August 1, 2021: Pharmaceutical Interview Questions and Answers
#WhatIsCoating #WhyCoating #TechniquesForCoating
1. What is Coating?
The uniform deposition of a layer of material on or around a solid dosage form.
2. Why coating is done?
Coating is done for the following reasons:
a. Protect the drug from its surrounding environment (air, moisture, and light), with a view to improving stability.
b. Mask unpleasant taste, odor, or color of the drug.
c. Increase the ease of ingesting the product for the patient.
d. Impart a characteristic appearance to the tablets, which facilitates product identification and aids patient compliance.
e. Provide physical protection to facilitate handling. This includes minimizing dust generation in subsequent unit operations.
f. Reduce the risk of interaction between incompatible components. This would be achieved by coating one or more of the offending ingredients.
g. Modify the release of drug from the dosage form. This includes delaying, extending, and sustaining drug substance release.
h. Modify the dosage form by depositing the API or drug substance on or around a core tablet, which could be a placebo core tablet or a tablet containing another drug or a fractional quantity of the same drug.
3. What are the major techniques used for coating?
The coating material deposition typically is accomplished through one of six major techniques:
a. Sugar Coating – Deposition of coating material onto the substrate from aqueous solution/suspension of coatings, based predominately upon sucrose as a raw material.
b. Film Coating – The deposition of polymeric film onto the solid dosage form.
c. Core Enrobing – The gelatin coating of gravity or force fed pre- formed tablets or caplets.
d. Microencapsulation – The deposition of a coating material onto a particle, pellet, granule, or bead core. The substrate in this application ranges in size from submicron to several millimeters. It is this size range that differentiates it from the standard coating described in 1 and 2 above.
e. Compression Coating (also addressed in the Unit Dosing section) – A coating process where a dry coatings blend is applied on a previously compressed core tablet using a tablet compression machine.11 Therefore, this process is also known as a dry coating process that does not involve any water or any other solvent in the coating process.
f. Active/API coating – Deposition of active pharmaceutical ingredient (API or drug substance) on or around a core tablet utilizing any of the above five coating techniques.