Sedation with non sedating antihistamines
The data collection periods for the four drugs were May to August 1989 for cetirizine and loratadine, May 1989 to September 1990 for acrivastine, and March to August 1997 for fexofenadine.The response rates (number of green forms returned/number of green form sent) were 50.7% for loratadine, 50.9% for fexofenadine, 56.5% for acrivastine, and 57.4% for cetirizine.Interactions with other drugs are more common with first-generation antihistamines compared with second-generation antihistamines.
They also act on muscarinic, alpha-adrenergic, and serotonin receptors.
They act on histamine-1 receptors in the periphery and are unlikely to penetrate the brain, so are less likely to cause side effects or interact with drugs.
Most second-generation antihistamines do not cause drowsiness, although some (such as cetirizine and fexofenadine), may be more likely to do so at higher dosages.
All reported pregnancies are followed up to determine the outcome and the cause of all deaths are established.
Both the exposure (prescription) and the outcome (event) data are computerised for analysis.
After three, six, or 12 months, “green form” questionnaires are sent to the general practitioners who wrote the original prescriptions.