Astemizole
Astemizole (marketed under the brand name Hismanal, developmental code R43512) was a second-generation antihistamine drug that has a long duration of action. Astemizole was discovered by Janssen Pharmaceutica in 1977. It has been withdrawn from the market in most countries because of rare but potentially fatal side effects (QTc interval prolongation and related arrhythmias due to hERG channel blockade).
Mizolastine
Mizolastine (Mizollen) is a once-daily, non-sedating antihistamine. It blocks H receptors and is commonly fast-acting. It does not prevent the actual release of histamine from mast cells, it just prevents it binding to receptors. Side effects can include dry mouth and throat.