fexofenadine and pseudoephedrine (Allegra-D)

Allegra-D is a combination of an antihistamine (fexofenadine) and a decongestant (pseudoephedrine). Fexofenadine is an oral, "second generation" antihistamine that is used to treat the signs and symptoms of allergy and hives. It is similar to the other second generation antihistamines loratadine (Claritin), cetirizine (Zyrtec) and azelastine (Astelin).

Histamine is a chemical that is responsible for many of the signs and symptoms of allergic reactions, for example, swelling of the lining of the nose, sneezing, and itchy eyes. Histamine is released from histamine-storing cells (mast cells) and then attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to become "activated," releasing other chemicals that produce the effects that we associate with allergy (for example, sneezing).

Fexofenadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of H1 receptor-containing cells by histamine. Unlike the first generation antihistamines, fexofenadine and other second-generation antihistamines do not readily enter the brain from the blood. Therefore, they cause less drowsiness and are called non-sedating antihistamines. Pseudoephedrine causes blood vessels in the nasal passages to narrow (vasoconstrict). Vasoconstriction reduces nasal congestion by preventing fluid from draining from blood vessels into nasal passages. The FDA approved Allegra-D in December 1997.

What brand names are available for fexofenadine and pseudoephedrine?

Allegra-D

Is fexofenadine and pseudoephedrine available as a generic drug?

Yes

Do I need a prescription for fexofenadine and pseudoephedrine?

No

Side effects of Allegra-D include stimulation of the nervous system by pseudoephedrine leading to:

• nervousness,
• restlessness,
• excitability,
• dizziness,
• headache,
• fear,
• anxiety,
• tremor, hallucinations, and
• convulsions (seizures).

Other important side effects include:

• drowsiness,
• fatigue,
• nausea, and
• vomiting.

Allegra-D usually is taken once or twice daily. The recommended dose is one 60/120 mg tablet twice daily or one 180/240 mg tablet once daily. Persons with kidney disease and elderly persons may only need to take one tablet per day. Allegra-D should be taken without food. It must be used cautiously in patients with heart (coronary artery) disease and angina, and diabetes because of the heart-stimulating effects of pseudoephedrine.

Allegra-D should not be taken with monoamine oxidase (MAO) inhibitor drugs such as phenelzine (Nardil) and tranylcypromine (Parnate) because combining pseudoephedrine with MAO inhibitors can lead to dangerous increases in blood pressure and other serious side effects. Aluminum containing antacids (for example, Maalox) reduces the absorption of fexofenadine. Therefore, aluminum containing antacids and fexofenadine should not be administered together. Fruit juices (apple, orange, grapefruit) may reduce the absorption of fexofenadine, andexofenadine should only be administered with water.

Pseudoephedrine causes birth defects in some animal species. Additionally, there have been associations between first trimester exposure to drugs related to pseudoephedrine and fetal malformations, though the malformations have been primarily minor. Thus, Allegra-D should be used in pregnancy only if the physician feels that the potential benefit outweighs the risks. Fexofenadine has not been adequately studied in pregnant women.

Pseudoephedrine is secreted in breast milk. The American Academy of Pediatrics considers pseudoephedrine to be compatible with nursing. Fexofenadine has not been adequately studied in women who are breastfeeding.

What preparations of fexofenadine and pseudoephedrine are available?

Tablets (fexofenadine/pseudoephedrine): 60/120 mg, 180/240 mg

How should I keep fexofenadine and pseudoephedrine stored?

Tablets should be stored at room temperature between 15 C - 30 C (59 F - 86 F).