Muscarinic acetylcholine receptor antagonist | |
---|---|
Drug class | |
Class identifiers | |
Use | Allergies, asthma, atrial fibrillation with bradycardia, [1] motion sickness, Parkinson's disease, etc. |
ATC code | V |
Biological target | Metabotropic acetylcholinergic receptors |
External links | |
MeSH | D018727 |
Legal status | |
In Wikidata |
A muscarinic receptor antagonist (MRA), also called an antimuscarinic, is a type of anticholinergic agent that blocks the activity of the muscarinic acetylcholine receptor. The muscarinic receptor is a protein involved in the transmission of signals through certain parts of the nervous system, and muscarinic receptor antagonists work to prevent this transmission from occurring. Notably, muscarinic antagonists reduce the activation of the parasympathetic nervous system. The normal function of the parasympathetic system is often summarised as "rest-and-digest", and includes slowing of the heart, an increased rate of digestion, narrowing of the airways, promotion of urination, and sexual arousal. Muscarinic antagonists counter this parasympathetic "rest-and-digest" response, and also work elsewhere in both the central and peripheral nervous systems.
Drugs with muscarinic antagonist activity are widely used in medicine, in the treatment of low heart rate, overactive bladder, respiratory problems such as asthma and COPD, and neurological problems such as Parkinson's disease and Alzheimer's disease. A number of other drugs, such as antipsychotics and the tricyclic family of antidepressants, have incidental muscarinic antagonist activity which can cause unwanted side effects such as difficulty urinating, dry mouth and skin, and constipation.
Acetylcholine (often abbreviated ACh) is a neurotransmitter whose receptors are proteins found in synapses and other cell membranes. Besides responding to their primary neurochemical, neurotransmitter receptors can be sensitive to a variety of other molecules. Acetylcholine receptors are classified into two groups based on this:
Most muscarinic receptor antagonists are synthetic chemicals; however, the two most commonly used anticholinergics, scopolamine and atropine, are belladonna alkaloids, and are naturally extracted from plants such as Atropa belladonna , the deadly nightshade. The name "belladonna", Italian for "beautiful lady", is thought to derive from one of the antimuscarinic effects of these alkaloids: they were used by women for cosmetic purposes, to promote dilation of the pupils. [2]
Muscarinic antagonist effects and muscarinic agonist effects counterbalance each other for homeostasis.
Certain muscarinic antagonists can be classified into either long-acting muscarinic receptor antagonists (LAMAs) or short-acting muscarinic receptor antagonists (SAMAs), depending on when maximum effect occurs and for how long the effect persists. [3]
Scopolamine and atropine have similar effects on the peripheral nervous system. However, scopolamine has greater effects on the central nervous system (CNS) than atropine due to its ability to cross the blood–brain barrier. [4] At higher-than-therapeutic doses, atropine and scopolamine cause CNS depression characterized by amnesia, fatigue, and reduction in rapid eye movement sleep. Scopolamine (Hyoscine) has anti-emetic activity and is, therefore, used to treat motion sickness.
Antimuscarinics are also used as anti-parkinsonian drugs. In parkinsonism, there is imbalance between levels of acetylcholine and dopamine in the brain, involving both increased levels of acetylcholine and degeneration of dopaminergic pathways (nigrostriatal pathway). Thus, in parkinsonism there is decreased level of dopaminergic activity. One method of balancing the neurotransmitters is through blocking central cholinergic activity using muscarinic receptor antagonists.
Atropine acts on the M2 receptors of the heart and antagonizes the activity of acetylcholine. It causes tachycardia by blocking vagal effects on the sinoatrial node. Acetylcholine hyperpolarizes the sinoatrial node; this is overcome by MRAs, and thus they increase the heart rate. If atropine is given by intramuscular or subcutaneous injection, it causes initial bradycardia. This is because when administered intramuscularly or subcutaneously atropine acts on presynaptic M1 receptors (autoreceptors). Uptake of acetylcholine in axoplasm is prevented and the presynaptic nerve releases more acetylcholine into the synapse, which initially causes bradycardia.
