Asthma Inhalers

How do asthma inhalers work?

The medicine inside an inhaler goes straight into the airways when you breathe it in. This means that you need a much smaller dose than if you were to take the medicine as a tablet or liquid by mouth. The airways and lungs are treated but little of the medicine gets into the rest of the body.

The official drug/medicine name is called the generic name. Different drug companies can use the same generic medicine and produce different brands - these are the proprietary medicine names. There are many different brands of inhalers. Inhalers can have generic names and be produced by different drug companies too.

Types of asthma inhalers

There are different asthma inhaler devices that deliver the same medicine. In the treatment of asthma, the medicine inside inhalers can be divided into:

• Relievers (short-acting bronchodilators).
• Preventers (steroid inhalers).
• Long-acting bronchodilators.

Reliever inhalers - contain short-acting bronchodilator medicines (also known as SABAs)

These medicines are called bronchodilators as they widen (dilate) the airways (bronchi).

A reliever inhaler is used when needed to ease symptoms of breathlessness, wheeziness or feeling tight-chested. The medicine in a reliever inhaler relaxes the muscle in the airways which opens the airways wider,. Symptoms usually ease quickly.

The two main reliever medicines are called salbutamol and terbutaline. These come in various brands made by different companies. There are different asthma inhaler devices that deliver the same reliever medicine. Salbutamol brands include Airomir®, Asmasal®, Salamol®, Salbulin®, Pulvinal Salbutamol® and Ventolin®. Terbutaline often goes by the brand name Bricanyl®. These inhalers are usually (but not always) blue in colour. Other inhalers containing different medicines can be blue too so it is important to check the label.

In children or adults whose asthma is only very occasional (for example, if triggered by hay fever or animals) the occasional use of a reliever inhaler may be all that they need.

If patients are using reliever inhalers regularly then a preventer inhaler would usually be advised. It is important to speak to a GP or asthma nurse if the reliever inhaler is being used regularly.

Preventer inhalers - usually contain a steroid medicine (inhaled corticosteroids - ICSs)

These are taken every day to help prevent asthma attacks and to reduce symptoms of asthma. The type of medicine commonly used in preventer inhalers is a steroid. Steroids work by reducing the inflammation in the airways. When the inflammation is reduced, the airways are much less likely to become narrow and cause symptoms such as wheezing.

Steroid inhalers are usually taken twice per day and sometimes more frequently during an exacerbation (flare-up) of asthma symptoms.

It takes 7-14 days for the steroid in a preventer inhaler to build up its effect. This means it does not give immediate relief of symptoms (like a reliever does). After a week or so of treatment with a preventer, the symptoms have often gone or are much reduced. It can sometimes take up to six weeks for maximum benefit.

If your asthma symptoms are well controlled with a regular preventer you should not then need to use a reliever inhaler very often, if at all.

The aim of treatment with asthma inhalers is to manage asthma symptoms so that the reliever inhaler should almost never be needed.

Inhalers that contain medicines called sodium cromoglicate (brand name Intal®) or nedocromil (brand name Tilade®) are sometimes used as preventers, particularly in adults and in children aged over 5 years. However, they do not usually work as well as inhaled steroids and have not been shown to work at all in children under 5.

The main inhaled steroid preventer medications are:

• Beclometasone. Brands include Asmabec®, Clenil Modulite®, and Qvar®. These inhalers are usually brown and sometimes red in colour.
• Budesonide. Brands include Easyhaler Budesonide®, Novolizer Budesonide® and Pulmicort®.
• Ciclesonide. Brand name Alvesco®.
• Fluticasone. Brand name Flixotide®. This is a yellow-coloured or orange-coloured inhaler.
• Mometasone. Brand name Asmanex Twisthaler®.

Bone strength (density) may be reduced following long-term use of high doses of inhaled corticosteroids. Therefore people who use steroid inhalers for asthma need to make sure they have a good supply of calcium in their diet. Milk is a good source of calcium.. Other good dietary sources of calcium include:

• Bread.
• Some vegetables (curly kale, okra, spinach and watercress).
• Some fruits (eg, dried apricots).

See the separate leaflet called Preventing Steroid-induced Osteoporosis.

Long-acting bronchodilator inhalers (LABAs)

The medicines in these inhalers work in a similar way to relievers, but work for up to 12 hours after each dose has been taken. They include salmeterol (brand name Serevent® and Neovent®) and formoterol (brand names Atimos®, Foradil®, and Oxis®).

