After compressing pills, the next critical step is the tablet coating process.
Why?
Well, through tablet coating, you introduce a range of functionalities that make drugs achieve specific functions. Whether you want to change color, improve teste or delay tablet dissolution, you must choose the right coating.
In this article, we will explore top 22 different types of table coating technologies.
1. Sugar Coating
Sugar coating is a traditional method in the manufacturing of tablets where sugar layers and other excipients are applied over the core of the tablet. This process mostly involves different steps like sealing (to keep the core safe), sub-coating (to make the tablet round), smoothing, coloring, and polishing.
Coating, when done, offers you that smooth and glossy finish. This enhances the visual look of the tablet and helps to mask any unpleasant odor or taste. Nonetheless, sugar coats mainly enhance the tablet’s size and weight, most times by 50%. This can be a con when you have to swallow pills, since they become large. Tablets that are sugar coated come with a lot of stability where moisture is concerned; that is, if they are well sealed.
2. Enteric Coating
Enteric coating is a unique tablet coating type designed to stay intact in the acidic environments of the stomach. At times, they are also called acid resistant coating on drugs.
However, they dissolve in the higher pH of small intestines. Due to its pH-dependent solubility, it secures acid-sensitive drugs such as probiotics or enzymes as they do not get damaged by stomach acid.
Also, it keeps the stomach lining safe from irritating drugs such as NSAIDs or aspirin. These coatings are mainly made using polymers like CAP or cellulose acetate phthalate, hydroxypropyl methylcellulose phthalate (HPMCP), or methacrylic acid copolymers. This coating aids with specific drug delivery, making sure active ingredients are released in the small intestines for you to have the best absorption or therapeutic actions.
Of course, to achieve this, you need a highly efficient tablet coating machine.
3. Film Coating
Film coating entails the use of thin polymer layers over tablets, offering protection and enhancing aesthetics. It is the most common coating type that is used in pharmaceutical manufacturing currently. This is due to its cost, cost-effectiveness, and efficiency. Film coatings can either be non-functional or functional based on their ideal use.
Furthermore, the process involves spraying a suspension or solution of film-forming polymers like hydroxypropyl methylcellulose, ethyl cellulose, and plasticizers onto rotating tablets. This can be done in a pan or fluid bed. Compared to other coatings, you will be enthused to know that this coating dries almost immediately due to the heated air. Therefore, forming a continuous and uniform film. Film coatings safeguard your tablets from moisture, light, and mechanical damages.
But more importantly, to achieve this, you need a highly efficient film tablet coating machine.
4. Compression Coating
Compression coating, which is also referred to as dry coating, is a unique tablet coating process. It involves a second layer of powder or granules compressed around a core tablet that is already compressed. No solvent is used with this process. This makes it ideal for all your heat-sensitive or moisture-sensitive drugs.
The outer coating can be made or designed to modify, delay, or control drug release. Although the inner core can contain another active pharmaceutical ingredient (API), this method is ideal for combination therapies. It is mostly used to have incompatible substances separated within single tablets. The process necessitates unique tablet presses that are capable of handling the dual compression method.
5. Aqueous Coating
Aqueous coating refers to applying film coats using water as the main solvent for coating excipients and polymers. This method is an environmentally friendly method that has replaced organic solvent-based coatings due to toxicity, flammability, and environmental pollution issues.
Polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), and cellulose derivatives are mainly used in these coatings. With this process, coating solutions are sprayed onto tablets in fluidized bed or coating pan systems, while warm air facilitates quick drying. This process is reasonable and safe for you and other operators. However, it requires the right or ideal control of parameters like spray rate, humidity, or temperature to prevent any issues such as rough coating or tablet sticking.
6. Delayed-release Coating
Delayed-release coating is mostly designed to ensure active pharmaceutical ingredient (API) release is postponed for an ideal period after administration orally. Unlike enteric coatings, which depend on pH for dissolution, delayed-release coatings might rely on time, enzymatic activity, or some other physiological triggers.
This coating type makes it possible or allows your drugs to go through the stomach without getting dissolved. Also, it releases the API within your small intestines or other targeted areas, enhancing efficacy and cutting down on any side effects. This type of coating is mostly used for drugs that are inactivated by gastric fluids or irritate the stomach lining.
7. Gelatin Coating
Gelatin coating entails the use of gelatin, which is a protein that is derived from collagen, as the coating material for tablets. It is mostly used in soft gel capsules. However, it can be applied as a coating for your hard tablets. This is to enhance their appearance and swallowability.
With gelatins, drugs get to have that smooth, slippery surface. This way, it is easier for you to swallow, ideally for you if you struggle with geriatric and pediatric issues. Additionally, it acts as a barrier to oxygen and light. This helps in preserving the integrity of your light- or oxygen-sensitive pills or drugs. You can find these coatings in flavored or colored forms. All these are done to make better patient compliance.
