Pharmacodynamics and Receptor Theory

Which pharmacodynamic property best distinguishes a full agonist from a partial agonist at the same receptor?

A 38-year-old woman with asthma is prescribed albuterol (salbutamol) 2 puffs every 4–6 hours as needed. After 3 months of frequent use (8–10 puffs daily), she reports that each dose now provides only 2–3 hours of bronchodilation instead of the usual 4–6 hours, and her peak flow improvement is noticeably reduced. She denies any change in inhaler technique or adherence to other medications. Pulmonary function testing shows baseline FEV₁ has declined. Which receptor-level mechanism best explains her loss of bronchodilator efficacy?

Which of the following is the most common mechanism of receptor-mediated drug action in the body?

A 52-year-old man with essential hypertension and type 2 diabetes mellitus presents for antihypertensive therapy. He has mild proteinuria and a serum creatinine of 1.2 mg/dL. Which drug is the preferred first-line agent for this patient?

All of the following statements regarding G-protein coupled receptors (GPCRs) are correct EXCEPT: