Neuraxial analgesia and non sedating antihistamines
Although the non-sedating antihistamines have been widely used for daytime control of allergies, the sedative effect of sedating antihistamines may be preferred by patients who suffer from insomnia or by patients who need a good night sleep.
It may be especially advantageous to administer a sedating antihistamine in combination with a decongestant, such as phenylephrine, since decongestants such as phenylephrine often stimulate nervousness and anxiety in a patient.
Interactions with other drugs are more common with first-generation antihistamines compared with second-generation antihistamines.
Second generation antihistamines were developed in the 1980s and are much less sedating than first-generation antihistamines.
Daytime sedation can be a problem especially for those who drive or who operate machinery.
In view of these problems with sedative antihistamines, non-sedative antihistamines have been developed.
Histamine-1 receptors are located in the airways, blood vessels and gastrointestinal tract (stomach and esophagus).The table below shows the elimination half-life of some common non-sedating H1 antihistamines: When the non-sedating antihistamine, or its metabolite, has a long half life (for example, the Loratadine metabolite Descarboethoxyloratadine), plasma levels reach a steady state after repeated use and as a result there are minimal changes in C. Immunology 112(4), S96-S100 October 203), “Prospects for antihistamines in the treatment of asthma”, describes improvement in asthma control with montelukast, a leukotriene receptor antagonist, by co-administration with loratidine, a non-sedating antihistamine.In those cases where one daily dose of a non-sedating antihistamine provides 24 hour relief, a dose of a sedating antihistamine can be followed within a few hours, for example within the first eight hours after ingestion, preferably within the first six hours, and more preferably by the beginning of the release of the non-sedating antihistamine. As described in the abstract, the combination is thought to minimize the sedating effects of high levels of even non-sedating antihistamines, by reducing the amount required.Compositions containing both a sedative compound and a non-sedative antihistamine are provided.More particularly, compositions for administration at bedtime containing a sedating antihistamine or other sedating compound in immediate release form and a non-sedating antihistamine in delayed-release form are described.