It’s so common for most of us to pop pills from the blister package. There are so many types of tablets that we come across, which we will know about later. Due to the countless advantages of tablets, the tablet is mostly administered.

The tablet is a pharmaceutical dosage form, which contains active ingredients and excipients. Active ingredient / Active pharmaceutical ingredients are responsible for therapeutic effect and excipients provide proper structure to form a dosage form. The tablet is a popular dosage form where the compressed tablet is most common. Solid dosage form consists of 90% of all dosage forms.  

Types of tablets: 

According to it’s dosage form

1. Compressed tablet
2. Coated tablet
3. Uncoated tablet
4. Effervescent tablet
5. Enteric-coated tablet
6. Prolonged released tablet
7. Implantable tablets
8. Hypodermic tablets
9. Chewable tablets

According to it’s route of administration:

1. Oral route of administration
2. Vaginal route of administration

Tablets classified according to it’s dosage form:

1. Compressed tablets:

The compressed tablet is a common type of tablet, it is simply compressed granules or powders. Coated and uncoated tablets can come under compressed tablets. 

Methods of preparation of compressed tablets are mainly dry granulation and wet granulation. Dry granulation can be termed as a slugging method, in which a slug is formed and compressed into a finished product. Whereas wet granulation is a complicated method and time-consuming. Wet granulation cannot be useful for thermolabile substances. 

Procedure for wet granulation:

 Powder ingredients are weighted and mixed by gravimetric dilutions. Granulating solution is prepared. Mechanical arms knead a granulating preparation and powder to gain proper consistency later it is forced through a screen which is dried in an oven. Particle size is a screen to make sure to have a uniform size. After the screening of particle size, lubricant and disintegrating agents are mixed and then granulation is compressed to form a finished tablet.

2. Coated tablets: 

In this type of tablet. Sugar-coated tablets can be coined under coated tablets. Tablet coating can be done for many reasons, primarily it is for mask bitterness and prolonged release of the tablet. 

Types of tablet coating.

Sugar coating: 

Steps involved in sugar coating, which is mainly for the reason to enhance the bitterness of the tablet. 

Step 1: Sealing
Step 2: Subcoating
Step 3: Smoothing
Step 4: Colouring
Step 5: Polishing
Step 6: Printing

Film coating:

This coating is done for a drug to prevent it from degrading in gastric juice. 

Tablet coating machines:

1. standard Coating Pan/ conventional pan system
2. Perforated Coating Pan
3. Fluidized Bed Coater

Evaluation parameters for coated tablets: 

1. Disintegration test
2. Dissolution test
3. Organoleptic characters
4. Uniformity of tablet content
5. Friability test
6. Stability studies
7. Hardness and strength test.
8. Uncoated tab: Uncoated tablets are normal tablets that can fall under simple compressed table. Which can be classified into compressed layer tablets.
9. Drug content
10. Adhesion test.   

Disadvantages of tablet coating: 

1. Tablet coating is a time-consuming process.
2. Tablet coating can affect the pharmacodynamic properties of the tablet.
3. Tablet coating is a complicated process, which requires high techs and expertise. 
4. Tablet coating can be prone to defects.

According to its route of administration:

Tablets used for oral administration:

1. Dental Cone: A dental cone is used for smoothening toothache, which is placed between teeth.
2. Lozenges: It can be classified under Buccal tablet but mostly medication that relieves throat irritation can come under in this classification.
3. Buccal tablets: Buccal tablets are administered into the buccal civility, which is placed between the gums and the inner layer of the skin. It has been shown that buccal tablet gives rapid onset of action.
   Buccal tablets bypass the gastrointestinal tract, they can minimise gastrointestinal irritation. In buccal tablets, they disintegrate slowly. Drugs can absorbed into the blood stream easily, which can be termed as the absorption of tablets. The advantage of this type of tablet is also that it can be useful for people who feel uncomfortable swallowing a medication. 
4. Sublingual tablets: Sublingual tablets are placed under the tongue, where they get absorbed and avoid fist-pass metabolism. Drugs that are used to lower blood pressure are administered sublingually. Nitrogen glycerides are given sublingually. The disadvantages of this type of tablet are drinking, smoking can affect the working of the drug. 

Evaluation of tablet:

Evaluation of the tablet is important to ensure sure quality of the tablet. 

Method to evaluate tablets:

Analytical determination of tablets: 

It is to measure the variation of weight in a batch of tablets. According to USP 24 NF guideline, “shall be not less than 90% and not more than 110% of the theoretically calculated weight for each unit.” 

Tablet hardness: it can be coined as a friability test. The tablet should be hard enough to withstand stress during packaging, and shipment. Devices used to check the hardness of tablets are Pfizer, strong cob and stokes hardness. 

Tablet disintegration and dissolution: 

Tablet disintegration is used to check the disintegration and dissolution of tablets after their administration. There are apparatus that are commercially available to check the dissolution and disintegration of tablets.

The disintegration time of the tablet should be 15-30 mins, although it depends on the type of tablet. Mostly dissolution rate doesn’t prove anything. A drug can have rapid dissolution which can have low bioavailability. But in some formulations, dissolution is rate rate-determining step for absorption of a drug. It is an important parameter to determine but many pharmaceutical industries don’t have equipment to measure. 

Tablet defects:

To ensure the quality of tablets, it is important to address defects in tablets. Tablet defects and manufacturing defects should not be acceptable. Tablet defects are either related to virtual effects or functional defects. 

The following defects are:

1. Capping
2. Picking
3. Cracking
4. Lamination
5. Chipping
6. Sticking
7. Double impression
8. Layers are not sharply defined
9. Uneven breakage

Capping: 

In compressed types of tablets, capping is common. Capping is the complete and partial separation of the top or button crown from the main part of the body. The most common effect occurs during manufacturing is capping. 

Lamination:

 Lamination is also common in all types of tablets. It can be the same as capping, but separating in more than two layers. 

Cause: 

1. Too dry granules.
2. Entrapment of air
3. Too soft granules
4. Excess compaction force.

Remedies:

1. Using the optimum amount of lubricant.
2. Using or changing of excipients.
3. Compressed at room temperature.

Motting:

Motting is appearing in light or dark spots on tablets. It can be seen in any type of tablet. The most common cause of this type of defect is an unequal distribution of colours or ingredients. A coloured excipient is used with white coloured excipent. :