In the atrioventricular node, the resting potential is lowered, which facilitates conduction. This is seen as a shortened PR-interval on an electrocardiogram. It[ clarification needed ] has an opposite effect on blood pressure. Tachycardia and stimulation of the vasomotor center causes an increase in blood pressure. But, due to feedback regulation of the vasomotor center, there is a fall in blood pressure due to vasodilation.
Important [5] muscarinic antagonists include atropine, hyoscyamine, hyoscine butylbromide and hydrobromide, ipratropium, tropicamide, cyclopentolate, pirenzepine and scopalamine.
Muscarinic antagonists such as ipratropium bromide can also be effective in treating asthma, since acetylcholine is known to cause smooth muscle contraction, especially in the bronchi.
Substance | Selectivity | Clinical use | Adverse effects | Notes | Trade names |
---|---|---|---|---|---|
Atropine (D/L-Hyoscyamine) | NS |
| CD [5] | Symax, HyoMax, Anaspaz, Egazil, Buwecon, Cystospaz, Levsin, Levbid, Levsinex, Donnamar, NuLev, Spacol T/S and Neoquess | |
Atropine methonitrate | NS |
| Blocks transmission in ganglia. [5] Lacks CNS effects [7] | ||
Aclidinium bromide | Selective[ clarification needed ] |
| Long acting antagonist | Tudorza | |
Benztropine | M1-selective |
| Reduces the effects of the relative central cholinergic excess that occurs as a result of dopamine deficiency. | Cogentin | |
Cyclopentolate | NS |
|
| Short acting, CD [5] | |
Diphenhydramine | NS |
|
| Acts in the central nervous system, blood vessels and smooth muscle tissues | Benadryl, Nytol |
Doxylamine | NS |
|
| Unisom | |
Dimenhydrinate | Combination of diphenhydramine with a methylxanthine salt | Dramamine, Gravol | |||
Dicyclomine | Bentyl | ||||
Darifenacin | Selective for M3 [7] | Urinary incontinence [7] | Few side effects [7] | Enablex | |
Flavoxate | Urispas | ||||
Glycopyrrolate (Glycopyrronium bromide) | NS |
| Does not cross the blood–brain barrier and has few to no central effects. [9] | Robinul, Cuvposa, Seebri | |
Hydroxyzine | Very mild/negligible action | Vistaril, Atarax | |||
Ipratropium bromide | NS | Asthma and bronchitis [5] |
| Lacks mucociliary excretion inhibition. [5] | Atrovent and Apovent |
Mebeverine |
|
| A muscolotropic spasmolytic with a strong and selective action on the smooth muscle spasm of the gastrointestinal tract, in particular of the colon. | Colofac, Duspatal, Duspatalin | |
Oxybutynin | M1/3/4 selective | Ditropan | |||
Pirenzepine | M1-selective [5] |
| (fewer than non-selective ones) [5] | Inhibits gastric secretion [5] | |
Procyclidine | NS |
| Overdose produces confusion, agitation and sleeplessness that can last up to or more than 24 hours. Pupils become dilated and unreactive to light. Tachycardia (fast heart beat), as well as auditory and visual hallucinations | ||
Scopolamine (L-Hyoscine) | NS |
| CD [5] | Scopace, Transderm-Scop, Maldemar, Buscopan | |
Solifenacin |
| Competitive antagonist | Vesicare | ||
Tropicamide | NS |
|
| Short acting, CD [5] | |
Tiotropium | Spiriva | ||||
Trihexyphenidyl/Benzhexol | M1 selective | PD | Drug at relative dose has 83% activity of atropine, thus has the same side-effects | Artane | |
Tolterodine | Detrusitol, Detrol |
Compound | M1 | M2 | M3 | M4 | M5 | Species | Ref |
