Sympathomimetic drug

Last updated

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. [1] The primary endogenous agonists of the sympathetic nervous system are the catecholamines (i.e., epinephrine [adrenaline], norepinephrine [noradrenaline], and dopamine), which function as both neurotransmitters and hormones. Sympathomimetic drugs are used to treat cardiac arrest and low blood pressure, or even delay premature labor, among other things.

Contents

These drugs can act through several mechanisms, such as directly activating postsynaptic receptors, blocking breakdown and reuptake of certain neurotransmitters, or stimulating production and release of catecholamines.

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

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. [2] The presence of hydroxy group in the benzene ring at 3rd and 4th position shows maximum alpha- and beta-adrenergic activity.[ medical citation needed ]

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

The structure can be modified to alter binding. If the amine is primary or secondary, it will have direct action, but if the amine is tertiary, it will have poor direct action. Also, if the amine has bulky substituents, then it will have greater beta adrenergic receptor activity, but if the substituent is not bulky, then it will favor the alpha adrenergic receptors.

Direct-acting

Adrenergic receptor agonists

Direct stimulation of the α- and β-adrenergic receptors can produce sympathomimetic effects. Salbutamol is a widely used direct-acting β2-agonist. Other examples include phenylephrine, isoproterenol, and dobutamine.

Dopaminergic agonists

Stimulation of the D1 receptor by dopaminergic agonists such as fenoldopam is used intravenously to treat hypertensive crisis.

Indirect-acting

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.

Abuse potential

Illegal drugs such as cocaine and MDMA also affect dopamine, serotonin, and norepinephrine.

Norepinephrine is synthesized by the body from the amino acid tyrosine, [3] and is used in the synthesis of epinephrine, which is a stimulating neurotransmitter of the central nervous system. [4] 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. The symptoms of physical withdrawal from stimulants can include fatigue, dysphoric mood, increased appetite, vivid or lucid dreams, hypersomnia or insomnia, increased movement or decreased movement, anxiety, and drug craving, as is apparent in the rebound withdrawal from certain substituted amphetamines.

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, [5] phenylpropanolamine, [6] methamphetamine [7] and other drugs at prescribed doses as well as at over-doses.

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.[ medical citation needed ]

Examples

See also

Related Research Articles

<span class="mw-page-title-main">Neurotransmitter</span> Chemical substance that enables neurotransmission

A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell.

<span class="mw-page-title-main">Stimulant</span> Drug that increases activity of central nervous system

Stimulants are a class of drugs that increase the activity of the brain and the spinal cord. They are used for various purposes, such as enhancing alertness, attention, motivation, cognition, mood, and physical performance. Some of the most common stimulants are caffeine, nicotine, amphetamines, cocaine, and modafinil.

<span class="mw-page-title-main">Catecholamine</span> Class of chemical compounds

A catecholamine is a monoamine neurotransmitter, an organic compound that has a catechol and a side-chain amine.

<span class="mw-page-title-main">Ephedrine</span> Medication and stimulant

Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in nasal congestion. It can be taken by mouth or by injection into a muscle, vein, or just under the skin. Onset with intravenous use is fast, while injection into a muscle can take 20 minutes, and by mouth can take an hour for effect. When given by injection it lasts about an hour and when taken by mouth it can last up to four hours.

<span class="mw-page-title-main">Monoamine neurotransmitter</span> Monoamine that acts as a neurotransmitter or neuromodulator

Monoamine neurotransmitters are neurotransmitters and neuromodulators that contain one amino group connected to an aromatic ring by a two-carbon chain (such as -CH2-CH2-). Examples are dopamine, norepinephrine and serotonin.

