PHAR 505 EXAM 1 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026

PHAR 505 EXAM 1 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026 What are the two major divisions of the nervous system? - Answers Central nervous system (CNS) and peripheral nervous system (PNS). What structures make up the CNS? - Answers Brain and spinal cord. What are the two major functional divisions of the PNS? - Answers Sensory (afferent) and motor (efferent). What do afferent neurons do? - Answers Carry sensory input toward the CNS. What do efferent neurons do? - Answers Carry signals away from the CNS to muscles and organs. What are the two divisions of the efferent system? - Answers Somatic motor system and autonomic nervous system. What does the somatic motor system control? - Answers Conscious voluntary movement. What does the autonomic nervous system control? - Answers Subconscious involuntary functions like heart rate and digestion. What are the main divisions of the autonomic nervous system? - Answers Sympathetic and parasympathetic systems. What is the sympathetic nervous system associated with? - Answers Fight-or-flight responses. What is the parasympathetic nervous system associated with? - Answers Rest-and-digest functions. What is the outflow of the sympathetic system? - Answers Thoracolumbar outflow. What is the outflow of the parasympathetic system? - Answers Craniosacral outflow. Give examples of parasympathetic effects. - Answers Miosis, increased salivation, decreased heart rate, bronchoconstriction, increased peristalsis, bile release. Why is understanding autonomic physiology important in pharmacology? - Answers Drugs act by manipulating autonomic pathways and receptors. What are the major steps in neurochemical transmission? - Answers Axonal conduction, transmitter release, receptor interaction, postsynaptic response, and transmitter destruction or dissipation. What is the key neurotransmitter in the cholinergic nervous system? - Answers Acetylcholine (ACh). Where is acetylcholine used in the nervous system? - Answers All preganglionic autonomic sites, postganglionic parasympathetic sites, some sympathetic sites, skeletal muscle, and CNS. What neurotransmitter is released at most sympathetic neuroeffector junctions? - Answers Norepinephrine. What kind of amine is acetylcholine structurally? - Answers A quaternary amine. Why does ACh not easily cross the blood-brain barrier? - Answers It is positively charged and water-soluble. What AChE inhibitor crosses the BBB? - Answers Physostigmine. What AChE inhibitor does not cross the BBB? - Answers Pyridostigmine. What important group is NOT present in acetylcholine? - Answers A phosphate group. What two molecules are used to synthesize ACh? - Answers Choline and acetyl-CoA. What enzyme synthesizes acetylcholine? - Answers Choline acetyltransferase (ChAT). What does ChAT do? - Answers Transfers an acetyl group from acetyl-CoA to choline. What transporter brings choline into the nerve terminal? - Answers CHT1, the high-affinity choline transporter. What is the rate-limiting step in ACh production? - Answers Uptake of choline into the nerve terminal. What drug blocks high-affinity choline uptake? - Answers Hemicholinium. How does hemicholinium decrease cholinergic signaling? - Answers It depletes choline uptake, reducing ACh synthesis. What transporter packages ACh into vesicles? - Answers VAChT, the vesicular acetylcholine transporter. What drug blocks VAChT? - Answers Vesamicol. What is the effect of blocking VAChT? - Answers Less ACh is packaged and released, so cholinergic signaling decreases. What triggers exocytosis of ACh-containing vesicles? - Answers Calcium entry through voltage-gated calcium channels. What toxin interferes with ACh release from vesicles? - Answers Botulinum toxin. What enzyme breaks down ACh in the synapse? - Answers Acetylcholinesterase (AChE). What are the breakdown products of ACh? - Answers Choline and acetate. What are the two major cholinergic receptor types? - Answers Nicotinic and muscarinic receptors. What type of receptor is the nicotinic receptor? - Answers A ligand-gated ion channel. What type of receptor is the muscarinic receptor? - Answers A G protein-coupled