WaveLength | Spray Drying

Spray Drying Services

What is spray drying?

The spray drying process is a particle engineering technique that has been widely used to enhance the solubility of oral, inhaled, and topical drugs. To produce dry powders, fluid material is atomized into a hot drying gas medium, usually air or nitrogen. Food and pharmaceutical industries have successfully used spray drying to convert liquid feed into powder. This particle engineering technology involves dissolving the API in a solvent with one or more polymers (to prevent crystallization) and any necessary excipients, before injecting the mixture into a specialized spray dryer apparatus.

What happens during the spray drying process?

As the liquid enters the spray dryer, it is atomized by a nozzle to form small, spherical droplets; these are then rapidly dried by a powerful blast of heated air (or nitrogen when working with organic solvents) within the spray drying chamber. The resulting ASD is collected and can be used to manufacture the final Drug Product after some additional drying cycles, and particle separation in a cyclone. The main objective of the spray drying process (Figure 2) is to transform the API into an ASD exhibiting improved solubility and physical Stability compared to the parent material.

What are the Advantages of Spray Drying?

Improved aqueous solubility- In drug development, low aqueous solubility of active pharmaceutical ingredients (APIs) can result in poor bioavailability. Improved aqueous solubility is therefore a primary goal of formulation development.
Rapid process- Spray drying has a major advantage over other particle engineering technologies in that it is a rapid, continuous process. With this, any limitations on Batch size are removed, and process analytical technology can be implemented to ensure reliable operation.
No need for a milling step- unlike technologies such as micronization and lyophilization, spray drying avoids the need for a milling step (during lyophilization, milling is occasionally required to convert the dried material into a fine powder) that can compromise the performance of thermolabile APIs or biologics that are sensitive to abrasion or shearing.
Tight control over critical product parameters- perhaps most importantly, spray drying provides tight control over critical product parameters such as particle size, density, and morphology; these can be fine-tuned by adjusting key process parameters or changing the sprayed Solution composition to ensure consistent production of a high-quality product. Additionally, when compared directly with lyophilization, spray drying is more cost-effective and compatible with a broader range of solvents; these include both water-based solutions and class 3 solvents such as methanol, ethanol, acetone, and ethyl acetate, which can be recovered and recycled.

Why is it important that spray drying is done by an experienced CDMO?

Despite being a leading technology to enhance drug solubility, spray drying requires an experienced operator to accurately control particle quality and yield. Factors that must be considered include the composition, concentration, and stability of the parent solution (both the drug and any polymers need to dissolve in the solvent system) and whether heating is required to decrease the viscosity of the feed; in this scenario, both the API and any excipients must be stable at high temperature.

It is also important to select an appropriate nozzle. While pressure nozzle atomization may be more suitable where a larger average particle size is required, rotary nozzle atomization is often preferred for achieving a narrower particle size distribution (PSD), and multi-feed nozzles should be used where two or more liquids will be injected in parallel. Other considerations include whether the air/nitrogen should be blown from the bottom of the drying chamber or the top (the latter is frequently employed as a means of preventing over-heating), and the temperature at both the inlet and the outlet points, which is critical for producing stable particles and ensuring process robustness. The size of the spray dryer will be dictated by the required production scale; models range from benchtop size for initial development stages through larger commercial scale spray dryers capable of producing kilograms of material per hour.

Spray Drying Contract Manufacturing

Spray drying is an effective method for solving solubility and bioavailability challenges in drug manufacturing, but it requires strong expertise in process design and development, as well as an understanding of all quality and regulatory requirements for commercial production.

A great deal of experience is also required to establish early whether a particular Drug Substance is a good candidate for spray drying or more suitable for other bioavailability enhancing technologies, and to efficiently identify formulation conditions which provide the desired solubility, dissolution rate, uniformity, and bioavailability.

To find this expertise, it is important to partner with API CDMOs experienced in spray drying contract manufacturing for a wide range of drugs including high potency APIs (HPAPIs),which can provide the right equipment, team and facilities.

Due to the increasing number of poorly soluble small molecule drugs, the demand for spray drying capacity continues to grow and production slots fill up in advance.

Although next generation spray drying technologies promise to alleviate the bottleneck, Wavelength Pharmaceuticals continues to invest in both current and novel spray drying methodologies to meet these strategic market needs.

With more than 30 years of experience developing and manufacturing its own product portfolio, Wavelength has invested in state-of-the-art equipment to support a wide range of manufacturing requirements, from small-scale clinical drug development to commercial scale GMP production and is an experienced spray drying contract manufacturer.

Spray drying is also faster, more cost-effective and easier to manage than many other particle engineering technologies, and is readily scalable, especially in the hands of an experienced API CDMO .