Medications for Allergy

While spending the day with her grandmother, one-year-old Natalie Kalitsi suddenly began acting strangely. First the little girl grew very sleepy; then red blotches broke out all over her body. She seemed to struggle to breathe. An ambulance rushed her to the hospital, where doctors questioned her grandmother: What had Natalie eaten that day?

Nothing unusual — but Natalie did have her first bite of fish. That small bite of fish was enough to almost kill her.

Today Natalie is an active, happy three-year-old with big brown eyes. Like other toddlers, she loves going to preschool, playgrounds, and birthday parties. But wherever Natalie goes, a special shot that contains powerful medicine always follows. If Natalie accidentally eats seafood, peanuts, or dairy products — all of which give her allergic reactions — the shot will help her breathe until she can be taken to a hospital.

“At first it was hard getting used to, but it’s routine now,” says Gale Kalitsi, Natalie’s mother. “Everywhere Natalie goes, I pack a special lunch box for her — it’s like a game. We even do it at birthday parties — or when she goes to her cousin’s house.”

All parents try to look out for their child‘s safety, but being the mother of a severely allergic child means that Gale must be extra careful. Before Natalie began to attend a preschool near her home in Bethesda, Maryland, Gale called meetings with her teachers and the school’s director to make sure that they understood how serious allergies can be.

“Until you have an experience with food allergies, you don’t know how deadly allergies can be,” says Gale. “In Natalie’s case, it can close down her air passages and kill her. Everyone who comes in contact with her needs to be able to read food labels. And because children like to share food, or they may kiss her and have peanuts on their lips, we need to be especially careful.”

So a special rule was set for Natalie’s classroom: No students could bring in peanut-butter sandwiches for lunch.

By now. Gale is an expert at reading the labels of everything Natalie eats, but in the beginning food labels were filled with confusing words. For example, Natalie is allergic to milk, but how could Gale know that many unfamiliar-sounding ingredients such as “casein” or “whey” contained milk? Gale says that an organization called the Food Allergy and Anaphylaxis Network (1-800-929-4040) has been an enormous help and has even provided her with special note cards listing ingredients that aren’t safe for Natalie.

Gale and her husband have learned so much about food allergies that when their second daughter was diagnosed with an allergy to wheat, they felt confident of their ability to handle her special needs. “You really need to become an educator and a campaigner for your child,” says Gale.

But Gale and her husband recently learned they’re not the only ones watching Natalie’s diet. Now that Natalie is growing up, she can speak up for herself.

“At the age of three, Natalie can tell you what foods make her sick, and she can tell you what she can have,” says Gale proudly.

Drug Approvals

(BANM, US Adopted Name, rINNM)

Pharmacopoeias. In Europe and US.

European Pharmacopoeia, 6th ed. (Fexofenadine Hydrochloride). A white or almost white powder. Slightly soluble in water freely soluble in methyl alcohol very slightly soluble in acetone. It exhibits polymorphism.

The United States Pharmacopeia 31, 2008 (Fexofenadine Hydrochloride). Store at a temperature of 20° to 25°, excursions permitted between 15° and 30°. Protect from light.

Adverse Effects and Precautions

As for the non-sedating antihistamines in general.

Arrhythmias. A 67-year-old man suffered syncope after taking fexofenadine 180 mg daily for 2 months. His ECG showed an abnormally prolonged QT interval which shortened once fexofenadine was stopped, although the interval tended to be long even without drug therapy. Nonetheless rechallenge was positive. The manufacturers of fexofenadine have commented that the patient was at risk of developing arrhythmias before taking the drug.

The ECG effects of fexofenadine have been studied in normal subjects and doses of up to 480 mg daily [4 times the recommended dose for seasonal allergic rhinitis] did not prolong the QT interval.

Breast feeding. No adverse effects have been seen in breastfed infants whose mothers were receiving fexofenadine, and the American Academy of Pediatrics considers that it is therefore usually compatible with breast feeding.

See also under Adverse Effects and Precautions, in Terfenadine.

Psoriasis. Exacerbation of psoriasis has been reported in association with the use of fexofenadine.

Interactions

As for the non-sedating antihistamines in general.

Plasma concentrations of fexofenadine have been increased when given with erythromycin or ketocona-zole, but, unlike terfenadine, licensed product information states that this was not associated with adverse effects on the QT interval.

Antacids containing aluminium and magnesium hydroxide have reduced the absorption of fexofenadine. Fruit juices including grapefruit may reduce the bioa-vailability of fexofenadine and use together should be avoided.

