Understanding the Importance of Capsules in Dry Powder Inhalers

Abstract

Pulmonary drug delivery is currently the focus of research and development because of its potential to produce maximum therapeutic benefit to patients by directing the drug straight to the lung disease site. Among all the available delivery options, one popular, proven and convenient inhaler device is the capsule-based dry powder inhaler (cDPI) for the treatment of an increasingly diverse range of diseases. cDPIs use a hard capsule that contains a powder formulation which consists of a mixture of a micronized drug and a carrier usually the lactose, known for its good lung tolerance. The capsule is either inserted into the device during manufacturer or by the patient prior to use. After perforating, opening or cut the capsule in the device, patients take a deep and rapid breath to inhale the powder, using air as the vector of drug displacement. The system is simple, relatively cheap and characterized by a lower carbon footprint than that of pressurized metered dose inhalers. This article reviews cDPI technology, focusing particularly on the importance of capsule characteristics and their function as a drug reservoir in cDPIs.

An Enhanced Dissolving Cyclosporin-A Inhalable Powder Efficiently Reduces SARS-CoV-2 Infection In Vitro

“…These data, albeit preliminary, show that the use of mannitol as a bulking excipient was able to protect the physicochemical stability of the formulation, preserving its initial characteristics. The use of Quali_V ® _I capsules in this work, specifically produced for DPI, with optimised puncturing properties and internal lubricant features, certainly contributed to this positive achievement [ 47 ]. Finally, the CsA_M20 showed a differential scanning calorimetry profile at three months equal to that at time zero, evidencing that the powder did not undergo solid-state transformations during the observation time (see Supplementary Materials ).…”

Inhalable Excipient-Free Dry Powder of Tigecycline for the Treatment of Pulmonary Infections

“…The lower EF of TIG from the Handihaler (66.6%), an oscillation-based device, as opposed to that of the Plastiape RS01 (90.15%), a capsule rotation-based device, at 4 kPa can be attributed to both device and material properties . The Plastiape RS01 is an impaction-based device in which the capsule that contains pin holes on the domes of each side receives a tangential flow of air . This results in a turbulent airflow field, causing the capsule to rotate and shake with high frequency, thereby dispersing the powdered dose.…”

“…46 The Plastiape RS01 is an impaction-based device in which the capsule that contains pin holes on the domes of each side receives a tangential flow of air. 47 This results in a turbulent airflow field, causing the capsule to rotate and shake with high frequency, thereby dispersing the powdered dose. In the case of the Handihaler, the abrupt opening from a smaller inlet chamber to the capsule chamber causes a sudden expansion in the inhalation flow.…”

Pulmonary

“…Gelatine capsules provide poor protection of the drug formulation against a high relative air humidity and often have high pow-der residues. More recently, alternatives for gelatine have been developed, including hydroxypropyl methylcellulose (HPMC) [84], and different processes are used for their manufacture, resulting in different internal surface properties [e.g., 75,85]. HPMC capsules have better puncturing performance [82] lower active substance retention, improved aerodynamic performance and provide better stability of the drug formulation compared to gelatine capsules [86].…”

“…This can be subjecting the capsule to a vibratory, spinning or combined motion (e.g., spinning and wiggling) in the inhaled air stream. Many different principles have been developed for the piercing (puncturing) mechanism as well as for obtaining the desired motion, as described elsewhere [e.g., 44,75]. During inhalation, the powder particles are directed towards and through the holes in the capsule wall and subsequently entrained by the inhaled air stream.…”