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11 Cards in this Set
- Front
- Back
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What role does histamine have in the body?
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CNS - Excitatory neurotransmitter, regulates sleep wake cycle
Periphery - Bronchoconstriction, vasodilation GIT - increased gastric acid secretion |
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What is the difference between H1 and H2 histamine receptors? |
H1 - CNS and periphery CNS and peripheral effects H2 - parietal cells GIT effects |
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What are H1-antihistamines and what are they used for?
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Antagonise H1-histamine receptors leading to decrease in H1 effects.
Used for histamine-mediated inflammatory reactions (ie allergies) |
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What are H2-antihistamines and what are they used for? |
Antagonise H2-hitamine receptors leading to decreased H2 effects. Used for histamine-mediated gastric acid disorders (gastric ulcers) |
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What property of the different H1 antihistamines effects their capacity to alter the sleep-wake cycle? |
Lipophilicity - More lipophilic drugs more readily cross BBB leading to depression of CNS -Older antihistamine generally are more lipophilic |
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Why are H1-antihistamines not used in the treatment of anaphylaxis? What is used? |
- Not fast enough - Other mediators involved other than just histamine so simply blocking that will not have great enough effect ADRENALINE (symptomatic treatment) |
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What side effects are associated with H1-antihistamines? |
CNS Sedation (Although can cause seizures after extremely high doses) Antimuscarinic effects Dry mouth, pupil dilation, tachycardia |
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What must not be done when administering H1-antihistamines? |
Must not be given IV (may cause CNS excitatory side effects such as seizures) |
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What are the 1st generation H1 antihistamines? (3) |
Promethazine Dimenhydrinate Chlorpheniramine |
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What are the 2nd generation antihistamines? (3) |
Loratidine Cetirizine Fexofenadine |
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How do the 1st and 2nd generation antihistamines differ? |
Lipophilicity and thus capacity to cross the blood brain barrier. 1st gen more lipophilic 2nd gen less lipophilic |