<span class="mw-page-title-main">Phenethylamine</span> Organic compound, a stimulant in humans

Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace amine-associated receptor 1 (TAAR1) and inhibiting vesicular monoamine transporter 2 (VMAT2) in monoamine neurons. To a lesser extent, it also acts as a neurotransmitter in the human central nervous system. In mammals, phenethylamine is produced from the amino acid L-phenylalanine by the enzyme aromatic L-amino acid decarboxylase via enzymatic decarboxylation. In addition to its presence in mammals, phenethylamine is found in many other organisms and foods, such as chocolate, especially after microbial fermentation.

A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine. Intranasal corticosteroids can also be used as decongestants and antihistamines can be used to alleviate runny nose, nasal itch, and sneezing.

A biogenic amine is a biogenic substance with one or more amine groups. They are basic nitrogenous compounds formed mainly by decarboxylation of amino acids or by amination and transamination of aldehydes and ketones. Biogenic amines are organic bases with low molecular weight and are synthesized by microbial, vegetable and animal metabolisms. In food and beverages they are formed by the enzymes of raw material or are generated by microbial decarboxylation of amino acids.

<span class="mw-page-title-main">Phenylpropanolamine</span> Sympathomimetic agent

Phenylpropanolamine (PPA) is a sympathomimetic agent which is used as a decongestant and appetite suppressant. It was commonly used in prescription and over-the-counter cough and cold preparations. In veterinary medicine, it is used to control urinary incontinence in dogs.

An adrenergic agonist is a drug that stimulates a response from the adrenergic receptors. The five main categories of adrenergic receptors are: α1, α2, β1, β2, and β3, although there are more subtypes, and agonists vary in specificity between these receptors, and may be classified respectively. However, there are also other mechanisms of adrenergic agonism. Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology.

Cross-tolerance is a phenomenon that occurs when tolerance to the effects of a certain drug produces tolerance to another drug. It often happens between two drugs with similar functions or effects—for example, acting on the same cell receptor or affecting the transmission of certain neurotransmitters. Cross-tolerance has been observed with pharmaceutical drugs such as anti-anxiety agents and illicit substances, and sometimes the two of them together. Often, a person who uses one drug can be tolerant to a drug that has a completely different function. This phenomenon allows one to become tolerant to a drug that they have never used before.

<span class="mw-page-title-main">Trace amine</span> Amine receptors in the mammalian brain

Trace amines are an endogenous group of trace amine-associated receptor 1 (TAAR1) agonists – and hence, monoaminergic neuromodulators – that are structurally and metabolically related to classical monoamine neurotransmitters. Compared to the classical monoamines, they are present in trace concentrations. They are distributed heterogeneously throughout the mammalian brain and peripheral nervous tissues and exhibit high rates of metabolism. Although they can be synthesized within parent monoamine neurotransmitter systems, there is evidence that suggests that some of them may comprise their own independent neurotransmitter systems.

<span class="mw-page-title-main">Cyclopentamine</span> Decongestant and stimulant drug

Cyclopentamine is a sympathomimetic alkylamine, classified as a vasoconstrictor. Cyclopentamine was indicated in the past as an over-the-counter (OTC) medication for use as a nasal decongestant, notably in Europe and Australia, but has now been largely discontinued.

<span class="mw-page-title-main">Norepinephrine</span> Catecholamine hormone and neurotransmitter

Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone, neurotransmitter and neuromodulator. The name "noradrenaline" is more commonly used in the United Kingdom, whereas "norepinephrine" is usually preferred in the United States. "Norepinephrine" is also the international nonproprietary name given to the drug. Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic.

<span class="mw-page-title-main">Benzofuranylpropylaminopentane</span> Chemical compound

Benzofuranylpropylaminopentane is a drug with an unusual monoamine-release potentiating mechanism of action. It can loosely be grouped with the stimulant or antidepressant drug families, but its mechanism of action is quite different.

