WASHINGTON, D.C. - Asthma researchers have made significant progress in eliminating ozone-hostile, CFC-based inhalers in exchange for more environment-friendly, powder-based inhalers. Several pharmaceutical companies are launching a myriad of powder-based inhalers and delivery systems, but these new systems have created confusion among asthmatics and doctors.
Some of the systems rely on excipient particles (often lactose) which help the powder flow and the drug to enter more easily into a patient's lungs. The devices need patient power and must be used correctly, said Peter Byron, PhD, professor in the school of pharmacy at the Virginia Commonwealth University in Richmond.
"Much of the technology reaching the marketplace has enabled researchers to realize how important control of drug delivery is to the lungs. These various technologies are enabling medicine to deliver low therapeutic index compounds, like insulin, systemically," Byron said. "The new medicines and inhalers are expected to reduce the need for patient education, but that's highly unlikely at least for a while since the number of complicated devices coming onto the market continues to grow."
Byron said that the pharmaceutical industry has not done a good job of targeting the asthmatic's alveoli and conducting airways, the two arenas in the battle against asthma. Many doctors have lobbied for better dose-control development that regulates the amount of drug travelling in the person's lungs and the pathway, Byron said.
"If science is to make good on these long-term goals - the control of drug dosing to the lung regions - [drug companies] had better work on [improved drug delivery devices] since patients breathe in different ways through different devices," Byron said. "[Doctors] would like all delivery devices to produce uniform concentrations of therapy with reproducible particle and droplet size distributions. They want to also see improved aerosol stability."
Compliance is another problem that must be considered. Evidence suggests that some patients are inherently non-compliant, despite their doctor's best efforts and the patient's level of education. The complexities of many dosing regimens and adverse events can limit patient compliance, creating difficulties for them and their physicians, said Paul O'Byrne, MD, professor of medicine at McMaster University in Hamilton, Ontario, Canada.
"The ideal inhaler should be one that is easy to use, portable, safe and effective, inexpensive, can handle multiple doses and requires minimal coordination," O'Byrne said. "Often devices that are used can be difficult to carry around, so they can only be used by the patient at home."
It is important to educate patients about the need for regular therapy with inhaled steroids, especially when their asthma is well-controlled and the doctor has established the lowest dosage needed to control the patient's symptoms. However, keeping patients on this dose can be difficult if they are symptom free because the patient assumes they only need medication when symptoms flare up.
Dosage regimens should be simple. Most patients follow morning and evening inhaler dosing. This "toothbrush treatment of asthma" does have its advantages, O'Byrne said. Patients brush their teeth, wash up, then use their inhaler - it becomes a routine.
"We are moving toward an age where combination inhalers with b-agonists and corticosteroids are going to be widely available for use," O'Byrne said. "This will get around the problem of lack of rapid response to and rapid effect from an inhaler with a b-agonist. However, this would only be for those patients with moderate to severe asthma symptoms."
Some adverse events have been reported with new asthma medications. Oral candidiasis is reported to occur as symptomatic candidiasis in about 5% of adult asthmatics. For those on inhaled corticosteroids, that number is probably higher. Candidiasis is usually not reported in children, but in adults it's made much worse through antibiotic use.
Dysphonia is even more common. Half of adults reported some voice changes due to inhalers. Though the condition can be noticeable, most patients are not bothered by it. The use of space inhalers reduces candidiasis but has no effect on dysphonia.
Steroid phobia is much more pronounced in the United States than in Europe. Many asthma patients in this country are simply not comfortable taking steroid medications. That's not very encouraging for doctors prescribing steroid-based treatments to non-compliant patients. Compliance is something that is important and must be increased, said Sorin Pederson, MD, professor of pediatrics at the Skovvangen in Kolding, Denmark.
"You get a better effect from the drugs when you are compliant," Pederson said. "But to improve compliance, we must ask patients what they want, because if they don't agree, they won't take [their medicine]."
One long-term study done by Pederson indicated 75% compliance rates when patients received the medications they wanted. Pederson said if patients could be educated, re-enforced and guided by doctors on how to properly perceive asthma inhalers and their medicine, compliance could be improved to 100%, he said. The attitude of the doctor can influence whether the patient accepts or rejects steroid-based medication.
"We can't reassure doctors if we can't reassure patients," Pederson said. "Patients listen to what they are told to take, making it a necessity for drug education and follow up. Steroid-based drugs are not as bad as many believe they are, so if [doctors] convey this, everyone [can] benefit."
For more information:
- O'Byrne PM. Pederson S. Shapiro GG. Inhaled drug delivery and compliance: a closer look. Presented at the American Academy of Allergy, Asthma and Immunology's 54th Annual Meeting. March 13-18. Washington, DC.
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