INTRODUCTION TO TABLETS IN PHARMACEUTICS
Tablets are the most commonly used solid dosage forms because they are easy to take, safe, affordable, and convenient for patients. A tablet contains a fixed dose of medicine compressed into a small, easy-to-swallow shape. Tablets also allow accurate dosing and good long-term stability, making them the preferred choice in healthcare worldwide.
Tablets may be designed for immediate action, taste masking, delayed release, or prolonged release depending on the therapeutic need. They are produced in large numbers with uniformity in size, weight, and drug content. This makes tablets one of the most important and widely accepted dosage forms in modern pharmaceutics, and a frequently tested topic in D.Pharmacy examinations.
Uncoated Tablets
Uncoated tablets are the simplest type of tablets. They do not contain any outer covering and are made by compressing the drug along with excipients such as binders, fillers, lubricants, and disintegrants.
Advantages of Uncoated Tablets
- Simple and cost-effective to manufacture
- Fast disintegration in the stomach
- Easy for large-scale production
Disadvantages of Uncoated Tablets
- Poor taste and smell cannot be masked
- Not suitable for drugs sensitive to stomach acid
- Less protection from moisture and heat
Coated Tablets
Coated tablets are covered with an additional layer such as film, sugar, or polymer to improve appearance, taste, stability, and swallowing experience. Coating also protects the drug from light, moisture, and acidic conditions in the stomach.
Types of Tablet Coating
1. Sugar-Coated Tablets
These tablets are coated with a thick sugar layer. It masks bitter taste and gives a shiny, attractive look. Mostly used for paediatric patients.
2. Film-Coated Tablets
A thin polymer film is applied to improve strength, appearance, and taste masking. These tablets are lighter than sugar-coated tablets.
3. Enteric-Coated Tablets
Enteric coating prevents the tablet from dissolving in the acidic environment of the stomach. It dissolves only in the intestine, ideal for acid-sensitive drugs like omeprazole and aspirin.
4. Gelatin-Coated Tablets
These tablets have a gelatin layer that makes swallowing easier and gives a capsule-like feel. They also help prevent tampering and counterfeiting.
Modified Release Tablets
Modified tablets are specially designed to release the drug in a controlled or targeted way. They improve therapeutic effectiveness and patient convenience.
1. Sustained Release (SR) Tablets
Sustained release tablets release the drug slowly over several hours. This helps maintain a steady drug level in the body for a long time.
- Reduced dosing frequency
- Better patient compliance
- Lower chances of side effects
2. Extended Release (ER/XR) Tablets
Extended release tablets release medicine over 12 to 24 hours. They prevent peaks and drops in drug levels and are usually taken once or twice a day.
3. Fast Dissolving Tablets (FDT/ODT)
Fast dissolving tablets melt quickly in the mouth without needing water. These are best for children, elderly patients, or those who have difficulty swallowing.
4. Multilayered (Bilayer) Tablets
Multilayer or bilayer tablets contain two or more layers of drug. This allows combining different release patterns and improves therapeutic flexibility.
- Two incompatible drugs in one tablet
- Immediate and sustained release in a single dose
- Better control over drug release
Manufacturing Methods of Tablets
Tablets are produced by three main manufacturing methods, chosen based on the properties of the drug and excipients used:
1. Wet Granulation Method
In this method, powdered drug and excipients are mixed with a liquid binder to form a wet mass, which is then granulated, dried, and compressed. It is the most widely used method and works well for drugs that are stable in the presence of moisture and heat.
2. Dry Granulation Method
This method is used when the drug is sensitive to moisture or heat. Powders are compacted into large, hard tablets called “slugs” using a heavy-duty press, which are then broken down into granules and re-compressed into final tablets. This is also called slugging.
3. Direct Compression Method
Here, the drug and excipients are blended and compressed directly into tablets without any granulation step. It is the fastest and simplest method but requires the drug to have good flow properties and compressibility on its own.