receptor (GPCR). How many subunits make up a nicotinic receptor? - Answers Five subunits. Where is the ACh binding site on the nicotinic receptor? - Answers At the interface between receptor subunits. What happens when ACh binds the nicotinic receptor? - Answers A conformational change opens the ion channel and allows ions to flow. Why is the closed nicotinic pore not favorable for ion flow? - Answers It is too narrow and lined with hydrophobic residues. What structural change opens the nicotinic channel? - Answers Rotation or movement of helices shifts hydrophobic residues out of the way. How many transmembrane segments does a muscarinic receptor have? - Answers Seven. What happens after ACh binds to a muscarinic receptor? - Answers A conformational change activates intracellular G proteins and downstream signaling. Where is M1 mainly found and what does it do? - Answers CNS and gastric glands; enhances cognition and increases gastric acid secretion. Where is M2 mainly found and what does it do? - Answers Heart and CNS; slows heart rate and reduces neurotransmitter release. Where is M3 mainly found and what does it do? - Answers Smooth muscle, glands, and eyes; causes smooth muscle contraction, gland secretion, and pupillary constriction. Where is M4 mainly found and what does it do? - Answers CNS; inhibits neurotransmitter release and modulates CNS signaling. Where is M5 mainly found and what does it do? - Answers CNS and blood vessels; involved in dopamine regulation and vasodilation. Which muscarinic receptor is most associated with slowing heart rate? - Answers M2. Which muscarinic receptor is most associated with glandular secretion and smooth muscle contraction? - Answers M3. What does an agonist do? - Answers Mimics the natural ligand and activates the receptor. What does an antagonist do? - Answers Blocks receptor activation and prevents the natural ligand from working. What is a cholinergic agonist? - Answers A drug that mimics ACh by activating cholinergic receptors. What are the two broad types of cholinergic agonists? - Answers Direct-acting and indirect-acting agonists. How do direct-acting cholinergic agonists work? - Answers They bind directly to cholinergic receptors. How do indirect-acting cholinergic agonists work? - Answers They inhibit AChE and increase endogenous ACh. Why is acetylcholine itself rarely used therapeutically? - Answers It is rapidly degraded by AChE. What is bethanechol used for? - Answers Urinary retention and ileus. What receptor type does bethanechol primarily activate? - Answers Muscarinic receptors. What is pilocarpine used for? - Answers Glaucoma and xerostomia. What is methacholine used for? - Answers Asthma diagnosis via methacholine challenge. What effect of methacholine is used diagnostically? - Answers Bronchoconstriction. What is carbachol used for? - Answers Glaucoma. Which direct-acting agonists can act at both muscarinic and nicotinic receptors? - Answers Acetylcholine and carbachol. What modification makes carbachol and bethanechol more resistant to hydrolysis? - Answers Carbamoyl substitution. What does beta-methyl substitution on the ACh skeleton tend to produce? - Answers Selective muscarinic agonist activity. What does alpha-methyl substitution on the ACh skeleton tend to produce? - Answers Selective nicotinic agonist activity. What happens if both alpha and beta positions are modified in the way shown in the slides? - Answers Activity can be lost or inactivated. What is neostigmine used for? - Answers Myasthenia gravis and reversal of neuromuscular blockade. What is pyridostigmine used for? - Answers Long-term management of myasthenia gravis. What is donepezil used for? - Answers Alzheimer's disease. What is physostigmine used for? - Answers Reversal of anticholinergic toxicity such as atropine overdose. Why is physostigmine useful in central anticholinergic toxicity? - Answers It crosses the BBB and inhibits CNS AChE. What is edrophonium used for? - Answers Diagnosis of myasthenia gravis. What is the general effect of reversible AChE inhibitors? - Answers Increase ACh availability at synapses and NMJs. What is the key difference between reversible and irreversible cholinesterase