Adrenergic Agents - Pharmaceutical and Medicinal Organic Chemistry

Vocabulary-style flashcards covering the biosynthesis, SAR, and classification of adrenergic agonists and antagonists.

Phenylalanine

An amino acid that serves as the starting point in the catecholamine biosynthetic pathway.

L-Tyrosine

A derivative of phenylalanine formed via the enzyme Phenylalanine Hydroxylase.

Phenylalanine Hydroxylase

The enzyme responsible for converting Phenylalanine into L-Tyrosine.

Tyrosine Hydroxylase (TH)

The enzyme that catalyzes the conversion of L-Tyrosine to L-Dopa.

L-Dopa

The metabolic product formed from L-Tyrosine that is then decarboxylated to form Dopamine.

L-Aromatic Amino Acid Decarboxylase (AAAD)

The enzyme that converts L-Dopa into Dopamine by removing a carboxyl group.

Dopamine

The immediate metabolic precursor of norepinephrine and a potent agonist at D1 receptors.

Dopamine $\beta$-Hydroxylase (DBH)

The enzyme that converts Dopamine into Norepinephrine.

Norepinephrine

A catecholamine neurotransmitter formed from Dopamine and specialized for neural vesicles storage.

Phenylethanolamine N-Methyltransferase (PNMT)

The enzyme responsible for the conversion of Norepinephrine to Epinephrine.

Epinephrine

A catecholamine hormone and neurotransmitter containing a methyl substituent on the amino nitrogen.

Normetanephrine

A metabolite of norepinephrine formed through O-methylation.

3-methoxy-4-hydroxy-mandelic acid (VMA)

A metabolite of catecholamines, also known by the abbreviation VMA.

Metanephrine

A metabolite of epinephrine characterized by a methoxy group on the 3rd carbon of the benzene ring.

Adrenergic Agonists

Compounds that are derivatives of $\beta$ phenylethylamine and activate the sympathetic nervous system.

Catecholamines

Sympathomimetic amines that contain a 3,4 dihydroxybenzene group.

Catechol

The chemical name for 1,2 -dihydroxybenzene.

3,4-dihydroxy substitution

A feature on the benzene ring that yields the highest potency in activating $\alpha$ or $\beta$ receptors.

COMT

Catechol-O-methyltransferase; an enzyme that causes rapid inactivation of catecholamines postsynaptically and in the gut wall.

MAO

Monoamine oxidase; an enzyme that causes rapid inactivation of catecholamines intraneurally, in the liver, and the gut wall.

Poor CNS penetration

A physical property of catecholamines due to their polar nature.

Metaproterenol

A 3,5 dihydroxy adrenergic agent with increased $\beta_2$ activity.

Albuterol

An adrenergic agent with a 3-(hydroxymethyl)-4-(hydroxy) substitution that increases $\beta_2$ selectivity.

Phenylephrine

A non-catecholamine $\alpha_1$ agonist that lacks one or both -OH groups, leading to increased oral bioavailability and CNS distribution.

Isoproterenol

A non-selective $\beta$ agonist containing a large isopropyl substituent on the amino nitrogen.

Phenylisopropylamines

Another name for $\alpha$-methyl compounds that have an enhanced ability to displace catecholamines from storage sites.

Ephedrine

A noncatechol phenylisopropylamine that activates $\beta$ receptors and acts as a mild CNS stimulant.

Amphetamines

Phenylisopropylamines that act as central nervous system stimulants and indirect-acting sympathomimetics.

Dobutamine (+) isomer

A potent $\beta_1$ agonist and an $\alpha_1$ receptor antagonist.

Dobutamine (–) isomer

A potent $\alpha_1$ agonist capable of causing significant vasoconstriction when administered alone.

Fenoldopam

A selective D1 receptor agonist used intravenously for treating severe hypertension via peripheral vasodilation.

Methyldopa

An $\alpha_2$ agonist metabolically converted to $\alpha$-methyl norepinephrine and used to treat essential hypertension.

Clonidine

An $\alpha_2$ agonist chemically named 2-(2,6-dichlorophenylamino)-2-imidazoline.

2-arylimidazolines

A class of $\alpha_1$ agonists containing an imidazoline ring and a phenyl ring, such as Xylometazoline and Oxymetazoline.

Xylometazoline

A member of the 2-arylimidazolines class used as an $\alpha_1$ agonist.

Oxymetazoline

A 2-arylimidazoline $\alpha_1$ agonist that includes an additional hydroxy group compared to Xylometazoline.

Tetrahydrazoline

An $\alpha_1$ agonist that is part of the 2-arylimidazolines chemical group.

Naphazoline

A 2-arylimidazoline $\alpha_1$ agonist commonly used in medicinal applications.

Metaraminol

A phenylethanolamine agent categorized as an $\alpha_1$ agonist.

Methoxamine

A direct-acting $\alpha_1$ agonist belonging to the phenylethanolamine class.

Guanfacine

A drug classified as an $\alpha_2$ agonist for sympathetic nervous system modulation.

Guanabenz

An $\alpha_2$ agonist used in cardiovascular pharmacology.

Pirbuterol

A $\beta_2$ agonist with a substitution pattern that increases activity and resists COMT.

Salmeterol

A long-acting $\beta_2$ agonist used for bronchodilation.

