Tablets in Pharmaceutics: Definition, Types, Formulation, Evaluation Tests, and Importance in Drug Delivery

Tablets in Pharmaceutics: Definition, Types, Formulation, Evaluation Tests, and Importance in Drug Delivery Definition of Tablets A tablet is a solid unit dosage form of medication containing one or more active pharmaceutical ingredients (APIs) along with suitable excipients. Tablets are usually prepared by compressing powder or granules using a tablet press. They are one of the most popular and convenient dosage forms due to their accuracy in dosing, stability, and patient compliance. Pharmaceutical Definition: A tablet is a solid dosage form prepared by compressing or molding, containing a specific quantity of drug with or without excipients. Types of Tablets Tablets can be classified based on their route of administration, method of manufacture, or intended use. Below are the major categories: A. According to Route of Administration 1. Oral Tablets o Compressed Tablets: Standard tablets swallowed with water. o Chewable Tablets: Intended to be chewed before swallowing (e.g., antacids). o Buccal Tablets: Placed in the cheek pouch for absorption through the buccal mucosa. o Sublingual Tablets: Placed under the tongue for rapid absorption (e.g., nitroglycerin). o Effervescent Tablets: Contain acids and carbonates that release CO₂ in water. o Lozenges/Troches: Dissolve slowly in the mouth, releasing medication gradually. 2. Vaginal Tablets (Pessaries) Inserted into the vagina for local effects, such as antifungal or antibacterial action. 3. Implant Tablets Sterile tablets inserted subcutaneously for prolonged drug release (e.g., contraceptive implants). B. According to Method of Manufacture 1. Compressed Tablets – Prepared by direct compression of powders. 2. Multiple Compressed Tablets – Contain multiple layers or cores to separate incompatible drugs or provide controlled release. o Layered Tablets o Press-coated Tablets C. According to Function or Release Profile 1. Immediate Release Tablets – Disintegrate rapidly after swallowing. 2. Controlled Release Tablets – Release the drug over an extended period. 3. Delayed Release Tablets – Release drug after a specific time (e.g., enteric-coated tablets). 4. Dispersible Tablets – Disintegrate in water before administration. 5. Orodispersible Tablets (ODTs) – Disintegrate rapidly in the mouth without water. Formulation of Tablets The formulation of a tablet involves combining the active ingredient with excipients to ensure proper compressibility, stability, and bioavailability. A. Essential Ingredients in Tablet Formulation 1. Active Pharmaceutical Ingredient (API): The main therapeutic agent. 2. Diluents (Fillers): Add bulk to the formulation (e.g., lactose, microcrystalline cellulose). 3. Binders: Provide cohesiveness to the powder (e.g., starch paste, PVP, gelatin). 4. Disintegrants: Help the tablet break apart after swallowing (e.g., sodium starch glycolate). 5. Lubricants: Prevent sticking to punches and dies (e.g., magnesium stearate). 6. Glidants: Improve powder flow (e.g., colloidal silicon dioxide). 7. Coloring and Flavoring Agents: Enhance appearance and palatability. 8. Coating Agents: Protect the tablet from moisture and mask taste (e.g., HPMC, shellac). B. Steps in Tablet Formulation (Manufacturing Process) 1. Weighing and Mixing of Ingredients 2. Granulation o Wet Granulation or Dry Granulation to improve flow and compressibility. 3. Drying of Granules 4. Sizing and Sieving 5. Blending with Lubricants and Glidants 6. Compression into Tablets using tablet presses. 7. Coating (if required) – film coating, sugar coating, or enteric coating. 8. Packaging and Storage Evaluation Tests for Tablets Before release, tablets undergo a series of quality control tests to ensure consistency, safety, and efficacy. Test Purpose Typical Limit/Requirement 1. Appearance Check for color, shape, surface defects Should be uniform 2. Weight Variation Test Ensures uniformity of weight ±5% deviation allowed 3. Hardness Test Measures mechanical strength 4–10 kg/cm² 4. Friability Test Measures tablet’s resistance to abrasion ≤1% weight loss 5. Disintegration Test Time taken to break into particles ≤15 min for uncoated tablets 6. Dissolution Test Measures rate of drug release Must meet pharmacopeial standards 7. Thickness and Diameter Ensures uniform size Within set limits 8. Content Uniformity Test Ensures each tablet has uniform drug amount 85–115% of label claim Importance of Tablets in Drug Delivery 1. Accurate Dosage: Ensures uniform and precise drug delivery. 2. Patient Convenience: Easy to handle, store, and administer. 3. Stability: Longer shelf life compared to liquid forms. 4. Cost-Effectiveness: Low manufacturing and packaging costs. 5. Controlled Release Options: Modified release tablets improve therapeutic efficiency. 6. Masking Taste and Odor: Through coatings and excipients. 7. Ease of Identification: Through unique shape, size, and imprint.


