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    Friday, May 04, 2007

    Breathe Free: Have asthma but no insurance? Your local community health clinic may have some free inhalers for you:

    The new partnership, called the "2007 ASPIRE Campaign," is the result of a generous donation of 500,000 units of PROVENTIL® HFA, an environmentally-friendly albuterol inhaler, by Schering-Plough.

    Due to a federally-mandated ban on chlorofluorocarbons (CFCs), asthma patients who use albuterol CFC inhalers must switch to an environmentally-friendly albuterol inhaler by December 31, 2008. The ASPIRE Campaign will make it easier for low-income patients enrolled in participating clinics to make the transition to the HFA inhalers sooner.

    "With this government mandate, asthma patients will find themselves having to get a new prescription for an albuterol inhaler that may look, feel, and taste different and for some patients may cost more," said Arturo Brito, Chief Medical Officer of The Children's Health Fund. "We're grateful to Schering-Plough for helping us prepare children and families in need by providing a free Proventil HFA inhaler as well as critical information about their patient assistance program to ease the transition."

    Patients will receive educational materials on the change in albuterol inhalers and information on the patient assistance program offered by the donating pharmaceutical company, Schering-Plough.

    More information on the new environment-friendly inhalers can be found here. More detailed information here, though a subscription is required for full access. Here's the important part:

    The HFA inhalers provide the same amount of albuterol base, 90 µg per puff, as the CFC inhalers, with generally similar particle-size distribution.11 However, patients may find that the HFA inhaler has a different taste (a result of differences in the propellant and elastomers and excipients) and feel (because the spray emitted from the actuator has less force and a smaller plume).12 In addition, because of differences in spray characteristics, HFA inhalers may result in greater deposition in the lungs than CFC inhalers.13 Differences in serum levels of albuterol are not detectable after a standard 2-puff dose,14 but after 12 puffs, the HFA inhaler produces higher plasma levels of albuterol than the CFC inhaler.15

    The different spray characteristics of the HFA inhaler may affect delivery of albuterol to the lungs when the inhaler is used with an aerosol inhalation spacer device. With its less forceful spray and smaller plume, the HFA inhaler may deposit a smaller amount of albuterol in the spacer; consequently, more albuterol may be inhaled.16 However, the interaction of inhalers with spacers is complicated by performance differences in spacers17 and formulations within the inhaler, as well as by the development of electrostatic charges, which increase the deposition of albuterol within the spacer. Cleaning a spacer with a household detergent reduces the electrostatic charge and improves delivery of both CFC and HFA albuterol.18,19 The effect of spray differences between HFA and CFC albuterol inhalers on their performance with spacers has not been adequately explored. Clinical data are not available on the delivery of HFA albuterol through ventilator circuits. However, in an in vitro neonatal lung model, there were no differences in lung delivery between CFC and HFA inhalers when the drug was administered by a spacer through a ventilator circuit.20

    Clogging of HFA albuterol actuators has been reported,21 but this is a potential problem with all metered-dose inhalers, including CFC albuterol inhalers. HFA inhalers perform reliably if cleaned at least once a week by removing the metal canister, running warm water through the plastic actuator for 30 seconds, shaking the actuator to remove excess water, and then allowing it to air-dry. However, if a reduction in the force of emitted spray is noted, the actuator should be recleaned. Patients should be advised not to immerse an HFA albuterol canister in water to determine whether the canister is empty; this is not a reliable method for determining the number of metered doses remaining,22 and water may enter the stem and obstruct the spray. With the exception of Ventolin HFA, which has a counter, it is difficult to determine when the inhaler is nearly empty. Patients should be advised to keep a spare on hand.

    The excipients added to the propellant formulation differ according to the brand of HFA inhaler. For instance, each puff of Proventil HFA releases 4 µl of ethanol. This small amount of ethanol will not have a discernible clinical effect, but it may be of concern for patients who for religious or other reasons abstain from alcohol. Breath-alcohol levels of up to 35 µg per 100 ml may be detected for up to 5 minutes after two puffs of Proventil HFA.23 Unlike CFC propellants, HFA propellants may cause false positive readings in anesthetic gas–monitoring systems.24 The infrared spectrums of HFA overlap with commonly used anesthetic gases in the range of 8 to 12 µm. One albuterol product, Ventolin HFA, contains no excipients other than the propellant, a characteristic that may improve tolerability for some patients. However, Ventolin HFA comes packaged in a moisture-resistant protective pouch containing a dessicant and has a limited shelf life once it has been removed from the pouch (Table 2). Ventolin HFAs have a greater affinity for moisture than do CFCs,25 which means that water vapor is more likely to enter the canister around the metering-valve gaskets. The other approved HFA inhalers are less susceptible to moisture permeation and do not require a protective pouch.

    The reformulation of albuterol with HFA propellants required a reengineering of the inhaler's metering valves.11 With these modified valves, the HFA inhalers may need less frequent repriming (i.e., the firing of the unit to load the metering valve) than the CFC inhalers, although the frequency with which repriming is required varies among the HFA products (Table 2).26 All albuterol inhalers contain more doses than indicated on the label. When the label amount is exceeded, however, CFC inhalers deliver inconsistent amounts of albuterol (i.e., there is an erratic tailing off in the dose delivered). With the reengineered HFA inhalers, puffs delivered beyond the labeled amount may contain more albuterol, but the tail-off may be more abrupt (with puffs delivering doses close to the indicated amount of drug followed by puffs that deliver nothing).27

    (Sorry, not enough time to remove all the reference numbers.) The most important difference from a users perspective is that you can't tell when the new inhalers are nearly empty. The float test doesn't work.

    posted by Sydney on 5/04/2007 08:52:00 AM 0 comments


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