Formoterol

A $\beta_2$ selective agonist used in the management of respiratory conditions.

Terbutaline

A $\beta_2$ agonist characterized by a 3,5-dihydroxy substitution pattern.

Ritodrine

A $\beta_2$ agonist often used for its effects on smooth muscle.

Methylphenidate

An amphetamine variant used primarily for the treatment of ADHD in children.

Pemoline

A stimulant drug used for ADHD that is considered an amphetamine variant.

Phenylpropanolamine (PPA)

The N-desmethyl analog of ephedrine used in OTC weight reduction and cold medications.

Tyramine

A by-product of tyrosine metabolism found in fermented foods like cheese, showing a high first-pass effect.

Nonselective $\alpha$-blockers

Adrenergic antagonists that block both $\alpha_1$ and $\alpha_2$ receptors, such as Tolazoline and Phentolamine.

Tolazoline

An imidazoline derivative that acts as a non-selective, reversible $\alpha$ antagonist.

Phentolamine

A reversible, non-selective $\alpha$ antagonist containing an imidazole derivative.

Phenoxybenzamine

An irreversible $\alpha$ antagonist that forms a covalent bond with the receptor via an aziridinium ion electrophile.

Aziridinium ion

The reactive electrophilic intermediate formed by Phenoxybenzamine to bind covalently to $\alpha$ receptors.

Zosins

A name for selective $\alpha_1$-adrenergic blocking agents like Terazosin and Prazosin.

Terazosin

A selective and competitive $\alpha_1$ antagonist consisting of a quinazoline, piperazine, and acyl moiety.

Prazosin

The prototypical selective $\alpha_1$ blocker used in hypertension treatment.

Doxazosin

A selective $\alpha_1$ antagonist used to treat hypertension and benign prostatic hyperplasia.

Alfuzosin

A selective, competitive $\alpha_1$ antagonist structurally related to Prazosin.

Quinazoline

One of the three structural components of the 'Zosin' class of $\alpha_1$ blockers.

Yohimbine

A selective $\alpha_2$-adrenergic blocking agent that is an indolealkylamine alkaloid.

Aryloxypropanolamines

A chemical class of $\beta$-blockers, such as Propranolol, containing an -OCH2- group.

Propranolol

The prototypical aryloxypropanolamine $\beta$ antagonist.

Acebutolol

A $\beta_1$-selective blocker with a specific acylamino group on the aromatic ring.

Atenolol

A $\beta_1$-selective adrenergic antagonist used widely for cardiovascular conditions.

Betaxolol

A $\beta_1$-selective blocker used in the treatment of hypertension and glaucoma.

Bisoprolol

A selective $\beta_1$ blocker known for its long half-life and use in heart failure.

Esmolol

A very short-acting $\beta_1$-selective blocker, typically administered intravenously.

Metoprolol

A commonly used $\beta_1$-selective blocker for hypertension and angina.

Labetalol

An adrenergic antagonist that possesses both $\beta$ and $\alpha_1$ antagonistic activity.

Carvedilol

A $\beta$-blocker with additional $\alpha_1$-antagonistic activity used in heart failure management.

Reserpine

A plant alkaloid that blocks the Mg/ATP dependent transport of biogenic amines into synaptic vesicles.

Guanethidine

An adrenergic neuron blocker that inhibits the release of NE and displaces NE from storage vesicles.

Orthostatic hypotension

A side effect caused by Guanethidine due to its interference with adrenergic nerve stimulation.

Alpha-methyl compounds

Compounds substituted at the alpha carbon that block oxidation by MAO and prolong drug action.

3,5-dihydroxybenzene

A substitution pattern associated with increased $\beta_2$ receptor activity.

3-(hydroxymethyl)-4-hydroxy substitution

A specific structural modification that increases selectivity for $\beta_2$ receptors over $\beta_1$.enerally

Direct-acting agonists

Sympathomimetics that typically possess a $\beta$-hydroxyl group for receptor interaction and storage.

Piperazine

The heterocyclic component found between the quinazoline and acyl moieties in selective $\alpha_1$ blockers.

Acyl Moiety

The part of the 'Zosin' structure that differs between Prazosin, Terazosin, and Doxazosin.

Indolealkylamine alkaloid

The chemical classification of the $\alpha_2$ blocker Yohimbine.

Mesomeric compound

A chemical description of Clonidine indicating it exists as a resonance-stabilized structure.

Alpha-methyl DOPA

The chemical name for Aldomet, a precursor converted to $\alpha$-methyl norepinephrine.

Non-catecholamines

Sympathomimetic compounds that lack catechol hydroxyl groups on the benzene ring.

Phenylethanolamines

A sub-class of $\alpha_1$ agonists including Phenylephrine and Methoxamine.

2-imidazoline

The specific nitrogen-containing ring found in the structure of Clonidine and 2-arylimidazolines.

N-alkyl group branching

A structural feature where bulky substitutions on the amino nitrogen enhance $\beta$-antagonistic effects.

Biogenic amines

Neurotransmitters like NE, Epi, Dopamine, and 5-HT whose transport is blocked by Reserpine.

Aziridinium electrophile

The specific reactive form of Phenoxybenzamine that allows it to act as an irreversible antagonist.