Intelligent inhaler

With recent advances in electronics, it has become possible to incorporate reliable technology into an inhaler at reasonable cost and size.The design of Sensohaler, an intelligent inhaler from Sagentia, could improve compliance when treating asthma and other respiratory diseases.

Noncompliance is a major obstacle to effective healthcare delivery, and is especially problematic in the treatment of asthma, a chronic inflammatory disease of the respiratory tract that affects about 300 million people worldwide. The U.S. National Institutes of Health reports that noncompliance is the main treatment problem in 30% to 70% of asthma patients.

Additionally, noncompliance is an issue in clinical trials when it affects not only the patient’s health, but also the ability of researchers to develop more effective drugs and treatment protocols.

To address these problems, Sagentia developed Sensohaler as a monitoring device that accurately measures the inspiratory flowrate and analyzes the amount of medication delivered through the inhaler, giving patients and healthcare providers immediate feedback on inhaler operation and inhaling technique. Sensohaler monitors performance using advanced acoustic analysis – a means of processing the noise created by the airflow through the inhaler – together with acoustic signatures attributable to other functions such as breath actuation mechanisms, metering of doses, piercing blisters, and passage of powdered drug medicament through the inhaler’s airway system.

Sensohaler’s ability to gauge the effectiveness of drug delivery aims to improve the compliance of asthma patients and the management of their care. It will also help researchers better determine drug efficacy in clinical trials. Almost any inhaler product could benefit from this technology, but Sagentia is focusing its initial efforts on inhalers for asthma.

Two kinds of inhalers currently make up the vast majority of the market: pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). Both are designed to dispense measured doses, but a lot can go wrong between the inhaler and the lungs to prevent a patient from receiving the appropriate dose. A patient needs to inhale at the correct flowrate, and, in the case of most pMDIs, press the drug canister at the right point during their inspiratory profile. This requires a level of training and dexterity many patients may lack.

Recent studies show, that 19 out of 20 patients inhale too quickly through pMDIs for optimal drug delivery. Pressing the canister too early or too late is another common mistake, especially among children and geriatric patients. In addition, many patients try to spray the medication into their open mouths, rather than putting their lips around the device’s outlet. In one Australian study of patients who had used an inhaler for an average of two to three years, only 10%  demonstrated correct technique.

These mistakes carry a high price tag. A 2005 study by J.B. Fink and B.K. Rubin determined that noncompliance among asthmatics added as much as $16 billion to the cost of therapy in the U.S. alone, as additional drugs or extended periods of treatment were required to manage the condition. With each poorly timed activation or poorly executed inhalation, expensive medication is wasted.

Designed to help patients avoid those mistakes, Sensohaler features a user interface consisting of three LEDs in the colors of a traffic light – green, yellow, and red. These guide the user to slow down or speed up an inhalation, prompting when to press the dose canister, and when to stop. The feedback can be used during training and/or subsequent self-administration to reinforce correct technique and encourage user compliance with positive feedback. An intelligent monitoring and feedback system also creates the opportunity for patients to adjust their dosage according to changes in their disease state, which the device has the potential to detect through its processing software.

In feasibility studies, Sagentia researchers found that for swirl based DPIs the volumetric flowrate correlates linearly with dominant acoustic frequencies and harmonics. Equipped with an inexpensive microphone and a number of simple processing algorithms tailored to a specific inhaler type, Sensohaler can measure airflow rate and other critical parameters of inhaler function to a high degree of accuracy. In Sagentia’s tests, the volumetric flowrate measurements, for both pMDIs and DPIs, were approaching the accuracy of a thermal mass flowmeter and in no way interfered with the performance of the inhaler.

Although the theoretical framework for Sensohaler’s operation was established decades ago, only with recent advances in electronics has it become possible to incorporate reliable technology into an inhaler at reasonable cost and size. The basic components of the Sensohaler consist of a condenser microphone e.g. as in a cell phone, a PIC (programable integrated circuit), a battery, and tricolor LEDs for the user interface. The electronic components can be built into the inhaler by a single manufacturer, or made separately in a module that the manufacturer can retrofit into their inhaler.

Sagentia also plans to build additional advanced versions of Sensohaler for clinical research and other specialized purposes. A usage monitor like Sensohaler has the potential to enhance the value of clinical data by showing whether the inhaler is actually used in the manner prescribed by the study as well as the efficacy of the drug. The device can give clinical researchers real-time confirmation of correct inhaler usage and highlight usage problems early on in the trials, removing sources of uncertainty in clinical data. Additional features might include a display screen to communicate detailed feedback; a small, inexpensive memory chip to store data on inhaler usage; a USB card for sending data to external computers for advanced analysis; or a WiFi chip to communicate with a doctor or patient’s iPhone or iPad. The information can be gathered discreetly without the clinical trial subject being aware.

Sensohaler componentry could also be modified to confirm that canisters containing drug suspensions were shaken adequately just prior to use, yet another step patients need to take to ensure correct dosing. In addition, Sensohaler could include advanced dose counters that record how much medicine has been dispensed. The U.S. Food and Drug Administration already requires that all regulated inhalers come equipped with dose counters so that patients recognize when the drug reservoir in the device has been depleted. However, these counters do not measure actual doses; instead, they measure events that act as proxies for dose release, without verifying that the dose has been delivered. Sensohaler can directly measure active drug release and hence provide a more reliable indication of efficacious delivery.

Sagentia filed a patent application for Sensohaler in November 2010, and is now seeking to collaborate with pharmaceutical companies to determine how the device can best work in combination with existing inhalers, either in production or in undergoing development.

With noncompliance remaining a costly barrier to effective treatment of one of the most prevalent chronic health conditions in the world, the need for an intelligent monitoring device like Sensohaler is clear. Sensohaler has the potential to bring marked improvements in health outcomes and health care savings to asthma patients and other users of inhalers across a spectrum of diseases.


Sagentia
Cambridge, MA
sagentia.com