Table: Commonly used sympathomimetic drugs
| Subclass | Mechanism of action | Effects | Clinical applications | Pharmacokinetics Pharmacokinetics Pharma ... |
| Α-1 agonists (midodrine, phenylephrine) | Activates phospholipase C Phospholipase ... | Vascular smooth muscle contraction Smoot ... | Orthostatic hypotension Hypotension Hypo ... | Oral administration Peak effect: 1 hour ... |
| Α-2 agonists (clonidine) | Stimulates α-2 adrenoceptors in the brai ... | Vasoconstriction Vasoconstriction The .. ... | Hypertension Hypertension Hypertension, ... | Oral, transdermal Peak effect: 1–3 hours ... |
| Β-1 agonists (dobutamine) | Activates adenylyl cyclase (increases my ... | Positive inotrope | Cardiogenic shock Shock Shock is a ... | IV administration Requires dose titratio ... |
| Β-2 agonists (albuterol) | Activates adenylyl cyclase | Bronchial smooth muscle dilation | Asthma Asthma Asthma is a chronic inflam ... | Administration via inhalation Duration: ... |
How do sympathomimetic drugs work?
Sympathomimetic drugs are agents which in general mimic responses due to stimulation of sympathetic nerves. These agents are able to directly activate adrenergic receptors or to indirectly activate them by increasing norepinephrine and epinephrine (mediators of the sympathoadrenal system) levels.
What is the pharmacological profile of direct sympathomimetics?
Direct sympathomimetics function as agonists upon one or more adrenergic receptors. The pharmacological profile of direct sympathomimetics has its primary basis on the subtype of adrenergic receptors.
Why do sympathomimetic drugs raise blood pressure?
Sympathomimetic drugs mimic or stimulate the adrenergic nervous system, and they can raise blood pressure to alarming heights, particularly in hypertensive patients. Many hypertensive patients are sensitive to all pressors, probably because they have hypertrophied vascular smooth muscles.
What is a sympathomimetic agonist?
The sympathomimetics constitute a very important group of agonists used for cardiovascular, respiratory, and other conditions. They are readily divided into subgroups on the basis of their spectrum of affinity for α, β, or D receptors.
What is the mechanism of action of sympathomimetics?
Sympathomimetics. Sympathomimetic drugs are agents which in general mimic responses due to stimulation of sympathetic nerves. These agents are able to directly activate adrenergic receptors or to indirectly activate them by increasing norepinephrine and epinephrine (mediators of the sympathoadrenal system) levels.
What is the effect of sympathomimetic drugs?
Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system. Examples of sympathomimetic effects include increases in heart rate, force of cardiac contraction, and blood pressure.
What is the mechanism of action of the sympathomimetic bronchodilators?
Abstract. Sympathomimetic bronchodilators relax bronchial smooth muscle via stimulation of the enzyme adenylcyclase. Furthermore, they stabilize the membrane of the bronchial mast cell. Therefore, they are used in the treatment of acute asthma as well as in long-term prophylaxis.
What are sympathomimetic drugs also known as?
Sympathomimetic drugs, also known as adrenergic agonists, mimic the action of the stimulators (α, β, or dopamine. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine.
What is an example of a sympathomimetic drug?
A sympathomimetic used to manage exogenous obesity short term. An adrenergic beta agonist used to treat premature labor....Sympathomimetics.DrugTargetTypeDobutamineCatechol O-methyltransferaseenzymeDobutamineBeta-2 adrenergic receptortargetDobutamineAlpha-1 adrenergic receptorstargetDobutamineEstrogen receptor alphatarget108 more rows
What is sympathomimetic activity?
Abstract. Intrinsic sympathomimetic activity (ISA) characterizes a group of beta blockers that are able to stimulate beta-adrenergic receptors (agonist effect) and to oppose the stimulating effects of catecholamines (antagonist effect) in a competitive way.
What do Parasympathomimetic drugs do?
Parasympathomimetics are a class of medications that activate the parasympathetic nervous system by mimicking or modifying the effects of acetylcholine.
What is the difference between sympathomimetic and sympatholytic drugs?
