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50 Cards in this Set

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  • Back
What is the triple response, and what causes it?
it is a small red spot at the center of an intradermal injection, surrounded by a red edematous wheel. (is mediated by H1 and H2 receptors)
The H1 receptor is what type of receptor?
the Gq coupled receptor, especially those caused by IgE mediated responses
What are the second messengers for the H1 Gq receptors?
Inositol Triphosphate (IP3) and Diacylglycerol (DAG)
Typical responses seen in activating the H1 receptor
pain, itching, bronchoconstriction, local vasodilation, and increased capillary permability (leading to edema). these make up an allergic reaction
What does the H1 receptor affect in the body?
is important for smooth muscle effects
What does the H2 receptor affect in the body?
mediates gastric acid secretion by parietal cells in the stomach, has a small cardiac stimulant effect, and also slightly reduces histamine release from mast cells.(negative feedback)
The H2 receptor is what type of receptor, and how are its actions mediated?
Gs receptor, mediated by activation of Adenylyl Cyclase, which in turn increases intracellular cAMP
What is the H3 receptor, and what is its role?
is a Gi coupled receptor, seems to be involved in presynaptic modulation of histaminergic neurotransmission., in periphery it seems to modulate release of other tansmitters
What is the H4 receptor, and what is its role?
is also Gi coupled, but it is found on leukocytes, (especially eosinophils) and Mast cells. Is involved in chemotactic responses by these cells
What are the older 1st generation H1 blockers, and what is their major side effect?
diphenhydramine,act at H1 receptors as antagonists have significant autonomic effects. Highly sedating
What are the newer 1st generation H1 blockers, how do they differ?
Chlorpheniramine and cyclizine. Are still receptor blockers, have no effect on release. are less sedating, much less autonomic blocking effect. oral drugs
What are the 2nd generation H1 Blockers?
Cetirizene, fexofenadine, and loratidine. Much less sedating and autonomic effects. far less lipid soluble, oral drugs
What are the side effects of the 2nd generation H1 blockers?
can cause extremely high levels of either antihistamine, because they only block receptors. This can precipitate lethal arrythmias
What are the side effects of 1st Gen H1 blockers?
sedation (older more than newer) autonomic blocking effects (dry mouth and blurred vision) can also cause orthostatic hypotension
H1 receptor blockers are to be avoided if taking what other drugs?
other drugs with sedative effects (especially with older 1st gen). Drugs that inhibit hepatic metabolism. (could cause dangerously high levels of antihistamine drugs
Side effects of some older H1 antagonists that led to their marketing for a different purpose
the have anti motion sickness effect, and are potent local antisthetics
Clinical use for H1 receptor blockers
immediate allergic reactions, should be taken prior to attack. good for hay fever and urticartia
Three uses of older 1st generation H1 blocker Diphenhydramine
1) anti motion sickness 2) antiemetic for chemotherapy induced vomiting 3) hypnotic, used for OTC sleep aids
H2 antagonists and their primary use
Cimetide, (Fimotidine, Rantidine, and Nizatidine) can be given in large doses for extended duration of action, used to reduce gastric acid secretion (used in Acid (PUD), and other GI acid related disorders
Toxicity of H2 receptor blockers
Cimetidine is a potent inhibitor of hepatic drug metabolizing enzymes and may reduce hepatic blood flow. This leads to possible overdose of drugs that are metabolized by these enzymes. Also has significant antiandrogen effects at high doses
From what is Serotonin produced, and where is it stored?
produced from tryptophan, stored in the enterochromaffin cells in the gut, as well as neurons of the CNS and enteric nervous system
What enzyme is responsible for metabolizing serotonin once released
monoamine oxidase
What metabolite can be measured in the urine to diagnose carcinoid syndrome? (excess serotonin production)
5-hydroxyindole acetic acid.
(5-HIAA)
Role of Serotonin in the CNS and the ENS, as well as local hormone activity.
serves as neurotransmitter in CNS and ENS, has local hormone action, modulating GI activity
Other place where serotonin is stored, and synthesized in small quantities
platelets
Types of Serotonin receptors
5-HT1, 5-HT2, 5-HT3, and 5-HT4
What is the function of the 5-HT1 receptor?
is most important in the brain, it mediates synaptic inhibition via increased K+ conductance. Peripheral receptors mediate excitory and inhibitory effects in smooth muscle. (G1 coupled protein receptors)
What is the function of the 5-HT2 receptor?
