The β2-adrenoceptor agonist bronchodilators terbutaline and orciprenaline are also weak α1-adrenoceptor antagonists

Electrospun nanofibers modified with zeolitic imidazolate framework-8 for electrochemiluminescent determination of terbutaline

For the first time it is demonstrated that zeolitic imidazolate framework-8 electrospun nanofibers (ZIF-8 NF) could serve as electrochemiluminescence (ECL) accelerator for the facile detection of terbutaline residual. A novel ECL sensor for the determination of terbutaline was fabricated based on ZIF-8 NF. The ZIF-8 NF were successfully prepared according to electrospinning and in-situ growth method. First, chitosan was modified on the surface of the electrode, and then the ZIF-8 NF was modified onto the upper layer of the chitosan. Taking advantages of chitosan and ZIF-8 NF in conductivity and electrocatalysis, the modified electrode presents obvious ECL phenomenon in 0.2 M PBS solution (pH 10.0) containing 0.025 M luminol. After the addition of terbutaline, ECL intensity decreased significantly, and the decreasing value showed a linear relationship with the logarithm of terbutaline concentration. The linear range was from 2.0 × 10^-10 to 2.0 × 10^-5 M, and the detection limit was 1.41 × 10^-11 M (3σ/m). The method had high sensitivity, good stability, and good applicability to actual pork samples.

α1-adrenoceptor activity of β-adrenoceptor ligands - An expected drug property with limited clinical relevance

Many β-adrenoceptor agonists and antagonists including several clinically used drugs have been reported to also exhibit binding to α₁-adrenoceptors. Such promiscuity within the adrenoceptor family appears to occur more often than off-target effects of drugs in general. It should not be considered surprising based on the amino acid homology among the nine adrenoceptor subtypes including the counter-ions for binding the endogenous catecholamines. When β-adrenoceptor ligands also bind to α₁-adrenoceptors, they almost always act as antagonists, regardless of being agonists or antagonists at the β-adrenoceptor. The α₁-adrenoceptor affinity of β-adrenoceptor ligands in most cases is at least one, and often more log units lower than at their cognate receptor. Consistent evidence from multiple investigators indicates that β-adrenoceptor ligands relatively have the highest affinity for α_1A- and lowest for α_1B-adrenoceptors. While promiscuity among adrenoceptor subtypes causes misleading interpretation of experimental in vitro data, it is proposed based on the law of mass action that α₁-adrenoceptor binding of β-adrenoceptor ligands rarely contributes to the clinical profile of such drugs, particularly if they are agonists at the β-adrenoceptor.