GB2431883A

GB2431883A - Rapid mixing inhaler

Info

Publication number: GB2431883A
Application number: GB0522622A
Authority: GB
Inventors: Anthony Gregory Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-05
Filing date: 2005-11-05
Publication date: 2007-05-09
Anticipated expiration: 2025-11-05
Also published as: GB2431883B; GB0522622D0

Abstract

An inhaler comprising a housing 1, mouthpiece 5, a canister 2 containing a drug, a plunger 3 which releases the drug when depressed and a surface 4 downstream of the plunger 3 which interacts with the drug flow to mix it with the air being sucked in by the patient. Preferably surface 4 is curved from the outlet of the plunger 3 towards the mouthpiece 5 to encourage the drug flow to attach to it according to the Coanda effect and mix it with the surrounding air for delivery to mouthpiece 5. The surface 4 may be planar or angled in the direction normal to the flow and may also be porous to encourage airflow. The plunger 3 may be in contact with a porous element (6, fig 2). Vanes may be placed between the inhaler body and canister 2 to swirl the air being sucked in by the patient.

Description

I

Improvements to Inhalers by Rapid Mixing Inhalers are used in the treatment of bronchial diseases such as asthma. Such inhalers normally consist of a pressurised canister of the required drug in liquid form. This drug is atomised as it leaves the nozzle of the inhaler and mixes with the surrounding air.

It is known that the effectiveness of the treatment is dependent upon the patient receiving the required dose at the surface of the lungs. Because of poor mixing between the atomised drug and the air inhaled by the user, the drug is often desposited on the surfaces of the patient's mouth and trachea where it performs no useful purpose.

Devices exist to try to improve the mixing between the air and the drug. These often involve the use of a large volume between the inhaler and the patient's mouth. This increase the time allowed for mixing before the patient inhales the mixture.

Such devices are cumbersome and often cannot be carried around with the inhaler which by contrast is often carried on the person. Furthermore, these devices still collect much of the drug and require periodic cleaning.

This invention relates to the use of rapid mixing technology to inhalers.

A number of techniques exist for increasing the mixing rate between a jet flow and its surroundings. One particular technique is to use Coanda effect. According to this effect, a jet flow remains attached to a surface which is curving away from the initial trajectory of the jet. As the jet flows around such a surface, the mixing rate is usually increased over that of an equivalent circular jet in free conditions.

The invention is more particularly described by way of Figures 1 and 2. Figure 1 shows a cross section through an inhaler. The inhaler consists of an outer body, 1, which houses the canister, 2, which contains the drug. When the canister, 2, is pushed downwards the plunger, 3, releases some of the drug. The Coanda surface, 4, turns the mixing flow of atomising drug and air sucked by the patient towards the mouthpiece, 5. Figure 2 shows the region around the Coanda surface, 4 in more detail. The plunger, 4, acts against a porous surface, 6, and injects an atomising jet, 8, of the drug at high speed relative to the surroundings.

The action of inhalation by the patient cause air to flow through the body, 1, and this air flow, 7, is entrained through the porous surface, 6, and mixes with the atomising jet, 8, from the canister. The Coanda surface, 4, turns away from the initial direction of the atomising jet, 8 and towards the mouthpiece, 5. The two flows remain attached to the Coanda surface a leave it as mixed flow, 8.

Variations are possible within this invention. The drug can be in powder, liquid or gaseous form within the canister. The exit of the plunger can be plane circular or can be fluted to further enhance mixing. The Coanda surface can be planar in the direction normal to the flow or it can be curved. The porosity of the porous layer can be varied being completely open in the limit, with the plunger operated by separate lever. Small vanes can be inserted between the canister and the inhaler body in order to introduce swirl into the air and increase the mixing rate further. The distance between the plunger and the Coanda surface can be varied and reduced to zero W appropriate. The Coanda surface itself can be made porous in order to allow some air to continue to mix through the surface.

Claims

Improvements to Inhalers by Rapid Mixing

CLAIMS

1. An inhaler comprising a canister which contains a drug to be administered to a patient, and which is housed within a body which has a mouthpiece, and a plunger which when depressed releases the drug, and a surface downstream of the plunger which interacts with the flow of the drug to produce a mixed flow of air sucked in by the patient, and the drug.

2. An inhaler as in claim 1 in which the surface is curved from the outlet of the plunger towards the mouthpiece so as to encourage the flow from the plunger to attach to it according to the Coanda effect and mix with the surrounding air as it turns towards the mouthpiece.

3. An inhaler according to claims 1 and 2 in which a porous surface is placed in contact with the plunger and the surface such that the plunger is restrained relative to the body of the inhaler whilst the canister is depressed and which will allow the flow of drug and air inhaled by the patient to pass onto the Coanda effect surface 4. An inhaler according to any of the preceding claims 2 and 3 in which the surface is planar in the direction normal to the flow.

An inhaler according to any of claims I to 3 in which the surface is angled in the direction normal to the flow.

6. An inhaler according to any of the preceding claims in which the plunger outlet is circular.

7. An inhaler according to claims 1 to 5 in which the plunger outlet is non-circular.

8. An inhaler according to any of the preceding claims in which vanes are placed between the inhaler body and the canister in order to introduce swirl of the air sucked in by the patient 9. An inhaler according to any of the preceding claims in which the plunger outlet is immediately next to the surface such that the flow of drug is in immediate contact with the surface.

An inhaler according to any of claims I to 9 in which there is a gap between the plunger outlet and the surface such that the flow of drug is not in immediate contact with the surface.

11. An inhaler according to any of the previous claims in which the surface is porous to allow flow through it.