All of the following are β-adrenergic agonists EXCEPT:

Correct Answer: D

Rationale: In this question, the correct answer is D) Phenylephrine. The rationale behind this is that Phenylephrine is an alpha-adrenergic agonist, not a beta-adrenergic agonist. Understanding the classification of adrenergic receptors is crucial in pharmacology. Adrenaline (epinephrine), Noradrenaline (norepinephrine), and Dopamine are all beta-adrenergic agonists. Adrenaline and Noradrenaline act on both beta-1 and beta-2 receptors, while Dopamine primarily acts on beta-1 receptors. Educationally, this question tests the student's knowledge of adrenergic receptors and their corresponding agonists. It requires students to differentiate between alpha and beta adrenergic agonists, emphasizing the importance of understanding drug classifications in pharmacology. By knowing which receptors specific drugs act on, healthcare professionals can predict their effects and potential side effects accurately. This knowledge is vital in clinical practice when prescribing or administering medications to achieve the desired therapeutic outcomes.

Correct Answer: D

Rationale: Certainly! Atropine is an anticholinergic drug that works by blocking the action of acetylcholine. Xerostomia (dry mouth) is a symptom caused by decreased salivary gland activity, so using atropine would exacerbate this condition. In contrast, atropine is used in pre-anesthetic medication to reduce secretions, in organic phosphate poisoning to counteract the cholinergic effects, and in intestinal colic to relax smooth muscles. Therefore, the correct answer is D because atropine would worsen dry mouth.

Correct Answer: D

Rationale: The correct answer is D: Alpha 1 receptor stimulation releases IP3 and DAG. When alpha 1 receptors are stimulated by sympathomimetics, they activate G-proteins which then stimulate phospholipase C. Phospholipase C cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers the release of calcium from intracellular stores, leading to smooth muscle contraction, while DAG activates protein kinase C to initiate various cellular responses. Choices A, B, and C are incorrect because beta receptor stimulation increases cAMP, alpha 2 receptor stimulation inhibits adenyl cyclase leading to decreased cAMP levels, and alpha 2 receptor stimulation does not increase cAMP.

Correct Answer: D

Rationale: The correct answer is D because ephedrine and amphetamine are not catecholamines. A is correct as catecholamines contain a catechol nucleus. B is true as they act directly on receptors. C is also true since catecholamines have a short duration of action. Therefore, D is the incorrect statement as ephedrine and amphetamine do not fall under the category of catecholamines due to their chemical structure and mode of action.

Correct Answer: B

Rationale: Propranolol is a non-selective beta-blocker that can cause bronchoconstriction, making it contraindicated in bronchial asthma. It can worsen asthma symptoms by blocking beta-2 receptors in the lungs. Angina pectoris, hypertension, and arrhythmia are conditions where propranolol is commonly used due to its beta-blocking effects on the heart and blood vessels.