A measurable dose inhaler ( MDI ) is a device that gives certain drugs to the lungs, in the form of short bursts of aerosol drugs normally given by patients through inhalation. This is the most commonly used delivery system to treat asthma, chronic obstructive pulmonary disease (COPD) and other respiratory diseases. Drugs in the most commonly measured dose inhalers are bronchodilators, corticosteroids or a combination of both for the treatment of asthma and COPD. Other drugs that are less commonly used but also given by MDI are mast cell stabilizers, such as cromoglicate or nedocromil.
Video Metered-dose inhaler
Description
The measured dose inhaler consists of three main components; tubes produced in aluminum or stainless steels using deep drawing, in which formulations are located; a measuring valve, allowing a number of measurable measurements to be shared with each actuation; and an actuator (or funnel) that allows the patient to operate the device and direct the aerosol into the patient's lungs. , The formulation itself consists of medications, liquid gas propellants and, in many cases, stabilizing the excipient. The actuator contains a marriage disposal nozzle and generally includes a dust cap to prevent contamination.
To use the inhaler, the patient presses the top of the tube, with their thumb supporting the underside of the actuator. The actuation of the device releases a single dose formulation containing the drug either dissolved or suspended in the propellant. The breakdown of volatile propellant into droplets, followed by rapid evaporation of these droplets, produces an aerosol generation composed of micrometer-sized drug particles which are then inhaled.
Maps Metered-dose inhaler
Usage
Inhaled-dose inhalers are just one type of inhaler, but they are the most commonly used type. Replacement of chlorofluorocarbon propellant with hydrofluoroalkane (HFA) resulted in the redesign of measured dose inhalers in the 1990s. For one variation of the beclomethasone inhaler, this redesign resulted in much smaller aerosol particles being produced, and led to an increase in potential by a factor of 2.6.
- The asthma inhaler contains medications that treat asthma symptoms.
- Measurable dose inhalers can be used to treat COPD, both in a stable state and during lung attacks.
- Dry powder inhaler involves micronised powders that are often packaged in a single dose amount in blisters or gel capsules containing powdered drugs to be drawn into the lungs by the user's own breath. These systems tend to be more expensive than MDI, and patients with highly impaired lung function, such as those that occur during asthma attacks, may find it difficult to generate sufficient airflow to get a good function from them.
- A nicotine inhaler allows smokers to smoke to get nicotine without using tobacco, such as nicotine gum or nicotine. Nicotine inhalers marketed as nicotine replacement therapy should not be confused with electronic cigarettes, which produce steam. Nicotine inhalers are also known by their nickname "the puffer". This device is made of thin plastic, sometimes resembling a cigarette, or a cylindrical shape. Contains nicotine filled filled connectors, located at the base of the product. When you inhale the inhaler, the nicotine vapor is inhaled and absorbed in the lining of the mouth. Each inhaler gives nearly four hundred breaths of this nicotine vapor. It's also healthier than traditional cigarettes. Nicotine inhalers are also sensitive to temperature. In cold weather, less nicotine is delivered. Nicotine inhalers are considered easier to use than electronic cigarettes because they are usually disposable, and contain fewer parts than electronic cigarettes. Evidence suggests that the US Food and Drug Administration (FDA) receiving products such as nicotine inhalers may be the safer way to deliver nicotine than electric cigarettes.
History
Prior to the discovery of MDI, asthma medication was delivered using a fragile and unreliable bean nebulizer. The relatively coarse nature of these devices also means that the particles they produce are relatively large, too large for effective drug delivery to the lungs. Nonetheless these nebulizers pave the way for inhalation drug delivery that inspires MDI.
MDI was first developed in 1955 by Riker Laboratories, now a subsidiary of 3M Healthcare. At that time the MDI represented the convergence of two relatively new technologies, CFC propellants and Meshburg measuring valves originally designed to remove perfumes. The initial design by Riker uses a glass tube coated with vinyl plastic to increase its durability. In 1956 Riker has developed two MDI-based products, Medihaler-Ept containing epinephrine and Medihaler-Iso containing Isoprenaline. Both products are agonists that provide short-term relief from asthma symptoms and are now largely supplanted in the treatment of asthma by salbutamol, which is more selective.
