Silicon Containing Derivatives of the Antihistamines Diphenhydramine and Fenpiprane

1 Silicon Containing Derivatives of the Antihistamines Diphenhydramine and Fenpiprane 

The antihistamine diphenhydramine 169a) exhibits strong histaminolytic effects on the isolated guinea pig ileum, whereas its sila-analogue 169b hydrolyses [Eq. (24)] so fast that characteristic effects could not be detected. This can be explained easily by the presence of the sensitive Si—H and Si—OC bond. 

Toxicological tests121 (white mice, i.p.) resulted also in significant differences. The silicon compound was found to be more toxic than its carbon analogue. It is not clear so far, whether this difference is connected with the hydrolysis or not. 

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