inhibitors? - Answers Reversible inhibitors can dissociate; irreversible ones form tight covalent bonds. What drug class includes parathion and malathion? - Answers Organophosphates. How do organophosphates affect AChE? - Answers They irreversibly inhibit it, causing cholinergic crisis. What is echothiophate? - Answers An irreversible cholinesterase inhibitor rarely used for glaucoma. How are cholinergic agonists useful in myasthenia gravis? - Answers They increase ACh action at NMJs to improve muscle strength. Which cholinergic agonists are used in glaucoma? - Answers Pilocarpine and carbachol. Which drug is used for urinary retention and ileus? - Answers Bethanechol. Which drug is used to reverse non-depolarizing neuromuscular blockade after surgery? - Answers Neostigmine. Which test temporarily boosts ACh to diagnose myasthenia gravis? - Answers Edrophonium test. Which test assesses airway hyperreactivity in asthma? - Answers Methacholine challenge test. What cardiovascular adverse effects can cholinergic agonists cause? - Answers Bradycardia and hypotension. What respiratory adverse effects can cholinergic agonists cause? - Answers Bronchoconstriction and difficulty breathing. What GI adverse effects can cholinergic agonists cause? - Answers Nausea, diarrhea, and abdominal cramps. What glandular adverse effects can cholinergic agonists cause? - Answers Excess salivation, sweating, and tearing. What is the general pattern of cholinergic agonist overdose? - Answers Too much rest-and-digest activity. What do muscarinic antagonists do? - Answers Competitively block muscarinic receptors and reduce parasympathetic activity. What do nicotinic antagonists do? - Answers Block nicotinic receptors at NMJs or autonomic ganglia. What effect does muscarinic blockade have on the heart? - Answers Increases heart rate. What effect does muscarinic blockade have on smooth muscle and glands? - Answers Reduces smooth muscle contraction and decreases secretions. What effect does nicotinic blockade at the NMJ have? - Answers Prevents muscle contraction. What effect does ganglionic nicotinic blockade have? - Answers Inhibits autonomic signaling. What is atropine used for? - Answers Bradycardia and organophosphate poisoning. How does atropine help in bradycardia? - Answers Blocks M2 receptors in the heart. What are ipratropium and tiotropium used for? - Answers COPD and asthma. What receptor do ipratropium and tiotropium block? - Answers M3 receptors in the airways. What are oxybutynin and solifenacin used for? - Answers Overactive bladder. What receptor do oxybutynin and solifenacin block? - Answers M3 receptors in the bladder. What is scopolamine used for? - Answers Motion sickness. Where does scopolamine primarily act for motion sickness? - Answers CNS muscarinic receptors. What are rocuronium and pancuronium used for? - Answers Muscle relaxation during surgery. What are common muscarinic antagonist adverse effects? - Answers Dry mouth, blurred vision, constipation, urinary retention, tachycardia, confusion, and sedation. What are common nicotinic antagonist adverse effects? - Answers Paralysis, respiratory depression, orthostatic hypotension, and loss of autonomic control. What memory phrase matches anticholinergic adverse effects? - Answers Can't see, can't spit, can't sit. What early observation linked cholinergic signaling to memory? - Answers Drugs like scopolamine impair memory. What happens to ACh receptors or ACh signaling in pre-AD and AD brain regions? - Answers They decrease. Why can increasing ACh help in Alzheimer's disease? - Answers It may improve cognitive symptoms and stabilize decline. What are the three main AD drugs named in the slides? - Answers Donepezil, rivastigmine, and galantamine. What is special about rivastigmine? - Answers It inhibits AChE and BuChE. What is special about galantamine? - Answers It inhibits AChE and stimulates nicotinic receptors to increase ACh release. Preganglionic autonomic neurotransmitter? - Answers ACh. Postganglionic parasympathetic neurotransmitter? - Answers ACh. Main postganglionic sympathetic neurotransmitter? - Answers NE. Nicotinic receptor type? - Answers Ligand-gated ion channel. Muscarinic receptor