Vol 10, Issue 2, 2017 Online - 2455-3891 Print - 0974-2441 ADVANCEMENTS IN DRY POWDER INHALER ADVAIT SHETTY, GANGA SRINIVASAN* Department of Pharmaceutics, Vivekanand Education Society’s College of Pharmacy, Hashu Advani Memorial Complex, Chembur (E), Mumbai, Maharashtra, India. Email: ganga.srinivasan@ves.ac.in Received: 24 July 2016, Revised and Accepted: 16 December 2016 ABSTRACT The dry powder inhaler (DPI) has become widely known as a very attractive platform for drug delivery. DPIs are being used for the treatment of asthma and chronic obstructive pulmonary disease by many patients. There are over 20 devices presently in the DPI market. DPIs are preferred over nebulizers and pressurized metered dose inhalers. However, some of the challenges of DPI are dependence on inspiratory flow (unsuitable for young children, elderly people), systemic absorption due to deposition of drug in deep lung (unsuitable for local diseases treatment), and increase in upper airway deposition of a large fraction of coarse particles. Hence, there is a need to address these unmet issues. The interpatient variation can be minimized by developing devices independent of patient’s inspiratory flow rate or active based powder mechanism. This article reviews DPI devices currently available, advantages of newly developed devices, and formulation technologies. The platform technologies are developed to improve aerosolization and dispersion from the device and decrease the patient related factors. The DPI delivery system has been expanded to treatment of non-respiratory diseases such as migraine and diabetes. The development of innovative DPI device and formulation technologies for delivering therapeutic proteins such as insulin has been accelerated to overcome the problems associated with conventional insulin therapy. Keywords: Dry powder inhaler, Inspiratory flow rate, Insulin, Platform technologies. PULMONARY DRUG DELIVERY SYSTEM Pulmonary route is gaining attention for local or systemic delivery of therapeutic agent because it is non-invasive and bypasses first pass metabolism. Lungs provide a large absorptive surface area, have good blood supply and a thin mucous membrane and hence, can be targeted for delivery of drugs [1]. In 2013, the global market for pulmonary drug delivery technologies reached $32.4 billion, with an expectation to grow to $43.9 billion till 2018 at a compound annual growth rate (CAGR) of 6.2%. The increased global market share of pulmonary drug delivery is due to the rise in cases of respiratory diseases. Newer technical advancements in the design of pulmonary devices have been applied for the treatment of respiratory disorders such as asthma and chronic obstructive pulmonary disorder as well as non-respiratory conditions like diabetes and migraine [2,3]. Nebulizers, dry powder inhalers (DPI), and metered dose inhalers (MDI) are the three major segments of global pulmonary drug delivery systems market [3]. The DPI is the fastest growing segment in this market, growing at significant CAGR of 12.5% and is estimated to reach $31.5 billion till 2018. Its global market is estimated to overtake the previously dominant segment of MDI by 2018 [2,3]. DPI DPI are breath actuated devices which contain powder formulation of micronized drug (approximately below 5 µm) and delivers this medication to the respiratory airways on oral inhalation. The energy emitted from the patient’s inspiratory airflow is the driving force for powder dispersion from the device [4]. Why DPIs are preferred over MDIs For the last 30 years, the drug delivery to lungs has been dominated by pressurized metered-dose inhalers (pMDIs) as they are believed to constitute more than 80% of the global market. The most prescribed MDIs have disadvantages both in terms of use and effectiveness [5]. MDIs contain propellants like chlorofluorocarbons that are harmful to the environment [4-6]. MDIs require good coordination between activation and inhalation. Poor coordination is main concern related to proper use of MDIs and causes inefficient therapeutic delivery. The use of pressurized MDIs results in high oropharyngeal deposition and a low amount of drug is delivered to the lungs [5,6]. These device require shaking before use to mix the drug and propellant, failure to do so will lead to inefficient drug delivery [5]. The absence of dose counters in these devices also causes a problem as it gets difficult to track the dose taken or remaining [5,6]. DPIs are a better alternative to MDIs as they have many advantages over them. These device are propellant-free and contain micronized drug alone or in combination with a suitable excipient preferably lactose monohydrate. The need for the patient coordination with respect to actuation and inhalation is eliminated as DPIs are breath- activated. This helps in effectively delivering therapeutic agents to the lungs and lower oropharyngeal deposition as compared to MDIs [5,6]. Thorrson et al. (1994) showed that the lung deposition of budesonide in healthy volunteers through the Turbuhaler (DPI) was over twice that through a pMDI (32% versus 15%, respectively). This suggests that a lower dose of budesonide using the Turbuhaler reduces the systemic side effects and helps achieve the same degree of asthma control [7]. Most of the DPI devices have dose counters that help in detecting the number of doses remaining. As the DPI formulation contains only solid dosage from there is less potential for extractable from components of device [4]. The DPI devices are user-friendly and more convenient to use, hence are preferred by patients over MDIs [5]. Need for advancement in DPI To achieve adequate inspiratory flows for reproducible and effective dose delivery, the patients’ efforts are important that is determined by DPI’s internal resistance. Patients with significant airflow obstruction find high-resistance not suitable as they require greater effort to generate the inspiratory airflow [8]. The area of concern with respect to DPIs is that the dependence on inspiratory flow rate since patients with respiratory © 2017 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2017.v10i2.14282 Review Article