Coating is a very important and critical process which is carried out in pharmaceutical industries and if you are looking for interview questions related to the coating process then read the complete article.
Q:1
What is coating?
Coating is a process where a layer of coating materials is applied over the surface of solid dosage form to get extra benefits which are not possible to achieve without coating.
Q:2
For which dosage form can we apply the coating?
We can coat the following solid dosage forms,
- Tablets
- Pills
- Granules
- Powders
- Crystals
- Pellets
Q:3
What Is MFT?
MFT is in an important term used for minimum film-forming temperature and is defined as
the minimum temperature above
which film formation takes place.
Q:4
What is the purpose of tablet coating?
A layer of coating materials is applied over the surface of tablets to get the following added benefits
- To mask the unpleasant taste or colour.
- To give protection from moisture & humidity.
- Protection from light degradation.
- Alter the drug release pattern.
- To protect the sensitive APIs from degradation in the stomach.
- To swallow tablets is easier.
- To reduce friction during blistering.
- To remove chances of dust contamination during the blistering process.
- To give strength to tablets to avoid breaking during transportation.
- To enhance the elegance of the tablet.
- To prevent mix up by adding colors in the tablet coating.
Q:5
What is the principle of tablet coating?
The basic principle of tablet coating is very simple, it works on the principle of weight gain and evaporation.A suspension of coating materials is sprayed after automation over a warm bed of rotating tablets.
Hot air is supplied to evaporate the solvent and coating material is deposited over the tablets surface until the achievement of required weight gain or colour uniformity.
Q:6
What are the types of tablet coating?
Common tablet coating types are 3 but on advanced level there are four types of tablet coating which are as,
- Sugar Coating
- Film Coating
- Enteric Coating
- Drug Coating
Q:7
What Is Film Coating?
Film coating is the type of tablet coating where we apply a very thin layer of polymer over any solid dosage form. The layer formed over the tablet is very thin, usually 5 to 100 microns and this thin layer is known as film which is why the name film coating is used.
Q:8
What is sugar coating?
Sugar coating is the type of tablet coating where we apply a heavy coat of thick sugar solution with other excipients and weight gain reaches over 50 to 100%.
Q:9
Film coating vs. sugar coating?
The first basic difference between sugar coating and film coating is the percentage of weight gain.In the case of film coating, only 1 to 5 percent gain in weight is observed but during sugar coating fifty to hundred percent gain is achieved.
The layer formed in film coating is very thin and in the case of sugar coating, it is thick.
Q:10
Why do we use Enteric coating?
Enteric coating is done for those active pharmaceutical ingredients which cause stomach irritation or are degraded by the stomach’s acidic environment, so these API-containing products are coated with a polymer which dissolves in the basic pH media and protects the release of active pharmaceutical ingredients in the acidic media.
Q:11
Which polymers are used for film coating?
The following polymer classes are most commonly used for film coating.
- Cellulosic polymer (HPMC)
- Vinyl polymer (PVP)
- Glycols polymer (PEG)
- Acrylates Polymer (Eudragit)
Q:12
What Are Idle Properties Of Filmformers?
- Easily soluble in the selected solvent.
- Facilitates release of API.
- Should form a strong, clear and non-tacky film.
Q:13
Which polymers are used for enteric coating?
Following polymers are used for enteric coating,
- Cellulose acetate phthalate (CAP)
- Cellulose acetate trimellitate (CAT)
- Eudragit L
- Eudragit S
Q:14
What Is Drug Coating?
The process where active pharmaceutical ingredients are added in coating suspension and sprayed over the tablets surface is known as tablet drug coating.
Q:15
What is weight gain during film coating?
1 to 5% weight gain is obtained during the film coating process.
Q:16
What is weight gain during enteric coating?
In enteric coating, the weight gain is usually 10 to 12% or may vary depending on the stability of drug in acidic media as per specifications
Q:17
What is weight gain during sugar Coating?
In the case of sugar coating the highest percentage of weight gain is achieved and it is usually 50 to 70% and sometimes 100% weight gain of the original tablet is also observed.
Q:18
What are the stages of sugar coating?
Sugar coating is completed in the following
- Sealing
- Sub coating
- Smoothing or grossing
- Colouring
- Polishing
Q:19
Enlist Excipients Used as Sealants In Sugar Coating?
