Nebulizers reservoirs

Reconstitution-The contents of 1 vial must be dissolved in 6 mL Sterile Water for Injection, LISP. It is important to use only sterile water saline solution will cause the drug to precipitate. Place the entire reconstituted contents of the vial into the Respirgard II nebulizer reservoir for administration. Do not mix the pentamidine solution with any other drugs. 

Fig. 3 Schematic diagram of nebulizer output. Droplets small enough will be carried out by air stream (route A), and the large droplets will be either recycled to the nebulizer reservoir (route B) or carried out by the outgoing air stream (route Bl). Some of the solvent will be evaporated (route C). (Adapted from Ref.. )...

Table 2 Final drug concentration (mg/ml) in the nebulizer reservoirs...

The air entering the nebulizer is normally not humidified, and the large concentration of aerosol water droplets circulating in the device results in rapid two-way coupled mass transfer that causes droplet evaporation and humidification of the air. The latent heat associated with this evaporative mass transfer causes cooling of the liquid in the reservoir over time, and the humidification of the compressed air increases the concentration of the drug in the nebulizer reservoir over time [3, 16]. 

Repetitive routine analysis of a specific sample (e.g., for Quality Control) will usually require a dedicated instrument. Therefore, the chromatograph and, in particular, the detector will be chosen for that specific analysis. Consequently, only one detector will be necessary and the purchase of an armory of detectors on the basis that they might be needed in the nebulous future is not advised. An alternative detector can always be obtained if and when the demand arises. The same argument applies to multi-solvent reservoirs and multi-solvent gradient programmers and other accessories that are not immediately required for the specific analysis in mind. 

In cases of severe acute asthmatic attacks, bronchodilators and steroids for direct dehveiy to the lungs may be needed in large doses. This is achieved by direct inhalation via a nebulizer device this converts a liquid into a mist or fine spray. The dmg is diluted in small volumes of Water for Injections BP before loading into the reservoir of the machine. This vehicle must be sterile and preservative-fiee and is therefore prepared as a terminally sterilized unit dose in polyethylene nebules. 

Nebulizers are specialized atomizers which permit recycling of the liquid. They have in-built baffles to ensure that large primary drops are returned to the reservoir and thus the aerosol emitted from the device has a size distribution which will aid airway penetration. 

During nebulization from airjet nebulizers, cooling of the reservoir solution occurs which, together with vapor loss, results in concentration of the dmg solution. This in turn produces an aerosol output in which the drag concentration increases with time. Concentration of the dmg solution in the reservoir can lead to drug recrystallization with subsequent blockage within the device or variation in aerosol particle size. 

The Bespak Piezo Electric Actuator is a novel aerosol delivery system based on a piezoelectric crystal combined with an electroformed mesh (Fig. 3). It produces droplets of adjustable size from a single metered drop or fluid reservoir. The mesh hole dimension (as small as 3 pm) determines the size of the droplets produced, whereas the size and density of the holes control the rate of fluid delivery. These can be varied according to the formulation. Although solutions are more readily nebulized, suspensions can be aerosolized if the particle size of the suspended particles is two to three times smaller than the mesh size. 

Fig. 3 A typical self-aspirating CE-ICP-MS interface. The make-up buffer/sheath electrolyte reservoir is positioned above the interface to provide the correct pressure and flow of buffer to the pneumatic nebulizer.

Fig. 7 Electropherogram showing separation of metallothio-nein I and ferritin. Zinc (mass 64) response at top and copper (mass 65) showed low signals for metallothionein. Cadmium (mass 114) showed a good response for metallothionein, and iron (mass 54) showed a good response for ferritin. This electropherogram was run using a run buffer of 15 mM Tris (hydroxymethyl) aminoethane (pH 6.8) at 15 kV, and the makeup buffer reservoir was positioned 2.5 cm above the MicroMist nebulizer. (Conditions are from Ref. [16].)...

A liquid-junction interface has also been suggested and applied for CE-ESI-MS [8]. Electrical contact with this interface is established through the liquid reservoir which surrounds the junction of the separation capillary and a transfer capillary, as shown in Fig. lb. The gap between the two capillaries is approximately 10-20 fim, allowing sufficient makeup liquid from the reservoir to be drawn into the transfer capillary while avoiding analyte loss. The flow of makeup liquid into the transfer capillary is induced by a combination of gravity and the Venturi effect of the nebulizing gas at the capillary tip [8]. 

Nebulizers and atomizers used in aerosol research produce a polydisperse aerosol consisting of particles under 10 pm in diameter. Most nebulizers use compressed air for atomization, whereas some use ultrasonics. Many models of compressed-air nebulizers have been developed, but they basically use the principle of air blast atomization of liquids issuing through a small orifice. Impaction plates or baffles are used to remove the larger droplets. Mass median diameters normally range from 2 to 5 pm, with a compressed-air pressure of 20-30psig. A detailed discussion of nebulizers can be found in Raabe [5]. Most nebulizers or atomizers tend to have a small liquid reservoir and cannot be used for long duration unless the reservoir is refilled continuously. 

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