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30 Cards in this Set
- Front
- Back
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What is an autocoid
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This word is derived from the Greek words autos (self) and akos (medicinal agent or remedy)—hence self agent. Autocoids can be thought of as locally acting hormones that involve a wide variety of pharmacological activities. These agents are not secreted into the systemic blood-stream as are true hormones
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Name 4 of the principle autocoids within the body
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Serotonin; Histamine; Bradykinins; Prostaglandins
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What is serotonin
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Serotonin is an indole ethylamine found in both plant and animal tissues
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What is serotonin derived from
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L-tryptophan
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Where is most of the serotonin in the body found
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The enterochromaffin cells of the GI tract contain approximately 90%, the CNS contains most of the remaining 10%
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How does serotonin exert its actions
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Through seven major 5-HT cell membrane receptor subtypes
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How is serotonin metabolized
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By monoamine oxidase
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What are serotonin’s physiologic actions
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Neurotransmission; Regulation of the pituitary gland; Vasoconstriction (except for skeletal muscle and heart, where it causes vasodilation); Contraction of GI smooth muscle; Stimulation of pain receptors; Precursor to melatonin
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Name a serotonin agonist
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Sumatriptan
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What is sumatriptan used for
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To treat migraine headaches
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What are the adverse effects of sumatriptan
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Dizziness and muscle weakness and neck pain
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Name three serotonin inhibitors
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Ketanserin; Ondansetron; Cyproheptadine
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What is the clinical use of ketanserin
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Lowers blood pressure
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What is the clinical use of ondansetron
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Treatment of nausea and vomiting associated with surgery and chemotherapy
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What is the clinical use of cyproheptadine
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Treatment of smooth muscle constriction in carcinoid tumor
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Are ketanserin, ondansetron, and cyproheptadine selective serotonin inhibitors
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No. They block 5-HT receptors, but they also inhibit H1 and α receptors
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What is the mechanism of action of histamine
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Histamine formed from the amino acid histidine exerts its effects by binding to H1 and H2 receptors which are located on cell surfaces and mediate a variety of physiological responses
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Where is histamine found within the body
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Within granules of mast cells and basophils
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What is the physiologic role of histamine
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Histamine when released from mast cells causes: Constriction of bronchioles (H. receptors); Constriction of intestinal smooth muscle (H. receptor); Stimulates sensory nerve endings mediating pain (H. receptors) and itching; Lowers blood pressure (H2 receptors); Stimulates gastric HCl secretion (H2 receptors); Increases permeability of skin capillaries (H2 receptors)
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What are the clinical uses of histamine
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Histamine itself is of no use clinically. However, histamine blockers are very important
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Name some H1-receptors blockers and their clinical uses
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Diphenhydramine—allergic reaction, motion sickness; Hydroxyzine—allergic reactions; Promethazine—motion sickness
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Name a few H2-receptor blockers
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Cimetidine; Ranitidine; Famotidine
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What are ergot alkaloids
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A group of compounds produced by the fungus Claviceps purpurea
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What is the mechanism of action of the ergot alkaloids
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The ergot alkaloids interact with adreno-receptors, 5-HT receptors, and dopamine receptors
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What are the physiologic actions of the ergot alkaloids
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Hallucinations and psychoses at high doses; Vasoconstriction; Stimulation of uterine muscle
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Give some examples of ergot alkaloids
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Bromocriptine; Ergonovine; Ergotamine
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What is the clinical use of Bromocriptine
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Hyperprolactinemia
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What is the clinical use of Ergonovine
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Postpartum hemorrhage
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What are the clinical uses of Ergotamine
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Migraine—ergotamine diminishes cerebral vascular pulsations; Postpartum hemorrhage
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What are the adverse effects of the ergot alkaloids
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Prolonged vasoconstriction—may result in gangrene (Nitroprusside can be administered to treat ergotamine-induced vasoconstriction); Diarrhea; Nausea, vomiting; Unwanted uterine contraction; CNS psychosis
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