Tablet coating is a process used in the pharmaceutical industry to apply a layer over tablets. This layer is not only for aesthetic purposes. It improves performance, stability, and patient compliance.
For designing effective and stable drug products. Fundamental knowledge about different kinds of coating is essential. Moreover, with increasing demands on drug efficacy, branding, and safety, choosing the right type of coating is more critical than ever.
This article explains the various types of pharmaceutical tablet coating and highlights their respective roles and advantages in the solid oral dosage forms.
What is film coating on tablets?
Pharmaceutical tablet coating involves applying a thin, uniform polymer-based layer over a tablet using aqueous, organic, or hydroalcoholic solutions. It is the most widely used coating method due to its versatility, speed, and functional flexibility. E.g.. NOVOMIX PLAIN, NOVOMIX GEN, NOVOMIX GEN II
Typical composition of tablet coating:
The typical composition of a pharma tablet coating depends on the type of coating (e.g., film, enteric, sugar), but most coating generally contain a combination of the following key components:
- Polymers: HPMC, PVA, etc.
- Plasticisers: PEG, triacetin, etc.
- Colourants: Lake pigments, titanium dioxide
- Solvent: Water, Solvent, and hydroalcoholic
Read more: The Science Behind Film Coating: Materials, Methods, and Mechanisms
Different types of tablet coating
There are different types of coating available, depending on how the drug needs to behave in the body, how it’s handled, or how it’s marketed. Let us understand each of these in detail.
Sugar coating for an attractive and smooth finish
Description: Sugar coating is a classic technique with a multistep process involving the application of syrup layers over the core tablet. Though mostly replaced by film coating, it is still used in nutraceuticals and herbal formulations for its glossy and colourful appearance.
There are four steps involved in this coating process:
- Sealing to protect the tablet’s core
- Subcoating to build size and shape
- Syruping to add bulk and sweetness
- Polishing to add the final shine with wax
Typical composition:
- Sugar
- Calcium Carbonate
- Talc
- Gelatin
- Waxe
- Starch
- Shellac
Applications and benefits:
Attractive, glossy finish
Limitations:
- Time intensive
- High Rejections/ Low Yield
- Skill dependent
To address the limitations of older, conventional multistep sugar coating processes, innovative excipient manufacturers have developed ready-mix film coating for tablets.
Read more: The Role of Ready-Mix Coating Systems in Reducing Tablet Coating Costs.
Example: Novo Excipient’s NOVOMIX S
Enteric coating to protect the API and the patient
Description: Enteric-coated tablets are designed to remain intact in the acidic pH of the stomach and dissolve in the higher pH of the intestine. This is critical for drugs that are acid-labile or cause gastric irritation.
Typical composition:
- Polymers: Methacrylic acid copolymers, HPMC phthalate, Cellulose acetate phthalate
- Plasticisers: Triethyl citrate, PEG
- Solvents: Aqueous, Organic, and Hydroalcoholic
Applications and benefits:
- Protects acid-sensitive APIs (e.g., enzymes, PPIs)
- Reduces gastric irritation
- Enables targeted intestinal drug release
- Used in colon-targeted and delayed-release formulations
Example: NOVOMIX ENT
Moisture barrier coating to protect sensitive drugs:
Description: Moisture barrier coating is a specialised pharmaceutical tablet coating that reduces water vapour transmission to protect hygroscopic or hydrolytically sensitive drugs.
Typical composition:
- Polymers: HPMC + Ethyl cellulose, PVA-PEG copolymers,
- Plasticisers: TEC, DEP, etc.
- Additives: Talc, Stearic Acid, Opacifiers
Applications and benefits:
- Improves shelf life of sensitive APIs
- Maintains tablet integrity in humid environments
- Useful for global markets with varying climates
Example: NOVOMIX MR (If you are using the organic solvent version, it is referred to as an HPMC-based tablet coating, as it uses Hydroxypropyl Methylcellulose (HPMC) and Ethyl Cellulose. The aqueous version, however, is based on Polyvinyl Alcohol.)
Sensory coating for patient-centric products:
Description: Sensory factors such as taste, odour, and appearance affect the patient’s mindset to adhere to the doctor’s prescription. Various flavours, clean label ingredients, odour masking, and attractive colours are incorporated in the coating to enhance the patient’s experience. Tablets coated with these coating are commonly used in over-the-counter (OTC), Pediatric, Geriatric, and Nutraceutical products.
Typical composition:
- HPMC or PVA
- Ti02 or Calcium Carbonate
- Talc
- PEG
- Flavours
- Mica Pigments
- Synthetic or Natural Colourants
Applications and benefits:
- Enhances product branding through colour or shine
- coating with sweeteners and flavours
- Clean Label Coating
- Promotes patient compliance
Example: NOVOMIX SP, NOVOMIX OM, NOVOMIX MICA, NOVOMIX ES, NOVOMIX TF , NOVONUTRA TF
Conclusion :
The choice of tablet coating is a strategic formulation decision that affects stability, efficacy, compliance, and brand differentiation.
At Novo Excipients, we offer a wide range of fully formulated coating systems. For more information on our film coating solutions, please get in touch with our team of experts.
FAQs:
Can tablet coating affect how quickly a drug works?
How is tablet coating applied in manufacturing?
Tablet coating is typically done in coating pans where coating solutions are sprayed onto rotating or fluidised tablets, followed by drying.
Are coating ingredients safe for consumption?
Yes. All coating components used in pharmaceutical products are carefully selected to be non-toxic, biocompatible, and approved by regulatory agencies like the FDA and EMA.