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MODA Drugs > Lecture Course 2: Peripheral Neural Transmission > Flashcards

Lecture Course 2: Peripheral Neural Transmission Flashcards

0
Q

* Botulinum toxin (general) *

A
  • Prevents neurotransmitter release
    • Preferential for cholinergic neurones
    1. Heavy chain C terminus -> ganglioside receptor
    2. N terminus translocates peptidase light chain into cell/vesicle
    3. Peptidase cleaves target snare
  • Symptoms
    • Somatic muscle weakness
    • Loss of autonomic cholinergic activity
      • (constipation, blurred vision, dry skin)
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1
Q

* Botulinum toxins B, D, F and G *

A
  • Prevent neurotransmitter release
    • Preferential for cholinergic neurones
    • Cleaves v-SNARE Synaptobrevin
  • Symptoms
    • Somatic muscle weakness
    • Loss of autonomic cholinergic activity
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2
Q

*Botulinum toxins A and E*

A
  • Prevent neurotransmitter release
    • Preferential for cholinergic neurones
    • Cleaves t-SNARE SNAP-25
  • Symptoms
    • Somatic muscle weakness
    • Loss of autonomic cholinergic activity
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3
Q

* Botulinum toxin C1 *

A
  • Prevent neurotransmitter release
    • Preferential for cholinergic neurones
    • Cleaves v-SNARE **Synaptobrevin **and t-snare SNAP-25
  • Symptoms
    • Somatic muscle weakness
    • Loss of autonomic cholinergic activity
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4
Q

* Tetanus toxin *

A
  • Blocks vesicle release in inhibitory interneurones
    • Retrogradedly transported to cell body, then transferred to inhibitory interneurone
    • Targets t-snare synaptobrevin whichprevents inhibitory neurotransmitter release
    • Motor neurones become more excitable
    • => tetanus
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5
Q

* Hemicholinium *

A
  • Blocks sodium-choline cotransporter, responsible for reuptake of choline into the cell to form Ach
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6
Q

Triethylcholine

A

Competitive substrate for Ach at transporters.

Released in place of Ach- a false transmitter.

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7
Q

Vesamicol

A

Non competitive reversible blocker of the vesicular ACh transporter.

This prevents vesicles from being filled with ACh.

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8
Q

* Beta Bungarotoxin *

A
  • Blocks ACh release.
    • Potassium channel binding region
    • Phospholipase A2 activity
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9
Q

* Alpha latrotoxin *

A
  • Binds to neurexins on plasma membrane and causes mass release of ACh by forming calcium permeable channels.
  • Can also inhibit potassium channels.
  • Black widow spider toxin
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10
Q

Alpha bungarotoxin

A
  • Irreversibly blocks n.m.j.
  • Does not block ganglions.
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11
Q

Trimetaphan

A
  • Competitive antagonist for ganglionic nAChR
  • Used for controlled lowering of blood pressure during surgery.
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12
Q

* Nicotine *

A
  • nAChR agonist
    • Selective for ganglionic nAChR
  • ​Phase I- depolarising block. Neuron cannot be stimulated further.
  • Phase II - desensitisation of nicotinic receptor - sodium channel inactivation. Neuron can be stimulated electrically directly but not via presynaptic neurone.
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13
Q

* Hexamethonium *

A
  • Non competitive ganglion blocker.
  • Use dependent blockade.
  • Causes loss of sympathetic and parasympathetic systems - ‘hexamethonium man’.
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14
Q

* D-tubocurarine *

A
  • Nicotinic receptor antagonist.
  • Non selective between ganglionic and nmj.
  • Leads to flaccid paralysis.
  • Cannot cross intestinal epithelium or placenta.
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15
Q

* Atracurium *

A
  • Competitive nAChR antagonist.
    • Also may block nicotinic autoreceptors => tetanic fade
  • Not orally active
  • Used in anaesthesia
    • Selective for white muscle
  • Short half life.
    • Ester - Broken down by plasma esterases.
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16
Q

