Polymer mouth throat models are available in three sizes, Small, Medium and Large for use with either the NGI or ACI.

Models are robust and made from solvent-resistant polymer. They are lightly frosted inside to permit coating with artificial mucus, which is widely used in the realistic in vitro evaluation of inhaled products.

Purchasers assume responsibility for solvent compatibility (samples of polymer can be provided) since RDD does not warrant that they are appropriate for particular experimental applications.

Models

Stainless steel mouth-throat models are available in Small, Medium and Large versions.

The interior of the stainless steel models are dimensionally identical to their polymer counterparts but have several design enhancements that provide additional flexibility when designing in vitro studies to assess real-world inhaled product performance. The two-piece design of the stainless steel model allows separation of aerosol into ‘mouth’ and ‘throat’ regions to provide a more detailed picture of aerosol deposition of inhaled particles that do not progress into the cascade impactor. Separation into 'mouth' and 'throat' fractions also facilitates the validation of in silico models.

Using one of two patented downstream adaptors, stainless steel mouth-throat models can be used in conjunction with the Next Generation or Andersen Cascade Impactor, or the adaptor can be omitted to permit direct connection to a Pulmoguard^™ filter (or equivalent with a 27.3 mm ID patient end connection). This allows for Aerodynamic Particle Size Distribution (APSD) and Total Lung Dose (TLD) to be evaluated using the same mouth-throat model, which reduces cost and potentially improves comparability across data sets.

The stainless-steel models are robust and resistant to a wider range of drug recovery solvents than the polymer models, and the interior surface is amenable to coating with artifical mucus.

Purchasers assume responsibility for solvent compatibility of all mouth-throat models since RDD does not warrant that they are appropriate for particular experimental applications.

Models

The Mouth-Throat geometry was developed and described in:

• Pharmaceutical aerosol deposition in a stainless-steel version of the Virginia Commonwealth University mouth-throat models
  Dalton CJ, Hall F, Momin M, Farkas DR, Longest P, Hindle M
  Respiratory Drug Delivery 2024: 524-526
• In vitro tests for aerosol deposition. I: Scaling a physical model of the upper airways to predict drug deposition variation in normal humans
  Delvadia RR, Longest PW, and Byron PR
  Journal of Aerosol Medicine and Pulmonary Drug Delivery 2012, 25(1): 32-40
• In vitro prediction of regional drug deposition from dry powder inhalers
  Delvadia RR, Byron PR, Longest PW, and Hindle M
  Respiratory Drug Delivery 2010 (2010), Vol 3: 907-911
• Stepping into the trachea with realistic physical models: Uncertainties in regional drug deposition from powder inhalers
  Byron PR, Delvadia RR, Longest PW, and Hindle M
  Respiratory Drug Delivery 2010 (2010), Vol 1: 215-224
• Effects of oral airway geometry characteristics on the diffusional deposition of inhaled nanoparticles
  Xi J, and Longest PW
  ASME Journal of Biomechanical Engineering 2008, 130: 011008
• Transport and deposition of micro-aerosols in realistic and simplified models of the oral airway.
  Xi J, and Longest PW
  Annals of Biomedical Engineering 2007, 39: 572-591

Recent FDA Draft Product Specific Guidance recommend the use of mouth throat models:

FDA: Draft Guidance on Albuterol Sulfate August 2024

All Nephele Mixing Inlets are manufactured with hard-anodized aluminum housings and a stainless steel inner nozzle. While all components are intended to be solvent resistant, prolonged exposure to washing solutions and mobile phase should be avoided.

Nephele Mixing Inlets gently merge a particle-free sheath air stream with a second central air stream containing an aerosol, with virtually no turbulence and minimal aerosol losses. A Nephele Mixing Inlet mounted between the aerosol entry port (for example, a VCU Realistic Throat Model or USP throat) and the inlet to the cascade impactor allows the impactor to be operated at a constant flow rate (e.g., 60 LPM) while allowing a lower fixed or variable flow rate to draw aerosol from the inhaler device and throat model. A typical experimental set-up is shown below.

Experimental Set Up for Breath Profile Simulator – Nephele Mixing Inlet.
Adapted from Olsson et al, Respiratory Drug Delivery 2010, pp 225-234.

The Original Nephele Mixing Inlet is available by special order only and requires an adaptor to fit NGI.

