Non sedating antihistamine drugs
Mizolastine does not induce, in usual dosage, prolongation of QT interval; however its combination with macrolides and imidazol antifungal agents is disadvised because of a possible inhibition of its catabolism.Fexofenadine, the active metabolite of terfenadine is not associated with an averse prolongation of the QT interval.Protocol-directed sedation versus non-protocol-directed sedation in mechanically ventilated intensive care adults and children.The sedation needs of critically ill patients have been recognized as a core component of critical care that is vital to assist recovery and ensure humane treatment.
In addition, each compound can have or not have parallel properties, antimuscarinic effects for example.
The first-genaration antihistamines have alpha adrenolytic activity which can decrease the vasoconstrictive effect of adrenaline and noradrenaline and an antimuscarinic effect with the corresponding adverse effects.
Certain H1 antagonists, such as promethazine, have a local anesthetic effect.
It is not advised to prescribe a sedating a H1-antihistamine to infants because, although this is not documented, it could increase the risk of sudden death.
New H1-antihistamines, terfenadine and astemizole, which were associated with cardiac adverse effects, prolongation of QT interval, torsades de pointes by inhibition of potassium channels, are no longer approved for use. Other adverse effects of H1-antihistamines have been reported, in particular allergic reactions.
Evidence suggests that sedation requirements are not always optimally managed. Strategies to improve sedation assessment and management have been proposed.