Impact of genetic polymorphisms of the β -adrenergic receptor on albuterol bronchodilator pharmacodynamics

TLDR

The study aimed to determine whether β2‑adrenergic receptor polymorphisms influence the relationship between albuterol plasma concentrations and FEV1 in moderate‑asthma patients, and to recommend that future pharmacodynamic studies include genotype determination. Sixteen stable moderate‑asthma patients provided blood for β2‑adrenergic receptor genotyping by PCR, and their FEV1 and albuterol plasma levels were measured at multiple time points after an 8‑mg oral dose while withholding inhaled β2‑agonists and corticosteroids. Albuterol evoked a significantly greater and faster FEV1 response in Arg16 homozygotes versus Gly16 carriers, with higher %ΔFEV1, AUC, and initial slope, indicating that β2‑adrenergic receptor polymorphism is a major determinant of bronchodilator response. Published in Clinical Pharmacology & Therapeutics, 1999, vol.

Abstract

Objective To determine whether genetic polymorphisms of the β2-adrenergic receptor gene affect the relationship between albuterol (INN, salbutamol) plasma concentrations and the forced expiratory volume in 1 second (FEV1) in subjects with moderate asthma. Methods Sixteen clinically stable patients with moderate asthma who participated in a pharmacokinetic-pharmacodynamic study of albuterol volunteered to provide a blood sample for determination of β2-adrenergic receptor genotype. FEV1 and plasma concentrations of albuterol were determined at various times after administration of an oral solution that contained 8 mg albuterol. Patients withheld inhaled β2-agonist and corticosteroid therapy 12 and 24 hours, respectively, before the study. β2-Adrenergic receptor genotype was determined by polymerase chain reaction with allele-specific oligonucleotide hybridization. Results Albuterol-evoked FEV1 was higher and the response was more rapid in Arg16 homozygotes compared with the cohort of carriers of the Gly16 variant: Maximal percentage increase in FEV1 (%ΔFEV1), 18% versus 4.9% (P < .03); area under FEV1 albuterol concentration curve, 194%·mL/ng versus 30%·mL/ng (P < .05); initial slope (dE/dC), 1.43%·mL/ng versus 0.55%·mL/ng (P < .003). Conclusions The β2-adrenergic receptor gene polymorphism is a major determinant of bronchodilator response to albuterol. Future pharmacodynamic studies of β2-agonists should include determination of β2-adrenergic receptor genotype. Clinical Pharmacology & Therapeutics (1999) 65, 519–525; doi: