Loratadine is a white to off-white powder not soluble in water, but very soluble in acetone, alcohol, and chloroform. It has a molecular weight of 382.89, and empirical formula of C22H23ClN2O2; its chemical name is ethyl4-(8-chloro-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene)-1-piperidinecarboxylate.
Loratadine is a tricyclic antihistamine with long-acting selective peripheral H1 receptor antagonist activity. It does not readily cross the blood brain barrier. Following administration, maximal serum levels are reached within 1,5 hours and clinical effect is achieved within 2 hours. Most of a dose is excreted equally in the urine and faeces.
Loratadine is a long acting tricyclic antihistamine with selective peripheral H1-receptor antagonistic activity and no central sedative or anticholinergic effects. It acts by competing with histamine for H1-receptor sites on effector cells. Loratadine thereby prevents, but does not reverse responses mediated by histamine alone.
Loratadine is well absorbed from the gastro-intestinal tract after oral administration. Bioavailability is increased when administered with food. Loratadine undergoes extensive metabolism. The major metabolite, descarboethoxyloratadine, has potent histamine-H1 blocking activity. Reported half-lives for loratadine and descarboethoxyloratadine are 8 +6 hours and 18 +6 hours respectively. Loratadine is about 97% bound to plasma proteins; descarboethoxyloratadine is less extensively bound (73-77%). The volume of distribution is about 120 +80 L/kg. Loratadine and its metabolites have been detected in breast milk, but do not appear to cross blood-brain barrier to a significant extent. Loratadine and its metabolites are excreted in the urine and faeces.
Betamethasone also decreases the numbers of white blood cells circulating in the blood. This, along with the decrease in inflammatory chemicals, can prevent the rejection of organ transplants, as it prevents the body from attacking foreign tissue. It is useful for the treatment of certain types of leukaemia, where there is an abnormally large production of certain white blood cells. It is also used to treat some diseases which are caused by the immune system attacking itself (auto immune diseases).