How film coating technology has evolved over sugar coating technology to cater to the demands of the pharma industry
Film coating technology plays a vital role in formulation development of drugs. This modern technology is most preferred over sugar coating technology which was invented in 1800s.
In India, film-coating is widely used due to its cost effectiveness, whereas, in the global market, more advanced techniques such as fluid bed processing is used for particles as well as tablet coating. Film-coating technology has gone through various modifications to meet the demand of the pharma industry. It is not only limited to the pharma sector but also widely used in FMCG and food industry.
Evolution of film coating technology
Film coating has evolved with time, keeping pace with demands of the pharma industry. Necessary modifications were undertaken such as improved production equipment and development of highly-efficient film coating formulations, evaluation and use of new polymers and decrease in use of conventional polymers were undertaken.
Girish Kumar Jain, President-R&D, Alkem, explained that each drug has its own characteristics like bitterness, unpleasant odour, light sensitivity, oxidation or hygroscopicity. Tablet coating evolved during the last decade to help in solving such problems and provide formulation which takes care of all these problems with much better patient acceptability. The major attribute of film coating has come up in modulation of released profile of drugs in the form of extended release, enteric coating (delayed release), osmotic pump, pulsatile delivery system. This has helped to improve bioavailability and therapeutic potential of a drug as well as improved patient compliance.”
Newly introduced film coating materials are specially designed considering the sensitivity of active pharmaceutical ingredients (APIs) used in the formulation. Film coatings are available for moisture sensitive drugs and flavoured film coating materials for the products having bad odour and functional coating.
“Over a period of time, due to the challenges and demand faced by the pharma industry, there has been significant changes in the production equipment of film coating like conventional coating pans to perforated coated pans, fluidised bed coater etc, coating formulations like organic film coating to aqueous film coating, high solid content premix e.g. Instacoat/ Opadry etc and polymers like HPMC /PVA etc, which has accelerated the acceptance of coating technology,” said Vinod Arora, Technical & Regulatory Expert, Medicines Patent Pool.
At present, liquid coating technology is one of the popular technology used for coating solid dosage forms. Generally a mixture of polymers/ pigments and excipients are added in organic solvent or water to form a solution or dispersed to form a dispersion and then sprayed into solid dosage forms and dried uninterruptedly by providing heat/ air until a dry and smooth coating film is formed. Nowadays, usage of organic solvent in film coating is reduced significantly due to its toxic/ flammable nature, cost and causes environmental pollution/ affects coating equipment operator.
“Future trend in film coating will be towards continuous manufacturing and solvent/ liquid free coating. Discussions are being held on different modelling systems like digital video imaging, discrete element methodologies, computational fluid dynamics to study various film coating parameters. Process analytical technique will help further monitor and control various unit operations.”
Speaking on the improvement which the technology has gone through in the past decade, Pramod Pimplikar, MD, Shalina Laboratories, said, “One major improvement that has taken place in recent years is the shortening of coating process length. This improvement was brought about by using coating solutions with a high solid content thereby reducing the cost. With regards to functional coatings, most of these are non-water soluble and the challenge for coating manufacturers was to stop using organic solvents because of their negative impact on the environment. For non-functional coatings, innovations have been limited because of the commonly used cellulose derivatives and polymethacrylate coatings, which continue to provide satisfactory results for most uses.”
“While at present aqueous film coating is firmly entrenched, more work is going on making this coating amenable with use of high percentage of solids. This means less time for coating and less use of energy, thus making coating more productive and less costly. Equipment manufacturers are working on reducing the loss during coating process to make the whole process less costly. However, future trends includes dry coating and electrostatic dry coating,” informed Jain
According to Suresh Pareek, MD, Ideal Cures, one of the major trends that this industry is seeing is the insistence on continuous coating over batch coating. With the FDA giving a go-ahead on continuous manufacturing, we will soon see the wide-spread set up of continuous coaters and in turn the use of high-solid content, novel coating formulations such as INSTACOAT 4G. As machines advances, they will require equivalent coating materials that can shoot up productivity, reducing time and cost. In developing countries, organic solvents are still being used in coating formulation, but the near future will see movement out of these to complete aqueous-based systems. With the introduction of graft co-polymers, the need of adding separate plasticizers/ binders will reduce, reducing the number of ingredients and thus mixing time.
“Sugar-coatings seem to be coming back to the market, now modified and redesigned as sugar-fast coatings. Another trend that I foresee is the need for powder/ dry tablet coating, that completely eliminates the need for a solvent. Such coatings will revolutionise the process of tablet coating and will introduce new deposition techniques,” he further said.
Jain feels that the high regulated international markets has opened avenues for Indian pharma exports. He informs, “The Indian pharma industry has expanded at a very fast rate especially due to extensive exports. Indian pharma companies have an advantage as markets such as US, Europe and Australia are highly regulated. Better quality of medicines along with requirement of high yields and less wastage has put pressure on film coating industry (coating material supplier and equipment manufacturer) to upgrade film coating material technology. The industry has upgraded from using 10 per cent w/v dispersions to about 30 per cent w/v dispersions presently.”
