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J.R.W. Wilkinson et al., "Paradoxical bronchoconstriction in asthmatic patients after salmeterol by metered dose inhaler", British Medical Journal 305 (1992) 931.The first sentence in the conclusion is: "Bronchoconstriction after both salmeterol and placebo by metered dose inhaler but not after salmeterol by diskhaler suggests that the irritant is not the salmeterol itself." . . . "The similarity in characteristics of bronchoconstriction after beclomethasone by metered dose inhalers implicates one or both chlorofluorocarbons . . . as the irritant. That salbutamol caused no bronchoconstriction was attributed to its faster onset of action opposing any bronchoconstrictor effects of the propellants."
** However, according to the 1994 Physicians' Desk Reference, Intal Spinhaler capsules are "contraindicated in those patients who have shown hypersensitivity to . . . lactose." So asthmatics who are lactose-intolerant may not have this form of cromolyn sodium as an option.
All too often the puffs are mis-timed and only make it part of the way into the airways, and some of the medication is invariably deposited into the mouth and on the back of the throat instead of into their lungs. In addition to being less effective, this can lead to other side effects (e.g., for inhaled steroids, an increased potential for thrush, an oral fungal infection described in section 2.3.3.).
Several devices have become available that address these difficulties to varying degrees. The devices are generally referred to as "spacers" since they place additional space between the patient and the MDI. The medication is sprayed into the spacer instead of the mouth. As the patient inhales, the column of medication passes through the mouth and throat relatively quickly, leaving little opportunity for the medication to be deposited in the mouth or throat. This is a more efficient means of delivering the medication to the airways where it's most needed.
The simplest kind of spacer is basically a tube. The patient sprays the medication in one end of the tube and inhales it out the other end. Azmacort has a simple spacer attached to it. A cardboard tube from the core of a roll of bathroom tissue can be used as a spacer (as long as it's clean, lint-free and germ-free). While a simple spacer reduces the amount of medication that gets deposited in the mouth and throat, it still requires you to carefully time your inhalation with the discharge of the medication to minimize the amount of the medication that escapes from the spacer.
A "holding chamber" is a more sophisticated device. It is a sealed chamber (once the inhaler is inserted) that traps and holds the medication, allowing the patient to spray the medication into the chamber and take a few seconds to inhale the medication. Since the medication is temporarily suspended in the holding chamber, the timing of the inhalation is not nearly as critical as with simple spacers or no spacer. AeroChamber is a brand of holding chamber. It's a plastic tube with a mouthpiece on one end and a place to insert the MDI on the other. The mouthpiece has a one-way valve built in that temporarily contains the sprayed medication, and also allows the patient to exhale without displacing the medication in the chamber (as without a spacer, the patient should exhale as completely as possible before taking in any medication, so that the medication can be inhaled as deeply as possible).
In addition to improving the timing of the inhalation, a holding chamber makes it possible to take in the medication more slowly than is possible without a spacer or with a simple spacer. This is important for the symptomatic patient, since rapid inhalation of the medication is more likely to trigger coughing and cause the patient to lose the medication before it has had a chance to be absorbed.
Some spacers are clear so that you can see the puff of medicine, and so that you can see when the medication is building up on the inside, indicating that the spacer needs cleaning.
Spacers and holding chambers need periodic cleaning; clean carefully, following the manufacturer's instructions so as not to damage any delicate internal parts or allow molds or other contaminants to be introduced.
There are special holding chambers for younger children. There's a pediatric Aerochamber that has a mask built in; the child breathes normally for a few seconds with the mask held over his/her mouth and nose. This is typically used when a nebulizer is not available or not required, and for medications that are not available in a nebulized form, such as Beclovent or Vanceril.
There is also a device for children (and for people that have trouble holding their breath) called an InspirEase. It's kind of like a plastic bellows or balloon with a plastic mouthpiece. The patient inflates it, the medicine is sprayed into it, and the patient inhales, holds his/her breath for the count of 5 (or whatever the doctor recommends), exhales into the device, and then repeats. Some patients are instructed to breath slowly in and out several times instead of holding their breath. The InspirEase really helpful for younger children who yet aware of the difference between breathing in and breathing out or don't yet know how to hold their breath or breathe evenly and slowly. It gives them immediate physical feedback, and it also has a whistle built in to tell them when they're breathing too fast (although they seem to like making it whistle, so it's positive reinforcement for something that they shouldn't be doing). As the child grows, the Inspirease becomes less effective, since it has a limited capacity, although I've been told that it is available in different capacities.
Knowing the difference between a simple spacer and a holding chamber can help you use each in its proper way. If you use both a holding chamber *and* a simple spacer (e.g., a holding chamber for your Ventolin and the simple spacer attached to your Azmacort), you need to remember which you're using and adjust your style accordingly.
Spacers and holding chambers are sometimes provided by some HMOs and covered by some insurers.