Important in brain and peripheral tissue. mediate synaptic excitation in the CNS and smooth muscle contraction (gut, bronchi, uterus, and vessels) or relaxation (other vessels). mediates some of the vasodilation, diarrhea, and bronchoconstriction seen in carcinoid tumor
What is the function of the 5-HT3 receptor?
found in the CSF, especially in the chemoreceptive area and vomiting center, and in peripheral sensory and enteric nerves.
What is the function of the 5-HT4 receptor?
found in the GI tract, extremely important role in GI motility
What are the 5-HT1D agonists? what do they do?
Sumatriptan and Naratriptan? 1st line treatment for acute migraine and cluster headaches.
What are the 5-HT4 partial agonists? what do they do?
Tegaserod, acts as an agonist in the colon. for use in chronic constipation. due to cardiovascular toxicity, it is now restricted
What are SSRI's what do they do, where do they act?
antidepressants, used to increase activity at central synapses, by inhibiting the serotonin reuptake transporter
What is serotonin syndrome?
a drug reaction characterized by high fever, hyperreflexia, clonus, tremor, clonus, hypertension, hyperactive bowells, diarrhea, mydriasis, and coma within hours.
Causes of serotonin syndrome
drug interaction between SSRIs, Serotonin agonists, and serotonin. MAOI's, linezolid, tramadol, meperidine, fentanyl, etc...
What are the 5-HT2 antagonists? What are they used for?
Ketanserin and phenoxybenzamine (also are nonselective A blockers), and cyproheptadine (also an H1 blocker). Ketanserin and cyproheptadine are competitive blockers, phenoxybenzamine is an irreversible blocker. these are used in carcinoid tumor therapy
What are the 5-HT3 antagonists? What are they used for?
Odansetron, granistron, dolasetron, and alosetron. have antiemetic actions in the area prostrema, and on peripheral enteric nerves. used as antiemetics in chemotherapy
What is a clinical use other than antiemetic of Alosetron?
used in women with IBS associated with diarrhea
Toxicities of the 5-HT2 antagonists
symptoms of A and H1 blockade
Toxicities of the 5-HT3 antagonists
diarrhea and headache for all but alosetron. Alosetron causes constipation and sometimes fatal bowel complications. Dolasetron causes QRS and QTC prolongation, and shouldnt be used with heart disease
How are the Ergot Alkaloids produced?
produced by a fungus found in wet or spoiled grain
Actions of Ergot Alkaloids
most are partial agonists at the A adrenoceptors and 5-HT receptors, some are also agonists at the dopamine receptors
How are the Ergot Alkaloids classified, and what three areas are they active?
broken down by site of action, Vessels, Brain, and Uterus
Which ergot works in the vessels by producing a marked and prolonged A receptor mediated vasoconstriction? What is it used for?
Ergotamine. (overdose can cause ischemia and gangrene of the limbs) also used for epinephrine reversal. used to treat migraines
What ergot works to cause powerful contractions in the uterus?
Ergonovine. works best near term. the uterine contraction is sufficient to cause abortion or miscarriage. early in pregnancy or in non pregnant women, much higher doses are needed to cause contraction. can be used after placental delivery to reduce post birth bleeding
What ergots work in the brain, in what areas do they work, and what are they used for?
Bromocriptine and pergolide. these are semisynthetic, and they act at dopamine D2 receptors in the pituitary and basal ganglia. Used to reduce prolactin release in pituitary tumors (reduce their size) also used in treatment of parkinsons disease
Side effects of Vascular Ergots
prolonged or excessive use can cause ischemia and gangrene, (antidote is nitroprusside) may also cause hyperplasia of connective tissue
Side effects of all ergot alkaloids
GI side effects such as nausea, vomiting, and diarrhea
Side effects of CNS acting ergots
hallucinations are seen with LSD, a synthetic ergot derivative.
Side effects of Uterine acting ergots
could cause abortion or miscarriage.