Fexofenadine
Fexoted®
Category:
Antihistaminic (H1- receptor).
(USP DI)
Chemistry:
(±)-ƿ-{l-Hydroxy-4-[4-(hydroxydiphenylmethyl)-piperidino]butyl}-α-methylhydratropic acid hydrochloride. C32H39NO4HCl= 538.1.
Mechanism of action:
Fexofenadine is an antihistamine with selective peripheral H1-receptor antagonist activity. Fexofenadine, an active metabolite of terfenadine, is a non-sedating antihistamine. It does not possess significant sedative or antimuscarinic actions.
(USP DI, Martindale)
Pharmacokinetics:
Absorption Rapidly absorbed
Protein binding High (60 to 70%)
Volume of distribution 5.4 to 5.8 liters/kilogram
Biotransformation About 5% of the total dose is metabolized, approximately 0.5 to 1.5% by cytochrome P450 3A4 isoenzyme metabolism and 3.5% transformed by intestinal microflora.
Half-Life 14.4 hours
Time to Peak Concentration 2-3 hours
Elimination Excretion is mainly in the feces with only 10% being present in the urine.
(Facts, USP DI, Martindale)
Indications:
• Chronic idiopathic urticaria: for the treatment of uncomplicated skin manifestations of chronic idiopathic urticaria in adults and children 6 months of age and older.
• Seasonal allergic rhinitis: for the relief of symptoms associated with seasonal allergic rhinitis in adults and children 2 years of age and older.
(Facts)
Contraindications:
Patients with known hypersensitivity to Fexofenadine and any of the ingredients of Fexofenadine- Tedapharm.
(PDR)
Warnings & Precautions:
1- Fexofenadine may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The impairment may be amplified by concomitant use of other CNS depressants such as alcohol, sedatives/ hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers.
2- Use Fexofenadine with caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy, bladder neck obstruction, bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease, and hypertension.
3- In general, Fexofenadine is not recommended to treat lower respiratory tract symptoms (e.g., emphysema, chronic bronchitis, asthma).
4- Antihistamines have varying degrees of atropine-like actions; use with caution in patients with a predisposition to urinary retention, history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease, or hypertension. Antihistamines may thicken bronchial secretion caused by anticholinergic properties and may inhibit expectoration and sinus drainage.
5- Hypersensitivity reactions may occur, and any of the usual manifestations of drug allergy may develop.
6- Photosensitization may occur, therefore, caution patients to take protective measures (e.g., sunscreens, protective clothing) against exposure to ultraviolet light or sunlight until tolerance is determined.
(Facts)
Pregnancy:
Adequate and well-controlled studies in humans have not been done. Fexofenadine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. FDA pregnancy category C.
(USP DI)
Breast-feeding:
It is not known whether fexofenadine is distributed into breast milk.
(USP DI)
Drug Interactions:
1- Fexofenadine should not be taken closely in time with aluminum and magnesium containing antacids.
2- Plasma concentrations of fexofenadine have been increased when given with erythromycin or ketoconazole.
3- Rifampin may reduce the absorption of fexofenadine, thereby decreasing the pharmacologic effect.
4- Fruit juices such as grapefruit, orange and apple may reduce the bioavailability and exposure of fexofenadine.
(Martindale/ Facts)
Adverse Reactions:
Anaphylaxis and hypersensitivity reactions, back pain, coughing, dizziness, drowsiness, dysmenorrhea, dyspepsia, fatigue, fever, headache, myalgia, nasopharyngitis, nausea, otitis media, pain in extremity, upper respiratory tract infection, viral infections such as cold, flu.
(USP DI)
Over dosage:
Dizziness; drowsiness; dry mouth.
(USP DI)
Dosage & Administration:
• Usual adult and adolescent dose:
Rhinitis, seasonal, allergic (treatment)
Oral, 60 mg two times a day, or 180 mg once a day with water.
• Urticaria (treatment)
Oral, 60 mg two times a day, or 180 mg once a day with water.
• Note: For patients with decreased renal function, an initial dose of 60 mg once a day is recommended.
• Usual pediatric dose:
Rhinitis, seasonal, allergic (treatment)
• Urticaria (treatment)
Children 12 years of age and older: See usual adult and adolescent dose.
Children 6 to 11 years of age: Oral, 30 mg two times a day with water.
Children up to 6 years of age: Safety and efficacy have not been established.
• Note: For pediatric patients with decreased renal function, an initial dose of 30 mg once a day is recommended.
• Usual geriatric dose:
Rhinitis, seasonal, allergic (treatment)
• Urticaria (treatment)
See usual adult and adolescent dose.
(USP DI)
Storage:
Store below 30˚ C and protect from humidity and direct light.
How supplied:
Fexofenadine- Tedapharm is as available as 120 mg, oval, pink, scored & coated tablets. There are blisters of 10’s in a box of 100’s.
References:
1- Drug Facts 2009
2- Martindale (36) 2009
3- PDR 2010
4- USP DI 2007