---|---|---|---|---|---|---|---|
3-Quinuclidinyl benzilate | 0.035–0.044 | 0.027–0.030 | 0.080–0.088 | 0.034–0.037 | 0.043–0.065 | Human | [10] [11] |
4-DAMP | 0.57–0.58 | 3.80–7.3 | 0.37–0.52 | 0.72–1.17 | 0.55–1.05 | Human | [12] [13] |
AF-DX 250 | 427 | 55.0 | 692 | 162 | 3020 | Human | [12] |
AF-DX 384 | 30.9 | 6.03 | 66.1 | 10.0 | 537 | Human | [12] |
AQ-RA 741 | 28.8 | 4.27 | 63.1 | 6.46 | 832 | Human | [12] |
Atropine | 0.21–0.50 | 0.76–1.5 | 0.15–1.1 | 0.13–0.6 | 0.21–1.7 | Human | [10] [14] [13] |
Benzatropine (benztropine) | 0.231 | 1.4 | 1.1 | 1.1 | 2.8 | Human | [10] |
Biperiden | 0.48 | 6.3 | 3.9 | 2.4 | 6.3 | Human | [10] |
Darifenacin | 5.5–13 | 47–77 | 0.84–2.0 | 8.6–22 | 2.3–5.4 | Human | [13] [15] |
Dicycloverine (dicyclomine) | 57 (IC50) | 415 (IC50) | 67 (IC50) | 97 (IC50) | 53 (IC50) | Human/rat | [14] |
Glycopyrrolate | 0.37 | 1.38 | 1.31 | 0.41 | 1.30 | Human | [9] |
Hexahydrodifenidol | 11 | 200 | 16 | 76 (IC50) | 83 | Human/rat | [14] |
Hexahydrosiladifenidol | 44 | 249 | 10 | 298 (IC50) | 63 | Human/rat | [14] |
(R)-Hexbutinol | 2.09 | 20.9 | 2.14 | 3.02 | 5.50 | Human | [12] |
Hexocyclium | 2.3 | 23 | 1.4 | 5.5 | 3.7 | Human/rat | [14] |
Himbacine | 107 | 10.0 | 93.3 | 11.0 | 490 | Human | [12] |
Ipratropium | 0.49 | 1.5 | 0.51 | 0.66 | 1.7 | Human | [15] |
Methoctramine | 16–50 | 3.6–14.4 | 118–277 | 31.6–38.0 | 57–313 | Human | [14] [12] [16] |
N-Methylscopolamine | 0.054–0.079 | 0.083–0.251 | 0.052–0.099 | 0.026–0.097 | 0.106–0.125 | Human | [12] |
Orphenadrine | 48 | 213 | 120 | 170 | 129 | Human | [11] |
Otenzepad (AF-DX 116) | 1300 | 186 | 838 | 1800 (IC50) | 2800 | Human/rat | [14] |
Oxybutynin | 0.66 | 13 | 0.72 | 0.54 | 7.4 | Human | [13] |
pFHHSiD | 22.4 | 132 | 15.5 | 31.6 | 93.3 | Human | [12] |
Pirenzepine | 6.3–8 | 224–906 | 75–180 | 17–37 | 66–170 | Human | [10] [14] [12] [13] |
Procyclidine | 4.6 | 25 | 12.4 | 7 | 24 | Human | [10] |
Propiverine | 476 | 2970 | 420 | 536 | 109 | Human | [13] |
Scopolamine (hyoscine) | 1.1 | 2.0 | 0.44 | 0.8 | 2.07 | Human | [10] |
Silahexacyclium | 2.0 | 35 | 1.2 | 3.2 | 2.0 | Human/rat | [14] |
Timepidium | 34 | 7.7 | 31 | 18 | 11 | Human | [13] |
Tiquizium | 4.1 | 4.0 | 2.8 | 3.6 | 8.2 | Human | [13] |
Trihexyphenidyl | 1.6 | 7 | 6.4 | 2.6 | 15.9 | Human | [10] |
Tripitamine (tripitramine) | 1.58 | 0.27 | 38.25 | 6.41 | 33.87 | Human | [16] |
Zamifenacin | 55 | 153 | 10 | 68 | 34 | Human | [13] |
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. |
Compound | M1 | M2 | M3 | M4 | M5 | Species | Ref |
---|---|---|---|---|---|---|---|
Brompheniramine | 25700 | 32400 | 50100 | 67600 | 28800 | Human | [17] |
Chlorphenamine (chlorpheniramine) | 19000 | 17000 | 52500 | 77600 | 28200 | Human | [17] |
Cyproheptadine | 12 | 7 | 12 | 8 | 11.8 | Human | [11] |
Diphenhydramine | 80–100 | 120–490 | 84–229 | 53–112 | 30–260 | Human | [10] [18] |
Doxylamine | 490 | 2100 | 650 | 380 | 180 | Human | [18] |
Mequitazine | 5.6 | 14 | 5.3 | 11.1 | 11.0 | Human | [11] |
Terfenadine | 8710 | 8510 | 5250 | 30900 | 11200 | Human | [17] |
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. |
Compound | M1 | M2 | M3 | M4 | M5 | Species | Ref |
---|---|---|---|---|---|---|---|
Amitriptyline | 14.7 | 11.8 | 12.8 | 7.2 | 15.7 | Human | [11] |
