Today here we will briefly go through Tablets coating issues
Advantages and Process and the Problem and their Solutions
A typical method of dispersion is as follows:• The water/solvent is charged into the mixing vessel, with the mixer positioned off
center to create a vortex.
• The dry ingredients are added and drawn into the vortex.
• Mixing continues until the ingredients are fully dissolved.
• The finished coating is applied to the tablets by spraying in coating pans.
In order to achieve the above, a number of processing factors must be considered:
• The mixer must be capable of circulating the entire contents of the vessel to ensure
• A wide range of colors are used in tablet coatings, and batch sizes are generally small.
• Equipment must be easily cleaned and ideally adapted to be cleaned in place (CIP).
• The mixer must be capable of processing at ambient temperatures as some
ingredients may be heat sensitive.
Pharmaceutical tablets are given a coating for a number of reasons:
• To improve the appearance and aid identification.
• To protect the tablet from moisture and other adverse conditions.
• To lubricate the tablet to ease swallowing.
• To disguise unpleasant tastes.
• To create a barrier between the active ingredient and the gastrointestinal tract.
• To control the release of drug into the body.
Coatings generally consist of a sugar or cellulose based binder, plasticizer, film forming
agent and colorant.These are supplied in granulated or powder form for dispersion in
aqueous or organic solvents at concentration varying from 10 -20% depending on the
desired properties and formula.
Manufacture of Pharmaceutical Tablet Coatings
Whilst many proprietary coatings are designed to be easily dispersed, a number of
problems are frequently encountered when using conventional mixers and agitators:
• Conventional agitators cannot rapidly dissolve materials at ambient temperatures.
• Agitators are not capable of rapidly breaking down agglomerates.
• A low particle size is required in order to avoid clogging of the spraying
• If the colorant is not properly dispersed, flecks of color can occur in the tablets.
A high shear mixer can overcome all of these manufacturing difficulties. The
rotor/stator work head is capable of dissolving sugar and dispersing cellulose type
materials in a fraction of the time taken by conventional agitators, operating as follows:
This develops a circulatory pattern of mixing within the (see also pharmaceutical validation)
vessel which ensures that all material passes through the
work head many hundreds of times, quickly dissolving the
granules into the liquid and progressively reducing the particle size. This is achieved without the need for raised temperatures.
The granules are milled by the intense action provided by
the rotor/stator work head.Agglomerates are broken down
and dispersed.The materials are then forced out through
the stator into the body of the mix. Fresh liquid and
powdered ingredients are drawn into the work head.
The vessel is charged with the base liquid.The mixer is
started and the coating granules and other ingredients are
added.The high speed rotation of the rotor creates a
powerful suction which draws the granulated or powdered
coating material and liquid into the work head. They are
rapidly mixed and driven towards the periphery of the
work head by centrifugal force pharma process validation
• Consistent product quality and repeatability.
• Agglomerate-free mix.
• Rapid mixing time.
• Maximized yield of raw materials as thickening agents are fully hydrated and other
ingredients fully dispersed.
A In-Line Mixer Agitator for in-tank uniformity
Pipeline return below fluid
level to prevent aeration
High Shear Batch Mixers.
• Suitable for batch sizes up to 400 gallons.
• Can be used on mobile floor stands.
• Sealed units available for pressure/vacuum operation.
• Small units available for R&D and pilot production.
High Shear In-Line mixers.
• Ideal for larger batches
• Easily retro fitted to existing plant
• Self pumping
• Can be used to discharge vessel
• Ultra Hygienic models available
Bottom Entry Mixer Stirrer/Scraper Unit
High Shear Bottom Entry mixers.
• Suitable for use on high viscosity products in
conjunction with an anchor stirrer/scraper
• Ultra Hygienic
tablets dosage form advantages and desadvantages