* Pancuronium *

A
  • Competitive nAChR antagonist.
    • Also may block nicotinic autoreceptors => tetanic fade
    • Not orally active
  • Used in anaesthesia
    • Selective for white muscle
  • Long half life
    • Not broken down by plasma esterases.
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17
Q

Decamethonium

A
  • Depolarising nmj blockade.
    • Phase I - spastic paralysis.
      • Prolonged in multiply innervated muscles.
        • Deepened by anticholinesterases, reversible with non depolarising blockers
    • Phase II- flaccid paralysis.
    • Desensitisation block.
    • Reversed by anticholinesterases, deepened by curare like drugs.
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18
Q

Suxamethonium

A
  • Depolarising nmj blockade.
  • Used for short term muscle relaxation
    • eg. Intubation.
    • Can cause dangerous increases in plasma K+.
  • Phase I - spastic paralysis.
    • Prolonged in multiply innervated muscles.
    • Deepened by anticholinesterases, reversible with non depolarising blockers
  • Phase II- flaccid paralysis.
    • Desensitisation block.
    • Reversed by anticholinesterases, deepened by curare like drugs.
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19
Q

Acetylcholine

A
  • Non selective agonist for muscarinic and nicotinic receptors.
  • Broken down by AChE and BuChE
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20
Q

Carbachol

A
  • Non selective agonist for nicotinic and muscarinic receptors.
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21
Q

** * Muscarine ***

A

Muscarinic receptor agonist

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22
Q

Methacholine

A
  • Non selective muscarinic agonist.
  • Two isomers:
    • +-Methacholine is broken down by AChE and 200x more potent than - isomer
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23
Q

Cevimeline

A
  • Selective agonist for M3 muscarinic receptors (on glands and smooth muscle).
  • Used to treat dry mouth in Sjögren’s syndrome.

