Inhalandum

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An inhalandum is a solid or liquid preparation that can be administered as a vapor or aerosol . Such preparations exert either a local or a systemic effect in the lungs .

Classification

In the monograph "Preparations for inhalation", the European Pharmacopoeia differentiates between the following preparations:

  • Preparations that are converted into steam
  • Liquid preparations for nebulization
  • Liquid preparations in pressurized gas metered dose inhalers
  • Powder for inhalation.

The devices that are to administer the preparations for inhalation are also subdivided in the pharmacopoeia. There are:

Lung as an application site

The lungs as an application site offer several advantages. As an organ responsible for gas exchange, the lungs provide a very large area (approx. 100 m²). The numerous air bubbles ( alveoli ) are enveloped by the alveolar epithelium and the endothelial membrane and have a weaker barrier function than the gastrointestinal tract and the skin. The pulmonary application also circumvents the first-pass effect , and thus the bioavailability of many drugs is optimized.

Deposition Mechanisms

Impaction

Particles larger than 10 μm cannot follow the changes in direction of the air flow due to their inertia and are deposited in the mouth and throat. Smaller particles are only deposited by impaction when the lungs later branch out (e.g. bronchioles ).

diffusion

The separation of smaller particles takes place mainly through diffusion and is subject to the law of diffusion. The smaller the particles, the more effective the deposition by diffusion.

sedimentation

Sedimentation is described by Stokes law . Particles with a size between 1 and 5 μm sediment mainly in the intrathoracic space. Since these particles are not separated out earlier by impaction and diffusion or are not exhaled again, this particle size is aimed for. Particles between 0.01 and 0.1 μm are also deposited intrathoracically (by diffusion). However, the production of such particles would be too difficult and expensive.

literature

  • Deutscher Apotheker Verlag (Ed.): European Pharmacopoeia 8th Edition . 1st edition. Slipcase, 2014, ISBN 978-3-7692-6512-5 .