Sympathomimetics and Sympatholytics: Introduction Drugs that bind to these receptors and modulate or mimic the function of the sympathetic nervous system may be divided into those which augment the system (sympathomimetics) and those which antagonize the system (sympatholytics).
Are beta blockers sympathomimetic?
Certain β-blockers have an intrinsic sympathomimetic activity (partial agonist activity) at β1-adrenergic receptor sites, β2-adrenergic receptor sites, or both. In a β-blocker, this property is identified as a slight cardiac stimulation that can be blocked by propranolol.
When are sympathomimetics used?
Sympathomimetics are used to provide inotropic support for patients in acute cardiac failure. Most sympathomimetics have the ability to increase contractility about 100% above baseline, but many are unsuitable for treating heart failure because of other drug properties.
What are the signs and symptoms of sympathomimetic toxicity?
In low doses they induce effects such as increased energy and mood elevation, but high doses or binge use causes severe symptoms that include hallucinations, psychosis, increased heart rate, high blood pressure, and hyperthermia, often accompanied by combative or violent behaviors.
Why are sympathomimetic drugs grouped together?
The sympathomimetic drugs are grouped together because they can increase blood pressure and, in part, act like norepinephrine (NE). Drugs in this group work by a variety of mechanisms, including the release of NE from synaptic granules (benzphetamine, phendimetrazine, phentermine, and diethylpropion); the blockade of NE reuptake (mazindol); or the blockade of reuptake of both NE and serotonin (5-hydroxytryptomine, 5-HT; i.e., sibutramine).
What are sympathoadrenal drugs?
Sympathomimetic drugs are agents which in general mimic responses due to stimulation of sympathetic nerves. These agents are able to directly activate adrenergic receptors or to indirectly activate them by increasing norepinephrine and epinephrine (mediators of the sympathoadrenal system) levels. Chemically these drugs are catecholamines (Figure 1) or are structurally similar to catecholamines. The parent structure is β -phenylethylamine. When hydroxyls are placed on β -phenylethylamine at the 3 and 4 positions of the aromatic ring ( Figure 1 ), the drugs are called a catecholamine. There are three naturally occurring catecholamines (dopamine, norepinephrine, and epinephrine) as well as various synthetic amines (e.g., isoproterenol and dobutamine).
What are catecholamines and dopamine?
Catecholamines are sympathomimetic drugs. Dopamine and norepinephrine are used as vasopressors (antihypotensives). Catecholamines are water-soluble and are 50%-bound to plasma proteins, and are always seen in the circulating blood. Epinephrine stimulates both the alpha- and beta-adrenergic systems, causes systemic vasoconstriction and gastrointestinal relaxation, stimulates the heart, and dilates bronchi and cerebral vessels. It is also used as a vasoconstrictor, cardiac stimulant, or bronchodilator to counter allergic reaction, anesthesia, and cardiac arrest. Epinephrine is used to treat severe allergic (anaphylactic) reactions because it can prevent or minimize the effects of histamine. It is also an antiglaucoma agent.
What drugs can cause hypertension?
Sympathomimetic drugs—such as cocaine, amphetamines, phencyclidine hydrochloride (PCP), and lysergic acid diethylamide (LSD)—can precipitate a hypertensive emergency.44,133–136 Cocaine hypertensive emergencies have been documented in patients with illicit use and patients suffering from iatrogenic complications due to epistaxis treatment or when cocaine is used as a topical anesthetic for laryngoscopy. 137,138 Cocaine blocks the presynaptic reuptake of norepinephrine and dopamine, releases norepinephrine from sympathetic nerve terminals, and stimulates adrenal gland catecholamine release. Patients present with agitation, tachycardia, hypertension, mydriasis, and hyperthermia. Other agents that can precipitate a hypertensive emergency include dietary supplements such as Ephedra sinica, also known as ma-huang. This supplement contains ephedrine, a chemical that stimulates the nervous and endocrine systems to generate an acute rise in BP and has been temporally associated with stroke, MI, and sudden death. 139 Although banned by the U.S. Food and Drug Association in 2006, it can still be obtained outside the United States and via Internet sources. 140 Patients receiving monoamine oxidase inhibitor therapy who consume tyramine-containing foods may develop a hyperadrenergic state and resultant hypertensive crisis. 141 Patients present with tachycardia, elevated BP, diaphoresis, chest pain, and—depending on the agent—mental status changes. Licorice can also cause acute elevations in BP and complications may include PRES. The active agent, glycyrrhic acid, inhibits 11β-hydroxysteroid dehydrogenase, causing mineralocorticoid excess. Most commercial preparations do not have enough of this compound to cause adverse effects, but some “original” or “old time” formulations may and, if consumed in large amounts, can lead to hypertensive crisis. 142
What drugs cause postural tremors?