Pharmacokinetics

Fexofenadine is rapidly absorbed after oral doses with peak plasma concentrations being reached in 2 to 3 hours. It is about 60 to 70% bound to plasma proteins. About 5% of the total dose is metabolised, mostly by the intestinal mucosa, with only 0.5 to 1.5% of the dose undergoing hepatic biotransformation by the cyto-chrome P450 system. Elimination half-life of about 14 hours has been reported although this may be prolonged in patients with renal impairment. Excretion is mainly in the faeces with only 10% being present in the urine. Fexofenadine does not appear to cross the blood-brain barrier.

Fexofenadine is a metabolite of terfenadine and as such has been detected in breast milk after the administration of terfenadine.

Uses and Administration

Fexofenadine, an active metabolite of terfenadine, is a non-sedating antihistamine. It does not possess significant sedative or antimuscarinic actions. Fexofenadine is used as the hydrochloride in the symptomatic relief of allergic conditions including seasonal allergic rhinitis and chronic urticaria.

In the UK a dose of fexofenadine hydrochloride 120 mg once daily is given orally in the treatment of seasonal allergic rhinitis the recommended dose in chronic idiopathic urticaria is 180 mg once daily. US licensed product information suggests a dose of 60 mg twice daily or 180 mg once daily for both indications.

Fexofenadine is also used with a decongestant such as pseudoephedrine hydrochloride.

For doses in children or in patients with renal impairment, see below.

Administration in children. Fexofenadine hydrochloride is used in children for the treatment of seasonal allergic rhinitis in an oral dose of 30 mg twice daily in the UK it is licensed for use in children aged 6 to 11 years whereas in the USA it may be used in children as young as 2 years.

In the USA, fexofenadine is also licensed for use in paediatric chronic idiopathic urticaria. The dose in children aged 6 months to less than 2 years is 15 mg twice daily older children may be given 30 mg twice daily.

For suggested doses in children with renal impairment see below.

Administration in renal impairment. US licensed product information recommends that initial oral doses of fexofenadine hydrochloride in adults with renal impairment should be reduced to 60 mg once daily. In children with renal impairment, the initial dose should be reduced to 30 mg once daily in patients aged 2 to 11 years, and to 15 mg once daily in children aged 6 months to less than 2 years.

UK product information advises that fexofenadine should be given with caution to patients with renal impairment however, it also states that dose adjustment is not considered to be necessary in such patients.

Preparations

The United States Pharmacopeia 31, 2008: Fexofenadine Hydrochloride and Pseudoephedrine Hydrochloride Extended-Release Tablets Fexofenadine Hydrochloride Capsules Fexofenadine Hydrochloride Tablets.

Proprietary Preparations

Argentina: Alerfedine Allegra Fexofen †

Australia: Fexotabs Telfast Xergic

Austria: Telfast

Belgium: Telfast

Brazil: Allegra Altiva

Canada: Allegra

Chile: Aerodan Alexia Allegra Fenax

Czech Republic: Afexil Ewofex Telfast

Denmark: Telfast

Finland: Telfast

France: Telfast

Germany: Telfast

Hong Kong: Telfast

Hungary: Altiva Telfast

India: Alernexf Allegra Fexigra Fexofen Fexova Odifex

Indonesia: Telfast

Ireland: Telfast

Israel: Telfast

Italy: Kalicet † Telfast

Malaysia: Telfast

Mexico: Allegra

The Netherlands: Telfast

Norway: Telfast

New Zealand: Telfast Xergic

Philippines: Telfast

Poland: Telfast

Portugal: Telfast

Russia: Fexadin Telfast

South Africa: Telfast

Singapore: Telfast

Spain: Telfast

Sweden: Telfast

Switzerland: Telfast

Thailand: Fenafex Telfast

Turkey: Fexadyne Fexofen Telfast

UK: Telfast

USA: Allegra

Venezuela: Allegra Fexidine Fexoril Rinolast

Multi-ingredient

Argentina: Alerfedine D Allegra-D

Australia:: Telfast Decongestant

Brazil: Allegra-D

Canada: Allegra-D

Chile: Alexia D Allegra-D

Hong Kong: Telfast-D

Indonesia: Telfast Plus

Malaysia: Altiva-D Telfast-D

Mexico: Allegra-D

New Zealand: Telfast Decongestant †

Singapore: Telfast-D

USA: Allegra-D

Venezuela: Allegra-D Rinolast D