BUCHI is known for laboratory scale spray drying; can you tell us about your capabilities?
Sure, we offer the Mini Spray Dryer B-290 and the Nano Spray Dryer B-90 that are used to spray dry both aqueous and organic solvent based formulations. The achievable powder particle size range is from 300 nm to 60 microns depending on your choice of nozzle and the solids loading of your formulation. We now offer an ultrasonic nozzle to create particles closer to what can be accomplished on the industrial scale.
Does BUCHI offer solutions to accomplish microencapsulation?
From left to right: The Mini Spray Dryer B-290 and the Nano Spray Dryer B-90Yes, both of our bench top spray dryers and the Encapsulator can be used for this technique.
Can you elaborate on the difference between the two technologies as it relates to encapsulation?
Essentially spray drying uses nozzle atomization and evaporation to accomplish a matrix encapsulation resulting in an amorphous powder. A matrix encapsulation refers to the active and excipients being mixed together in one particle. Whereas the Encapsulator makes both matrix beads and core shell capsules with a prilling by vibrational nozzle method with further cross-linking or solidification to produce ridge microspheres.
Why is microencapsulation important to the pharmaceutical market?
It is important for many aspects. For instance, encapsulation is used for controlled release delivery of an oral or injectable product and gets it into a usable format for further use. Another aspect is to protect the active from oxidation, or it can also be important to mask the taste of the active ingredient.
How is spray drying used to microencapsulate drugs?
You would make a formulation containing your API and the desired shell forming polymer in a solvent at a proper loading to accomplish the effective encapsulation. During the nozzle atomization and solvent evaporative process, the compounds mix to form a matrix encapsulation. In fact, a solid dispersion is considered an encapsulation, which has become the most popular spray dying application due the poor solubility of today’s drugs.
Can you tell use more about the pilling by vibration method?
Essentially it is an extrusion of material through a nozzle at a defined rate then enhanced by applying a vibrational frequency Hz to the nozzle to create extremely uniform droplets. Finally, an electric field is applied to spread the droplets before they are cross-linked or hardened to accomplish the encapsulation. Different nozzles are chosen based on the viscosity of the material or whether you need to create a matrix system or a core and shell.
What type of materials are typically used with the Encapsulator?
Sodium Alginate is the most prevalently used polymer. However, gelatin, waxes, lipids, biopolymers, and chitosan for instance can all be used as shell or matrix materials.
How do you control the particle or microsphere characteristics using these two methods?
The Encapsulator B-390/395 ProEncapsulation is a mixture of formulation science, art, and processing due diligence. Therefore, researchers must consider many factors including solubility, solid loading, viscosity, nozzle choice, feed rate, atomization flow, and solidification method. All of the factors impact the resulting particle size and morphology. Process parameter control is the piece of the process that can take time to develop in order to obtain the desired particle, release, and dissolution characteristics. Achievable particle size ranges are from 1 to 60 μm for lab spray dyers and 80 μm to 4 mm for the Encapsulator.
You mentioned the process parameters and material choice being a part of the R&D process. Where should the user start?
Since spray drying and encapsulation are not new technologies, I would use the vast amount of literature references available on the internet and in journals. For instance the CRS or AAPS websites would be a good starting point. Many papers have been published using all types of excipients for encapsulation, as well as modeling studies using known active ingredients. This is an ideal way to begin a project.
Are the two technologies scalable?
Absolutely, and that is what has made spray drying so popular. R&D teams can transfer the process created on the lab-scale to pilot scale through to full production scale. The Encapsulator is also scalable through contract manufacturing or with larger equipment with multiple nozzles.