Histamine, Serotonin and their agonists Flashcards
1
Q
physiologic actions of HA
A
- immediate fall in BP due to peripheral vasodilation (most imporant vascular effect in humans!) –> extensive systemic release can produce sharp drop in BP and anaphylactic shock
- endotheial cell contraction –> increase in vascular permeability –> edema
- bronchoconstriction (hyper-rxn in asthmatics
- diarrhea
- secretion of gastic acid, pepsin and intrinsic factor
- stimulant of sensory nerve ending –> pain and itching
- circadian rhythms, wakefulness
2
Q
diphenydramine (benadryl)
A
- H1 receptor antagonist
- popular antihistamines (excedrin PM, tylenol PM, dramamine)
- anti-muscarinic effects, sedating
3
Q
tripelennamine (PBZ)
A
- H1 receptor antagonist
- OTC sleep aid
4
Q
cyclizine (dramamin II, antivert)
A
- H1 antagonist
- anti motion sickness
5
Q
promethazine
A
- H1 antagonist
- antiemetic
- antimuscarinic effects, marked sedation
6
Q
chlorpheniramine (Chlor-Trimeton, Dimetane)
A
- H1 antagonist
- component of “cold” meds
- less sedating
7
Q
Loratidine (claritin) and fexofenadine (Allegra)
A
- 2nd generation antihistamines that don’t cross BBB and have few CNS effects (no sedation)
- allergic rhinitis
8
Q
H1 receptor antagonists (clinical uses and adverse effects)
A
Clinical Uses
- allergies (allergic rhinitis, urticaria, conjunctivitis)
- **largely ineffective for bronchial asthama or colds
- motion sickness
- nausea and vomiting of pregnancy
- sleep aids
Adverse effects
- sedation, impaired cognitive function
- anti-muscarinic effects (blurred vision, dyr mouth, urinary retention, constipation)
- poisoning (esp kids), convulsions
- local anesthesia
- ventricular tachy
9
Q
Cimetidine
A
- H2 receptor antagonist
- blocks gastric acid secretion
- used for dyspepsia, duodenal and gastric ulcers, hypersecretory conditions
- adverse side effects:
inhibits P450 oxidative enzymes –>potentiates the actions of other drugs
antiandrogen (gynecomastia in men; impotence)
CNS dysfuncion possible
10
Q
Ranitidine
A
- H2 receptor antagonist
- blocks gastric acid secretion
- used for dyspepsia, duodenal and gastric ulcers, hypersecretory conditions
- liver toxicity
- CNS dysfunction possible (slurred speech, confusion)
11
Q
Famotidine
A
- H2 receptor antagonist
- inhibits gastric acid secretion
- used for dyspepsia, gastric and duodenal ulcers, hypersecretory conditions
- CNS dysfunction possible
12
Q
Nizatidine
A
- H2 antagonist
- inhibits gastic acid secretion
- used to treat dyspepsia, gastric and duodenal ulcers, hypersecretory conditions
- CNS dysfunction possible
13
Q
pharmocologic actions of 5-HT (serotonin)
A
- contraction of GI smooth mm
- carcinoid syndrome (enterochromaffin cell tumors that release large amounts of 5-HT) –> diarrhea
- vasodilation in skeletal mm and heart
- platelet aggregation
- peripheral NS: stimulates nociceptive nerve endings (pain and itching)
- central NS: involved in food intake, mood, sleep
- pre-synaptic activation of receptors inhibits raphe cell firing/serotonin release
14
Q
cyproheptadine
A
- antihistaminic and antiserotinergic
- used for skin allergies (anti-H1: urticaria), diarrhea of carcinoid (anti-5HT)
- side effects: anti-muscarinic and sedation
15
Q
Ketanserin
A
- selective 5HT2A,2C antagonist, also alpha1 adrenorecptor and H1 receptors
- used as antihypertensive and antagonizes platelet aggregation
**think Ke= Kellsey –> cardio stuff