Drug-induced Postural Tremor. Several sympathomimetic drugs associated with increased noradrenergic activity tend to worsen physiologic and pathologic postural tremor. These include stimulants such as methylphenidate and amphetamines and β-adrenergic agonists such as albuterol and terbutaline.
What drugs cause ICH?
A number of sympathomimetic drugs have been implicated in causing ICH. These include the amphetamines, phenylpropanolamine, and cocaine. Hemorrhage has generally occurred shortly after use of the drug, within minutes to a few hours after exposure. The majority of the hematomas are lobar, with only occasional ones in the basal ganglia or thalamus. Transiently elevated blood pressure has been noted in approximately 50% of the reported cases, and angiographic changes of multifocal areas of arterial constriction and dilatation ("beading") have been documented, raising the possibility of a drug-induced angiopathy as their cause. On rare occasions, this angiographic pattern has been shown histologically to correspond to a true drug-induced vasculitis, after use of either phenylpropanolamine or cocaine. Use of these drugs can also result in ischemic stroke.
What are the most dangerous interactions between antidepressants?
One of the best-recognized drug interactions in all clinical pharmacology is the potentially dangerous interaction between antidepress ant monoamine oxidase inhibitors and either sympathomimetic agents or foods containing catecholamine pre cursors like tyramine (which is found in cheese and other foods).
What are the mechanisms of sympathomimetic drugs?
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
What is a sympathomimetic drug?
Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system. The primary endogenous agonists of the sympathetic nervous system are the catecholamines (i.e., epinephrine [adrenaline], ...
What drugs cause hypersensitivity?
Sympathomimetic drugs are sometimes involved in development of cerebral vasculitis and generalized polyarteritis nodosa like diseases involving immune-complex deposition. Known reports of such hypersensitivity reactions include the use of pseudoephedrine, phenylpropanlolamine, methamphetamine and other drugs at prescribed doses as well as at over-doses.
What stimulants block dopamine?
Dopaminergic stimulants such as amphetamine, ephedrine, and propylhexedrine work by causing the release of dopamine and norepinephrine, along with (in some cases) blocking the reuptake of these neurotransmitters.
Do sympathomimetic amines have tolerance?
Thus, all sympathomimetic amines fall into the larger group of stimulants (see psychoactive drug chart). In addition to intended therapeutic use, many of these stimulants have abuse potential, can induce tolerance, and possibly physical dependence, although not by the same mechanism (s) as opioids or sedatives.
What are sympathomimetic drugs?
Sympathomimetic drugs, also known as adrenergic agonists, mimic the action of the stimulators (α, β, or dopamine receptors) of the sympathetic autonomic nervous system. Sympathomimetic drugs are classified based on the type of receptors the drugs act on (some agents act on several receptors but 1 is predominate). Clinical uses of sympathomimetics include the treatment of hypotension, asthma, and anaphylaxis. The primary drugs used as IV vasopressors in the hospital are dopamine and norepinephrine. Dobutamine is given IV as an inotrope. Albuterol is used via nebulizer or metered-dose inhaler for asthma. Sympathomimetics may produce a wide range of adverse effects, which generally resemble excessive stimulation of the sympathetic nervous system. The effects may include palpitations, tachycardia, and/or arrhythmias due to stimulation of cardiac β receptors.
Which receptors do sympathomimetics affect?
Sympathomimetics affect the adrenergic receptors of epinephrine, norepinephrine, or dopamine to produce effects on α, β, or dopamine receptors.
What is the primary vasopressor used in the hospital?
