38 Questions
What is the primary categorization of the respiratory tract into?
Conducting and respiratory zones
What is the main goal of the pulmonary route for local treatments?
To target specific areas of the lung for local treatment
What is a key consideration when selecting drug candidates for pulmonary drug delivery?
The drug's molecular weight and lipophilicity
What is a major challenge in delivering drugs through the pulmonary route?
The rate of diffusion through respiratory membranes
What is the purpose of absorption enhancers in pulmonary drug delivery?
To increase the rate of diffusion through respiratory membranes
What is the main difference between the upper and lower respiratory regions?
The upper region is for conduction, while the lower region is for gas exchange
What is a key learning outcome of these lectures?
To explain the advantages of the pulmonary route for local and systemic treatments
What is the name of the professor teaching PHRS 313?
Prof. Alaa El-deen Bakry Yassin
What percentage of the total surface area of the lungs is composed of the alveolar area?
More than 90%
What is the main function of goblet cells in the respiratory membrane?
To secrete mucous
What is the main reason for the limited drug transport in the upper airways?
Smaller surface area and lower regional blood flow
What is the approximate thickness of the alveolar-vascular epithelium?
0.1-0.2 mm
What is the primary function of ciliated cells in the respiratory membrane?
To propel mucus upward and out of the lung
What percentage of delivered drug particles are removed in the upper airways?
Up to 90%
What is the effect of increasing the IFR on the particle size generated?
Smaller particle sizes
Why is co-ordination of aerosol generation with inspiration critical for MDIs?
To prevent deposition in the throat
Why are pulmonary drug delivery systems administered by oral inhalation and not nasal?
Because of anatomical limitations in the nasal airway
What is the effect of increasing the tidal volume on the penetration of particles to the terminal bronchioles and alveolar regions?
Increased penetration
What is the effect of increasing breath holding between inspiration and exhalation on the deposition of particles?
Increased time for deposition
Which disease state has a greater influence on exhalation than inhalation?
Asthma
What is the effect of bronchial obstruction on the deposition of particles by sedimentation?
More deposition than normal
Why is IFR important in devices such as DPIs?
Because it determines the size of the particles generated
What type of fatty acids have been studied as absorption enhancers due to their safety and effectiveness?
Medium chain fatty acids
Which type of drugs are especially vulnerable to metabolism in the lung?
Peptide, proteins, and nucleic acid-based drugs
What is the main function of cationic polymers in pulmonary drug delivery?
To enhance the absorption of water-soluble macromolecules
What is a crucial factor to consider when selecting a drug for pulmonary systemic delivery?
The noninvasive alternatives available for the drug
What is the effect of tight junction modulators on the absorption of hydrophilic drugs?
They increase the absorption of hydrophilic drugs
What is the main purpose of an ultrasonic nebulizer?
To aerosolize the liquid medication using a piezoelectric crystal
What type of enzymes constitute the majority of degrading enzymes present in the lung?
Serine proteases and aminopeptidases
What is the advantage of adaptive aerosol delivery in nebulizers?
It targets the aerosol delivery during inspiration only
What is the function of Octyl-h-D-glucoside in pulmonary drug delivery?
It is a non-ionic surfactant
What is the function of a nebulizer?
To turn liquid medication into a fine mist
What is the effect of cationic polymers on the mucosal barriers?
They interact with the mucosal barriers and enhance absorption
What is a characteristic of jet nebulizers?
They use compressed oxygen to aerosolize the medicine
What is the example of a tight junction modulator mentioned in the text?
Clostridium perfringens enterotoxin
What is a consideration when selecting a drug candidate for pulmonary systemic delivery?
The pharmacokinetics profile of the drug
What is a type of nebulizer that uses a piezoelectric crystal vibrating at a high frequency?
Ultrasonic nebulizer
What is an advantage of pulmonary systemic delivery over other routes of administration?
It provides a noninvasive alternative to injection
Study Notes
Pulmonary Drug Delivery
- Pulmonary route is suitable for local and systemic treatments due to its large surface area and rich blood supply.
Anatomy and Physiology of the Respiratory Tract
- The respiratory tract is divided into two major regions: the upper respiratory region (conducting zone) and the lower respiratory region (respiratory zone).
- The conducting zone consists of the nasal cavity, sinuses, nasopharynx, oropharynx, larynx, trachea, bronchi, and bronchioles.
- The respiratory zone consists of the respiratory bronchioles, alveolar ducts, and alveolar sacs.
- The alveolar area has a large surface area (90-100 m2) and a thin alveolar-vascular epithelium (0.1-0.2 mm) with a large capillary network.
Anatomical Features
- The upper airways have a smaller surface area and lower regional blood flow, limiting drug transport.
- The respiratory membrane thickness decreases as you move from the upper to the lower respiratory region.
- The bronchi and bronchioles contain goblet cells, serous cells, and ciliated cells.
Factors Affecting Drug Delivery
- Inhalation flow rate (IFR) affects particle size and deposition.
- Co-ordination of aerosol generation with inspiration is critical to avoid deposition in undesirable regions.
- Oral inhalation is preferred over nasal inhalation due to anatomical limitations and higher dose loss.
- Physiological factors such as tidal volume, breath holding, and disease states (e.g., bronchial obstruction) affect drug delivery.
Absorption Enhancers
- Fatty acids (e.g., capric acid and lauric acid) have been studied as absorption enhancers due to their safety and effectiveness.
- Non-ionic surfactants (e.g., octyl-h-D-glucoside) can also enhance absorption.
- Enzyme inhibitors (e.g., peptide, protein, and nucleic acid-based drugs) can prevent metabolism before absorption.
- Cationic polymers (e.g., cationated gelatins, poly-L-arginine, and chitosan) interact with mucosal barriers and enhance absorption.
- Tight junction modulators (e.g., clostridium perfringens enterotoxin) can open tight junctions and enhance absorption.
Properties of Candidate Drugs
- Suitable drugs for systemic pulmonary delivery should have no non-invasive alternatives or current limitations, high systemic absorption, and a pharmacokinetics profile that meets therapeutic needs.
Inhalation Devices
- Nebulizers are devices that convert liquid medication into a fine mist for inhalation.
- There are two types of nebulizers: jet and ultrasonic nebulizers.
- Adaptive aerosol delivery monitors a patient's breathing pattern and targets aerosol delivery to the first 50% of each inhalation, reducing drug loss during exhalation.
Lecture on pulmonary drug delivery, covering its advantages and delivery methods. Taught by Prof. Alaa El-deen Bakry Yassin and Dr. Obied.
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