- Shellac
- Zein
- PVAP
- HPC
- CAP
Q:20
Enlist Excipients used as polishing materials for sugar coating.
The following materials are used for polishing materials for sugar coating,
- Carnauba Wax
- Beeswax
- Candelilla Wax
- Hard Paraffin Wax
Q:21
What are the defects of sugar coating?
The following are common defects observed during the tablet coating process,
- Chipping of tablets
- Cracking of tablets
- Marbling
- Blooming & Sweating
Q:22
What are the components of tablet coating suspension?
- Polymer
- Solvent
- Plasticizer
- Opacifiers
- Antifoaming
- Anti Tacking
- Colourants
Q:23
What Are The Types Of Coating Based On Solvent?
On the basis of the solvent used, there are three types of tablet coating. The first one is the aqueous coating second one is the organic coating and the third one is the combination of aqueous plus organic which is known as hydro alcoholic coating.
Q:24
Critical process parameters for coating?
Following are the critical process parameters of tablet coating,
- Inlet air temperature
- Outlet air temperature
- Tablet bed temperature
- Airflow volume
- Pan speed
- Spray rate
- Atomization air pressure
- Spray gun to bed distance
Q:25
What is tablet bed temperature?
Tablet bed temperature is the term used to indicate the temperature of the rotating tablet surface, in simple words the temperature of tablets in the coating pan is known as tablet bed temperature.
Q:26
What is the recommended tablet bed temperature?
Tablet bed temperature is maintained depending upon the solvent used for coating suspension preparation.
For aqueous coating tablet bed temperature should be 40 to 42°C.
For organic coating tablet bed temperature should be 32 to 33°C.
For hydro alcoholic coating suspension tablet bed temperature should be 34 to 35°C.
Q:27
What is atomization air pressure?
The pressure of the compressed air that is supplied to the spray guns to convert the coating suspension into fine mist or droplets.
Q:28
What Is The Recommended distance between the tablet and spray nozzle
The distance varies depending upon the types of solvent & spray rate, usually, it is 8 to 12 inches.
Q:29
What are common tablet coating defects?
The following are the most common tablet coating defects,
- Sticking
- Picking
- Twinning
- Orange peel
- Weight gain issue
- Colour variation
- Chipping
- Logo bridging
Q:30
What is the tablet twinning?
Tablet twinning is the tablet coating defect which is usually observed in case of the capsule-shaped tablets and in this defect 2 tablets join with each other side by side & this effect is known as tablet winning as tablets look like twins.
Q:31
Types of tablet coating equipment?
There are 2 types of tablet coating pan
- Conventional coating pan
- Perforated coating pan
Q:32
What is a perforated tablet coating pan?
Advanced types of tablet coating machines have a coating pan which had small holes or perforations. These holes or perforations allow air to come inside the coating pan to warm the tablet and to evaporate the solvent. These perforations also allow the air to come out of the pan.
Q:33
What are the types of perforated coating pans?
Following are types of perforated tablet coating pan
- Accela cota
- Dria coater
- Hi coater
- Glatt coater
Q:34
What are the components of tablet coating equipment?
Tablet coating equipment has the following components.
- Coating pan
- Spray guns
- Peristaltic pump
- Solution transfer pipes
- Inlet air duct
- Outlet air duct
- Butterfly valve
- Exhaust fan
- Air handling unit
- HMI
Q:35
What is the function of the Peristaltic pump?
The function of the Peristaltic pump is to transfer the coating suspension from the suspension tank to the spray nozzle by the peristaltic movements.
Q:36
What is the polymer?
Polymer is also known as filmformer & these are the excipients which are used in coating suspension to form a film.
Q:37
What are the common tablet coating plasticizers?
- Glycerine
- Propylene glycol
- PEG
- Triacetin
- Castor oil
Q:38
What are the examples of opacifiers in tablet coating?
Most commonly used opacifiers for tablet coating are,
- Titanium dioxide
- Talc
- Magnesium carbonate
- Magnesium oxide
Q:39
What are the most commonly used solvents for coating?
The most commonly used solvents for tablet coating are
- Water
- IPA
- Dichloromethane
- Acetone
Q:40
What are the types of eudragit?
There are two types of eudragit
- Eudragit L
- Eudragit S
Q:41
Types of advanced tablet coating?
- Compression coating
- Dip coating
- Electrostatic spray powder coating
- Photocuring
- Vacuum film coating
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