The primary drugs used as IV vasopressors in the hospital are dopamine and norepinephrine. Dobutamine is given IV as an inotrope. Albuterol is used via nebulizer or metered-dose inhaler for asthma. Typical uses of certain medications include:
What is the name of the drug that mimics the action of the stimulators of the sympathetic autonomic nervous system?
Sympathomimetic drugs mimic the action of the stimulators of the sympathetic autonomic nervous system, specifically the α, β, or dopamine receptors; they are also known as adrenergic agonists.
What receptors do direct agonists act on?
Direct agonists (selective) act on 1 or more adrenergic (α and β) receptors:
What receptors does ephedrine release?
Ephedrine: acts on α and β receptors to cause norepinephrine release (used for anesthesia-related hypotension)
What substitution yields catecholamine?
Benzene ring: substitution by a hydroxyl group (-OH) at position 3 and 4 yields catecholamine (dopamine)
What drugs interact with sympathomimetics?
Other classes of drugs can interact with the sympathomimetics. α-Adrenergic blocking agents ( e.g., phentolamine), when added to a regimen containing a sympathomimetic, reduce vasoconstriction and attenuate the increase in blood pressure. 149 Tricyclic antidepressants (e.g., imipramine) tend to increase the pressor response to sympathomimetics such as epinephrine and norepinephrine and catecholamines such as phenylephrine. The effect has been shown to produce severe and persistent hypertension in patients receiving phenylephrine. 91, 92, 149 Ergot alkaloids may potentiate the pressor effects of sympathomimetics with pronounced α-adrenergic activity (e.g., epinephrine, norepinephrine, phenylephrine). 91, 92, 149 Antihistamines (diphenhydramine) and tricyclic antidepressants tend to inhibit tissue uptake of epinephrine and norepinephrine. They also can increase adrenoreceptor sensitivity to epinephrine. 149
What are sympathomimetic amines?
Sympathomimetic amines (epinephrine, norepinephrine, phenylephrine, dopamine, dobutamine, ephedrine, isoproterenol, metoproterenol, and isoetharine) are particularly susceptible to pharmacodynamic drug–drug interactions. The extent and significance of these interactions depend upon the selectivity of both the object drug and precipitant drug for adrenergic receptor types. β-Adrenergic blocking agents generally antagonize the cardiac and bronchodilating effects of the sympathomimetics. 149 However, propranolol and other nonspecific β-blockers ( Table 112-4) may enhance the vasoconstriction produced with epinephrine. As a result, the patient may experience hypertension and bradycardia. 91, 92 Labetalol possesses both α 1 and nonspecific β-blocking activity, which produces an increase in diastolic blood pressure and a decrease in heart rate when given during an epinephrine infusion. 91, 92 Metoprolol and possibly other β 1 -cardioselective blockers have minimal effects on the pressor response when given concomitantly with epinephrine. 91, 92
What is a sympathoadrenal drug?
Sympathomimetic drugs are agents which in general mimic responses due to stimulation of sympathetic nerves. These agents are able to directly activate adrenergic receptors or to indirectly activate them by increasing norepinephrine and epinephrine (mediators of the sympathoadrenal system) levels.
How does sympathomimetic poisoning cause hyperthermia?
Sympathomimetic poisoning can induce hyperthermia through excessive neuromuscular activity , resulting in increased thermogenesis.115 Ethanol and benzodiazepine withdrawal can present in a similar fashion. Aggressive treatment with benzodiazepines is the first-line treatment. However, in cases not responsive to benzodiazepines, treatment with haloperidol or droperidol may be effective. This is especially true in methamphetamine toxicity, for which haloperidol131 and droperidol 132 have been found safe and effective. If these medications are used, the patient should be monitored for prolongation of the QT interval and development of torsades de pointes.
Why are sympathetic trunks called paravertebral ganglia?
The ganglia of the sympathetic trunks are also called the paravertebral ganglia because they lie next to the vertebral column. Inferiorly the two trunks join in the midline and terminate on the anterior surface of the coccyx as the ganglion impar. Each sympathetic trunk shares important anatomic relationships with surrounding structures.
Which amine acts indirectly by releasing norepinephrine?
