Aerosolized agents: what's new in pulmonary pharmacology?
The general indication for use of an adrenergic bronchodilator is relaxation of airway smooth muscle in the presence of reversible airflow obstruction associated with acute and chronic asthma (including exercise-induced asthma), bronchitis, emphysema, bronchiectasis, and other obstructive airway diseases. The FDA has recently made several changes and additions to adrenergic bronchodilators.
Recently, Foradil Certihaler made it to market in the United States and is for adults and children 5 years and older. The small dry powder inhaler is breath actuated and delivers 8.5 meg of drug on each breath. It is recommended to be taken twice daily. This is a lower dose than Foradil (12 meg/inhalation) or Perforomist administered in a liquid nebulizer (20 mcg/2 ml).
The ongoing concerns of safety of long-acting [beta]2 agonists the FDA is now requiring changes on how long-acting [beta]2 agonists are used in the treatment of asthma. On June 2, 2010 the FDA now requires the following:
* Long-acting [beta]2 agonists are not to be used without a controller medication (i.e corticosteroid).
* Long-acting [beta]2 agonists should not be used if asthma is adequately controlled.
* Long-acting [beta]2 agonists should only be for short-term use. Once asthma is controlled the long-acting [beta]2 agonist should be discontinued, or the stepped down.
* Children should only use a Long-acting [beta]2 agonist in conjunction with a corticosteroid.
Earlier this year the FDA released a number of bronchodilators that will be phased out due to the use of chlorofluorocarbons (CFC). This phase out began a number of years ago due under the obligation of the Montreal Protocol. Since then manufactures have been switching to hydrofluoroalkanes (HFA) as an alternative or stopping production of the agent.
Alupent MDI was discontinued on June 14 of this year, however, it is still available in liquid nebulization form, tablet and syrup. Epinephrine (Primatene Mist) will no longer be available in CFC for after December 31, 2011. However, it is believed that the manufacturer is working on a HFA program that will come to market before the CFC version expires. Combivent and Pirbuterol December 31, 2013. It can be speculated that Combivent may be marketed in the nebulizer form, Respimat, a soft-mist, propellant free inhaler utilized by Boehringer Ingelheim with Atrovent.
Just last month the FDA approved a new the combination agent Dulera. Dulera is a combination of mometasone and for-moterol. It will compete with Advair and Symbicort. Dulear is available in two strengths (100 mcg mometasone/5 meg for-moterol and 200 meg mometasone/5 meg formoterol) and is FDA approved for individuals 12 and older.
Other Agents of Interest
Cromolyn like agents have been used as a prophylactic in the treatment of asthma. Although it may not be utilized as often in clinical practice today as it was previously, the agent is an alternative in mild persistent asthma. The chlorofluorocarbon (CFC) version of Tilade (nedocromil) was removed from market June 14, 2010 and Intal (cromolyn sodium) will be removed December 31, 2010. King Pharmacuticals the maker of both medications announced that it halted production because it could not find a qualified manufacture to reformulate a hydroflourocarbon metered dose inhaler. However, cromolyn sodium is still available as a liquid nebulizer solution.
Two long known inhaled corticosteroids will be removed from market due to formulation as a CFC metered dose inhaler. Azmacort (triamcinolone) the metered dose inhaler with a built in spacer will be removed December 31, 2010. Abbott Labrotories, maker of Azmacort has no plans to reformulate. Aerobid (flunisolide) will be removed from market June 30, 2011. However, Forest Laboratories not long ago introduced Aerospan an HFA form of flunisolide. This agent has a built in spacer similar to the one seen with Azmacort.
Aztreonam was approved in December 1986 by the FDA as a monobactam, a synthetic bactericidal antibiotic. It is given as an IV solution. Inhaled aztreonam (Cayston) was approved in Febuary 2010 to improve pulmonary symptoms in CF pateints colonized with Pseudomonas aeruginosa. Cayston is not indicated for patients younger than 7 years-old, or those with Burholderia cepacia. It has only been studied with patient that have an FEV1 above 25% or below 75% of predicted.
Cayston is supplied in a form that must be reconstituted. Each 2 mL single use glass vial contains 75 mg of lyophilized aztreonam and must be mixed with the provided 1 mL of sterile diluent (0.17% sodium chloride) in a 28 day kit. Once reconstituted it is delivered by itself using the Altera Nebulizer System.
Each patient should be pre-treated with a bronchodilator before each dosing. Cayston is given three times a day for 28 days on and 28 days off. It should be refrigerated, however, once the kit is ready to use it can be stored at room temperature for 28 days.
Treprostinil was first approved by the FDA as an injectable form in 2002. Since that time research has been ongoing to create and test an inhaled version. Inhaled treprostinil (tyvaso) was approved for use in the United States in 2009. Tyvaso is a prostacyclin analogue that causes vasodilatation of the pulmonary and systemic arterial vascular beds and inhibits platelet aggregation. It is administered using the Tyvaso Inhalation System, which is an ultrasonic, pulsed-delivery device.
The market for inhaled agents continues to grow. The direct use of inhaled agents sharply diminished side effects that are common if given in another form. Expect many more additions, as well as changes in the near future in how we utilize the pulmonary system for drug delivery.
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Douglas Gardenhire is a veteran therapist, author, educator and the Director of Clinical Education in the RC Program at GA State University.
By Doug Gardenhire MS, RRT-NPS
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|Title Annotation:||RESPIRATORY PHARMACOLOGY|
|Publication:||FOCUS: Journal for Respiratory Care & Sleep Medicine|
|Date:||Jul 1, 2010|
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