Caffeine:
Among the range of methylxanthines, caffeine is most commonly used for
preterm infants with apnea receiving non-invasive respiratory support
(Clark et al. 2006). Ventilating preterm
infants may result in severe pulmonary adverse like bronchopulmonary
dysplasia (BPD) (Moschino et al. 2020).
Therefore, as non-invasive respiratory support, caffeine has already
shown to reduce apnea of prematurity along with its associated improved
lung function at 11 years of age (Jobe
2017). Caffeine treatment on preterm infants at birth also showed
significant improvement in minute ventilation and tidal volume
(Dekker et al. 2017) as well as
extubation success (Henderson-Smart and
Davis 2001). In addition to that, caffeine is also of the few known
drugs shown to reduce the risk of BPD at 36 weeks post-menstrual age
(PMA) (Dobson et al. 2014). These
evidences suggest suggests a potential role of caffeine to treat the
respiratory symptoms in infants with COVID-19
(Hong et al. 2020). Furthermore, caffeine
showed asthma improvement in adults as well. It was reported that people
with mild to moderate asthma improved lung function even at a low dose
of 5mg/kg body weight (Welsh et al.
2010). Caffeine also showed a significant bronchodilator effect in
young patients with asthma (Becker et al.
1984). Among the various proposed mechanisms for the bronchodilator
effect, the most well-established mechanism Phosphodiesterase (PDE)
inhibition and adenosine receptor antagonism
(Tilley 2011). Along with the
well-established role in improving pulmonary functions and respiratory
symptoms as well as its bronchodilatory role on the upper respiratory
tract of patients (Figure 2) , caffeine makes itself a
compelling candidate as an adjuvant therapy for COVID-19 patients
showing respiratory symptoms.