Exam 1 Objectives.docx - Inhalation Objectives 1 2...

Inhalation Objectives:
1. Understand the advantages and disadvantages of the inhalation route of drug administration
 Advantages:
o Quick onset of drug action due to
 Large surface area (goes directly into the lungs while nasal does not and lungs are
very large)
 Thin alveolar epithelium (MUCH thinner than skin)
 Absence of extreme pH (don’t have to worry about ionization of the drug or
degradation)
 Rich blood supply resulting in rapid systemic delivery
 Relatively low-enzymatic activity (used to think there was none, but there’s some)
 Limited first pass effect (bypass liver and delivers more drug)
o Non-invasive delivery system
 Deliver drugs to site of action and reduce incidence of side effects
 Most are portable and convenient
 Disadvantages:
o Limited to potent low dose drug (can’t give amoxicillin or ampicillin via inhalation because
the doses are very high)
o Complicated geometry – branching architecture of the airways
o In case of conventional aerosols, the lack of synchronization between activating the inhaler
and inspiration could cause deposition of drugs in the upper airways (have to inhale and press
the actuator at the same time; spacer can help with this)
o Devices do not provide feedback on correct inhalation (no feedback whether the person is
doing it correctly or not how much is getting into their system; don’t know exactly how much
is gone or if drug loss occurs)
o Switching inhalers could change the level of treatment (could change the amount delivered if
the product is changed)
o High volume of mucus could hinder deposition of aerosolized into the alveoli (high volumes
of mucus are common in COPD; thick barrier layer reduces drug’s absorption)
o Insoluble drugs might precipitate within the container and valves, thereby reducing the
effective dose and the amount of drug reaching the alveolar area (some suspension products
but there is some situation in which insoluble drugs precipitate and can clog the valve)
o Critical particle size distribution (MOST IMPORTANT PART OF INHALATION
PRODUCT; particle size matters for airway structures and other factors)
o Mucus and mucociliary clearance may decrease drug bioavailability
o Difficult to deliver peptides due to the presence of peptidases and proteases (may inhibit the
drug from getting to its site of action without being degraded)
2. Understand the barriers to drug administration via the inhalation route
 Airway architecture
o Divided into 3 areas – nasopharyngeal (nasal airway and pharynx), tracheobronchial (where
the Y from trachea and bronchioles occurs), & alveolar (where the alveoli and where the drug
needs to get to be most effective; TARGET AREA)
o Mechanisms for particle deposition in the airways:
 Inertial impact – if a particle is bigger, inertial impact increases
 Areas affected = trachea and main bronchi
 Gravitational setting – sedimentation where larger particles fall more quickly;
particle doesn’t reach the area all the way and is still settling
 Areas affected = bronchi and bronchioles

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