More efficient coating equipment has also helped in reducing the wastage of coating dispersion during coating. This is especially important when drug is used in coating dispersion. Similar factors are driving the growth in global markets.
“The growth of the excipient industry and in turn film-coating technology will occur with the growth of the pharma industry. While growth in developed markets will slow down, emerging markets will become increasingly important in the coming decade. The Indian pharma market which is expected to expand at a CAGR of 12.89 per cent over 2015–20 to reach $ 55 billion, along with the markets of China, Brazil and Russia will spearhead growth within these markets,” said Pareek.
Constant rise in stress and lifestyle related diseases among Indian population will drive the need for innovation and research, bringing novel drug delivery systems to the market. This will in turn drive the need for innovative coating formulations. With increasing awareness of health insurance and better availability and affordability of drugs, the pharma industry is enroute exponential growth. With the government slowly increasing investment in healthcare under the National Health Policy and trying to reduce the time for approval of new facilities, we can expect the pharma and in tun, the excipient industry to grow.
Continuous innovation in the field of manufacturing – the process and the equipment allows for continuous innovation in coating formulation. From coating of just tablets, the industry now requires technology for coating other delivery systems such as catheters, stents, ingestible imaging instruments, joint plates etc. With the advent of such technologies, film coating will continue to grow hand-in-hand. However, such technologies require intricate coating techniques and will need to keep patient safety at the forefront. Drugs are required to be released at very specific intervals, imaging instruments must be delivered within the body without harm to the patient. Such requirements drive the film coating industry to bring about advanced and novel innovations, encourage research and ultimately bring about growth.
“With multiple R&D centres, application laboratories, new manufacturing facility and offices in the US, Israel, Italy, Spain, Turkey and distributor channels globally, Ideal Cures has immersed itself in bringing novel film-coating innovations to the market. They are continuously engaged in process and product improvement and does not restrict only to film-coating but have also diversified into other excipients such as acrylic polymers, cooling compounds, inert spheres and others,” said Pareek.
“Film coating is well established in solid dosage form that offers many advantages for pharma products. There are a number of manufacturers manufacturing coating equipment globally and can be procured with not much difficulty. Coating process time is much less as compared to sugar coating. Coating pre mix manufacturers provide support in training beside trained manpower is also available. These growth drivers are similar to other markets globally,” said Arora.
Pros and cons
Earlier sugar coating was mostly applied to tablets using conventional coating pan. It was a time consuming process, which used to take four to five shifts, besides use of skilled manpower. Now film coating has taken over sugar coating and we see very few products which are sugar coated. Additionally, use of perforated coated pans/ fluidised bed coating processor in film coating has reduced coating time significantly. Film coating minimises the risks of medication errors leveraging pigments/ colours for identification and also improves patient compliance through aesthetic appeal.
Jain said that there are certain disadvantages of film coating. These disadvantages limit adoption of newer equipment due to Expensive equipment & plant requires large space, High installation and energy costs. With the increasing potency and sensitivity of APIs, there is a constant need for inert materials that, as well as avoiding incompatibility issues, also protect drugs from degradation caused by environmental factors, such as moisture, light, heat and oxygen. However, designing such a material will be a challenge for the industry. Getting rid of organic solvents remains a topic of interest and getting rid of any solvent with dry coating could also be part of the future.
Pareek says, “As new technologies emerge, there is reluctance in their acceptance because of the time and energy needed to be spent in filing changes with the FDA. However, with new regulatory changes and the FDA encouraging continuous operations, this challenge will slowly be eliminated. Some countries around the world still use traditional methods for drying of tablets during coating operations. This continuation in use of organic solvent based coating limits the acceptance of aqueous-based systems that are much more capable of bringing about increased productivity. Reluctance in use of new technology and improvements in manufacturing process and switching over from old methods is a major challenge that limits the use of evolving film-coating technology. “I am sure with right kind of guidance and technical support we can bring the much needed change in these traditional practices,” he said.
“Going forward, I see the pharma industry adopt continuous manufacturing and in some cases solvent free coating for which a lot of work is going on in different countries with respect to production equipment etc. There would be changes in manufacturing equipment and also in coating pre mixes”, says Arora.
“As new technologies emerge, there is reluctance in their acceptance because of the time and energy needed to be spent in filing changes with the FDA. However, with new regulatory changes and the FDA encouraging continuous operations, this challenge will slowly be eliminated,” Pareek said.
Some countries around the world still use traditional methods for drying tablets during coating operations. This continuation in use of organic solvent-based coating limits the acceptance of aqueous-based systems that are much more capable of bringing about increased productivity. Reluctance in use of new technology and improvement in manufacturing process and switching over from old methods is a major challenge that limits the use of evolving film-coating technology. With the right kind of guidance and technical support, much needed change in these traditional practices can be brought.