type? - Answers GPCR. Enzyme that synthesizes ACh? - Answers ChAT. Enzyme that breaks down ACh? - Answers AChE. Rate-limiting step in ACh production? - Answers Choline uptake by CHT1. Drug that blocks choline uptake? - Answers Hemicholinium. Drug that blocks vesicular ACh uptake? - Answers Vesamicol. Drug that blocks ACh release? - Answers Botulinum toxin. M2 major effect? - Answers Decreases heart rate. M3 major effect? - Answers Smooth muscle contraction and gland secretion. Direct muscarinic agonist for urinary retention? - Answers Bethanechol. Direct muscarinic agonist for glaucoma or xerostomia? - Answers Pilocarpine. AChE inhibitor for myasthenia gravis long-term? - Answers Pyridostigmine. AChE inhibitor for Alzheimer's disease? - Answers Donepezil. Antidote for atropine toxicity? - Answers Physostigmine. Antimuscarinic for bradycardia? - Answers Atropine. Antimuscarinic inhalers for COPD or asthma? - Answers Ipratropium and tiotropium. Antimuscarinic for overactive bladder? - Answers Oxybutynin or solifenacin. What does the adrenergic nervous system mainly correspond to? - Answers The sympathetic nervous system, associated with fight-or-flight effects. What are the major adrenergic receptor families? - Answers α1, α2, β1, β2, and β3. Where is α1 activity especially important clinically? - Answers Blood vessels, where α1 activation causes vasoconstriction. Where is α2 activity especially important clinically? - Answers Presynaptic receptors, where α2 activation decreases norepinephrine release. Where is β1 activity most important? - Answers The heart. Where is β2 activity most important? - Answers Bronchial smooth muscle. Easy memory trick for β1 vs β2? - Answers 1 heart, 2 lungs. What are the key binding interactions for epinephrine at the β2 receptor? - Answers Catechol hydrogen bonding, aromatic pi-pi interaction, hydrogen bonding at the side-chain OH, and ionic interaction of the protonated amine. Which amino acid residues are listed for β2 receptor binding of epinephrine? - Answers Ser-204, Ser-207, Phe-290, Asn-293, and Asp-113. What structural feature is very important for strong agonist binding? - Answers A catechol-like aromatic ring with hydrogen-bonding capability. Why are catechol agonists usually potent but short-acting? - Answers Catechol increases receptor binding potency, but also makes the drug more susceptible to metabolism by COMT. What side-chain feature is common in many adrenergic agonists? - Answers A beta-hydroxyl group on the side chain. What happens when a drug looks a lot like norepinephrine or epinephrine? - Answers It is more likely to be an agonist. What kind of N-substituent generally favors alpha agonist activity? - Answers A small N-substituent. What kind of N-substituent generally shifts activity toward beta receptors? - Answers A bulkier N-substituent. What N-substituent is especially associated with β2 selectivity? - Answers Tert-butyl on the amine strongly favors β2 activity. If you see a bulky N group like isopropyl or tert-butyl, what should you think? - Answers Think beta agonist, especially β2. If you see a small amine substituent and a phenylethanolamine core, what should you think first? - Answers Think alpha agonist. What structural features favor α1 agonism among phenylethanolamines? - Answers Small N-substituent, and often loss of one catechol OH can still preserve α1 activity. What structural change tends to increase α2 selectivity in phenylethanolamines? - Answers Addition of a small alpha-methyl group. Why is alpha-methylnorepinephrine more potent at α2 than norepinephrine? - Answers The α2 receptor has an additional methyl-binding pocket that better accommodates the alpha-methyl group. What happens to alpha selectivity when N-substitution becomes bulky? - Answers Activity shifts away from alpha and toward beta. Phenylephrine is best classified as what? - Answers An α1 agonist. Alpha-methylepinephrine is best recognized as favoring which receptor? - Answers α2 agonist activity. Epinephrine has activity at which alpha receptors in the slide comparison? - Answers Mixed α1 and α2 activity. What pattern suggests an imidazoline-type α1 agonist? - Answers One ortho substituent on the aromatic ring