First generation tricyclic antihistaminics

SAR of Loratadine. The drug is intimately related to the first generation tricyclic antihistaminics and also to the antidepressants. 

The potentiation of sedative effects from benzodiazepines when combined with centrally acting drugs with antihistamine properties (for example first-generation antihistamines, tricyclic antidepressants, and neuroleptic drugs) can pose problems (143). Antihistamines that do not have central actions do not interact with benzodiazepines as in the case of mizolastine and lorazepam (144), ebastine and diazepam (145), and terfenadine and diazepam (143). 

The effects of cholinesterase inhibitors may be reduced by first-generation antihistamine medications, tricyclic antidepressants, and antipsychotics, and the client should not take these medications simultaneously. The nurse should ask the elient about other medications taken. 

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