Fexofenadine Hydrochloride

Fexofenadine, sold under the trade name Allegra & FX 24 among others is an antihistamine pharmaceutical drug used in the treatment of allergy symptoms, such as hay fever and urticaria. Therapeutically, fexofenadine is a selective peripheral H1-blocker. Fexofenadine, sold under the trade name Allegra & FX 24 among others is an antihistamine pharmaceutical drug used in the treatment of allergy symptoms, such as hay fever and urticaria. Therapeutically, fexofenadine is a selective peripheral H1-blocker. Fexofenadine is classified as a second-generation antihistamine because it is less able to pass the blood–brain barrier and cause sedation, compared to first-generation antihistamines.It has also been called a third-generation antihistamine, although there is some controversy associated with the use of the term. It was patented in 1979 and came into medical use in 1996. Fexofenadine has been manufactured in generic form since 2011. Fexofenadine is used for relief from physical symptoms associated with seasonal allergic rhinitis and for treatment of chronic urticaria. It does not cure but rather prevents the aggravation of allergic rhinitis and chronic idiopathic urticaria and reduces the severity of the symptoms associated with those conditions, providing relief from repeated sneezing, runny nose, itchy eyes or skin, and general body fatigue. The most common side effect demonstrated in adults was headache, but some also experienced back and muscle pain, miosis or pinpoint pupils, nausea, drowsiness, and menstrual cramps. There have also been rare reports of anxiety and insomnia. The most common side effects demonstrated during clinical trials were cough, upper respiratory tract infection, fever, and otitis media for children ages 6 to 11 and fatigue for children ages 6 months to 5 years. A patient over the age of 80 experienced auditory hallucinations and extreme energy bursts. The safety profile of fexofenadine is quite favorable, as no cardiovascular or sedative effects have been shown to occur even when taking 10 times the recommended dose. Research on humans ranges from a single 800 mg dose, to a twice-daily 690 mg dose for a month, with no clinically significant adverse effects, when compared to a placebo. No deaths occurred in testing on mice, at 5000 mg/kg body weight, which is one-hundred ten times (110x) the maximum recommended dose for an adult human. If overdose were to occur, supportive measures are recommended. Theoretically, an overdose could present as dizziness, dry mouth, and/or drowsiness, consistent with an exaggeration of the usual side effects. It does not appear that hemodialysis is an effective means of removing fexofenadine from the blood. Fexofenadine is a selectively peripheral H1-blocker. Blockage prevents the activation of the H1 receptors by histamine, preventing the symptoms associated with allergies from occurring. Fexofenadine does not readily cross the blood–brain barrier and is therefore less likely to cause drowsiness in comparison to other antihistamines that readily cross the blood-brain barrier (i.e. first-generation antihistamines like diphenhydramine). In general, fexofenadine takes about one hour to take effect, though this may be affected by the choice of dosage form and the presence/absence of certain foods. Fexofenadine also exhibits no anticholinergic, antidopaminergic, alpha1-adrenergic, or beta-adrenergic-receptor-blocking effects. Taking erythromycin or ketoconazole while taking fexofenadine does increase the plasma levels of fexofenadine, but this increase does not influence the QT interval. The reason for this effect is likely due to transport-related effects, specifically involving p-glycoprotein (p-gp). Both erythromcin and ketoconazole are inhibitors of p-gp, a transporter protein involved in preventing the intestinal absorption of fexofenadine. When p-gp is inhibited, fexofenadine may be better absorbed by the body, increasing its plasma concentration by more than what was intended.