MED ORG ADRE QUIZ

Which structural feature is responsible for rapid COMT metabolism?

The catechol (3,4-dihydroxy) moiety

specifically metabolizes catechol rings.

COMT

Which modification increases membrane retention and duration of action?

Increasing the lipophilicity (LogP) by adding a large lipophilic aralkyl group

___ = more membrane retention = longer duration (e.g., ___).

Higher LogP

salmeterol

Regarding SAR of indirect sympathomimetics

N-substituents larger than a methyl group generally render the compound inactive.

decrease indirect activity.

Large N-substituents

Why is phenoxybenzamine irreversible?

Formation of a reactive aziridinium ion that covalently bonds to the receptor

Why is tamsulosin uroselective?

It shows greater selectivity for the α1A receptor subtype found in the prostate.

What structural modification distinguishes propranolol?

The insertion of an oxymethylene bridge between the aromatic ring and the ethanolamine side chain

Which β1-selective blocker potentiates nitric oxide?

Nebivolol

Comparing carvedilol and labetalol

Carvedilol and labetalol both block α1, β1, and β2 receptors, and only the S-enantiomer of carvedilol has β-blocking activity, while both enantiomers contribute to α1 blockade.

Effect of adding an α-methyl group to phenethylamine?

prevents metabolism by MAO and enhances displacement of norepinephrine.

Why is isoproterenol non-selective?

It acts equally on both β1 and β2 adrenergic receptors.

Drug used in hypertensive emergencies because of an extremely short half-life?

Esmolol

Significance of the aryloxypropanolamine pharmacophore?

provides higher potency and greater beta-blocking activity compared to arylethanolamines.

Phentolamine is

A non-selective, reversible alpha-antagonist.

Primary clinical utility of dobutamine?

a selective β1 agonist that increases cardiac output with minimal peripheral vasoconstriction.

Which β-blocker exhibits intrinsic sympathomimetic activity (ISA)?

Pindolol

Non-selective β-agonist rapidly metabolized by COMT.

Isoproterenol

Selective β1 agonist that increases cardiac output.

Dobutamine

Prototype non-selective β-blocker.

Propranolol

Extremely short half-life due to hydrolysis by RBC esterases.

Esmolol

Quinazoline blocker selective for α1A receptors in the prostate.

Alfuzosin

Irreversible α-antagonist forming an aziridinium ion.

Phenoxybenzamine

β1-selective blocker that potentiates nitric oxide.

Nebivolol

Drug distinguished by insertion of an oxymethylene bridge.

Propranolol

Non-selective irreversible α-antagonist.

Phenoxybenzamine

Acts equally on β1 and β2 receptors.

Isoproterenol

β1-selective blocker ideal for continuous IV infusion.

Esmolol

α1-blocker that relaxes prostatic smooth muscle.

Tamsulosin (Alfuzosin and Silodosin also fit)

Non-selective β-blocker used as the benchmark for potency.

Propranolol

Selective β1 agonist used to treat shock.

Dobutamine

Agent whose effects persist long after the drug is cleared.

Phenoxybenzamine

Third-generation β-blocker with vasodilatory benefit plus β1 antagonism.

Nebivolol

Non-selective β-agonist with poor oral bioavailability because of COMT metabolism.

Isoproterenol

β-blocker with a unique metabolic pathway involving hydrolysis.

Esmolol

Preferred drug for BPH because it minimizes systemic cardiovascular effects.

Tamsulosin

Non-selective β-agonist producing significant cardiac stimulation.

Isoproterenol