Types Of Drug Delivery Devices - Medications To Treat Your Asthma: Asthma

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Types of drug-delivery devices

Different types of devices are used to deliver inhaled medications into the lungs. Inhalers are small pocket-sized containers that enable you to inhale the medication as an aerosolized powder or spray in precisely controlled doses with each inhalation. There are two types of inhalers: metered-dose (sometimes used with spacers) and dry-powder. The type of inhaler you choose will depend on which drugs you need and how easy the inhaler is for you to use.

If you have trouble using an inhaler, your doctor may recommend a nebulizer, a machine that delivers a continuous fine mist of medicine through a mouthpiece or facemask as you breathe normally for several minutes.

Two delivery devices Many people use a metered-dose inhaler with a spacer (left) for inhaled medications such as bronchodilators. Some people find a nebulizer easier to use because it delivers a continuous stream of medication and allows for a normal breathing pace.

Metered-dose inhalers

Traditionally, most inhaled asthma medications have been given by means of a metered-dose inhaler, which consists of a metal canister inside a plastic dispenser. You press down and then release the canister, which delivers a spray containing a set amount of medication.

To use a metered-dose inhaler correctly, you need to inhale the medication deep into your lungs, so that it distributes widely along the bronchial tubes. This can be tricky: The spray is released from the pressurized canister at high speed, and if you don't inhale at just the right time, the medication stays in your mouth or settles on the back of your throat and doesn't pass into your lower airways. The following three steps may help:

1. Start breathing in as soon as you press down on the canister and feel the spray. If you wait too long to inhale, you lose a lot of medication that settles onto your tongue and mouth rather than being drawn into your breathing tubes. On the other hand, if you inhale too soon, before activating the spray, you will not have enough breath left to pull the medicine into the bronchial tubes.

2. Breathe in slowly so that the medication has time to disperse to the thousands of bronchial tubes. If you inhale too quickly, the medication reaches only the upper breathing passages. It should take about three or four seconds to pull in a slow, full breath.

3. Hold your breath for a few seconds after completing the inhalation. If you breathe out immediately, you will exhale some of the medication. Try to hold your breath for about five seconds before exhaling.

CFC-free inhalers. Traditionally, the sprays released from metered-dose inhalers have used propellants known as chlorofluorocarbons (CFCs). After CFCs were banned because of their detrimental effect on the atmospheric ozone layer, it became necessary to develop alternative delivery systems. One approach uses an ozone-safe propellant, called hydrofluoroalkane (HFA), in metered-dose inhaler canisters.

The FDA instructed manufacturers to stop using CFCs as of December 2008, and manufacturers have responded by making HFA inhalers. If you use albuterol and haven't switched over to an HFA inhaler, talk to your doctor about doing so. You will need a new prescription from your doctor for the HFA inhaler. Patients won't find their new HFA inhalers any less effective than their CFC inhalers, but they will probably note a different taste or feel to the spray. You can use a standard spacer with an HFA inhaler.

Spacers

These simple devices can make using metered-dose inhalers easier and more effective. A spacer is a hollow chamber that fits onto the mouthpiece of your metered-dose inhaler. In its simplest form, it is a hollow plastic tube with a one-way valve at the end to direct exhaled breath away from the chamber. You place your mouth on the mouthpiece of the spacer, and instead of spraying the medication directly into your mouth, you spray it into the chamber, where it remains suspended for a few seconds. You inhale the medicine from the other end of the chamber in one or two slow, deep breaths, without any sense of urgency or need for split-second timing in relation to actuating the spray.

Spacers are most useful for people who have difficulty coordinating the hand-breath actions that a metered-dose inhaler requires. They are also useful for anyone taking inhaled steroids delivered by metered-dose inhaler, as the spacer reduces the amount of medication deposited onto the tongue and the back of the throat, thus lessening the chance of developing an oral yeast infection. If you are taking a quick-acting bronchodilator and you are good at inhaling it from a metered-dose inhaler, there is no need to use a spacer, as it provides no added benefit.

Dry-powder inhalers

Dry-powder inhalers are another response to the CFC ban. Instead of generating a pressurized spray, these devices release a fine, micronized powder as you inhale. As such, dry-powder inhalers may be easier to use than metered-dose inhalers because you don't have to coordinate your breathing with the device; the powder is released automatically when you inhale deeply. Currently available dry-powder devices include the Diskus, Flexhaler, Handihaler, Twisthaler, and Aerolizer, each containing different types of medicines.

Nebulizers

A nebulizer delivers a steady aerosol mist of medicine through a face mask or mouthpiece, allowing you to breathe normally while receiving treatment. The device consists of a chamber containing the drug in liquid form and a compressor pump. Operated by AC electrical power, the compressor sends air across the nebulizer chamber that contains the medicine. The stream of air scatters the drug into a fine mist, which passes into the face mask or mouthpiece. You breathe in and out through the mask or mouthpiece for about 10 minutes to obtain the full dose.

Smaller, battery-operated nebulizer systems, called ultrasonic nebulizers, are also available, but they cost more than traditional nebulizers. Ultrasonic nebulizers replace the traditional compressor pump with a vibrating mesh technology to create an aerosol mist.

An advantage of the nebulizer is that a lot of medicine is reliably delivered to the bronchial tubes in this way. Its major disadvantage is its lack of convenience. Unlike the inhaler, this device cannot readily be carried in your pocket or purse for prompt use at any time.

Medications available in liquid formulation for nebulization include the quick-relief bronchodilators albuterol, metaproterenol, and levalbuterol and the controller medications budesonide and cromolyn. A long-acting beta-agonist bronchodilator, arformoterol (Brovana), is also available for nebulization.

Last updated:	September 27, 2007