Introduction
Inhaled corticosteroids (ICS) are among the main choices in managing and
treating asthma and are recommended for mild-to-severe asthma in
children and adults. 1,2 It is essential to consider
active molecules, patients’ preferences, and user abilities while
prescribing an ICS for asthma. Metered dose inhalers (MDIs) and dry
powder inhalers (DPIs) are common ICS inhaler devices.3,4 MDI inhalers are well-known, compact, convenient
devices requiring actuation coordination to be used correctly. The
breath and actuation coordination sometimes makes using the MDI inhalers
difficult for some patients with low cognitive ability or difficulty
actuating. MDI can be used with a spacer to improve medication delivery
by extending the time of inhaling and allowing the lungs to absorb the
medication more slowly and smoothly. In addition, using a spacer
simplifies the inhaling process by reducing the need for actuation
coordination in MDI users, especially in children. 5MDI inhalers are cheaper than DPIs, and propellants are essential for
their formulation. Breath-dose coordination is unnecessary while using
DPI inhalers because DPIs are designed to release the medication in
response to the patient’s inhalation effort. However, sufficient
respiratory force is required for DPI inhalers to inhale the powder
effectively. User instruction is inconsistent among different DPI
inhalers, and a preparation step is usually needed before inhalation.3,4,6,7
The airway microbiome has been associated with the development and
severity of asthma. 6,8 It was shown that bacterial
diversity and enriched pathogenic species are higher in the airways of
asthma patients compared to healthy individuals. 8,9The lung microbiome is partly derived from the upper respiratory tract,
as well as its composition is being influenced due to interactions with
the oropharynx microbiome. 10 Hence, saliva may be a
more feasible and completely non-invasive source for microbiome studies,
especially in children where other samples like induced sputum,
biopsies, and bronchoalveolar collection are challenging and invasive.11 The saliva microbiome is in direct contact with
both airway and gastrointestinal (GI) entries. Different environmental
factors may influence the saliva microbiome, like food, drinks, and
medications. It has been previously shown that ICS treatment is
associated with the airway microbiome composition and diversity.12,13 However, more research is needed to better
understand the association between inhaled corticosteroid intake and
salivary microbiome in children to optimize risk assessment, monitoring,
and management strategies to protect patients’ oral and overall health
while using inhaled corticosteroids.
Local deposition of ICS in the oropharynx and larynx may lead to side
effects like dysphonia (hoarse voice), and oropharyngeal candidiasis
(thrush). The severity and frequency of side effects depend on
medication type, dose, administration rate, inhaler techniques, and
device type, which can be prevented by rinsing the mouth and throat with
water after using all ICS types. 14-16 The risk of
oral candidiasis and dysphonia was higher by using MDI devices than DPI
devices when compared to a placebo group.17 We
hypothesized that differences in formulation and ICS device types may
influence oral cavity microbiota composition. This study aims to compare
the saliva bacterial microbiome in children with moderate-to-severe
asthma under regular ICS treatment via MDI versus DPI devices.