Fexofenadine

Fexofenadine

Class:Antihistamine,systemic

Mechanism of action

Fexofenadine is an active metabolite of terfenadine and like terfenadine it competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract ,blood vessels and respiratory tract.It appears that fexofenadine does not cross blood brain barrier to any appreciable degree,resulting in a reduced potential for sedation.

Pharmacokinetics

Onset of action;60 minutes.Duration of antihistamine effect:Atleast 12 hours.Metabolism: ~5% metabolized mostly by gut flora;0.5% to 1.5% metabolized by cytochrome P-450 enzymes.Half life:14.4 hours.Time to peak serum concentration:~2.6 hours after oral administration.Elimination:primarily in feces and in urine as unchanged drug.

Indicatins

Indicated for the relief of symptoms associated with seasonal allergic rhinitis,symptoms:sneezing,rhinorrhea,itchy nose/throat/palate,itchy/watery//red eyes,chronic idiopathic urticaria.

Contraindications

Patients with known hypersensitivity to any of its ingredients.

Precautions

Safety and effectiveness in paediatric patients <12 years of age has not been established.

Side effects

Viral infection(Cold,Flu),nausea,dysmenorrhea,drowsiness,dyspepsia.

Pregnancy and lactation

Pregnancy risk factor C.There are no adequate studies in pregnant women and during lactation.

Drug interactions

In two separate studies,fexofenadine 120mg  twice daily (high doses) was co-administered with standard doses of erythromycin or ketoconazole to healthy volunteers and although fexofenadine peak plasma concentrations increased,no differences in adverse events or QTc intervals were observed.It remain unknown if a similar interaction occurs with other azole antifungal agents or other macrolide antibiotics.

Dosage

Oral:Children greater than or equal to 12 years and Adults:Seasonal allergic rhinitis:60 mg twice daily or 180mg once daily.Chronic idiopathic urticaria:60mg twice daily.Dosing adjustment in renal impairment:Recommended initial doses of 60mg once daily.

Brands

Tabs.Fexet 60,120,180mg,Tabs.Telfast,Tabs.Fexet-D.