export_kompella respiratory drug delivery Flashcards
What are some agents administered by inhalation?
Localized Effects:
- Anti-asthma: bronchodilators and anti-inflammatory.
- Mucokinetics.
- Antimicrobials.
Systemic Effects:
- General Anesthetics
- Peptide/Protein Drugs
Why respiratory delivery for systemic effects?
- Huge surface area
- Thin alveolar epithelium
- High blood supply
- No hepatic first pass metabolism
- Rapid onset of action
What are other routes can present problems for systemic delivery?
- Oral route: high metabolism of some drugs.
- Parental route: expensive, painful, and poor acceptance
- Pulmonary route - even proteins are absorbed
How are drugs absorbed through the epithelium?
- Passive diffusion through membranes or aqueous pores (most common).
- Carrier mediated transport.
- Endocytosis
How do you use an aerosol?
Remove dust cap, shake, exhale, mouth piece into mouth and close, inhale slowly and deeply while pressing actuator, remove the aerosol and hold breath, allow 5 minutes between doses.
What are some factors that influence particle deposition in lungs?
- Physical properties of the aerosol (particle size, density, shape, size distribution, charge, and hygroscopicity).
- Device: design of metered dose inhalers - pMDIs, dry powder inhalers (DPIs), and nebulizers. Use of spacer device.
- Patient related factors: Lung geometry and breathing pattern.
What are some patient related factors influencing particle deposition in lungs?
- Lung geometry: adults vs. infants, healthy vs. disease states, angle of patient’s neck.
- Breathing pattern: oral vs nasal inhalation, respiratory flow rate, tidal volume, time for breath hold.
slow, large volume breathing and control of cough improves deposition.
What are the mechanisms of particle deposition in lungs?
Impaction, Sedimentation, Diffusion
Where does impaction occur in the lungs and what are some properties?
- Occurs in upper and large conducting airways.
- Favored by high flow velocities and rapid changes in flow directions.
- Significant for particles > 2um
- Increases with particle size.
Where does sedimentation occur in lungs and what are some of its properties?
- Occurs in the small conducting airways and in alveolar regions.
- Favored by deep slow breathing.
- Negligible for particles less than .5 um.
- Main mechanism of deposition of aerosols.
Where does diffusion occur in the lungs and what are its properties?
- Occurs in lung periphery with small lung dimensions.
- Favors breath holding.
Becomes effective for particles less than 0.5 um
- Increases with decreasing particle size
Where are some places that deposition occurs and what are the mechanisms?
- Extrathoracic (nasal/oral, pharynx, larynx).- inertial impaction
- Tracheobronchial deposition - primarily sedimentation, but also inertial impaction.
- Alveolar - sedimentation, diffusion for very small particles.
How are drugs removed from the respiratory tract?
- mucociliary clearance
- coughing
- alveolar permeation into systemic circulation
- metabolism in the lung
What are the different inhalation delivery devices?
- Aerosols: pressurized canister releases drug and patient breathes in.
- Inhaler : patient receives drug into lungs by inhaling.
- Nebulizer: produces a fine mist for patient to inhale through a mask for about 10-15 min.
Note*: Aerosols are very finely subdivide liquid or solid particles that are dispersed in and surrounded by air
What are the classification of aerosol products?
Space spray: highly pressurized, finely divided particles <50um, 85% propellant.
Surface Spray: larger particles, wet and coarse, 30-70% propellant. E.g. dermatologic sprays.
Foam sprays: emulsions of propellants with product concentrate, 6-10% propellant. E.g. vaginal foams, medicated foams, shaving cream.