8. Organic Solvent-based Coating
Organic solvent-based coatings make use of non-aqueous solvents like isopropanol, ethanol, methylene chloride, or acetone. All these solvents help in dispersing or dissolving the coating materials. These coatings are mainly beneficial for your water-sensitive drugs or when you need a faster drying process. This is because the solvents evaporate quickly during the stage of drying.
Additionally, this leaves behind a standard or uniform film layer. Again, these coatings can provide your drugs with the moisture protection, controlled drug release, or even taste masking benefits you wish to have. All these benefits, though, will depend on the type of coating polymer used. Although they are effective, organic coatings pose challenges linked to flammability, toxicity, and environmental safety.
9. Extended-release Coating
Extended-release coatings, or ER coatings, are slowly used to release active ingredients over an extended time frame or period. So, there is a maintenance of therapeutic drug levels in your bloodstreams for a longer period. With this, dosing frequency can be reduced, mostly once or twice each day. All these enhance your adherence to drugs or prescriptions and make you feel very comfortable.
Remember, extended-release coatings can be customized to meet your specific needs, as their release rate can be adjusted through the modification of porosity, thickness, or composition. Also, film or compression coating methods are used in applying ER coatings. This is because they are ideal for drugs with short half-lives or that need consistent blood levels to work perfectly.
10. Controlled-release Coating
Controlled-release coating entails the use of sophisticated technology. This technology releases the drug at a specific rate over a specific period, mostly throughout a 24-hour period. This is not the same as with ER or extended release, where the release rate can be adjusted based on the body conditions.
Usually, the mechanism of release of this coating type could entail diffusion, osmosis, erosion, or a merger, of all these mechanisms. These coatings are made with hydrophobic or hydrophilic polymers, like HPMC, methacrylic, or ethyl cellulose acid derivatives. With these designs, you get to be free from all dosing peaks and troughs. This reduces the levels of toxicity or subtherapeutic dosing risks you can experience.
11. Taste-masking Coating
Taste-masking coating is mostly applied to granules or tablets to mask all metallic, bitter, or otherwise unpleasant tastes linked with some drugs you take. This is mostly necessary in geriatric and pediatric formulations, where taste compliance is affected by taste immensely. The coating stands as the barrier between your tongue and the drug.
Therefore, preventing your consumers from having direct contact with the tablet until it reaches their stomach. Mostly, polymers like ethyl cellulose, lipid-based coatings, and methacrylate copolymers are mostly used. Such materials are chosen depending on their insolubility in saliva but solubility in gastric fluids. With this coating, thickness and uniformity are vital to ensure that drugs stay undetectable by your taste receptors as you ingest them.
12. Color Coating
Color coating entails the use of pigments and dyes in coating to give tablets specific colors for branding, aesthetic, or identification purposes. These coating methods are used ideally by pharmaceutical companies to distinguish products. Also, it helps companies enhance patient compliance and cut down on errors with your medications.
Apart from enhancing the look of drugs, color coatings help to keep your drugs free from light, especially if they are light-sensitive. With these coatings, colorants are mostly incorporated into film coatings with insoluble polymers or water-soluble polymers. For color coating, the process involves organic or aqueous solvent systems, based on the specific formulation.
13. Moisture-barrier Coating
Moisture-barrier coatings are ideally designed to safeguard your tablets from from moisture and humidity. With this, sensitive and active ingredients in your drugs are not degraded as it increases shelf life.
For hygroscopic drugs that easily absorb water and for formulations that are prone to hydrolysis, you will need these coatings perfectly. The application of this coating is achieved through film coating in fluidized bed systems or pans.
With these coatings, you can be assured of long-term drug efficacy and quality in different environmental conditions. Again, it enhances the handling and packaging of your drugs by lessening clumping and stickiness. For cracks or adhesion to be prevented, the process needs to be well monitored.
14. Functional Coating
Functional coatings have to do with coatings that offer you ideal roles above aesthetics. These include enhancing bioavailability, modifying drug release, or safeguarding the API.
You can formulate these with different polymers and excipients to meet specific therapeutic needs. For example, functional coatings might delay release till tablets reach your intestines. Therefore, prolonging release over many hours, or preventing stomach irritation.
With these coatings, you can expect them to be enteric, enzyme-triggered, time-dependent, or pH-sensitive based on the intended effect you require. With advanced pharmaceutical technologies such as compression coating or fluidized bed, these coatings are well engineered.
15. Protective Coating
You can apply protective coatings to your tablets to shield their core from chemical, physical, or environmental factors. This way, its integrity is never compromised. These coatings will guard your tablets against moisture, light, mechanical damages, and oxygen during handling, transportation, and storage.