A long-acting bronchodilator will be added alongside a steroid inhaler if symptoms are not fully controlled by the steroid inhaler alone. This may be in two separate asthma inhalers or in a combined inhaler

Examples of combination inhalers are:

• Fostair® (formoterol and beclometasone).
• Seretide® (salmeterol and fluticasone). This is a purple-coloured inhaler.
• Symbicort® (formoterol and budesonide).

Because there are lots of different-coloured inhalers available, it is helpful to remember their names, as well as the colour of the device. This might be important when people are being treated by a doctor without the medical records - for example, in ED or on holiday. Keeping a list of the names of medicine and inhalers in a wallet or purse can help with this and reduce mistakes and confusion.

MART therapy

Where people are continuing to have asthma attacks despite full doses of inhaled corticosteroid inhalers and LABA inhalers, they may be recommended to use "Maintenance and Reliever Therapy" known as a "MART regime". This might also be recommended for people who are using large amounts of their SABA asthma inhaler, even without asthma attacks. In a MART regime, a combination ICS/LABA asthma inhaler is used which is prescribed for use both as a preventer and a reliever. Studies from 2020 show that control of asthma appears to be better with this regime and that lower doses of medication were required to achieve this control. It is likely that this will become a more popular way of managing moderate-severe asthma over time.

Inhaler devices

Different inhaler devices suit different people. Asthma inhaler devices can be divided into four main groups:

• Pressurised metered dose inhalers (MDIs).
• Breath-activated inhalers - MDIs and dry powder inhalers.
• Inhalers with spacer devices.
• Nebulisers.

The standard MDI inhaler

A standard MDI is shown above. The MDI has been used for over 40 years and is used to deliver various types and brands of asthma medicines. It contains a pressurised inactive gas that propels a dose of medicine in each 'puff'. Each dose is released by pressing the top of the inhaler. This type of inhaler is quick to use, small and convenient to carry. It needs good co-ordination to press the canister and breathe in fully at the same time. Sometimes these are known as evohalers (depending upon the manufacturer).

The standard MDI is the most widely used inhaler. However, many people do not use it to its best effect. Common errors include:

• Not shaking the inhaler before using it.
• Inhaling too sharply or at the wrong time.
• Not holding your breath long enough after breathing in the contents.

Until recently, the propellant gas in MDI inhalers has been a chlorofluorocarbon (CFC). However, CFCs damage the Earth's ozone layer and so are being phased out. The newer CFC-free inhalers work just as well, but they use a different propellant gas that does not damage the ozone layer. Some brands of the newer MDIs have much lower carbon footprints than others and many parts of the country are changing patients' asthma inhalers to the type which is best for the environment. This does not affect their efficacy as an asthma inhaler.

Breath-activated inhalers

These are alternatives to the standard MDI. Some are still pressurised MDIs, but don't require you to press a canister on top. The autohaler shown above is an example. Another example of a breath-activated MDI is the easi-breathe inhaler.

Other breath-activated inhalers are also called dry powder inhalers. These inhalers do not contain the pressurised inactive gas to propel the medicine. You don't have to push the canister to release a dose. Instead, you trigger a dose by breathing in at the mouthpiece. Accuhalers, clickhalers, easyhalers, novolizers, turbohalers and twisthalers are all breath-activated dry powder inhalers. You need to breathe in fairly hard to get the powder into your lungs. Some types are shown below.

The individual devices all have some differences in how they are operated but, generally, they require less co-ordination than the standard MDI. They tend to be slightly bigger than the standard MDI.

Spacer devices

Spacer for asthma

Spacer devices are used with pressurised MDIs. They can increase the amount of inhaled medication reaching the lungs by up to 70%, making them much more effective. They also reduce the amount of medication which gets into the rest of the body, therefore reducing side effects.

There are various types but they all work in the same way - an example is shown above. The spacer between the inhaler and the mouth holds the medicine like a reservoir when the inhaler is pressed. A valve at the mouth end ensures that the medicine is kept within the spacer until it is breathed in. On breathing out, the valve closes. Good co-ordination is not needed. Spacers are not easy to use when out and about as they are quite bulky - however all MDI asthma inhalers should be used through a spacer when at home.

A face mask can be fitted on to some types of spacers instead of a mouthpiece. This is sometimes done for young children and babies who can then use the inhaler simply by breathing in and out normally through the mask.