connected to an imidazoline ring. What pattern suggests an imidazoline-type α2 agonist? - Answers Two bulky ortho substituents that force a non-coplanar arrangement between the aryl ring and imidazoline ring. Why do two bulky ortho substituents favor α2 selectivity? - Answers They force the rings into the 3D orientation needed for selective α2 receptor binding. Tetrahydrozoline and naphazoline are examples of what? - Answers α1 agonist imidazoline derivatives used topically. Clonidine is best classified structurally and pharmacologically as what? - Answers A selective α2 agonist with an imidazoline-type scaffold. Brimonidine is mainly used as what kind of drug? - Answers An α2 agonist, especially for glaucoma. What para substituent decreases α2 affinity in mixed alpha agonists like oxymetazoline and xylometazoline? - Answers A bulky tert-butyl group at the para position. Oxymetazoline and xylometazoline are best thought of as what? - Answers Mixed alpha agonists with strong α1 agonism and partial α2 properties, used topically as decongestants. What is the biggest structural clue for β2 selectivity? - Answers A bulky N-substituent, especially tert-butyl. Isoproterenol is best classified as what? - Answers A nonselective beta agonist. What simple structural feature makes terbutaline more β2 selective? - Answers A tert-butyl group on the amine. Albuterol is a β2 agonist partly because its aromatic substituent does what? - Answers It preserves hydrogen-bonding capability at the modified meta position while helping β2 selectivity. What do β2 agonists with modified meta-OH groups still need? - Answers A functional group capable of hydrogen bonding. What is the slide's explanation for why modified meta-OH groups can still work for β2 agonists? - Answers The β2 receptor has a slightly larger binding pocket around the meta-OH binding site. Which β2 agonists in the slides are long-acting? - Answers Salmeterol and formoterol. Why are salmeterol and formoterol long-acting? - Answers They contain larger or bulkier substituents that prolong action. How can isoproterenol be made more β2 selective according to the slides? - Answers Move the 4-OH to 5-OH to make metaproterenol. Dobutamine is mainly selective for which receptor? - Answers β1. What structural feature of dobutamine is specifically pointed out in the slides? - Answers It is a dopamine analogue with no beta-OH and a bulky or chiral N-substituent. If you see a bulky N substituent and a structure meant for bronchodilation, which receptor should come to mind? - Answers β2. What is the easiest first-pass rule to distinguish adrenergic agonists from antagonists by structure? - Answers If it resembles norepinephrine, epinephrine, or isoproterenol, think agonist. If it has a bulkier, more medicinal-chemistry-looking scaffold, think antagonist. What classic irreversible alpha antagonist has a reactive alkylating intermediate? - Answers Phenoxybenzamine. What is the key structural clue for phenoxybenzamine? - Answers A haloalkyl amine that forms a reactive aziridinium intermediate and irreversibly alkylates the receptor. Phentolamine and tolazoline are what kind of alpha antagonists? - Answers Reversible, nonselective alpha antagonists. Why is tolazoline an antagonist rather than an alpha agonist? - Answers It lacks ortho substitution, which is needed for alpha agonist imidazoline activity. What structural pattern defines prazosin-like selective α1 antagonists? - Answers A 4-amino-6,7-dimethoxyquinazoline ring attached to a piperazine. What drug-name clue strongly suggests a selective α1 antagonist? - Answers The ending -zosin. Prazosin, terazosin, and doxazosin are what class? - Answers Selective α1 antagonists. What structural scaffold is emphasized for α1-selective antagonists used in hypertension? - Answers Quinazoline plus piperazine. Tamsulosin and silodosin are best classified as what? - Answers Selective α1A antagonists used for BPH. What is a useful structural clue for tamsulosin and silodosin compared with quinazoline blockers? - Answers They are bulkier and more specialized, and no longer use the old quinazoline core. Yohimbine and rauwolscine are selective for which receptor class? - Answers α2 