Additionally, this coating is particularly valuable for APIs that easily degrade when exposed to humidity or air. Commonly used polymers for these coatings include polyvinyl alcohol, or PVA, ethylcellulose, and other waxes. One thing you will love about protective coatings is their transparency and light tint. Due to these characteristics they have, they can be easily layered over sugar or film coatings.
16. Polishing Coating
Polishing coating is the final layer in some tablet coating methods, particularly sugar-coated or glossy tablets. You can use these coatings for aesthetic purposes mainly. The process entails the application of wax or glossy materials such as carnauba wax, beeswax, or shellac. These materials are used to make your tablets shine and smooth.
This provides your tablets with that visually appealing and classic finish, mostly linked with OTC or over-the-counter meds or consumer health products. If you want to make tablets that consumers will find easy to swallow, polishing coatings are best.
17. Immediate-release Coating
IR, or immediate-release coating, is designed to immediately dissolve when it comes into contact with gastrointestinal fluids. This makes it easy for the active ingredient to release quickly. For your drugs that must act quickly, this type of coating is ideal.
Examples of such drugs include antipyretics, pain relievers, or medications for severe symptoms. Unlike controlled-release or delayed coatings, IR coatings will offer you no barrier dissolution. Therefore, quick disintegration and absorption are assured in the stomach or small intestines. IR coatings mostly contain flavoring agents, colorants, and sweeteners.
All these enhance the experience of your consumers. Polymers employed include water-soluble substances such as hydroxypropyl methylcellulose (HPMC) and PVA, or polyvinyl alcohol.
18. Anti-counterfeit Coating
Anti-counterfeit coatings are unique coatings that you will love. They come embedded with markers, pigments, or codes. All these features help in the authenticity verification of your pharmaceutical products.
If you worry about your tablets or drugs being counterfeited, which is a major global health issue, this coating is your solution. Some technologies you can use include color-shifting pigments, chemical tracers, UV-reactive dyes, micro-tags, and even holographic films. All these can be detected under unique conditions.
Such coatings can ideally be applied over your standard coating. Additionally, they will not alter the therapeutic properties of the drug. You can consider advanced alternatives like invisible barcodes and digital fingerprinting.
19. pH-dependent Coating
pH-dependent coatings are designed only to dissolve at specific pH levels within your consumers’ gastrointestinal tracts. This ensures that active ingredients are released at the right site. If you manufacture drugs that are either unstable in stomach acid or are intended to act in the intestines, this coating is best.
These coatings will enhance drug absorption for your consumers, reduce gastrointestinal side effects, and enhance therapeutic efficacy. They are applied using a pan or fluid bed coating process. Additionally, precision in thickness and uniformity is required to function ideally. pH-dependent coatings will be best for targeted delivery systems, like drugs for Crohn’s disease, ulcerative colitis, or colon cancer.
20. Enzyme-degradable Coating
Enzyme-degradable coatings are designed to break down in response to the presence of specific enzymes present in some regions of the consumer’s body. Mostly, within the colon. Polymers used include dextran, pectin, chitosan, and other polysaccharides. These substances stay intact in the stomach and small intestine.
However, they degrade when they are exposed to enzymes such as pectinase, beta-galactosidase, or dextranase secreted by colonic bacteria. So, drugs are released where they are most needed. Therefore, reducing all systematic side effects and enhancing local therapeutic actions for your consumers.
21. Time-dependent Coating
Time-dependent coatings are ideally engineered to ensure drug release is done after a specific lag time post-ingestion, independent of pH or enzymes. If your aim is to manufacture drugs that can achieve pulsatile drug delivery, mimicking the natural rhythms of the body, these coatings are ideal.
Also, if you want to manufacture drugs that can be taken at specific times, such as midnight-release meds for early morning asthma or hypertension symptoms. Polymers used include waxes, ethylcellulose, or synthetic resins that dissolve or erode steadily. It’s designed so that your tablets stays intact for a specific time frame in your consumer’s digestive tract before the active ingredient is released.
22. Osmotic Coating
Osmotic coatings play a major role in the highly advanced drug delivery system where drugs are released through a controlled osmotic pump mechanism.
When you apply these coatings, they surround a semi-permeable core that contains the tablet and an osmotic agent. Immediately the tablet enters the gastrointestinal tract of that patient; water permeates through the coating into its core.
Therefore, it dissolves the drug and creates osmotic pressure. It is the pressure that pushes the drug out at a controlled rate through a pre-drilled orifice. Osmotic tablets are mostly used for chronic therapies that require steady levels of plasma. Although costly and quite complex, you will gain from them.
Conclusion
Tablet coatings keep increasing in fame due to the many benefits they offer. When you know about the right tablet coating, you are able to benefit from the ideal types to meet your needs.
At SaintyCo, we offer a wide range of tablet coating solutions depending on your industry needs are requirements. Ask us more about tablet coating machines, for a complete solution that matches your production requirements.