A sympathomimetic amine that acts indirectly by releasing norepinephrine and directly by exerting a slight effect on α and β 1 receptors and a moderate effect on β 2 receptors mediating vasodilation.
Can monoamine oxidase inhibitors cause hypertension?
The monoamine oxidase inhibitors block the normal degradation pathway for the sympathomimetics, and the combination can result in dramatic bursts of hypertension. This interaction prompted the common warning to patients taking drugs like pargyline to avoid red wines and ripe cheeses.
What is the role of sympathomimetics in the synapse?
Sympathomimetics (also called adrenomimetics) may directly activate their adrenoceptors, or they may act indirectly to increase the concentration of catecholamine transmitter in the synapse ( Figure 6–1 ). Amphetamine derivatives and tyramine cause the release of stored catecholamines; these sympathomimetics are, therefore, mainly indirect in their mode of action. Another form of indirect action is seen with cocaine and the tricyclic antidepressants; these drugs inhibit reuptake of catecholamines by presynaptic nerve terminals that release them ( Figure 4–3 ), and thus increase the synaptic activity of released transmitter.
What are the subgroups of sympathomimetic drugs?
Sympathomimetic drugs are readily divided into subgroups on the basis of which receptors they activate: alpha, beta, or dopamine (not shown). Alternatively, these drugs are divided into subgroups on the basis of whether their mode of action is direct (at postsynaptic receptors) or indirect (other than at postsynaptic receptors).
How are sympathomimetics divided?
Alternatively, sympathomimetics may be divided into subgroups based on whether their mode of action is direct or indirect. Sympatholytics are an important group of antagonists used in cardiovascular and other conditions.
What is the chapter 6 of Sympathomimetics?
Chapter 6. Sympathomimetics and Sympatholytics. Receptors of the sympathetic system may be divided into alpha (α), beta (β), and dopamine (D) receptors. Drugs that bind to these receptors and modulate or mimic the function of the sympathetic nervous system may be divided into those which augment the system ( sympathomimetics) ...
Which drugs inhibit catecholamines?
Another form of indirect action is seen with cocaine and the tricyclic antidepressants; these drugs inhibit reuptake of catecholamines by presynaptic nerve terminals that release them ( Figure 4–3 ), and thus increase the synaptic activity of released transmitter. + +.
Does MAO blockade affect autonomic activity?
Blockade of metabolism (i.e., block of catechol- O -methyltransferase [COMT] and monoamine oxidase [MAO]) has little direct effect on autonomic activity, but MAO inhibition increases the stores of catecholamines in adrenergic synaptic vesicles and thus may potentiate the action of other indirect-acting sympathomimetics subsequently discussed.
Overview
Mechanisms of action
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
Structure-activity relationship
For maximum sympathomimetic activity, a drug must have:
1. Amine group two carbons away from an aromatic group
2. A hydroxyl group at the chiral beta position in the R-configuration
3. Hydroxyl groups in the meta and para position of the aromatic ring to form a catechol which is essential for receptor binding
Structure-activity relationship
A primary or secondary aliphatic amine separated by 2 carbons from a substituted benzene ring is minimally required for high agonist activity. The pKa of the amine is approximately 8.5-10. The presence of hydroxy group in the benzene ring at 3rd and 4th position shows maximum alpha- and beta-adrenergic activity.
Cross-reactivity
Illegal drugs such as cocaine and MDMA also affect dopamine, serotonin, and norepinephrine.
Norepinephrine is synthesized by the body from the amino acid tyrosine, and is used in the synthesis of epinephrine, which is a stimulating neurotransmitter of the central nervous system. Thus, all sympathomimetic amines fall into the larger group of stimulants (see psychoactive drug chart). In addition to intended therapeutic use, many of these stimulants have abuse potential, ca…
Comparison
"Parasympatholytic" and "sympathomimetic" have similar effects, but through completely different pathways. For example, both cause mydriasis, but parasympatholytics reduce accommodation (cycloplegia) while sympathomimetics do not.
Examples
• amphetamine (Evekeo)
• benzylpiperazine (BZP)
• cathine (found in Catha edulis)
• cathinone (found in Catha edulis, khat)
See also
• Adrenergic storm
• Sympathetic nervous system
• Sympatholytic