E-triprolidine, for example, is 1000-fold more potent than Z-triprolidine.
This difference relates to the positioning and fit of the molecules in the histamine HThese compounds are structurally related to the ethylenediamines and the ethanolamines, and produce significant anticholinergic adverse effects.
Other common adverse effects in first-generation H-antihistamines include dizziness, tinnitus, blurred vision, euphoria, uncoordination, anxiety, increased appetite leading to weight gain, insomnia, tremor, nausea and vomiting, constipation, diarrhea, dry mouth, and dry cough.
Infrequent adverse effects include urinary retention, palpitations, hypotension, headache, hallucination, and psychosis.-receptors and have a better tolerability profile compared to the first-generation agents.
This histamine can then bind with receptors to trigger increased blood flow to the surrounding area, which can lead to symptoms such as swelling and increased secretions, resulting in a blocked or runny nose, watery eyes and, most importantly, itchiness.