Dose-response of Albuterol in Asthmatics

• Effective Dose 50% (ED50) [ Time Frame: 15 minutes after each dose ] [ Designated as safety issue: No ]
• Effect Maximum (Emax) [ Time Frame: 15 minutes after each dose ] [ Designated as safety issue: No ]

• 50% of Maximum Effect of Albuterol (ED50) [ Time Frame: After all doses had been administered ] [ Designated as safety issue: No ]
• Maximum Effect of Albuterol (Emax) [ Time Frame: After all doses had been administered ] [ Designated as safety issue: No ]

The purpose of this study was to determine the lung function response after increasing doses of albuterol (a bronchodilator) in children and adults with asthma.

Inhaled short-acting b2-agonists (SABA) are the most potent bronchodilators used today to treat acute symptoms of asthma and albuterol, a partial b2-agonist, is the most frequently prescribed asthma medication in the US. Although universally used in for acute asthma symptoms, SABA have been associated with a significant degree of interpatient variability. Many studies have characterized the SABA dose to bronchodilator response relationship under controlled conditions. However, few studies have explored the magnitude and sources of bronchodilator response variability, and no studies have characterized the dose versus bronchodilator response relationship using population pharmacokinetic/pharmacodynamic (PPK/PD) modeling. In the present study, we characterized the relationship between inhaled doses of albuterol and bronchodilation in 81 children and adults with moderate to severe persistent asthma using a population pharmacodynamic approach. The purpose of this study was to obtain estimates of the pharmacodynamic parameters that characterize the dose-response curve, including maximal dose for bronchodilation, and to quantify and identify sources of interpatient pharmacodynamic variability.

Eligibility Criteria:

• Well-defined history of physician diagnosed asthma
• Any ethnic background
• 8 to 65 years old
• Baseline pre-bronchodilator FEV1 of 40% to 80% predicted for age, height, and gender
• No oral corticosteroid use, emergency room visits, or hospitalizations within the previous 3 months
• Nonsmokers or less than a 5 pack-year history with no smoking in the previous year
• Normal physical exam and no confounding diseases were selected
• Able to withhold inhaled short-acting b2-agonists or inhaled anticholinergic drugs for 8 hours, oral antihistamines for 5 days, theophylline for 24 hours, and cromolyn, nedocromil, and inhaled corticosteroids for 2 hours prior to the study.