antagonists. Catechol plus small N group plus phenylethanolamine equals likely what? - Answers Alpha agonist. Catechol or modified phenylethanolamine plus bulky N group equals likely what? - Answers Beta agonist. Tert-butyl on the amine should make you think what? - Answers β2 selectivity. Alpha-methyl on a phenylethanolamine should make you think what? - Answers More α2 selectivity. One ortho substituent on an aromatic ring attached to imidazoline suggests what? - Answers α1 agonist. Two bulky ortho substituents on an imidazoline system suggest what? - Answers α2 agonist. No ortho substitution on imidazoline-type structure suggests what? - Answers More likely antagonist. Quinazoline plus piperazine suggests what? - Answers Selective α1 antagonist. Reactive haloalkyl chain that forms aziridinium suggests what? - Answers Irreversible alpha antagonist. A drug that looks very unlike norepinephrine or epinephrine and has multiple fused or bulky rings is more likely what? - Answers Antagonist. What structural change moves activity from alpha toward beta? - Answers Increasing N-bulk. What structural change moves activity from beta1 or mixed beta toward β2? - Answers Adding a larger N substituent, especially tert-butyl. What structural change moves norepinephrine-like activity toward α2? - Answers Adding an alpha-methyl group. What structural change can preserve α1 activity while reducing full catechol character? - Answers Removing one catechol OH. What is the major structural hallmark of many adrenergic agonists? - Answers A phenylethanolamine-like core. What is the major structural hallmark of many selective α1 antagonists? - Answers A quinazoline scaffold. What is the structural hallmark of phenoxybenzamine? - Answers An irreversible alkylating side chain. What is the structural hallmark of imidazoline alpha agonists? - Answers An imidazoline ring with a specific ortho substitution pattern controlling α1 versus α2 selectivity. How do I quickly identify an alpha agonist? - Answers Look for an NE-like phenylethanolamine with a small N group; alpha-methyl favors α2. How do I quickly identify a beta agonist? - Answers Look for bulkier N substitution; tert-butyl strongly suggests β2. How do I quickly identify an alpha antagonist? - Answers Look for a structure that does not resemble norepinephrine and is bulkier, such as quinazoline-piperazine or haloalkyl amine systems. How do I remember alpha1 versus alpha2 agonist imidazolines? - Answers One ortho substituent usually suggests α1 agonist; two bulky ortho substituents usually suggest α2 agonist. How do I remember agonist versus antagonist by resemblance? - Answers If it looks like the natural catecholamine template, think agonist. If it looks medicinally engineered and bulky, think antagonist. What is another name for the adrenergic nervous system? - Answers The sympathetic nervous system. What type of outflow does the sympathetic nervous system have? - Answers Thoracolumbar outflow. What is the general role of the adrenergic nervous system? - Answers It mediates the fight-or-flight response. What are the major neurotransmitters of the adrenergic nervous system? - Answers Norepinephrine and epinephrine. Why is the adrenergic system described as a systemic fire alarm? - Answers Because it produces diffuse activation of target organs. What type of receptors are adrenoceptors? - Answers G protein-coupled receptors (GPCRs). How many transmembrane domains do adrenoceptors have? - Answers Seven. How many major adrenergic receptor subtypes are listed in the slides? - Answers Nine: α1A, α1B, α1D, α2A, α2B, α2C, β1, β2, β3. Where are α1 receptors mainly located? - Answers On the postsynaptic membrane of effector organs. Where are α2 receptors located? - Answers On both presynaptic and postsynaptic membranes. What is the main action of α1 receptors on vascular smooth muscle? - Answers Contraction, causing vasoconstriction. What effect do α1 receptors have on the pupillary dilator muscle? - Answers Contraction, which dilates the pupil. What effect do α1 receptors have on pilomotor smooth muscle? - Answers They erect hair. What effect do α1 receptors have on the prostate? - Answers Contraction. What effect do α1 