Comparison of Tablet Manufacturing Methods
| Method | Uses Liquid Binder? | Best Suited For |
|---|---|---|
| Wet Granulation | Yes | Moisture- and heat-stable drugs |
| Dry Granulation | No | Moisture- or heat-sensitive drugs |
| Direct Compression | No | Drugs with good flow and compressibility |
Why Tablets Are Popular
Tablets offer many advantages such as accurate dosing, easy handling, long shelf life, and low manufacturing cost. They can be modified to suit different medical needs, such as taste masking, delayed release, fast action, or long-term release, which is why they remain the most preferred dosage form across the pharmaceutical industry.
👩🏫 Teacher’s Insight
A very common exam trap is confusing “sustained release” with “extended release” — students often use these interchangeably, but examiners expect you to know that SR maintains a steady level over several hours, while ER/XR specifically extends action to 12–24 hours, usually with once or twice daily dosing. Another point worth remembering for viva: enteric coating is not about taste masking — it’s about protecting the drug from stomach acid, or protecting the stomach from an irritant drug like aspirin.
When answering manufacturing method questions, always link the method to the reason it’s chosen — for example, “dry granulation is used because the drug is moisture-sensitive” scores better than simply listing the steps. Examiners look for that cause-and-effect understanding, not just memorized sequences.
Frequently Asked Questions (FAQs)
Q1. What is the difference between coated and uncoated tablets?
Uncoated tablets have no outer layer and disintegrate quickly, while coated tablets have an additional film, sugar, or polymer layer that improves taste, appearance, and stability.
Q2. Why are enteric-coated tablets used for drugs like omeprazole?
Enteric coating prevents the tablet from dissolving in the stomach’s acidic environment, allowing it to reach the intestine intact, which protects acid-sensitive drugs from degradation.
Q3. What is the difference between sustained release and extended release tablets?
Sustained release tablets release the drug steadily over several hours, while extended release tablets are formulated to act over a longer 12–24 hour period, typically requiring only one or two doses a day.
Q4. Who benefits most from fast dissolving tablets (FDTs)?
FDTs are especially useful for children, elderly patients, and individuals who have difficulty swallowing, since they dissolve in the mouth without needing water.
Q5. Which tablet manufacturing method is used for moisture-sensitive drugs?
Dry granulation is preferred for moisture- or heat-sensitive drugs, since it avoids the use of liquid binders and heat-drying steps.
Q6. What is the purpose of a bilayer tablet?
A bilayer tablet allows two different drugs, or two different release patterns of the same drug, to be combined in a single tablet, which is especially useful when the drugs are chemically incompatible with each other.
References
- Aulton, M.E., Aulton’s Pharmaceutics: The Design and Manufacture of Medicines, Churchill Livingstone.
- Ansel, H.C., Ansel’s Pharmaceutical Dosage Forms and Drug Delivery Systems, Lippincott Williams & Wilkins.
- Indian Pharmacopoeia, Government of India, Ministry of Health and Family Welfare.
- Lachman, L., Lieberman, H.A., The Theory and Practice of Industrial Pharmacy, CBS Publishers.
Dr. Saint Paul is a pharmacy educator, Pharm.D graduate, and academic content creator from Jawaharlal Nehru Technological University Kakinada (JNTUK), where he completed his Doctor of Pharmacy (Pharm.D) degree between 2015 and 2021.
He has more than 7 years of experience creating pharmacy educational content, writing study materials, and reviewing academic articles for pharmacy students. He has also contributed guest articles to pharmacy education platforms, including PharmD Guru.
At D.PharmGuru, his work focuses on simplifying complex Diploma in Pharmacy (D.Pharmacy) subjects into easy-to-understand notes, practical explanations, and exam-oriented educational resources for students across India.
His areas of focus include Human Anatomy and Physiology, Pharmaceutics, Pharmacology, Pharmaceutical Chemistry, Hospital and Clinical Pharmacy, and other core D.Pharmacy subjects.
