Podcast
Questions and Answers
Which first generation H1 antihistamine is characterized by being highly lipophilic and able to penetrate the blood-brain barrier?
Which first generation H1 antihistamine is characterized by being highly lipophilic and able to penetrate the blood-brain barrier?
What strategy was used to decrease the sedation effect of first generation H1 antihistamines?
What strategy was used to decrease the sedation effect of first generation H1 antihistamines?
Which type of H1 antihistamines can penetrate the blood-brain barrier and bind to central H1-histamine receptors?
Which type of H1 antihistamines can penetrate the blood-brain barrier and bind to central H1-histamine receptors?
What is a characteristic of most second generation H1 antihistamines in relation to the blood-brain barrier?
What is a characteristic of most second generation H1 antihistamines in relation to the blood-brain barrier?
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At pH = 7.4, are first generation Ethylenediamines protonated or not?
At pH = 7.4, are first generation Ethylenediamines protonated or not?
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How does the size of alkyl substituents affect the selectivity for histamine receptors vs cholinergic receptors in first generation Ethanolamine ethers?
How does the size of alkyl substituents affect the selectivity for histamine receptors vs cholinergic receptors in first generation Ethanolamine ethers?
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Which type of derivatives are more potent among Propylamine or alkylamine derivatives in first generation H1 antihistamines?
Which type of derivatives are more potent among Propylamine or alkylamine derivatives in first generation H1 antihistamines?
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How does E-Pyrrobutamine compare to Z-Pyrrobutamine in terms of potency in first generation H1 antihistamines?
How does E-Pyrrobutamine compare to Z-Pyrrobutamine in terms of potency in first generation H1 antihistamines?
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What is the important amino acid for interacting with the carboxylate group in second generation H1 antihistamines?
What is the important amino acid for interacting with the carboxylate group in second generation H1 antihistamines?
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Which compound is a zwitterionic at physiologic pH and does not easily penetrate the blood-brain barrier?
Which compound is a zwitterionic at physiologic pH and does not easily penetrate the blood-brain barrier?
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What is the predominant charge status of Cetirizine at physiological pH?
What is the predominant charge status of Cetirizine at physiological pH?
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Which compound is a prodrug of Loratadine?
Which compound is a prodrug of Loratadine?
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Study Notes
First Generation H1 Antihistamines
- Diphenhydramine is a highly lipophilic first-generation H1 antihistamine that can penetrate the blood-brain barrier.
Decreasing Sedation Effect
- The strategy used to decrease the sedation effect of first-generation H1 antihistamines is to reduce their ability to penetrate the blood-brain barrier.
Characteristics of H1 Antihistamines
- First-generation H1 antihistamines can penetrate the blood-brain barrier and bind to central H1-histamine receptors.
Second Generation H1 Antihistamines
- Most second-generation H1 antihistamines are characterized by their inability to penetrate the blood-brain barrier.
Ethylenediamines
- At pH 7.4, first-generation Ethylenediamines are protonated.
Selectivity of Receptors
- Increasing the size of alkyl substituents in first-generation Ethanolamine ethers increases their selectivity for histamine receptors vs cholinergic receptors.
Potency of Derivatives
- Among Propylamine and alkylamine derivatives in first-generation H1 antihistamines, alkylamine derivatives are more potent.
E- and Z-Pyrrobutamine
- E-Pyrrobutamine is less potent than Z-Pyrrobutamine in first-generation H1 antihistamines.
Interaction with Carboxylate Group
- Glutamic acid is the important amino acid for interacting with the carboxylate group in second-generation H1 antihistamines.
Zwitterionic Compound
- Fexofenadine is a zwitterionic compound at physiologic pH and does not easily penetrate the blood-brain barrier.
Charge Status of Cetirizine
- Cetirizine is predominantly zwitterionic at physiological pH.
Prodrug of Loratadine
- Descarboethoxyloratadine is a prodrug of Loratadine.
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Description
Test your knowledge of H1 antihistamines in Medicinal Chemistry I with this quiz. Identify first generation antihistamines, their activities, and chemical structures.
