oral+antihistamines

=Oral Antihistamines (Less sedating)=

How it works
Blocks the action of histamine, reducing the effects you see in hayfever. //Selectively antagonise the action of histamine at H1 receptors. Histamine release causes vasodilation and increases capillary permeability. They also have a lower binding affinity for the cholinergic and alpha-adrenergic receptor sites. This eliminates many of the adverse effects caused by the older sedating antihistamines, including CNS depression, blurred vision, dry mouth and tachycardia //

Questions to Ask
What medications? - medical conditions? //hepatic and renal impairment// - allergies? - Pregnant? //more evidence with sedating antihistamines (less sedating are Category B1-B2)//

How to take
Cetirizine: Initially, 10mg (one tablet) once daily; maximum 20mg once daily. Desloratidine: Adult, child >12 years: 5mg (one tablet) once daily Loratidine: Adult, child >30kgs: 10 mg once daily. Fexofenadine: Adult, child >12 years: 120 mg daily in 1 or 2 divided doses. //Onset of action between 1 and 3 hours//

Side effects
drowsiness, fatigue, headache, nausea, dry mouth

Other advice?
//- Cetirizine// (Zyrtec) is the most likely of the less sedating antihistamines to cause sedation. It is eliminated unchanged renally; reduce dose in moderate-to-severe impairment. Can be used in children >1 year. //- Desloratadine// (Claramax) //and loratadine// (Claratyne) appear to have similar adverse and therapeutic effects (desloratadine is the active metabolite of loratadine). Desloratadine can be used in children >12 years and loratadine in children >1 year. //- Fexofenadine// (Telfast) is least likely to cause sedation and anticholinergic effects in the elderly. Can be used in children >6 years. Space apart if using antacids

- Individual response to a specific antihistamine varies widely. It may be necessary to try a number of agents to determine which is best tolerated and most effective - Reduce nasal itching, sneezing and rhinorrhoea but are less effective in controlling nasal obstruction than INCS and sedating antihistamines

CMI
Cetirizine: [|AMH] Zyrtec Desloratidine: [|AMH] Claramax Fexofenadine: [|AMH] [|Telfast] Loratidine: [|AMH] Claratyne