Bupropion | >35,000 | >35,000 | >35,000 | >35,000 | >35,000 | Human | [11] |
Citalopram | 1430 | ND | ND | ND | ND | Human | [19] |
Desipramine | 110 | 540 | 210 | 160 | 143 | Human | [11] |
Desmethylcitalopram | >10000 | >10000 | >10000 | >10000 | >10000 | Human | [20] |
Desmethyldesipramine | 404 | 927 | 317 | 629 | 121 | Human | [20] |
Desvenlafaxine | >10000 | >10000 | >10000 | >10000 | >10000 | Human | [21] |
Dosulepin (dothiepin) | 18 | 109 | 38 | 61 | 92 | Human | [11] |
Doxepin | 18–38 | 160–230 | 25–52 | 20–82 | 5.6–75 | Human | [18] [11] |
Escitalopram | 1242 | ND | ND | ND | ND | Human | [19] |
Etoperidone | >35000 | >35000 | >35000 | >35000 | >35000 | Human | [11] |
Femoxetine | 92 | 150 | 220 | 470 | 400 | Human | [11] |
Fluoxetine | 702–1030 | 2700 | 1000 | 2900 | 2700 | Human | [11] [19] |
Fluvoxamine | 31200 | ND | ND | ND | ND | Human | [19] |
Imipramine | 42 | 88 | 60 | 112 | 83 | Human | [11] |
Lofepramine | 67 | 330 | 130 | 340 | 460 | Human | [11] |
Norfluoxetine | 1200 | 4600 | 760 | 2600 | 2200 | Human | [11] |
Nortriptyline | 40 | 110 | 50 | 84 | 97 | Human | [11] |
Paroxetine | 72–300 | 340 | 80 | 320 | 650 | Human | [11] [19] |
Sertraline | 427–1300 | 2100 | 1300 | 1400 | 1900 | Human | [11] [19] |
Tianeptine | >10000 | >10000 | >10000 | >10000 | >10000 | Human | [22] |
Trazodone | >35,000 | >35,000 | >35,000 | >35,000 | >35,000 | Human | [18] [11] |
Venlafaxine | >35000 | >35000 | >35000 | >35000 | >35000 | Human | [11] |
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. |
Compound | M1 | M2 | M3 | M4 | M5 | Species | Ref |
---|---|---|---|---|---|---|---|
Amisulpride | >10,000 | >10,000 | >10,000 | >10,000 | >10,000 | Human | [23] |
Aripiprazole | 6780 | 3510 | 4680 | 1520 | 2330 | Human | [24] |
Asenapine | >10000 | >10000 | >10000 | >10000 | ND | Human | [25] |
Bromperidol | 7600 | 1800 | 7140 | 1700 | 4800 | Human | [10] |
Chlorprothixene | 11 | 28 | 22 | 18 | 25 | Human | [10] |
Chlorpromazine | 25 | 150 | 67 | 40 | 42 | Human | [10] |
Clozapine | 1.4–31 | 7–204 | 6–109 | 5–27 | 5–26 | Human | [10] [25] [26] [27] |
Cyamemazine (cyamepromazine) | 13 | 42 | 32 | 12 | 35 | Human | [28] |
N-Desmethylclozapine | 67.6 | 414.5 | 95.7 | 169.9 | 35.4 | Human | [29] |
Fluperlapine | 8.8 | 71 | 41 | 14 | 17 | Human | [10] |
Fluphenazine | 1095 | 7163 | 1441 | 5321 | 357 | Human | [30] |
Haloperidol | >10000 | >10000 | >10000 | >10000 | >10000 | Human | [25] [26] |
Iloperidone | 4898 | 3311 | >10000 | 8318 | >10000 | Human | [31] |
Loxapine | 63.9–175 | 300–590 | 122–390 | 300–2232 | 91–241 | Human | [10] [32] |
Melperone | >15000 | 2400 | >15000 | 4400 | >15000 | Human | [10] |
Mesoridazine | 10 | 15 | 90 | 19 | 60 | Human | [10] |
Molindone | ND | ND | >10000 | ND | ND | Human | [33] |
Olanzapine | 1.9–73 | 18–96 | 13–132 | 10–32 | 6–48 | Human | [25] [26] [27] |
Perphenazine | ND | ND | 1848 | ND | ND | Human | [33] |
Pimozide | ND | ND | 1955 | ND | ND | Human | [33] |
Quetiapine | 120–135 | 630–705 | 225–1320 | 660–2990 | 2990 | Human | [25] [26] |
Remoxipride | >10000 | >10000 | >10000 | >10000 | ND | Human | [25] |
Rilapine | 190 | 470 | 1400 | 1000 | 1100 | Human | [10] |
Risperidone | 11000 | ≥3700 | 13000 | ≥2900 | >15000 | Human | [10] [25] |
Sertindole | ND | ND | 2692 | ND | ND | Human | [33] |
