Page 122 - Chemical and process design handbook

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ANTIHISTAMINES

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Antihistamines are sold under such trade names as Dimetapp , Actifed ,
®
and Benadryl . They have a structure including the group R-X-C-C-N=,
where X can be nitrogen, oxygen, or carbon (Fig. 1).
Antihistamines are produced by certain key steps, such as the synthesis
of diphenhydramine from diphenylmethane (Fig. 2).
Antihistamines are used to alleviate allergic conditions such as rashes and
runny eyes and nose and are decongestants that are used for swelled sinuses
and nasal passages during the common cold. These symptoms are caused by
histamine and hence the drugs that get rid of them are antihistamines.
Antihistamines are also sleep inducers.

CH 2 CH 2 NH 2
CH 3
CH CH CH N
N NH 2 2
CH 3
histamine brompheniramine
Br
N

C CH CH N CH O CH 2 CH 2 NH 2
2
triprolidine diphenhydramine

CH 3
FIGURE 1 Examples of antihistamines.

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