الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Inspite of the fact that the first generation classical H1-antihistamines, belonging to known structural models, have been known to display beneficial therapeutic effects; yet many serious side effects could also occur. Such effects were prominent on CNS due to the crossing of BBB. This might lead to needless sedation, fatigue, drowsiness, diminished alertness and impairment of cognitive function. Consequently, a second generation was developed known as classic nonsedating H1-antihistamines which would possess lower affinity to cross the BBB. Some of these agents were also proved to exhibit some of the undesirable side effects of the first generation.
In trials to alleviate such troublesome effects, many research projects were directed to synthesize various structurally different agents apart from those related to the known classic molecular models of antihistamines. These were suggested with the hope of reducing the ability to cross the BBB. These agents were, occasionally, referred to as nonclassic.