Development and evaluation of an inhalation chamber for in vivo tests

Abstract

The bioavailability, toxicity, and therapeutic efficacy of a drug is directly related to its administration route. The pulmonary route can be accessed by inhalation after fumigation, vaporization or nebulization. Thus, pharmacological and toxicological evaluation accessed by an apparatus specifically designed and validated for this type of administration is extremely important. Based on pre-existing models, an inhalation chamber was developed. This presents a central structure with five animal holders. The nebulized air passes directly and continuously through these holders and subsequently to an outlet. Evaluation of its operation was performed using clove essential oil, a nebulizer, and a flow meter. The air within the chamber was collected by static headspace and analyzed by gas chromatography with a flame ionization detector. For this purpose, a 2.5 minutes chromatographic method was developed. The air flow in each of the five outputs was 0.92 liters per minute. During the first minute, the chamber became saturated with the nebulized material. Homogeneous and continuous operation of the chamber was observed without accumulation of volatile material inside it for 25 minutes. The inhalation chamber works satisfactorily for in vivo tests with medicines designed to be administrated by inhalation.

Ethnopharmacological Evaluation of Breu Essential Oils from Protium Species Administered by Inhalation

“…This probably occurs because the excess water makes the medium quite polar, preventing the apolar components of the essential oil from remaining in the solution [ 28 , 29 ]. Despite the heterogeneous nature of the solution in the formulation cup, the compressed air injected by the nebulizer generates a vortex that guarantees homogeneous air nebulization inside the chamber [ 22 ].…”

“…In this chamber, the animal holders have an air output ( Figure 1(a) , 10) that can be sealed by a plastic screw cap. These outputs are opened during the tests, forcing the intake air to leave the chamber thought them since they are the only exits from the chamber [ 22 ]. The main components in each essential oil formulation, A – E, were quantified in the nebulized air and are shown in Table 2 .…”

“…Each group was represented by mice that inhaled the following: nebulized air only (control group); the formulation vehicle without essential oil (vehicle group); and one of the formulations (A–E). The inhalation process was carried out in a chamber that was previously developed by our group ( Figure 1 ) [ 22 ]. The chamber contains a central structure connected to five animal holders ( Figure 1(a) , 1) with lids ( Figure 1(a) , 2), and nebulized air passes directly and continuously through these animal holders.…”

“…Animals were placed into the animal holders; the nebulizer was turned on and the formulation was nebulized into the inhalation chamber and each of the five animal holders simultaneously. The nebulized air was blown into the chamber from the head ( Figure 1(a) , 4) to the bottom by a central tube, generating a vortex that optimizes saturation and allows more uniform air distribution to the animals [ 22 ].…”

An Efficient and Cost-Effective Nose-Only Inhalational Chamber for Rodents: Design, Optimization and Validation

“…The developed inhaler, however, had limitations of large inhalation chamber and inability to keep the holding chambers at equidistant levels from the inlet (i.e., DPI or nebulizer), resulting eventually in uneven distribution of the inhalable dose. Recently, Silva et al (2017) developed and evaluated a round-wall glass inhalation chamber for preclinical testing in rodents connected to a nebulizer on the upper side and animal holders the lower side (24).…”