Autocoids Flashcards by billie zidel

Activation of H1 receptor

Vasodilation (NO induced)
Increases vascular permeability
Bronchoconstriction

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Activation of H2 receptor

Increases gastric acid secretion

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Diphenhydramine

1st generation H1 receptor inhibitor
Muscarinic blocker - strong
Sedation - strong
Blocks motion sickness - strong

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Promethazine

1st generation H1 receptor inhibitor
Muscarinic blocker - strong
Sedation - strong
Blocks motion sickness - moderate
Some alpha blocker and local anesthetic action

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Chlorpheniramine

1st generation H1 receptor inhibitor
Muscarinic blocker - mild
Sedation - moderate
Blocks motion sickness - moderate
May cause CNS stimulation

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Meclizine, cyclizine, hydroxyzine

1st generation H1 receptor inhibitor
Muscarinic blocker - mild
Sedation - moderate
Blocks motion sickness - strongest 
For motion sickness

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Doxylamine

Includes vitamin B6

Used for morning sickness during pregnancy

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Which are the 2nd generation H1 receptor inhibitors?

Cetirizine (mild sedation)
Loratadine (Claritin, most used)
Fexofenadine
No CNS entry

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What are H1 receptor inhibitors used for?

Allergic or anaphylactic reaction 
Pruritis
Allergic rhinitis, conjunctivitis
Motion sickness (imbalance signal of motion from ear and eye ---histaminergic neurons in hypothalamus----H1 and M receptor in vomiting center in medulla----nausea, vomiting)
Vertigo - meclizine

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Side effects of H1 receptor inhibitors (1st generation)

Enter CNS, causing sedation; anti-muscarinic effect causing dry mouth and urine retention

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What is the marker of carcinoid syndrome?

5HIAA > 25mg

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Symptoms of carcinoid syndrome

Flushing ( caused by kallikrein, the precursor of bradykinin)
Intermittent abdominal pain
Diarrhea
BP decrease
Palpitation
Wheezing

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5-HT1 receptor

Gi –> decreases cAMP

Causes arterial contraction in carotid and cranial circulation

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5-HT2 receptor

Gq –> increases IP3
Causes vasoconstriction, platelet aggregation, increases GI peristalsis, increases gastric acid secretion, increases vascular permeability
In the CNS it causes excitation and hallucination

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5-HT3 receptor

Couples to Na+/K+ channel in the nervous system of the GIT and vomiting centre of the medulla
Causes vomiting

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5-HT4 receptor

Gs –> increases cAMP

In enteric nervous system, it increases Act release –> GI motility increases

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Sumatriptan

5-HT1D agonist

Used for acute migraine attacks

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Buspirone

Partial 5-HT1A agonist

Used for manage anxiety

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Clozapine, olanzapine, risperdone

Atypical anti-schizophrenic agents

5-HT2A antagonists

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Cyproheptadine

5-HT2 and H1 antagonist

Used in carcinoid syndrome, seratonin syndrome and allergy

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Ondansetron (and granisetron, dolasetron and alosetron)

5-HT3 antagonist
Central antiemetic
Used to control vomiting associated with chemotherapy
Alosetron used in IBS

Octreotide

Somatostatin analog
Suppresses GI 5-HT secretion
Reduces GI motility
Supresses gastrin, cholecystokinin, glucagon, growth hormone, insulin, secretin, pancreatic polypeptide, TSH, and vasoactive intestinal peptide secretion
Reduces secretion of fluids by the intestine and pancreas
Vasoconstriction
Decreases portal vessel pressure, treats variceal hemorrhage

Ergots (in general)

Partial agonist to alpha and 5-HT2 receptor

LSD

Ergots
Lysergic acid diethylamide
5-HT2A partial agonist in CNS
Causes hallucination

Bromocriptine, cabergoline, pergolide

Ergots Agonists to dopamine D2 receptor Used for hyperprolactinemia Pergolide can cause valvular heart disease Bromocriptine used for Parkinson's disease

Ergonovine

Ergots Contract uterus Used for obstetric bleeding, post part hemorrhage

Ergotamine

``` Ergots Vasocontrictor Contract uterus Used for obstetric bleeding, post part hemorrhage Can also be used for migraine attacks ```

Methysergide

Ergots Vasoconstrictor Used for diarrhea but can cause retroperitoneal fibrosis, subendocardial fibrosis, valvular disease

Side effects of ergots

GI distress --> nausea, vomiting, diarrhea

When are ergots contraindicated?

Coronary ischemic disease | Pregnancy

Drugs for acute migraines

Ergotamine | Sumatriptan

Drugs for prophylaxis of migraines

B blocker: Propranolol Calcium channel blocker: Verapamil Anti-histamine: Cyproheptadine Ergot: ergonovine, methysergide

Uses of NO

Pulmonary artery hypertension and acute respiratory distress syndrome in neonates - Given by inhalation Dietary supplements with arginine: slows process of atherosclerosis

Sildenafil MOA

Increases cGMP by inhibiting its breakdown by phosphodiesterase isoform 5 (PDE5) Potentiates the actions of NO --> vasodilation

What can happen if sildenafil is taken with nitrates?

Can result in severe hypotension an MI Patients who are maintained with nitrate for ischemic heart disease should never have viagra!!! Patients who are not on nitrate can have viagra but within 24 h should not use nitrate!!!

Side effects of sildenafil

Can affect colour vision, causing difficulty in blue-green discrimination

Which are the PDE-5 inhibitors?

Sildenafil, tadalafil, vardenafil

High dose PGE2 causes:

Uterus relaxation

Low dose PGE2 causes:

Uterus contraction

PGE/PGI2

Dilation

TXA2/PGF2a

Constriction

Alprostadil

PGE1 Maintains a patent ductus arteriosus Penile injection treats impotence (side effect: priapism) Treats pulmonary hypertension (half life is 5-10min)

Misoprostol

PGE1 Protects patients from NSAID-induced peptic ulcers COX-1 enzyme expressed in stomach synthesizes PGE1 stomach mucus secretion Mucus has cytoprotective action (protects mucosa from damage by gastric acid Chronic use of NSAIDs or corticosteroids (CS) COX-1 activity local PGE  mucosal damage by acid leads to peptic ulcer Can also be used with mifepristone to induce abortions

Dinoprostone

PGE2 | Induces labor and abortion ("cervical ripening")

Epoprostenol

PGI2 Treats pulmonary hypertension Half life is 3-5 mins

Latanoprost

PGF2a Treats glaucoma Side effect: dark pigment in iris

Which drug is used to close a PDA

Indomethacin

Carbaprost

PGF2a Contraction of uterine muscle Abortifacient Postpartum bleeding

Bosnian, ambrisentan, macitentan

Endothelin receptor antagonists Treat idiopathic pulmonary arterial hypertension ADR: flushing, headache, hypotension Contraindication: pregnancy

Drugs that treat idiopathic pulmonary arterial hypertension

Endothelin receptor antagonist (Bosentan, Ambrisentan, Macitentan) Prostacyclin (PGI2): Epoprostenol, Iloprost, Treprostinil PDE5 inhibitor-increases cGMP: Sildenafil, Tadalafil PGE1: Alprostadil Nitric oxide inhalation Guanylyl cyclase stimulator: Riociguat