Tablets

• Tablets


  Compressed solid dosage forms made by compression of a formulation containing one or more active pharmaceutical ingredients (API) and excipients
• Applications of tablets


  • Most are for oral administration, some are administered rectally or vaginally
  • Oral tablets are used for: systemic effects and local effects
  • Most are swallowed whole
  • Some are swallowed after being chewed
  • Some are dissolved or dispersed in water before being administered
  • Some are retained in the mouth where the active substance is liberated
• Advantages of tablets

  • Unit dosage forms with accurate and stable dose
  • Administration of minute dose of drug in accurate amount
  • Physical, chemical and microbiological stability
  • Low cost oral dosage form, possibility of large scale production
  • Easy handling, packaging and shipment
  • Easy to divide into halves and quarters whenever fractional dose is required
• Limitations of tablets


  • Hygroscopic drugs, drugs with low or poor water solubility/wetting might be not suitable for compressed tablets
  • Difficult to swallow in case of children and unconscious patients
  • Bitter taste drugs, or sensitive to oxygen or moisture may require encapsulation prior to compression or the tablets may require coating
• Excipients


  Pharmacologically inactive ingredients used as carriers for the active ingredients in a pharmaceutical product
• Ideal characteristics of excipients


  • Chemically and Physically Stable
  • Pharmacologically Inert
  • Non-reactive
  • Economical
  • Non-toxic
• Types of excipients


  • Fillers (Diluents)
  • Binders
  • Disintegrants
  • Lubricants
  • Glidants
  • Antiadherents
  • Coating Agents
  • Coloring Agents
  • Sweeteners
• Mechanism of disintegration


  The tablet breaks to primary particles by one or more of the mechanisms: Swelling, Capillary action /Wicking, Deformation, Particle/particle repulsive forces, Release of gases, Enzymatic action
• Powder flowability


  Tablets are often manufactured by filling the tablet die with powders or granules. The flow of powder from the hopper into the dies often determines weight, hardness, and content uniformity of tablets. Free-flowing powders are desirable to enable robust powder processing operations such as hopper discharge and die filling.
• Measurement of powder flow


  • Old methods including: Angle of repose, bulk density, tapped density, Carr's compressibility index, or Hausner ratio
  • New methods with technological advances: Cohesivity determination, avalanching determination, shear cell, dielectric imaging, atomic force microscopy, and penetrometry
• Parameters affecting powder flow


  • Particle size
  • Particle size distribution
  • Particle Shape
  • Porosity and density of powder
  • Moisture of powder
• Methods of tablet production


  • Direct Compression
  • Compression with granulation
• Direct Compression

  1. Drug + Excipients

  2. Turbula mixer

  3. Tablet machine
• Dry Granulation

  1. Mixing

  2. Roller compaction or Slug formation

  3. Milling/Screening

  4. Sieving

  5. Mixing

  6. Tableting machine
• Wet Granulation


  1. Mixing

  2. Wetting

  3. Granulation

  4. Drying

  5. Sieving

  6. Mixing

  7. Tableting machine
• Common Manufacturing Problems


  • Capping and laminating/splitting
  • Sticking and Picking
  • Chipping and cracking
  • Binding
  • Mottling
• Quality Control Tests for Tablets


  • Uniformity of mass (weight)
  • Uniformity of content (active ingredient)
  • Disintegration test
  • Dissolution test
  • Resistance to Crushing of Tablets (hardness)
  • Friability
• Pharmacopoeial Quality Control Tests


  • Uniformity of mass
  • Uniformity of content (active ingredient)
  • Disintegration test
  • Dissolution test
  • Resistance to Crushing of Tablets (hardness)
  • Friability
• Uniformity of mass (weight)


  Tablets should be of uniform weight. Slight variation is allowed by Pharmacopoeia.
• Uniformity of mass calculation: Average weight = Total of weights of 20 tablets / 20
• No more than 2 of the individual masses should deviate from the average mass by more than the percentage deviation allowed, and none should deviate by more than twice that percentage
• Uniformity of content (active ingredient) test: 10 tablets are selected at random, and each individual unit should be between 85% and 115% of the average content. Fail if more than one individual unit is outside these limits or if one is outside 75% to 125% of the average content.
• Disintegration test: 6 tablets are placed individually in tubes and vertically raised and lowered in a water bath at 37°C. All 6 tablets must completely disintegrate within the specified time.
• Dissolution test: To demonstrate the appropriate release of the active substance(s). At least 75% of the active substance is released within 45 min in most cases.
• Resistance to Crushing of Tablets (hardness)


  Measures the force needed to disrupt tablets by crushing. The mean force is expressed in Newtons (N).
• Friability test


  Measures the physical strength of compressed tablets upon exposure to mechanical shock. A maximum loss of mass not greater than 1.0% is considered acceptable for most products.