LUNG DEPOSITION

Spray velocity and duration

In the treatment of asthma and COPD it is essential that medication released from inhaler devices reaches the site of disease.^1-3 The speed at which the aerosol moves from the device is the spray velocity. Spray duration is the time an aerosol cloud remains upon release.⁴ Higher spray velocity in itself increases the risk for oropharyngeal impaction. Also, the shorter cloud duration allows less time to efficiently inhale the drugs, and requires optimal hand-breath coordination.^5-7

HISTORIC FACT

In the 1990s the soft mist inhaler (SMI) was developed. Through technical innovations this device created a slow-moving and long lasting aerosol, decreasing oral impaction and improving lung deposition.^6,12

SPRAY VELOCITY AND AEROSOL DURATION OF DIFFERENT INHALER DEVICES

Particle Speed

slow

medium

fast

Explanation of use
Inhalation simulator based on Demoly et al., 2014.⁸
This interactive simulator displays the effect of spray velocity on oropharyngeal deposition.
With the buttons, velocity can be varied in three steps: slow, medium or fast,
and the effect on particle deposition is shown.^6-8

Spray velocity (m/s) of four different types of SABA released from pMDIs

pMDI SABA

Sb(GSK)

Sb(3M)

Spray velocity (m/s) of three different types of ICS released from pMDIs

pMDI ICS

Spray velocity (m/s) of LAMA released from SMI

SMI LAMA

pMDI SABA

Sb(GSK) = salbutamol(GSK)
Sb(3M) = salbutamol(3M)
Fe = fenoterol
Pr = procaterol

pMDI ICS

Fl = fluticasone
Be = beclomethasone
Ci = ciclesonide

SMI LAMA

Ti = tiotropium

Figure adapted from Tamura et al., 2015.⁷
Spray velocities were measured at 80mm distant from a nozzle in m/s. Data are mean.
pMDI: pressurized metered dose inhalers | SABA: short acting β2-agonist
ICS: inhalation corticosteroids | SMI: soft mist inhaler
LAMA: long acting muscarinic antagonist.

Aerosol duration of five different drugs released from HFA MDI.

HFA MDI

Sa+Fl

Ip+Fe

Aerosol duration of drugs released from SMI.

SMI

Ip+Fe

HFA MDI

Sb = salbutamol
Sa+Fl = salmeterol + fluticasone
Ip+Fe = ipratropium bromide + fenoterol
Ip = ipratropium bromide
Fe = fenoterol

SMI

Ip+Fe = ipratropium bromide + fenoterol

Figure adapted from Hochrainer et al., 2005.⁶
Aerosol duration was measured upon release from inhalation device in seconds (s). Data are mean.
MDI: metered dose inhaler | HFA: hydrofluoroalkane | SMI: soft mist inhaler

Spray velocity and duration influence the ease of use of the device and the kinetic pathway of the drug particles.^2,9 A lower spray velocity and longer spray duration allow more time to efficiently inhale the released drug at a normal respiratory rate. This facilitates coordination between actuation and inhalation.⁵ Short spray duration with high particle velocity requires optimal hand mouth coordination and has an increased risk of oropharyngeal impaction.^6,7

In flow-independent devices like pressurized metered dose inhalers (pMDIs) and soft mist inhalers (SMIs), spray velocity and duration are characteristics of the device. In contrast, in flow-dependent devices like dry powder inhalers (DPIs), they are determined by the patient's respiratory effort.^10,11

Curious how the patient's inhalation influences lung deposition in flow-dependent devices? Tune in with the next scientific communication.

Do you have questions about this Scientific Communication? Please do not hesitate to contact your local medical BI representative.