There are several different types of spacer. Examples are Able Spacer®, Aerochamber Plus®, Nebuchamber®, Optichamber®, Pocket Chamber®, Volumatic® and Vortex®. Some spacer devices fit all MDIs; others are only compatible with specific brands of inhalers.

Tips on using a spacer device. The following are tips if you are prescribed a holding spacer. These have a valve at the mouth end - the spacer in the picture above is an example:

• If your dose is more than one puff then do one puff at a time.
• Shake the inhaler before firing each puff.
• Start breathing in from the mouthpiece as soon as possible after firing the puff.
• Try to hold your breath for a few moments when you have breathed in.
• Breathe in and out a few times before firing the next puff. Try to hold your breath for a few moments each time you breathe in.
• Check that the valve opens and closes with each breath.
• A face mask can be put on to the valve end for babies and young children. They just breathe normally with their face against the mask. The valve opens and closes with each breath in and out. Hold the spacer slightly tilted with the inhaler end uppermost to help the valve open and close easily.
• Static charge can build up on the inside of the plastic chamber. This can attract particles of medicine, and reduce the output when the spacer is used. To prevent this, wash the plastic spacer as directed by the maker's instructions. This is usually before first use, and then about once a month with washing up liquid and water. Let it dry in air without rinsing or wiping.

Nebulisers

Nebulisers are machines that turn the liquid form of your short-acting bronchodilator medicines into a fine mist like an aerosol. This is breathed in with a face mask or a mouthpiece. Nebulisers are no more effective than normal inhalers. However, they can be useful in people who are very tired (fatigued) with their breathing or in people who are very breathless.

Nebulisers are used mainly in hospital for severe attacks of asthma when large doses of inhaled medicines are needed. They are used less commonly than they were in the past as modern spacer devices are as good as nebulisers for giving large doses of inhaled medicines.

Are there any side-effects from asthma inhalers?

At standard doses, the amount of medicine in asthma inhalers is small compared with tablets or liquid medicines. Therefore side-effects tend to be much less of a problem than with tablets or liquid medicines which is one of their main advantages. However some side-effects do occur in some people. The leaflet which comes with the inhaler will detail all possible side effects but these are the more common or important ones:

Sore throat

Sometimes when using a steroid inhaler (particularly at high doses) the back of the throat can feel sore. Sometimes the voice can become more hoarse as well. Thrush infection in the mouth can also develop which can usually be treated easily with medication if needed.

Rinsing the mouth with water and brushing teeth after using a steroid inhaler reduces the likelihood of developing a sore throat or thrush. Also, some inhaler devices or using an asthma inhaler via a spacer are less likely to cause throat problems. A change to a different device may help if mouth problems or thrush occur.

Note: A persistent hoarse voice that does not settle after three weeks needs further investigation as it can be due to other causes. If you have this symptom you should tell your GP.

Osteoporosis

A high dose of inhaled steroid over a long time may be a risk factor for developing osteoporosis. You can help to prevent osteoporosis by taking regular exercise, not smoking, maintaining a healthy weight and eating a diet with enough calcium.

Delayed growth in children

Children who use an inhaled steroid over a long time should have their growth monitored. There is a small risk that enough steroid may get from the lungs and into the body (via the bloodstream), to delay growth. This risk has to be balanced against the risk of a child with asthma not having a steroid preventer. The latest studies suggest that adult height could be reduced by 1.2cm by the use of several years of inhaled steroids but the use of oral steroids for asthma attacks and the effects of long-term ill-health such as severe asthma also affect growth.

Mental health problems

Steroid medicines may aggravate depression and other mental health problems and may very rarely cause mental health problems. This is more common with steroid tablets but can occasionally be caused by steroid inhalers. Medical advice should be sought if worrying mood or behavioural changes occur.

Which asthma inhaler device should I use?

This depends on various factors such as:

• Convenience. Some inhalers are small, can go easily in a pocket, and are quick to use - foror example, the standard MDI inhaler.
• YAge. Children under the age of 6 years generally cannot use dry powder inhalers because they are unable to generate the strength of breath needed to inhale the medicine . Children aged under 12 years generally cannot use standard MDI inhalers properly without a spacer. Some elderly people find the MDI inhalers difficult to use.
• Co-ordination. Some devices need more co-ordination than others.
• Side-effects. As discussed earlier, if thrush or sore throat develops, a different device might be recommended.

Often the choice of inhaler is just personal preference. Most GPs and practice nurses have a range of devices to demonstrate