Introduction
Inhaled bronchodilators and inhaled corticosteroids were the mainstays
in the management of obstructive pulmonary diseases. These agents were
delivered through different inhaler devices as it was considered to be
the best route to administer for better safety and efficacy
outcomes.1,2 Unlike systemic drugs, inhaled medicines
are rapidly directed towards the airways, allowing for rapid onset. Some
of the commonly used delivery devices were nebulizers, pressurized
metered-dose inhalers (pMDI), dry powder inhalers (DPI), or Soft Mist
inhalers were the commonly used devices. pMDI was introduced in 1950 and
it became very popular and widely used for inhalation therapy in
patients with obstructive pulmonary diseases. The coordination between
inhalation and actuation of inhaler was an important issue3. There was an ocean of studies published in the last
few decades assessing the importance of optimal inhaler technique use
and its significance over the control status of the disease. Appropriate
use of inhaler devices is very important for both asthma and COPD
management as it results in compromised therapeutic outcomes leading to
inadequate control of symptoms. 4,5,6,7 Inhalation
therapy using a valve holding chamber MDI has been shown to play a key
role in the treatment of asthmatic patients as they encourage patients
to breathe out of a drug pool. 3, 8. However, several
studies concluded that a significant proportion of patients continue to
use their inhaler devices incorrectly. 9,10
For many years, measurements of pulmonary lung function (PFT) have been
used to compare efficacy. Besides the evaluation of variations in
systemic bioavailability, the concentration of the salbutamol excreted
in the urine post 30 minutes of inhalation is determined and correlated
with the amount of drug delivered to the lungs.11 The
assessment of the relative bioavailability of salbutamol in the lung by
obtaining a sample of urine 30 minutes after inhalation is reproducible,
clear, and effective. 12 The benefits of this approach
compared to others are the use of a patient’s own inhaler, no need for
either the ingestion of charcoal or the use of a radiolabelled inhaler
marker. The 30-minute urinary salbutamol concentration method may also
be used concomitantly with measurements of lung function to demonstrate
the association between improved deposition and enhanced
spirometry.11 Only a few studies employed 30 min
salbutamol urinary excretion post inhalation pharmacokinetic method to
determine lung bioavailability of inhaler drugs, compare inhaler
medications and devices in healthy volunteers, and only study in asthma
patients. 11-15 The aim of this paper is, therefore,
to evaluate the urinary salbutamol concentration as a measure of
relative bioavailability to the lung within the first 30 minutes after
inhalation and correlate it with the total inhaler scores assessed
through a standard questionnaire and control status of the disease.