Tablets

Coated and uncoated tablets, various modified tablets; Sustained release, extended-release, fast dissolving, multilayered, etc.

Tablets are solid unit dosage forms of medicament or medicaments with or without suitable excipients prepared by molding or compression.

Advantages:

• 1. Compact and light in weight,

• 2. Easy to pack, transport and store,

• 3. Easy to dispense,

• 4. Easy to administer,

• 5. Easy to maintain dosage accuracy,

• 6. Easy to administer in fractions by using draw lining on a tablet,

• 7. Easy to mask bitterness or nauseous smell of medicament,

• 8. Easy to manufacture at large scale,

• 9. High stability of medicaments, Long duration of self-life,

• 10. Easy to formulate sustained release dosage form as a tablet,

• 11. Easy to target the site of drug absorption in GIT.

• 12. Economical.

Disadvantages

• 1. Drugs with low density and low compressibility cannot be dispensed as compressed tablets,

• 2. Not suitable for poor wet ability, slow dissolution property, oxygen sensitive or moisture sensitive drugs,

Types of Tablets:

There are two types of tablets. These are molded tablets and compressed tablets. Molded tablets are not in use in allopathic systems.

• Compressed Tablets: Compressed tablets are unit solid dosage forms prepared by using high compression on medicament or medicaments with or without excipients in a desired shape. There are various types of compressed tablets

  • 1. Uncoated tablets: Single layered or multilayered tablets without any additional coating or covering is called uncoated tablet.

  • 2. Coated Tablets: Tablets with an additional layer of coating is called coated tablet. There are several types of coated tablets

    • a. Enteric Coated Tablets: These tablets are meant to disintegrate in the intestine not in the stomach after oral administration. They do not disintegrate in acidic media. They disintegrate only in alkaline media. Eg. Erythromycin tablet,

    • b. Sugar-Coated Tablet: They have a sugar coating to mask the bitter taste and unpleasant odor of the medicaments. Sugar coating also protects medicaments from the atmosphere and makes tablets elegant.

    • c. Film-coated tablets: They are thin layers of coating of polymers such as hydroxypropyl cellulose, hydroxypropyl methylcellulose, and ethyl cellulose. They protect medicaments from atmospheric conditions. They make tablets elegant but they are less elegant than sugar-coated tablets.

    • d. Press-coated tablets: Granules of incompatible medicaments are compressed around a compressed tablet.

  • 3. Multilayered tablets or multi-compressed tablets: Two or more layers of medicaments are compressed in one tablet. Multilayered tablets contain two or more layers of incompatible medicaments. These layers may have different colors.

  • 4. Chewable tablets: These tablets are broken by teeth and chewed before ingestion. These tablets are used for patients who face difficulty swallowing a tablet. Eg. Antacids tablets, and multivitamin tablets are dispensed as chewable tablets.

  • 5. Lozenge tablets: These tablets do not disintegrate and they are allowed to dissolve slowly inside the oral cavity. Normally they are used as demulcent to produce a soothing effect continuously on the mucus membrane of the throat.

• 6. Sublingual Tablets: These tablets are placed under the tongue or on the side of the cheek to release medicaments slowly with few exceptions. Nitroglycerin and mannitol hexanitrate are administered as sublingual tablets that release them quickly. Normally medicines that are destroyed in GIT, undergo fast-pas metabolism, or produce rapid action are administered as sublingual tablets. Drug absorption from the sublingual route is much faster.

• 7. Buccal tablet: These tablets are placed inside oral cavity between gum and lips or cheek. They dissolve slowly or disintegrate slowly. They do not undergo first-pass metabolism and are absorbed directly into the blood from the oral cavity.

• 8. Effervescent tablets: Ingredients of these tablets react with water to release carbon dioxide bubbles. These carbon dioxide bubbles produce effervescent to break tablets in water. It increases the rate of dissolution of medicaments in aqueous media and increases their palatability. Effervescence also increases the rate of absorption of acidic drugs in the stomach. Ingredients in the tablet that release carbon dioxide are sodium bicarbonate, citric acid, and tartaric acid. These ingredients react in the presence of water to release carbon dioxide. These tablets are required to be protected from moisture during storage.

• 9. Vaginal tablets (inserts): They are ovoid or pear-shaped tablets meant to dissolve slowly inside the vagina. Normally antibacterial, antiseptics, etc are administered as vaginal tablets to treat vaginal infections.

• 10. Hypodermic tablets: These are sterile tablets of soluble medicaments meant to be dissolved in water for injection for parenteral administration. These tablets are not preferred.

• 11. Soluble tablets: These tablets are meant to be dissolved in water before administration into the body.

• 12. Modified Tablets: Above said tablets are considered immediate-release tablets (IR Tablets). IR Tablets dissolve or disintegrate shortly to release medicaments inside the body. They are absorbed quickly and reach pick level in short duration. Medication level decreases slowly as the body eliminates it. It requires an increase in dose frequency. This problem is solved by slight modifications in the formulation of tablets. It is called modified-release tablets. It releases medication slowly for a longer duration.

  • a. Extended-release tablets: These tablets remain inside the body for a longer duration. This decreases the medication frequencies. It includes both sustained-release tablets and extended-release tablets.

  • b. Sustained release tablets (SR Tablets): These tablets release medicaments slowly for longer duration. These tablets are labeled as “SR” at the end of the name of the tablet. The body will get medicinal benefits for a longer duration. Fewer doses of this are required to administer. These tablets release medicaments for a longer duration but it does not mean they maintain medicament levels in the body for a longer duration.

  • c. Controlled release tablet: It releases medicaments at a constant rate to keep the medication level constant for a specified period. These tablets are labeled as “ER” at the end of the name of the tablet. It precisely controls the level of medicaments in the body. But SR Tablets release medicaments slowly but does not have any role in controlling the level of medicaments constant inside body.