The Nephele Mixing Inlet has been described in the following studies:

• Mouth-Throat Models for Realistic In Vitro Testing - A Proposal for Debate
  Bo Olsson, Per Bäckman
  Respiratory Drug Delivery 2014 (2014), Vol 1, pp 287-294
• Probing Dry Powder Inhaler Performance Robustness with an Inhalation Profile Simulator
  Adrian Goodey, Buchilingam Bupathi, Henry Tat, Xiuhua Fang, Maya George, Ying Li
  Respiratory Drug Delivery 2014 (2014), Vol 2, pp 485-488
• In Vitro Aerosol Performances of NEXThaler® Using Representative Inhalation Profiles from Asthmatic Patients
  Devis Casaro, Gaetano Brambilla, Irene Pasquali, Viviana Sisti
  Respiratory Drug Delivery 2014 (2014), Vol 2, pp 375-380
• Validation of a General In Vitro Approach for Prediction of Total Lung Deposition in Healthy Adults for Pharmaceutical Inhalation Products.
  Bo Olsson, Lars Borgström, Hans Lundbäck, Mårten Svensson
  Journal of Aerosol Medicine and Pulmonary Drug Delivery, 2013 Feb 19
• Comparing Aerosol Size Distributions that Penetrate Mouth-Throat Models Under Realistic Inhalation Conditions
  Bo Olsson, Elna Berg, Mårten Svensson
  Respiratory Drug Delivery 2010 (2010), Vol 1, pp 225-234
• Realistic In Vitro Assessment of Dry Powder Inhalers.
  Zhili Li, Richard N Dalby.
  Respiratory Drug Delivery VIII (2002), Vol 2, pp 687-690
• Aerodynamic Sizing With Simulated Inhalation Profiles: Total Dose Capture and Measurement
  Nicholas C Miller, M J Maniaci, Sarvajna K Dwivedi, Gary H Ward.
  Respiratory Drug Delivery VII (2000), Vol 1, pp 191-196

The standard collection tube and associated caps are manufactured from Dupont™ Delrin^®, which is inert, resistant to most solvents, and contains no extractables. Rinsing caps are fitted with fluorinated ethylene propylene (FEP) encapsulated silicone O-ring seals to virtually eliminate leakage and extractables with the majority of drug recovery solvent systems. Caps are quick-seal, ¼ turn to full positive stop: easy to assemble/disassemble reproducibly, independent of the torque applied by the technician.

The compendial method for delivered dose determination from a DPI, requires a 4 kPa pressure drop across the device. The corresponding flow rate through the inhaler can be measured with the Collection Tube with Pressure Tap (NE-D002B). The DUSA for DPIs is capable of sampling at a variety of flow rates up to 100 LPM. Standard Collection Tubes without a pressure tap (NE-D002A) are available for subsequent dose collections, once the test flow rate has been established.

Starter Kits include:

• One collection tube (DPI Starter Kit also includes Collection Tube with Pressure Tap)
• One filter support assembly: accommodates filter and readily produces airtight seal, fitted with hose barb to connect to vacuum pump.
• One cap (with FEP encapsulated silicone seal) with hose barb to connect to a flow meter, which permits easy setting and confirmation of the target airflow rate prior to use of the DUSA.
• Two rinsing caps (with FEP encapsulated silicone seals)
• A starter pack of glass fiber filters (25-mm for MDI / 47-mm for DPI)

In practice, most companies usually find it convenient and more efficient to supplement the starter kit described above with additional collection tubes and rinsing caps. The same filter support assembly can be used respectively with multiple DUSAs to achieve faster sample preparation.

ADULT UPPER TRACHEOBRONICHIAL (TB) MODELS were developed by the Respiratory and Aerosol Dynamics Research Group of Virginia Commonwealth University (School of Engineering, led by Dr. Worth Longest).

• Medium: Original TB geometry based on the measurements of Yeh and Schum (1980) applied to "physiologically realistic bifurcation units" (Heistracher and Hofmann 1995) and scaled to a FRC of 3.5 L (ICRP 1994).
• Small: Small geometry based on the medium configuration and scaled by a length factor of 0.748.
• Large: Large geometry based on the medium configuration and scaled by a length factor of 1.165.

