MRX004 SMI delivers single breath doses 3 to 5 times higher than nebulisers. We contend that nebulisers are serial SMIs and only achieve mg delivered doses because of repeat dosing. In short, Keep Breathing! SMIs deliver more – Q.E.D.
For many years, nebulisers have been the preferred choice for respiratory drug developers needing an inhaler to deliver high doses to the lungs. This preference is largely due to nebulisers’ ability to deliver a continuous stream of aerosol that can be inhaled via natural, tidal breathing over several minutes, thereby seemingly facilitating the delivery of high doses. However, a shift in perspective reveals a superior alternative: the soft mist inhaler (SMI), particularly the MRX004. SMIs deliver medication as a fine mist, which can be deeply inhaled in a single breath, offering greater efficiency and convenience.
Delivering High Doses To The Lungs – Nebulisers Are A Legacy Technology
To understand why an alternative to nebulisers is desirable, it is important to recognise their limitations. Nebulisers are bulky devices that require an external electric power source to aerosolise a drug solution. The patient sits and inhales for several minutes, making the use of a nebuliser a time-consuming process. This is compounded by the high level of manual handling required through the assembly of the device, dispensing of the dose, and cleaning and maintenance of the nebuliser. Nebulisers are not portable inhalers, unlike pMDIs, DPIs and SMIs.
Nebulisers are comparatively wasteful. The need for electricity creates a demand for power that is unnecessary for purely mechanical devices like SMIs. In addition to spare parts requiring changing (metering chambers, tubing, masks), the aerosol is continuous, meaning that the patient is only breathing in half of the emitted dose. The other half is exhaled, wasting valuable drug product and contaminating the air around the patients.
Nebulisers rely on tidal breathing to deliver the drug to the lungs; this is characterised by shallow breathing with a breathing cycle of about 15 breaths (inhale/exhale cycle) per minute, each characterised by an inhalation/exhalation cycle, or 6 effective inhalations per minute. This translates into a 4 seconds breathing cycle and an inhalation duration of 2 seconds. A single dose from a nebuliser therefore takes 2 seconds to be delivered; bear that number in mind.
The efficiency of a nebuliser is characterised by the fine particle fraction delivered to the deep lung, i.e. the proportion of droplets below 5 mm. Typically this is about 30%, in some exceptional cases 50%, once the losses from exhalations are discounted.