Spacer
Dose-dose inhalers are sometimes used with an auxiliary device called a retaining chamber or spacer, which is a tube attached to an inhaler that acts as a reservoir or retaining chamber and reduces the speed at which the aerosol enters the mouth. They serve to hold drugs sprayed by the inhaler. This makes it easier to use an inhaler and helps ensure that more drugs enter the lungs, not just into the mouth or air. With proper use, spacers can make the inhaler more effective in delivering the drug.
Spacer can be very helpful for adults and children who find unusual ordinary dose measurable inhalers that are difficult to use. People who use corticosteroid inhalers should use spacers to prevent drugs from entering their mouth, where yeast infections and dysphonia can occur.
Age and replacement
The deposition of the drug formulations on the canister surface can result in a shorter shelf life of the MDI inhaler. Applying a suitable surface coating for the components helps extend this shelf life. Over the years various coating processes have been developed that can be applied to tubes and valves to protect the contents of deposition and degradation. Gas plasma processing is an industrial technique performed in a vacuum to coat the entire MDI inhaler and involves constant or pulsed gas excitation either by Radio Frequency (RF) or a microwave field to produce an energetic plasma. This coating ensures that the drug formulations do not stick to the inner wall of the MD inhaler and result in the patient receiving prescribed doses of the drug, while also extending the shelf life of the product.
A measurable dose inhaler contains enough drugs for some actuation (or "puff") printed on the canister. Although the inhaler may continue to work beyond that amount of use, the amount of drug delivered may not be correct. It is important to keep track of how many times the inhaler is used, so it can be replaced after the recommended amount of use. For this reason, some authorities request that manufacturers add dosage counters or dose indicators to the actuators. Some inhalation products are now sold with dose-dose actuators. Depending on the manufacturer and product, the inhaler is sold as a complete unit or individual tube as a recharge recipe.
Propellants
One of the most important components of MDI is its propellant. The propellant provides the power to produce aerosol clouds and is also a medium in which the active component must be suspended or reconstituted. Propellant in MDI typically reaches more than 99% of the dose delivered, resulting in propellant properties that predominate over other individual factors. This is often overlooked in the literature and industry because so little propellant is used and its contribution is often taken for granted. Suitable propellants must pass strict criteria, they must:
- has a boiling point in the range -100 to 30Ã, Â ° C
- has a density of about 1.2 to 1.5 g cm -3 (about the drug to be suspended or reconstituted)
- has a steam pressure of 40 to 80 psig
- has no toxicity in patients
- not flammable
- can dissolve general additives (active ingredients must be fully soluble or completely insoluble)
Chlorofluorocarbons (CFC)
In the early days of MDI the most commonly used propellants were chlorofluorocarbons CFC-11, CFC-12 and CFC-114.
Transition to HFA propellant (hydrofluoroalkane)
In 2008 the Food and Drug Administration announced that inhalers using chlorofluorocarbons as propellants, such as the Primatene Mist, could no longer be produced or sold in 2012. This follows from the US decision to approve the Montreal Protocol 1987 on Ozone Depleting Substances.
Lipid surfactant
Phospholipids are important natural surfactant lipids used to enhance penetration and bioavailability. Phospholipids act by reducing the high surface tension forces at the air-air interface inside the alveoli, thereby reducing the pressure required to expand the lungs. Therefore, commercially available phospholipid formulations have been designed to spread rapidly through an aqueous interface, thereby reducing what is otherwise a very high water surface tension.
Color
For easy identification, many MDIs are color-coded
See also
- Inhaler
- Dry powder inhaler
- Asthma
References
External links
- UpToDate patient information: The measured dose inhaler technique in adults
- Use measurable dose inhalers with spacers: techniques for children, illustrated
- Use measurable dose inhalers without spacers: techniques for children, illustrated
Source of the article : Wikipedia
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