Relevant Publications

• Physiologically realistic models of bronchial airway bifurcations.
  Heistracher T and Hofmann W
  Journal of Aerosol Science 1995, 26(3): 497-509.
• Human Respiratory Tract Model for Radiological Protection
  ICRP
  Elsevier Science Ltd., New York 1994.
• Models of human lung airways and their application to inhaled particle deposition.
  Yeh HC and Schum GM
  Bull. Math. Biology 1980, 42: 461–480.

The medium TB geometry was developed and described in:

• Characterization of respiratory drug delivery with enhanced condensational growth (ECG) using an individual path model of the entire tracheobronchial airways.
  Tian G, Longest PW, Su G, and Hindle M
  Annals of Biomedical Engineering 2011, 39(3): 1136-1153.
• Development of a stochastic individual path (SIP) model for predicting the tracheobronchial deposition of pharmaceutical aerosols: Effects of transient inhalation and sampling the airways.
  Tian G, Longest, PW, Su G, Walenga RL, and Hindle M
  Journal of Aerosol Science 2011, 42: 781-799.

The small TB model was designed to mate with small MT, medium TB with medium MT and large TB with large MT. In addition one medium model was adjusted to represent the presence of cartilaginous rings in the trachea. The small, medium and large TB geometries were described and used in:

• In vitro tests for aerosol deposition. I: Scaling a physical model of the upper airways to predict drug deposition variation in normal humans.
  Delvadia RR, Longest PW, and Byron PR
  Journal of Aerosol Medicine and Pulmonary Drug Delivery 2012, 25(1): 32-40.

PEDIATRIC AIRWAY MODELS of the pediatric mouth-throat region (oral cavity, pharynx and larynx) and nose-throat region (nasal cavity, pharynx, larynx) that represent this airway region during oral or nasal inhalation from an inhaler were developed in the Pharmaceutical Physics Laboratory of Boehringer Ingelheim Pharma GmbH & Co. KG by the research team consisting of Deborah Bickmann, Andree Jung, and Dr. Herbert Wachtel.

Realistic (5 years): Volume of ~39.8 cm³

Idealized (5 yrs): Volume of ~50.3 cm³.

This value excludes the volume of the mouthpiece holder). The idealized model resembles a re-dimensioned version of the Alberta Throat (Warren Finlay). The idealized MT geometry interfaces an inhaler-dependent mouthpiece adapter. The respective adapters are filled with 2-component silicone resin; in this way they mate the mouthpieces of the inhalers so that there is a zero inhaler insertion depth and zero inhaler angle with respect to the horizontal plane of the mouth of the MT.

Realistic Nose-Throat (5 yrs): Volume of ~22.3 cm³

Relevant Publications

• In vitro performance of the Novolizer (DPI) using mouth-throat models of 4-5-year-old children.
  Below A
  3rd EuPFI Conference, Sept. 2011, Strasbourg.
• Can Pediatric Throat Models and Air Flow Profiles improve our Dose Finding Strategy?
  Wachtel H, Bickmann D, Breitkreutz J, Langguth P
  Respiratory Drug Delivery 2010: 195-204.
• Novel approaches in pulmonary administration.
  Bickmann D
  2nd EuPFI Conference, Sept. 2010, Berlin.
• Examining Inhaler Performance Using a Child's Throat Model.
  Bickmann D, Wachtel H, Kröger R, Langguth P
  Respiratory Drug Delivery 2008, Vol 2, pp 565-570.

All equipment is supplied according to the following Terms and Conditions:

Limited Warranty/ Limited Liability

RDD Online, LLC warrants only that this RDD^® equipment supplied was manufactured in accordance with its specifications. RDD Online, LLC, disclaims all other expressed and implied warranties including the implied warranty of merchantability and fitness for a particular purpose. The sole remedy of the buyer for any breach of this warranty is, at RDD Online’s option, to repair or replace the unit, or to refund the purchase price. This option applies only to new, unused equipment that is returned to RDD Online within 2 months of delivery.

Returns Policy

If we are notified of your intent to return stock items in re-saleable condition within 21 days of customer receipt we will issue a refund after subtracting a processing and restocking fee of $100. Please contact orders@rddonline.com for details of how and where to return the items, and what information to include with the shipment.

RDDOnline, LLC reserves the right to refuse return of RDD^® goods received in damaged condition.

RDD Online does not accept return of special order items.

Loss and Damage in Transit

Notification of damage in transit must be made within seven days of delivery. In the case of non-delivery or loss in transit, notification must be made within seven days after receipt of our invoice. Notifications should be made to orders@rddonline.com.