Tenilapine | 260 | 62 | 530 | 430 | 660 | Human | [10] |
Thioridazine | 2.7 | 14 | 15 | 9 | 13 | Human | [10] |
Thiothixene | >10000 | >10000 | >10000 | >10000 | 5376 | Human | [34] |
cis-Thiothixene | 2600 | 2100 | 1600 | 1540 | 4310 | Human | [10] |
Tiospirone | 630 | 180 | 1290 | 480 | 3900 | Human | [10] |
Trifluoperazine | ND | ND | 1001 | ND | ND | Human | [33] |
Ziprasidone | ≥300 | >3000 | >1300 | >1600 | >1600 | Human | [26] [35] |
Zotepine | 18 | 140 | 73 | 77 | 260 | Human | [10] |
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. |
Scopolamine, also known as hyoscine, or Devil's Breath, is a natural or synthetically produced tropane alkaloid and anticholinergic drug that is used as a medication to treat motion sickness and postoperative nausea and vomiting. It is also sometimes used before surgery to decrease saliva. When used by injection, effects begin after about 20 minutes and last for up to 8 hours. It may also be used orally and as a transdermal patch since it has been long known to have transdermal bioavailability.
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given intravenously or by injection into a muscle. Eye drops are also available which are used to treat uveitis and early amblyopia. The intravenous solution usually begins working within a minute and lasts half an hour to an hour. Large doses may be required to treat some poisonings.
Muscarine, L-(+)-muscarine, or muscarin is a natural product found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly C. dealbata. Mushrooms in the genera Entoloma and Mycena have also been found to contain levels of muscarine which can be dangerous if ingested. Muscarine has been found in harmless trace amounts in Boletus, Hygrocybe, Lactarius and Russula. Trace concentrations of muscarine are also found in Amanita muscaria, though the pharmacologically more relevant compound from this mushroom is the Z-drug-like alkaloid muscimol. A. muscaria fruitbodies contain a variable dose of muscarine, usually around 0.0003% fresh weight. This is very low and toxicity symptoms occur very rarely. Inocybe and Clitocybe contain muscarine concentrations up to 1.6%.
Tetracyclic antidepressants (TeCAs) are a class of antidepressants that were first introduced in the 1970s. They are named after their tetracyclic chemical structure, containing four rings of atoms, and are closely related to the tricyclic antidepressants (TCAs), which contain three rings of atoms.
Anticholinergics are substances that block the action of the acetylcholine (ACh) neurotransmitter at synapses in the central and peripheral nervous system.
Chlorphenamine, also known as chlorpheniramine, is an antihistamine used to treat the symptoms of allergic conditions such as allergic rhinitis. It is taken orally. The medication takes effect within two hours and lasts for about 4-6 hours.
Muscarinic acetylcholine receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end-receptor stimulated by acetylcholine released from postganglionic fibers in the parasympathetic nervous system.
Imipramine, sold under the brand name Tofranil, among others, is a tricyclic antidepressant (TCA) mainly used in the treatment of depression. It is also effective in treating anxiety and panic disorder. Imipramine is taken by mouth.
