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Medical Pharmacology Chapter 23: Ergot Alkaloids
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Chemistry and pharmacokinetics
Two Major Families:
Tetracyclic Ergoline Nucleus: Examples:-
Lysergic acid diethylamide (LSD)
Ergonovine
Methysergide (Sansert)
6-methylergoline
Lysergic acid
Peptide alkaloids: Examples:-
Ergotamine
α-ergocryptine
Bromocriptine (Parlodel)
Ergot alkaloids are variably absorbed from the GI tract
Absorption following oral administration is improved by caffeine
Bromocriptine (Parlodel) is well absorbed from the GI tract
Metabolism:
Extensively metabolized
Targets: several receptor types
Agonist effects
Partial agonist effects
Antagonist effects
Pre- and post-synaptic sites
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Ergot Alkaloids |
α-adrenergic receptor |
Dopamine receptor |
Serotonin receptor (5 HT2) |
Uterine smooth muscle stimulation |
|
Bromocryptine |
- |
+++ |
- |
0 |
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Ergonovine |
++ |
- (partial agonist) |
+++ |
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Ergotamine |
-- (partial agonist) |
0 |
+ (partial agonist) |
+++ |
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LSD |
0 |
+++ |
-- (++ in the CNS) |
+ |
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Methysergide |
+/0 |
+/0 |
--- (partial agonist) |
+/0 |
Katzung, B. Histamine, Serotonin and the Ergot Alkaloids (The Ergot Alkaloids), in Basic and Clinical Pharmacology, (Katzung, B. G., Masters SB, Trevor AJ ed) Appleton-Lange, 12th edition, 2012, on-line edition
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Burkhalter, A, Julius, D.J. and Katzung, B. Histamine, Serotonin and the Ergot Alkaloids (Section IV. Drugs with Important Actions on Smooth Muscle), in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 261-286.; New "Triptans" and Other Drugs for Migraine, The Medical Letter, Vol. 40 (Issue 1037); October 9, 1998
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