Tablets are the most commonly used dosage form which are manufactured in Pharmaceutical Industries. Many tablets in pharma are coated and some tablets are uncoated.
Tablet coating is the process where we apply a thin coat of film formers & related excipients over the tablet surface. In this article, we will discuss why we apply a coat over tablets or why tablets are coated.
Reasons For Tablet Coating
- Taste Masking
- Environmental Protection
- Gastric Protection
- Release Modification
- Increased Strength
- Reduce Friction
- GMP ComplianceÂ
- Brand Identification
- Prevent Mix Up
- Easy To Remember
1.0 Taste Masking
The basic purpose of tablet coating is to mask the bitter, sour or unpleasant taste of the drugs. Many APIs have a bad taste & it is challenging for patients to swallow the tablet.
We know that dosage form has first contact with the tongue where taste buds immediately sense the taste so a layer of polymer is applied over the tablet surface to hide the original taste of drugs.
Example
People working in the pharmaceutical industry are well aware of various tastes of drugs. Many APIs even if not tasted make our throat bitter due to dusty environment during handling like ciprofloxacin HCl, sitagliptin phosphate etc. So to mask their taste & make their intake easy we coat the tablets.
2.0 Environmental Protection
Tablet coating is applied over the tablet to protect from destructive effects of the environment like temperature & humidity.
Coating films also act as a barrier to prevent penetration of moisture & protect the drug to ensure its effectiveness.
3.0 Gastric Protection
Many drugs result in stomach irritations or are degraded by the acidic pH of the stomach. The ultimate goal for such drugs is to alter their release pattern, which means the drug release is modified to inhibit its release in the acidic pH of the stomach and it is released in the basic pH of the intestine.
ExampleÂ
Enteric coa
4.0 Release Modification
Delayed release & extended-release is other added benefit which is achieved by the process of tablet coating.
Various types of coating polymers are used to make the release of drugs slow to prolong their action.
5.0 Increased Strength
The process of coating over tablets is like the lamination sheet.As we apply lamination to protect fragile objects, in the same way, the coat of polymer over the tablet surface increases the mechanical strength of tablets & prevents their breakage during blistering, packaging & transportation.
6.0 Reduce Friction
We are familiar that tablets are blistered into Alu-Alu or Alu-PVC blister packaging. A blister machine is used for the blistering process where tablets are delivered to the blister pocket by a feeding system.
A film of coating over the tablet surface gives them a smooth finish & hides the rough surface. The smooth finishing reduces the friction during feeding & ensures a trouble-free blistering process.
7.0 GMP Compliance
There are chances of dust generation during the handling of core or uncoated tablets. This dust may result in cross-contamination which is why by applying a thin layer of coating, the tablet surface is covered to prevent chances of powder shredding or dust generation.
8.0 Brand Identification
Some coating types & colours are identification of a specific brand. For example, some well-renewed pharma are still using sugar-coating to maintain their brand identification.
9.0 Prevent Mix Up
The use of different colours in tablet coating for various tablets of the same shape & size is helpful to prevent mix-up.
Suppose we have two tablets A & B with the same shape e.g. round & same weight 500 mg having the same colour e.g. white.
It is not possible to differentiate these tablets physically. So apply a blue coat to product A & Green colour to product B, it will be helpful to prevent mix-up.
10 Easy To Remember
Coating colours may help many patients to remember their dose from the colour scheme. Less educated patients can easily remember their dose from colour eg which colour tablet they have to take in the morning & which in the evening.