Question 1

What are pressor agents and how do they work?

Accepted Answer

Pressor agents, or vasopressors, elevate low blood pressure and function as cardiac stimulants by increasing heart rate, force of contractility, and conduction velocity. Examples include endogenous catecholamines like noradrenaline and synthetic agents such as phenylephrine, making them essential for managing hypotensive conditions and supporting cardiovascular function.

Question 2

How do beta-2 agonists relieve respiratory symptoms?

Accepted Answer

Beta-2 agonists like salbutamol and terbutaline relax bronchial muscles and widen airways, making breathing easier for patients with obstructive pulmonary disorders and asthma. These drugs reduce airway constriction and improve airflow by directly relaxing lung smooth muscle tissue through receptor activation.

Question 3

What is the mechanism of action for decongestants?

Accepted Answer

Alpha-agonists like oxymetazoline and phenylephrine act as decongestants by constricting blood vessels in nasal tissues, reducing swelling and congestion. This vasoconstriction of the nasal mucosa helps relieve stuffy or blocked noses and sinuses by decreasing tissue edema and improving airflow through nasal passages.

Question 4

How do indirect-acting CNS stimulants produce their effects?

Accepted Answer

Noncatecholamine sympathomimetics like amphetamine act as indirect-acting CNS stimulants by triggering the release of dopamine and serotonin rather than binding directly to receptors. These neurotransmitters induce restlessness, euphoria, and insomnia, distinguishing indirect-acting agents from direct-acting agents that bind adrenergic receptors.

Question 5

What role do beta-2 agonists play in obstetrics?

Accepted Answer

Beta-2 agonists like ritodrine relax uterine smooth muscle and delay premature labor by reducing uterine contractions. By providing additional time for fetal development, these agents allow for interventions to improve maternal and fetal outcomes in at-risk pregnancies and support better neonatal health.

Question 6

How are adrenergic agonists classified therapeutically?

Accepted Answer

Adrenergic agonists are classified based on their therapeutic actions and mechanisms of action. Major categories include vasopressors for blood pressure support, bronchodilators for airway relaxation, decongestants for nasal relief, CNS stimulants for neural effects, uterine relaxants for labor management, and beta-3 agonists for treating urinary incontinence.

Question 7

What distinguishes catecholamine from noncatecholamine sympathomimetics?

Accepted Answer

Catecholamines like noradrenaline and dopamine are endogenous compounds that bind directly to adrenergic receptors, while noncatecholamine sympathomimetics like amphetamine lack the catechol moiety and work indirectly. Indirect agents trigger drugs affecting neurotransmitter release or uptake rather than direct receptor binding, producing different pharmacological profiles.

Agonistas adrenérgicos: Clasificación terapéutica

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