<span class="mw-page-title-main">TAAR1</span> Protein-coding gene in the species Homo sapiens

Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the TAAR1 gene. TAAR1 is an intracellular amine-activated Gs-coupled and Gq-coupled G protein-coupled receptor (GPCR) that is primarily expressed in several peripheral organs and cells, astrocytes, and in the intracellular milieu within the presynaptic plasma membrane of monoamine neurons in the central nervous system (CNS). TAAR1 was discovered in 2001 by two independent groups of investigators, Borowski et al. and Bunzow et al. TAAR1 is one of six functional human trace amine-associated receptors, which are so named for their ability to bind endogenous amines that occur in tissues at trace concentrations. TAAR1 plays a significant role in regulating neurotransmission in dopamine, norepinephrine, and serotonin neurons in the CNS; it also affects immune system and neuroimmune system function through different mechanisms.

<span class="mw-page-title-main">Deoxyepinephrine</span> Chemical compound

Deoxyepinephrine, also known by the common names N-methyldopamine and epinine, is an organic compound and natural product that is structurally related to the important neurotransmitters dopamine and epinephrine. All three of these compounds also belong to the catecholamine family. The pharmacology of epinine largely resembles that of its "parent", dopamine. Epinine has been found in plants, insects and animals. It is also of significance as the active metabolic breakdown product of the prodrug ibopamine, which has been used to treat congestive heart failure.

<span class="mw-page-title-main">Norepinephrine releasing agent</span> Catecholaminergic type of drug

A norepinephrine releasing agent (NRA), also known as an adrenergic releasing agent, is a catecholaminergic type of drug that induces the release of norepinephrine (noradrenaline) and epinephrine (adrenaline) from the pre-synaptic neuron into the synapse. This in turn leads to increased extracellular concentrations of norepinephrine and epinephrine therefore an increase in adrenergic neurotransmission.

<span class="mw-page-title-main">Norepinephrine–dopamine reuptake inhibitor</span> Drug that inhibits the reuptake of norepinephrine and dopamine

A norepinephrine–dopamine reuptake inhibitor (NDRI) is a drug used for the treatment of clinical depression, attention deficit hyperactivity disorder (ADHD), narcolepsy, and the management of Parkinson's disease. The drug acts as a reuptake inhibitor for the neurotransmitters norepinephrine and dopamine by blocking the action of the norepinephrine transporter (NET) and the dopamine transporter (DAT), respectively. This in turn leads to increased extracellular concentrations of both norepinephrine and dopamine and, therefore, an increase in adrenergic and dopaminergic neurotransmission.

References

  1. Ellie Kirov (9 November 2021). Herlihy's the Human Body in Health and Illness 1st Anz Edition. Elsevier Health Sciences. pp. 234–. ISBN   978-0-7295-8853-9. OCLC   1287761421. If a drug causes effects similar to the activation of the sympathetic nervous system, it is called a sympathomimetic [...] A sympathomimetic agent increases heart rate, force of cardiac contraction and blood pressure.
  2. Medicinal Chemistry of Adrenergics and Cholinergics Archived 2010-11-04 at the Wayback Machine
  3. Campbell, Neil A.; Reece, Jane B. (2005). Biology (7th ed.). Pearson - Benjamin Cummings.
  4. Patestas, Maria A.; Gartner, Leslie P. (2006). A Textbook of Neuroanatomy. Blackwell Publishing.
  5. "Pseudoephedrine Disease Interactions". Drugs.com. Retrieved 2021-11-21.
  6. Forman, Howard P.; Levin, Stanley; Stewart, Barbara; Patel, Mahendra; Feinstein, Stuart (1989-05-01). "Cerebral Vasculitis and Hemorrhage in an Adolescent Taking Diet Pills Containing Phenylpropanolamine: Case Report and Review of Literature". Pediatrics. 83 (5): 737–741. doi:10.1542/peds.83.5.737. ISSN   0031-4005.
  7. Imbesi, S G (December 1999). "Diffuse cerebral vasculitis with normal results on brain MR imaging". American Journal of Roentgenology. 173 (6): 1494–1496. doi:10.2214/ajr.173.6.10584789. ISSN   0361-803X.