Дәрі-дәрмекті өкпеге жеткізуге арналған құрал

Device that helps deliver a specific amount of medication to the lungs

A metered dose inhaler (MDI) is a device that delivers a specific amount of medication to the lungs in the form of a short burst of aerosolized medicine that is usually self administered by the patient via inhalation. It is the most commonly used delivery system for treating asthma, chronic obstructive pulmonary disease (COPD) and other respiratory diseases. The medication in a metered dose inhaler is most commonly a bronchodilator, corticosteroid or a combination of both for treating asthma and COPD. Other medications less commonly used but also administered by MDI are mast cell stabilizers, such as cromoglicate or nedocromil.

A metered dose inhaler consists of three major components: the canister, which is produced in aluminum or stainless steel by means of deep drawing, where the formulation resides; the metering valve, which allows a metered quantity of the formulation to be dispensed with each actuation; and an actuator (or mouthpiece) which enables the patient to operate the device and directs the aerosol into the patient's lungs.

Metered dose inhalers are only one type of inhaler, but they are the most commonly used type. The replacement of chlorofluorocarbons propellants with hydrofluoroalkanes (HFA) resulted in the redesign of metered dose inhalers in the 1990s. For one variety of beclomethasone inhalers, this redesign resulted in considerably smaller aerosol particles being produced and increased in potency by a factor of 2.6. Asthma inhalerscontain a medication that treats the symptoms of asthma. Nicotine inhalersallow cigarette smokers to get nicotine without using tobacco, much like nicotine gum or a nicotine patch. The US Food and Drug Administration (FDA) has approved some nicotine inhaler products for smoking cessation. Nicotine inhalers that are marketed as nicotine replacement therapy should not be confused with electronic cigarettes, which produce an aerosol, usually from a tobacco extract, using a heating coil, while nicotine inhalers produce a noncombusted nicotine aerosol.

Before the invention of the MDI, asthma medication was delivered using a fragile and unreliable squeeze bulb nebulizer. The relatively crude nature of these devices also meant that the particles that they generated were relatively large, too large for effective drug delivery to the lungs. Nonetheless, these nebulizers paved the way for inhalation drug delivery, inspiring the MDI. MDIs were first developed in 1955 by Riker Laboratories, now a subsidiary of 3M Healthcare. The initial design by Riker used a glass canister coated with vinyl plastic to improve its resilience. Spacers can be especially helpful to adults and children who find a regular metered dose inhaler hard to use. People who use corticosteroid inhalers should use a spacer to prevent getting the medicine in their mouth, where oral yeast infections and dysphonia can occur.

The deposition of the content of drug formulation on the canister surface can result in a shorter shelf life of an MDI inhaler. Applying a suitable surface coating to the components helps to extend this shelf life. Over the years, various coating processes have been developed that can be applied to both the canister and valve to protect the contents from deposition and degradation. Gas plasma processing is an industrial technique carried out in a vacuum to coat the entire MDI inhaler. It involves constant or pulsed gas excitation by radio frequency (RF) or the microwave field to produce an energetic plasma. This coating ensures that the drug formulation does not stick to the interior wall of the MD inhaler and results in the patient receiving the prescribed dose of medication, extending the product's shelf life. A metered dose inhaler contains enough medication for a certain number of actuations (or "puffs") printed on the canister. Even though the inhaler may continue to work beyond that number of uses, the amount of medication delivered may not be correct. It is important to keep track of the number of times an inhaler is used so that it can be replaced after its recommended number of uses. For this reason, several regulatory authorities have requested that manufacturers add a dose counter or dose indicator to the actuator. Several inhalation products are now sold with a dose counter actuator. Depending on the manufacturer and the product, inhalers are sold as a complete unit or the individual canister as a refill prescription.

While MDIs are commonly used in the treatment of lung based disorders, their use requires dexterity to complete the required sequential steps to achieve the application of these devices. Incorrect completion of one or more steps in using an MDI can substantially reduce the delivery of the administered medication and, consequently, its effectiveness and safety. Numerous studies have demonstrated that between 50 100% of patients do not use their inhaler devices correctly, with patients often unaware that they are using their inhaled medication incorrectly. Incorrect inhaler technique has been associated with poorer outcomes. Incorrect maintenance and cleaning of metered dose inhalers is also an issue identified by many users, highlighting the need for clear guidance for patients prescribed MDIs.

Hydrofluorocarbon propellants have replaced CFC propellants. Concerns about the use of hydrofluorocarbon propellants have, however, since arisen since these compounds are potent greenhouse gases; propellants released during the use of a single inhaler result in a greenhouse footprint equivalent to greenhouse gases released during a 180 mile car journey.

Phospholipids are important natural surfactant lipids. used to enhance penetration and bioavailability. Phospholipids reduce the high surface tension forces at the air water interface within the alveoli, thereby reducing the pressure needed to expand the lungs. Thus, commercially available formulations of phospholipids have been designed to spread rapidly over an air aqueous interface, thereby reducing what is otherwise a very high surface tension of water.