Definition of Tablets

A tablet is a solid unit dosage form of medication containing one or more active pharmaceutical ingredients (APIs) along with suitable excipients. Tablets are usually prepared by compressing powder or granules using a tablet press. They are one of the most popular and convenient dosage forms due to their accuracy in dosing, stability, and patient compliance.

Pharmaceutical Definition:

A tablet is a solid dosage form prepared by compressing or molding, containing a specific quantity of drug with or without excipients.

 

Types of Tablets

Tablets can be classified based on their route of administration, method of manufacture, or intended use.
Below are the major categories:

A. According to Route of Administration

  1. Oral Tablets
    • Compressed Tablets: Standard tablets swallowed with water.
    • Chewable Tablets: Intended to be chewed before swallowing (e.g., antacids).
    • Buccal Tablets: Placed in the cheek pouch for absorption through the buccal mucosa.
    • Sublingual Tablets: Placed under the tongue for rapid absorption (e.g., nitroglycerin).
    • Effervescent Tablets: Contain acids and carbonates that release CO₂ in water.
    • Lozenges/Troches: Dissolve slowly in the mouth, releasing medication gradually.
  2. Vaginal Tablets (Pessaries)
    Inserted into the vagina for local effects, such as antifungal or antibacterial action.
  3. Implant Tablets
    Sterile tablets inserted subcutaneously for prolonged drug release (e.g., contraceptive implants).

 

B. According to Method of Manufacture

  1. Compressed Tablets – Prepared by direct compression of powders.
  2. Multiple Compressed Tablets – Contain multiple layers or cores to separate incompatible drugs or provide controlled release.
    • Layered Tablets
    • Press-coated Tablets

 

C. According to Function or Release Profile

  1. Immediate Release Tablets – Disintegrate rapidly after swallowing.
  2. Controlled Release Tablets – Release the drug over an extended period.
  3. Delayed Release Tablets – Release drug after a specific time (e.g., enteric-coated tablets).
  4. Dispersible Tablets – Disintegrate in water before administration.
  5. Orodispersible Tablets (ODTs) – Disintegrate rapidly in the mouth without water.

 

Formulation of Tablets

The formulation of a tablet involves combining the active ingredient with excipients to ensure proper compressibility, stability, and bioavailability.

A. Essential Ingredients in Tablet Formulation

  1. Active Pharmaceutical Ingredient (API): The main therapeutic agent.
  2. Diluents (Fillers): Add bulk to the formulation (e.g., lactose, microcrystalline cellulose).
  3. Binders: Provide cohesiveness to the powder (e.g., starch paste, PVP, gelatin).
  4. Disintegrants: Help the tablet break apart after swallowing (e.g., sodium starch glycolate).
  5. Lubricants: Prevent sticking to punches and dies (e.g., magnesium stearate).
  6. Glidants: Improve powder flow (e.g., colloidal silicon dioxide).
  7. Coloring and Flavoring Agents: Enhance appearance and palatability.
  8. Coating Agents: Protect the tablet from moisture and mask taste (e.g., HPMC, shellac).

 

B. Steps in Tablet Formulation (Manufacturing Process)

  1. Weighing and Mixing of Ingredients
  2. Granulation
    • Wet Granulation or Dry Granulation to improve flow and compressibility.
  3. Drying of Granules
  4. Sizing and Sieving
  5. Blending with Lubricants and Glidants
  6. Compression into Tablets using tablet presses.
  7. Coating (if required) – film coating, sugar coating, or enteric coating.
  8. Packaging and Storage

 

Evaluation Tests for Tablets

Before release, tablets undergo a series of quality control tests to ensure consistency, safety, and efficacy.

Test

Purpose

Typical Limit/Requirement

1. Appearance

Check for color, shape, surface defects

Should be uniform

2. Weight Variation Test

Ensures uniformity of weight

±5% deviation allowed

3. Hardness Test

Measures mechanical strength

4–10 kg/cm²

4. Friability Test

Measures tablet’s resistance to abrasion

≤1% weight loss

5. Disintegration Test

Time taken to break into particles

≤15 min for uncoated tablets

6. Dissolution Test

Measures rate of drug release

Must meet pharmacopeial standards

7. Thickness and Diameter

Ensures uniform size

Within set limits

8. Content Uniformity Test

Ensures each tablet has uniform drug amount

85–115% of label claim

 

Importance of Tablets in Drug Delivery

  1. Accurate Dosage: Ensures uniform and precise drug delivery.
  2. Patient Convenience: Easy to handle, store, and administer.
  3. Stability: Longer shelf life compared to liquid forms.
  4. Cost-Effectiveness: Low manufacturing and packaging costs.
  5. Controlled Release Options: Modified release tablets improve therapeutic efficiency.
  6. Masking Taste and Odor: Through coatings and excipients.
  7. Ease of Identification: Through unique shape, size, and imprint.