properties)
• Acceptable taste
• Inexpensive

Lactose

• Advantages: Water-soluble, pleasant taste, non-hygroscopic, non-reactive, and low cost.
• Disadvantages: Some people have lactose intolerance, existing in hydrous, anhydrous, and spray-dried forms.

Other Sugars or Sugar Alcohols

• Used in lozenges or chewable tablets due to pleasant taste.
• Mannitol: Negative heat of solution = cooling sensation
• Sorbitol: Optical isomer of mannitol, hygroscopic above 65% humidity

Starch

• Derived from rice, wheat, or potatoes
• Free-flowing, directly compressible form; multifunctional (diluent, binder, disintegrant)

Cellulose

• Widely used filler
• Biocompatible, chemically inert, good tablet-forming and disintegrating properties
• Hygroscopic
• Often used as dry binder or disintegrant
• Microcrystalline cellulose (Avicel) is a common type

Binders/Adhesives

• Role: Ensure that granules and tablets have the required mechanical strength (glue that holds particles together).

Different Ways to Add a Binder

• Dry binder: Mixed with other ingredients before compaction
• Solution binder: Used as a solution (granulating fluid) in wet granulation.

Example of Commonly Used Binders

• Dry binders: Microcrystalline cellulose and cross-linked PVP
• Solution binders: Starch, sucrose, and gelatin

Types of Binders

• Sugars
• Natural polymers (starches, gums, gelatin)
• Synthetic polymers (methyl, ethyl, hydroxypropyl cellulose, PVP)

Disintegrant

• Role: Ensures the tablet breaks into small fragments when it contacts liquid, promoting rapid drug dissolution.
• Mechanisms:
  • Increase porosity and wettability of the compressed tablet matrix
  • Swelling in the presence of aqueous fluids leads to increased internal pressure
  • Production of gas when the tablet contacts aqueous fluids (effervescent tablets)

Methods of Disintegrant Addition

• Intragranular addition: Mixed with other ingredients prior to granulation, and thus incorporated within the granules
• Extragranular addition: Mixed with dry granules before compaction

Commonly Used Disintegrants

• Starch
• Modified Starch (e.g., Explotab - sodium starch glycolate)
• Modified cellulose (e.g., Ac-di-Sol - cross-linked form of sodium carboxymethyl cellulose)
• Alginic acid and its salts (high cost)

Lubricants

• Role: Ensure tablet formation and ejection with low friction between solid and die wall, facilitating ejection from die cavity
• Poor lubrication leads to pitted tablet surfaces
• Concentration is less than 1%
• Added in the last step before granulation

Common Lubricants

• Hydrophobic (water-insoluble):

  • Magnesium stearate
  • Stearic acid

• Hydrophilic (water-soluble):

  • Sodium lauryl sulfate
  • Polyethylene glycol (PEG)

Antiadherent

• Role: Reduces adhesion between powder and punch faces, preventing particles from sticking to punches
• Common examples include magnesium stearate, talc, and starch

Glidant

• Role: Improves powder flowability by reducing friction between particles
• Common examples include talc, colloidal silicon dioxide, and magnesium stearate

Sorbent

• Definition: Substances that absorb fluids while remaining in a solid, dry state.
  • Moisture absorption
  • Incorporating liquid or semi-solid components (oily drugs, flavors) into tablets

Examples of Sorbents

• Microcrystalline cellulose
• Silica

Flavour

• Role: Providing the tablet with a more pleasant taste or masking an unpleasant one
• Often added as a solution to the granulation liquid, or mixed with the granules. Flavoring agents are often thermolabile avoiding heat-related degradation
• Added after granulation, avoids heat degradation.

Colorant

• Role: Aid in identification and patient compliance.
• Added during coating or prior to compaction as an insoluble powder or dissolved in the granulation liquid

Sweetener

• Role: Used in lozenges, orodispersible, and chewable tablets to replace or limit sugar use
• Examples: Mannitol, Saccharin, Aspartame