Pharmaceutical scientist Imco Sibum about our soft mist inhaler

The multifold benefits of our Soft Mist Inhaler

Could you tell us more about the soft mist inhaler?

Resyca’s soft mist inhalers are devices which take a dissolved drug (the formulation) and aerosolize it in small droplets suitable for inhalation. This aerosolization happens by use of a nozzle plate containing small holes. These holes, or nozzles, are around 40x smaller than the average human hair. By pressing the liquid through these nozzles liquid jets are formed, which break up into small droplets. When the user actuates one of our devices, by pressing a button or compressing a lever, it presses the liquid through these nozzles.

What is the difference between the Soft Mist Inhaler and a Dry Powder inhaler?

In short, soft mist inhalers create small droplets for inhalation, dry powder inhalers release small particles. The working principle is radically different between the two.

Current dry powder inhalers on the market have quite some requirements on the formulation. The powder needs to consist of small particles so that they can be inhaled. However, because these particles are small, they have the tendency to be sticky (think powdered sugar). This makes them difficult to dose accurately. This problem is solved by sticking these small particles on larger ones. These large particles flow freely (like crystal sugar), so they can be dosed accurately. During inhalation the small particles need to be released from the large particles. If the small particles are stuck too strongly they aren’t released during inhalation, if they are stuck too weakly they will separate during storage of the device, negatively influencing dosing. To release the small particles a patient needs to inhale strongly to generate enough force. This increases the throat deposition of these particles, lowering the amount reaching the lungs.

As explained above, Resyca’s soft mist inhalers use small nozzles to aerosolise a formulation into small droplets. There are few requirements to the formulation, lowering the time and effort needed to make a formulation work with one of our devices. The drug needs to be in solution and there is a limit to the viscosity of the formulation. However, this viscosity limit is quite high, approximately 3 times the viscosity of water. In our soft mist inhaler the droplets are not generated by the patient inhaling, thus the patient can inhale slowly, increasing the amount of droplets that reach the lungs.

What is the SMI already used for?

One of our soft mist inhalers is used in multiple clinical trials at the moment. As explained previously, there is limited interaction between the dissolved drug (the formulation) and the soft mist inhaler. As such the step from formulation development to a clinical trial can be made quickly. In general, no changes must be made to the formulation to make it work in one of our devices. Furthermore, one of our devices uses a standard syringe as dose compartment. This syringe can easily be filled at the trial site, speeding the process up further.

For which type of doses is the product suitable?

The product is suitable for a wide range of doses, and this is partially dependent on the formulation itself. Our devices can dose 15 to 50 microliters per breath. Depending on the concentration of drug in the formulation (how much drug is dissolved in the liquid) this determines the dose of the drug per single breath. We have designed our devices to make it easy and quick to take multiple breaths after each other. This way patients can inhale up to 1 mL over multiple breaths in three minutes.

What are the benefits of the SMI?

The benefits of a soft mist inhaler over other devices are multifold.

• As explained above, developing the drug formulation is simple compared to, for example, dry powder inhalers.
• The patient’s inhalation is not needed for particle generation. Meaning that the patient can inhale slowly during dosing. This has the advantage that less drug is deposited in the throat and more drug gets to the location where it is needed in the lungs.
• The soft mist inhaler does not require any propellant and the generation of the formulation does not require a lot of energy (like spray drying) either. This lowers the environmental burden substantially.