Contributed by:
Mark Feblowitz / mfeblowitz@GTE.com[Maintainer's note: Some spacers seem to be prescription only, while others are not. Whether you need a prescription also seems to vary from state to state in the US. When in doubt, ask. As to why you would need a prescription (i.e. how could you abuse this simple plastic tube?), the nurses at National Jewish were as puzzled as I was.]
Thrush is a very common side effect of taking inhaled corticosteroids, since steroids alter the local bacteria and fungal population of the mouth, enhancing fungal growth. The way to avoid this complication is to ensure that the back of the throat doesn't remain coated with corticosteroid after use of the inhaler, either by using a spacer or by rinsing the mouth very thoroughly afterwards. Unfortunately, some people still get it even when they are very thorough about rinsing.
The Rotahaler and the Spinhaler are very different animals. The Rotahaler is a pussycat, the Spinhaler a ferocious lion.
The Rotahaler is a two-part mouthpiece that you snap apart, put a capsule in, twist, and inhale. When you twist the device, the capsule breaks open. When you inhale, the medicine lands in your lungs.
The Spinhaler is a three-piece device: a mouthpiece, a tiny fan, and a cap to cover the fan. You open it, put the capsule in a space on the fan, close it, push down then up on the cap (this breaks the capsule) and then tilt your head back, put the mouthpiece in your mouth, and inhale. The fan throws the medicine into the back of your throat. Then you gag.
I don't like the propellants in MDIs, so I was highly motivated to get a Spinhaler. It took me a month to get my drugstore to find it, and now I must admit I'm disappointed. I tried using an Intal capsule in the Ventolin Rotahaler, since that device works so well, but the medicine seems to be of the wrong consistency, and the capsule is too large for the space it should go into.
Another difference: The Spinhaler comes in a little container like a medicine bottle, but the lid doesn't stay on very well in a purse. The Rotahaler comes in a little plastic case sort of like a compact and stays shut (i.e. clean) in a purse, backpack, or jeans pocket.
Contributed by:
Paula Ford / pxf3@psuvm.psu.eduThe idea behind an inhaler is that the full dose is delivered to the lungs, where it is immediately absorbed by the lung tissue, and starts to take effect locally. Excess drug may be absorbed by the bloodstream and delivered to the rest of your body, but this amount tends to be minimal. So your lungs receive an immediate, high concentration of the drug, and the rest of your body receives very little.
If you take the drug orally in tablet or capsule form, then you need a much higher dose. The reason is that for the same amount of drug to reach the lungs through the bloodstream, you need the same concentration of drug in the rest of your body. For example, most people take one or two puffs of albuterol (Ventolin or Proventil) every four to six hours, and each puff is 90 micrograms of albuterol. The usual dosage of Ventolin in tablets is 2-4 milligrams three or four times a day, which is something like 200 times the amount inhaled.
However, one advantage that tablets have is that the medication may be available in a time-release format. So for a short-acting medication like albuterol, the inhaled version might need to be taken every four to six hours, while a extended-release tablet such as Volmax would need to be taken only every twelve hours.
One variation of dose counting, for medications that are taken regularly, is to calculate the date on which the medication will be used up, and discard the old canister for a new one on that date.
+ There is also a gadget called The Doser. It fits on top of any MDI, and keeps track of how many doses you've dispensed from the inhaler. It provides daily totals for the past 30 days, and is useful if (like me) you tend to forget whether you've taken your maintenance inhalers already! See http://www.doser.com for more information. The Doser is over the counter, but the units can be hard to locate - if a drugstore can get them at all, the pharmacist usually has to special order them.
Products which relied on CFCs, such as air conditioning units, refrigerators, and most aerosol products, have been modified to use alternative chemicals which do not damage the ozone layer. Due to their nature, however, metered dose inhalers have been granted an "essential use" exemption to the worldwide ban, which grants the manufacturers an extra few years to develop alternatives.
Since the inactive ingredients (i.e., everything but the drug itself) must be changed, it's not as simple as using a different chemical for the propellant - the new device must go through much the same approval process as the original inhaler did, to ensure that the same dosage is delivered to the patient, that there are no side effects, that patients tolerate the new formulation well, etc.
The FDA has already approved one new non-CFC inhaler, Proventil HFA (albuterol), which uses hydrofluoralkane instead of CFC propellants. Other non-CFC devices are currently in the works. It is expected that future non-CFC inhalers may be reviewed and approved more quickly than the earlier ones.
CFC-based MDIs will continue to be available for some time. Proposed guidelines for final phaseout include that there be at least 3 multi-use (see below) non-CFC devices available in a drug class (i.e., bronchodilators, corticosteroids), providing at least 2 different drugs, before all CFC inhalers in that class are banned. As an example, CFC-based bronchodilators would be permitted as long as Proventil HFA is the only alternative; if Ventolin (also albuterol) and Alupent (metaproterenol) had non-CFC versions, then all CFC formulations might be banned.
The term "multi-use" refers both to aerosol inhalers and multi-use dry-powder inhalers such as the diskhaler. It does not include single-use dry-powder inhalers such as the rotahaler, which requires insertion of a new capsule of medication with each use.
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