receptors have on the heart according to the slides? - Answers Increased force of contraction. What effect do α2 receptors have on nerve terminals? - Answers They inhibit transmitter release. What effect do α2 receptors have on platelets? - Answers Aggregation. What effect do α2 receptors have on fat cells? - Answers They inhibit lipolysis. What are the main effects of β1 receptor activation? - Answers Increased heart rate, increased force of contraction, and increased renin release. Where are β1 receptors prominently found? - Answers In the heart and juxtaglomerular cells. What are the main effects of β2 receptor activation? - Answers Relaxation of respiratory, uterine, and vascular smooth muscle. What effect do β2 receptors have in skeletal muscle? - Answers Promote potassium uptake. What effect do β2 receptors have in the liver? - Answers Activate glycogenolysis. What effect do β3 receptors have in the bladder? - Answers Relax detrusor muscle. What effect do β3 receptors have in fat cells? - Answers Activate lipolysis. What signaling pathway is associated with α1 receptor activation? - Answers Activation of phospholipase C to IP3 to calmodulin to increased intracellular calcium to vasoconstriction. What signaling pathway is associated with β1 receptor activation? - Answers Activation of adenylyl cyclase to increased cAMP and calcium influx to increased myocardial contractility. What signaling pathway is associated with β2 receptor activation? - Answers Activation of adenylyl cyclase to increased cAMP to protein kinase A to smooth muscle relaxation. What is desensitization? - Answers A decreased response to continuous or repeated exposure to some agonists. What are other names for desensitization? - Answers Down-regulation, tolerance, refractoriness, and tachyphylaxis. What is homologous desensitization? - Answers Loss of responsiveness only in receptors repeatedly or continuously exposed to an agonist. What is heterologous desensitization? - Answers Desensitization of one receptor causing desensitization of another receptor not directly activated. What are adrenergic agonists? - Answers Drugs that mimic the effects of adrenergic nerve stimulation or adrenal medulla stimulation. What are synonyms for adrenergic agonists? - Answers Sympathomimetics, adrenergic agonists, and adrenomimetics. How are adrenergic agonists classified by structure? - Answers Catecholamines and non-catecholamines. How are adrenergic agonists classified by action? - Answers Direct-acting, indirect-acting, and mixed-acting. What structural feature defines a catecholamine? - Answers A catechol ring with two OH groups on the phenyl ring. How are catecholamines mainly metabolized? - Answers By COMT and MAO. What is the typical half-life of catecholamines? - Answers About 1 to 3 minutes. Why are catecholamines not given orally? - Answers They are rapidly metabolized and have inactive metabolites. Can catecholamines cross the blood-brain barrier? - Answers No. Give examples of catecholamines from the slides. - Answers Epinephrine, norepinephrine, dopamine. What defines a non-catecholamine? - Answers It lacks the two OH groups on the phenyl ring. Why do non-catecholamines last longer than catecholamines? - Answers They resist MAO metabolism better, especially with alpha-carbon substitution. Can non-catecholamines be given orally? - Answers Yes. Can non-catecholamines cross the blood-brain barrier? - Answers Yes, so they can have CNS stimulant effects. Give examples of non-catecholamines from the slides. - Answers Ephedrine and amphetamine. How do direct-acting adrenoceptor agonists work? - Answers They act directly on one or more adrenoceptors. Which direct-acting agonist is selective for α1? - Answers Phenylephrine. Which direct-acting agonist is selective for β2? - Answers Terbutaline. Which direct-acting agonist is selective for α2? - Answers Clonidine. Which direct-acting agonist is selective for β1? - Answers Dobutamine. What blocks the effects of direct-acting agonists? - Answers Receptor-blocking drugs such as adrenergic antagonists. How do indirect-acting adrenergic agonists work? - Answers They increase the availability of norepinephrine or epinephrine in the synapse.