​

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**\* Atropine \***
* Non selective antagonist for muscarinic receptors. * Used to dilate eye (opthalmic examination) - although too long lasting * Decrease bronchial and salivary secretions, bronchodilatation, increase heart rate, decrease GI motility ![]()
25
**Pirenzepine**
* Selective antagonist for muscarinic M1 receptors (on the PNS and CNS). * Used to decrease gastric acid secretion.
26
\* **Darifenacin \***
* Selective antagonist for muscarinic M3 receptors (on glands and smooth muscle and oxytinic cells). * Used in cases of urinary incontinence.
27
M1 and M3 muscarinic receptors
Mechanism: * couple through Gq/11 - generation of IP3 and DAG through cleavage of PIP2 * M1 only also inhibits potassium channels * M3 only also increases intracellular calcium concentration
28
M2 muscarinic receptors
Mechanism: * Couple to Gai * inhibits adenylyl cyclase. * cAMP decrease. * decreased VG calcium channel activation, lower heart excitability and less neurotransmitter release * beta gamma subunit opens potassium channel in SAN, decreasing heart rate ![](http://www.cvpharmacology.com/antiarrhy/atropine-Gi%20protein.gif)
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**\* Bethanechol \***
* Non selective agonist for muscarinic receptors. * Poorly absorbed from GI tract. * Used for systemic treatment for urinary retention.
30
**\* Pilocarpine \***
* Non selective agonist for muscarinic receptors. * Poorly absorbed across GI tract. * Used topically for glaucoma - absorbed through cornea and contracts cillary muscle.
31
**\* Edrophonium \***
* Short acting Anticholinesterase. * Reversible ionic interaction with AChE. * Used to diagnose myasthenia gravis. ![](http://app1.unmc.edu/hexum/images/Edro.jpg)
32
**\* Neostigmine \***
* Medium length Anticholinesterase. * Forms weak covalent bonds with AChE. * Carbamylates active site * Reverses surgical block and used to treat myasthenia gravis.
33
**Sugammadex**
* Forms inactive complex in the plasma with non-depolarising n.m.j agents (eg. Atracurium) * Excreted in the urine.
34
**\* Pralidoxime \***
* Reverses organophosphoric agent inhibition at n.m.j * Binds to phosphoric group and removes it
35
**Noradrenaline**
* Catecholamine. * Main sympathetic neurotransmitter, also involved in CNS. * Acts on: * a1 \> a2 = B1 \> B2
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**Adrenaline**
* Catecholamine. * Synthesised in adrenal gland - hormone in periphery. * Acts on: * **a2 \> a1 \> B** * Used in treatment of extreme conditions eg. Anaphylatic shock, acute cardiac failure.
37
**Dopamine**
* Catecholamine. * Precursor for noradrenaline.
38
**Alpha-Methyltyrosine**
* Competitively Inhibits Tyrosine hydroxylase (TOH) * Catalyses Tyrosine -\> DOPA * The rate limiting step for dopamine/noradrenaline/adrenaline production.
39
**\* Carbidopa \***
* Inhibits DOPA decarboxylase * Catalyses the conversion of DOPA -\> dopamine. * Only works peripherally * Administered alongside L-DOPA in treatment of parkinsons to reduce peripheral side effects
40
**Disulphiram**
* Inhibits dopamine Beta-hydroxylase (DBH) * catalyses dopamine -\> noradrenaline. * Used in the treatment of alcohol abuse by a different mechanism.
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**\* Methyldopa \***
* False transmitter * acts on alpha 1 and alpha 2 adrenergic receptors * Less active than noradrenaline on alpha 1 * More active on alpha 2 * Used as an antihypertensive.
42
**\* Reserpine \***
* Binds tightly to vesicular monoamine transporter. * This blocks uptake of NA and DA into vesicles. * Vesicular leakage of stored NA and DA into the cytoplasm causes long lasting depletion. * Use as an antihypertensive discontinued due to depression.
43
**\* Tyramine \*** ![]()
* Indirect sympathomimetic amine. * Displaces NA from vesicles. * Some displaced NA reaches synaptic cleft and activates adrenoreceptors. * Found in cheese, wine, marmite, soya beans. * May cause widespread vasoconstriction if too much ingested -'cheese effect'. * In normal amounts converted to octopamine, a false transmitter. * Repeated use produces lower response due to less NA in vesicles - tachyphylaxis.
44
**Dexamfetamine**
* Indirectly acting sympathomimetic amine. * Evades monoamine oxidase and is taken up into vesicle. * Displaces noradrenaline, which may leave nerve and activate adrenoreceptors. * MDMA has similar effects, but also acts on 5HT2 receptors. * Repeated use produces lower response due to less NA in vesicles - tachyphylaxis.
45
**\* Guanethidine \***
* Adrenergic neurone blocker. * Taken up into nerve by uptake 1 - compete with NA. * Block NA release in low repeated doses. * Unknown mechanism. * Act as indirect sympathomimetic amines in large doses.
46
**\* Imapramine \***
* Tricyclic antidepressant which blocks NET (uptake 1). * Blocks catecholamine reuptake - sustains action
47
**\* Cocaine \***
* Catecholamine uptake 1 blocker. * Blocks NET (presynaptic) * Sustains action of catelcholamines
