Advanced Tablet Coating
Precise coatings are key to pharmaceutical and nutraceutical brands, impacting the look of the tablet or capsule, as well as the finished product's taste, odor, stability, ease of swallowing, and stability in the gastric environment.
Outstanding uniformity can be achieved more readily today, as complicated sugar coating processes of the past have given way to modern film and enteric coatings. Not only do these coatings provide greater flexibility, they allow a wider range of dosage forms, including pellets, granules, and drug crystals.
To ensure exceptional results, careful attention must be paid to the spray pattern, drop size, and nozzle spacing, as well as a wide range of other parameters. Fortunately, innovative nozzle and equipment designs help ensure consistent distribution of the coating material for higher-quality, more viable end products.
Top-Spray Coating for Food, Pharmacy, and More
Spray coating can be applied to a wide range of ingredients and products—from chocolate and olive oil to fire retardants and sanitizers, as well as pharmaceutical and nutraceutical coatings. Top-spray systems can be ideal whether you need a general protective layer, where the exact application thickness is not critical, or require even, consistent application.
For top spraying, nozzles are positioned above the product bed or belt so that they spray directly onto products. Top-spray technology can also be used as a cost-effective alternative to Wurster coating, in which particles suspended in an airstream are gently spray coated before they dry and drop back down into the product bed.
Top spraying provides the best results when the particle size distribution is narrow. However, products with a wide particle size distribution may be preagglomerated to allow for effective top spraying.
Ultrasonic Coating for Fine Particles
A unique, relatively new approach, ultrasonic spray devices coat fine particulate substances in a fluid bed. High-frequency vibration is used instead of high-pressure or compressed air to produce extremely small, uniform droplets, making this process ideal for high-precision coatings as well as vaporization, spray drying, and humidification.
When a liquid binder, coating material, or other liquid inside an ultrasonic spray device vibrates at a specific frequency, capillary waves are produced on the surface of the liquid. During atomization, the amplitude is increased until the wave peaks form droplets. The wavelength and droplet size are determined by vibration frequency—the higher the frequency, the finer the droplets.
When a liquid binder, coating material or other liquid inside an Ultrasonic spray device vibrates at a specific frequency, capillary waves are produced on the surface of the liquid. During atomization, the capillary waves are transformed into droplets by increasing the amplitude until the peak of the wave forms droplets. The wavelength and subsequently, the droplet size, are determined by vibration frequency. High vibration frequency generates fine droplets and low vibration frequency generates coarse droplets.
Recognized for superior fluid bed microencapsulation, the Wurster process is often the choice for coating particles, spheres, granules, and tablets. Wurster technology uses an air stream to separate and suspend particles, then coats them using a spray nozzle positioned at the bottom of the fluid bed. This approach can produce very high-quality results with a variety of coating formulations, including aqueous and organic solvents, hot saturated solutions, and hot melts.