Pharmacology of non sedating antihistamines
The patient can therefore choose the particular drug that they find works best, or the formulation (tablet size) that suits them.
For paediatric suspensions, the choice may be determined by a preferred flavour.
They are useful for treating the itching that results from the release of histamine.
The early so-called ‘first generation’ antihistamines, such as promethazine, caused sedation.
Desloratadine and fexofenadine are registered for use in infants six months and older, while loratadine and cetirizine can be used from 12 months of age.
Some antihistamines are used for their antinausea or sedative Loratadine is metabolised in the liver, while cetirizine, desloratadine and fexofenadine are not metabolised extensively.
Antihistamines are used in the management of allergic conditions.This is less of a problem with newer ‘second generation’ antihistamines, such as loratadine, and ‘third generation’ antihistamines such as desloratadine.The oral antihistamines available in Australia to treat allergic conditions are listed in the Box.However, pregnant women must be warned about the other aspects of safety such as sedation and consider whether they should not drive while taking these drugs.The newer antihistamines are likely to be as safe in pregnancy but have not been used by as many women, so they do not have the same evidence of safety.