Spray Drying is a commonly used method in the pharmaceutical industry to produce powdered forms of drugs and other pharmaceutical products. One of the most amazing technologies used in pharmaceuticals today is spray drying. It is a continuous process that turns a liquid feed into a powder in a single step. It is the best option when exact characteristics like stability, morphology, and particle size are needed. This overview explains the technology, its existing and prospective uses, and how modeling tools and current understanding allow for a risk-free and lean process development stage.
Spray drying is atomizing a liquid feed into tiny droplets in a hot drying gas, which causes the droplets to flash dry into solid particles. As a finished spray-dried product, the particles are subsequently extracted from the drying gas using a cyclone or a filter bag. The final product can be categorized as a powder, granules, or agglomerates, depending on whether the feed is a solution, suspension, or emulsion.
Spray drying, thus, turns a liquid feedstock into a powder with specific qualities in one continuous operation. It is possible to significantly alter properties to target levels, including the amount of moisture or solvent left in the powder, the size or shape of the particles, and the density of the powder. Its widespread use in various industrial applications, such as cosmetics, fine chemicals, detergents, polymers, excipients, and pharmaceuticals, can be attributed to its exceptional adaptability in customizing the final powder’s properties, its gentle nature, and its cost-effectiveness when compared to alternative technologies like freeze drying.
Types and Scales of Equipment
The degree of finishing (i.e., the level of polish on the internal surfaces), the presence or absence of clean-in-place (CIP) or sterilization-in-place systems, the type of drying gas used (air, nitrogen, or argon), the type of atomizer or nozzle (pressure, two-fluid, ultrasonic, or rotary), the type of powder recovery system (often through a cyclone and/or a filter bag), and the degree of automation and instrumentation vary amongst spray dryers.
Pharmaceutical spray dryers frequently combine the most advanced control systems and finishing levels with the most straightforward hardware configurations for simpler cleanup. Nitrogen is frequently used over air as the drying gas because it minimizes product oxidation and permits the safe drying of organic liquids. Typically used in pilot and large-scale equipment, pressure and two-fluid nozzles are chosen based on the intended particle size of the finished product as well as the kind of feed.
Because they are hard to clean, rotary nozzles are used less frequently. The application of ultrasonic nozzles in small-scale equipment is highly intriguing since it enables the creation of sizable droplets that nearly mimic those of bigger equipment.
Applying Process Knowledge to Risk-Free & Fast Development
The amount of experimentation and generally very expensive API quantities needed to develop a reliable commercial spray-drying process have been significantly reduced by the modeling and simulation tools mentioned above, in addition to the ability to produce commercial scale-like powders from lab units.
Understanding the process and having past experience with similar procedures are also essential to reduce testing. Furthermore, scale-up can be facilitated and initial experimentation reduced to a few lab-scale runs using only a few grams of material by describing the process and its design space through meaningful and scale-independent parameters (e.g., relative saturation of the drying gas and mean droplet size, accurately estimated by modelling tools).
Today, instead of taking months, the creation of a spray drying process may be completed in a few days using a fraction of the material needed ten years ago. The pharmaceutical sector is spearheading this paradigm change in spray drying research since the production of innovative medications is typically exceedingly expensive and restricted in quantity.
Spray drying’s Potential Uses in the Pharmaceutical Industry
As amorphous materials gain greater traction and industrial acceptance, spray drying will probably continue to expand as an enabling technique for oral medications that are poorly soluble. However, its use in biopharmaceuticals, such as the extraction and production of peptides, proteins, and monoclonal antibodies, is projected to contribute to its significant future expansion.
Its progressive acceptance in these domains is expected to be driven by its advantages over traditional lyophilization in terms of cost and throughput, as well as its capacity to handle far more complicated formulations and solvent systems. Although aseptic powder filling, a complementary unit operation, and aseptic spray dryer are still in their early stages of development, significant steps have lately been made in their design.
The use of spray drying to produce inhalable drugs is another area with significant potential for growth. One of the main challenges with conventional lactose blends is the need to balance adhesive-cohesive forces between the drug and the carrier, as a significant portion of the drug will always remain attached to the lactose and end up in the mouth or throat.
By precisely fine-tuning the particle size distribution during development (and strict control during manufacture), spray drying might assist solve this difficulty by enabling the fabrication of composite particles where extremely high and reproducible respire fractions can be produced.
At Kerone, we manufacture spray dryers for pharmaceutical industry that range in complexity from simple to extremely complicated, depending on the types of drug being processed. Different design aspects include the atomization, airstream pattern, air heating systems and techniques, separation and collection unit, and others.
The main components of a spray dryer are an air heating system, a separating device to collect the dried output, an atomization and dispersion system for delivering fluid into the chamber in small droplets, and a drying chamber.