Dextrorphan (DXO) is a psychoactive drug of the morphinan class which acts as an antitussive or cough suppressant and dissociative hallucinogen. It is the dextrorotatory enantiomer of racemorphan; the levorotatory enantiomer is levorphanol. Dextrorphan is produced by O-demethylation of dextromethorphan by CYP2D6. Dextrorphan is an NMDA antagonist and contributes to the psychoactive effects of dextromethorphan.
Tiotixene, or thiothixene, sold under the brand name Navane among others, is a typical antipsychotic of the thioxanthene class which is related to chlorprothixene and is used in the treatment of psychoses like schizophrenia and bipolar mania. It was introduced in the United States in 1967 by Pfizer.
Chlorprothixene, sold under the brand name Truxal among others, is a typical antipsychotic of the thioxanthene group.
Dibenzepin, sold under the brand name Noveril among others, is a tricyclic antidepressant (TCA) used widely throughout Europe for the treatment of depression. It has similar efficacy and effects relative to other TCAs like imipramine but with fewer side effects.
Etoperidone, associated with several brand names, is an atypical antidepressant which was developed in the 1970s and either is no longer marketed or was never marketed. It is a phenylpiperazine related to trazodone and nefazodone in chemical structure and is a serotonin antagonist and reuptake inhibitor (SARI) similarly to them.
Lofepramine, sold under the brand names Gamanil, Lomont, and Tymelyt among others, is a tricyclic antidepressant (TCA) which is used to treat depression. The TCAs are so named as they share the common property of having three rings in their chemical structure. Like most TCAs lofepramine is believed to work in relieving depression by increasing concentrations of the neurotransmitters norepinephrine and serotonin in the synapse, by inhibiting their reuptake. It is usually considered a third-generation TCA, as unlike the first- and second-generation TCAs it is relatively safe in overdose and has milder and less frequent side effects.
Xanomeline is a small molecule muscarinic acetylcholine receptor agonist that was first synthesized in a collaboration between Eli Lilly and Novo Nordisk as an investigational therapeutic being studied for the treatment of central nervous system disorders.
Serotonin antagonist and reuptake inhibitors (SARIs) are a class of drugs used mainly as antidepressants, but also as anxiolytics and hypnotics. They act by antagonizing serotonin receptors such as 5-HT2A and inhibiting the reuptake of serotonin, norepinephrine, and/or dopamine. Additionally, most also antagonize α1-adrenergic receptors. The majority of the currently marketed SARIs belong to the phenylpiperazine class of compounds.
Tiospirone (BMY-13,859), also sometimes called tiaspirone or tiosperone, is an atypical antipsychotic of the azapirone class. It was investigated as a treatment for schizophrenia in the late 1980s and was found to have an effectiveness equivalent to those of typical antipsychotics in clinical trials but without causing extrapyramidal side effects. However, development was halted and it was not marketed. Perospirone, another azapirone derivative with antipsychotic properties, was synthesized and assayed several years after tiospirone. It was found to be both more potent and more selective in comparison and was commercialized instead.
Methoctramine is a polymethylene tetraamine that acts as a muscarinic antagonist. It preferentially binds to the pre-synaptic receptor M2, a muscarinic acetylcholine ganglionic protein complex present basically in heart cells. In normal conditions -absence of methoctramine-, the activation of M2 receptors diminishes the speed of conduction of the sinoatrial and atrioventricular nodes thus reducing the heart rate. Thanks to its apparently high cardioselectivity, it has been studied as a potential parasymphatolitic drug, particularly against bradycardia. However, currently it is only addressed for research purposes, since the administration to humans is still unavailable.
Triazoledione is a phenylpiperazine compound and a major metabolite of the antidepressant nefazodone. It is active, but with substantially reduced potency compared to nefazodone. As such, it has been suggested that it is unlikely that triazoledione contributes significantly to the pharmacology of nefazodone. However, triazoledione may reach concentrations as great as 10 times those of nefazodone, and hence could still be a significant contributor to its therapeutic effects.
Cholinergic blocking drugs are a group of drugs that block the action of acetylcholine (ACh), a neurotransmitter, in synapses of the cholinergic nervous system. They block acetylcholine from binding to cholinergic receptors, namely the nicotinic and muscarinic receptors.
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