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**\* Amitryptyline \***
* Catecholamine reuptake blocker. * Tricyclic antidepressant which blocks NET (uptake one on presynaptic terminal)
49
**\* Clorgiline \***
* Monoamine oxidase (MAO) A inhibitor - blocks Catecholamine metabolism. * Used as antidepressant.
50
**\* Selegiline \***
* Monoamine oxidase (MAO) B inhibitor - blocks Catecholamine metabolism. * Used in parkinsons treatment.
51
**\* Tranylcypromine \***
* Non selective Irreversible inhibitor of monoamine oxidase (MAO). * Used in treatment of refractory (treatment resistant) depression.
52
**\* Entacapone \***
* Catechol O-methyltransferase (COMT) inhibitor. * Blocks catecholamine metabolism, especially that associated with uptake 2. * Used in treatment of parkinsons disease.
53
**Mirabegron**
* Selective B3 adrenoreceptor agonist. -\> Negative ionotropic effect. * Used in treatment of overactive bladder. * Relaxes bladder detrusor muscle.
54
**\* Isoprenaline \***
* Beta-Adrenoreceptor agonist. P * reviously used in asthma to relax bronchial - but led to increase in heart rate.
55
**\* Phenylephrine \***
* Alpha1 adrenoreceptor agonist. * Some action at B1 * Used to raise blood pressure in acute hypotension
56
**MethylNA**
* Alpha adrenoreceptor agonist. * a2\>\>a1
57
**\* Clonidine \***
* Alpha adrenoreceptor agonist. * a2\>a1 * Used as an antihypertensive.
58
**\* Xylazine \***
* Selective a2 adrenoreceptor agonist. * Used as a sedative in veterinary medicine due to actions in CNS. * Advantage over other anaesthetics as no respiratory depression
59
**\* Salbutamol \***
* Beta 2 adrenoreceptor agonist. * Some action at B1. * B2 selectivity allows use as a bronchial dilate in asthma without increasing heart rate
60
**\* Dobutamine \***
* Beta adrenoreceptor agonist. * B1\>\> B2 * Used in acute cardiogenic shock.
61
**\* Phentolamine \***
* Alpha adrenoreceptor antagonist. * Obsolete antihypertensive due to reflex tachycardia. * Slight blocking action on toxic effects of noradrenaline in cardiac failure
62
**Phenoxybenzamine**
* Irreversible antagonist for alpha adrenoreceptors. * Similar to benzocholine mustard. * Used in combination with atenolol to prevent effects from catecholamine release during tumour removal surgery
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**\* Prazosin \***
* Alpha adrenoreceptor antagonist. * Selective for a1 * Used as an antihypertensive
64
**Yohimbine**
* Alpha adrenoreceptor antagonist. * Strongly selective for a2
65
**\* Idazoxan \***
* Alpha adrenoreceptor antagonist. * Strongly selective for a2
66
**\* Propranolol \***
* Beta adrenoreceptor antagonist. * Ex antihypertensive agent - non selectivity gave rise to bronchiconstriction * Attenuation of toxic noradrenaline effects in heart failure. * Class II antidysrythmic. Sympathetic innervation can lead to dysrhythmia
67
**\*\* Atenolol \***
* Beta adrenoreceptor antagonist. * Selective for B1 * Used in combination with Irreversible inhibitor phenoxybenzamine to prevent effects from catecholamine release during tumour removal surgery * Used as an antihypertensive * Class II antidysrythmic. Sympathetic innervation can produce dysrhytmia
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**\* Butaxamine \***
* Beta-Adrenoreceptor antagonist. * Strongly selective for B2
69
**\* Labetalol \***
* Adrenoreceptor antagonist. * Selective for a1, B1, B2 * Four isomers with different actions. * Used as an antihypertensive during pregnancy.
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**Tamsulosin**
* Selective a-1a adrenoreceptor antagonist. * Used in benign prostatic hyperplasia - relaxes smooth muscle of prostate and neck of bladder.
71
**Dutasteride**
* Used in conjunction with tamsulosin in treatment of benign prostatic hyperplasia. * Antiadrogenic effects - blocks testosterone synthesis.
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**\* Caffiene \***
* A1 receptor antagonist =\> wakefulness * Also non selectively inhibits phosphodiesterases.
73
**\* Dipyridamole \***
* Blocks adenosine inactivation * Potent vasodilator PDE V inhibitor - raises cAMP * Used in treatment of congestive heart failure
74
**Glyceryl trinitrate**
* Nitric oxide donor. * Nitrovasodilator.
75
**Isosorbide dinitrate**
* Nitric oxide donor. * Nitrovasodilator. * Used in angina treatment.
76
**\* Sildenafil \***
* Selective inhibitor of PDE 5 (selectively breaks down cGMP) * Used to treat impotence * Also in pulmonary arterial hypertension
77
**7-NI**
* NOS inhibitor. * Selective for NOS in neurones. * Does not effect eNOS or iNOS
78
**L-NMMA**
* Non selective inhibitor of NOS * D isomer not reactive
79
**L-NIO**
* Irreversible inhibitor of iNOS * Activated in macrophages
80
**\* Asymmetric Dimethylargenine (ADMA) \***
* endogenous NOS inhibitor * Synthesised during post translational protein methylation * Increased in hypercholesterolaemia and renal failure

MODA Drugs (9 decks)

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