Fexal - Precautions | Dosage | Side Effects
Fexal is a medicine available in Australia and contains active substance called fexofenadine (active metabolite of terfenadine). It belongs to the second-generation of H1 antihistamines and is derived from piperidine. It exhibits selective antagonistic activity on histamine H1 receptors in peripheral tissues. Antagonistic activity on adrenergic and cholinergic receptors was not seen in clinical trials. Fexal does not cause sedation as other antihistamines. Unlike terfenadine, Fexal does not cause prolongation of QT interval and arrhythmia.
It is used to treat allergic rhinitis, commonly known as hay fever, in patients above the age of 12. Fexal can also be used for the treatment of chronic idiopathic urticaria.
Randomized, double-blind clinical studies have confirmed that 180 mg of Fexal a day relieves sneezing, runny nose, itching of the palate, nose and throat as well as itchy, red and watery eyes. The effect occurs very quickly (usually after 60 minutes), and maximum effects are achieved 120-180 minutes after oral administration.
Fexal should not be administered concurrently with erythromycin (an antibiotic), because this increases the gastrointestinal absorption of the active substance but also reduces the excretion of the drug via bile. This leads to an increase in the concentration of Fexal in the blood which increases the risk of side effects.
Fexal should not be administered concurrently with ketoconazole(a drug used for the treatment of fungal infections) because ketoconazole also increases gastrointestinal absorption and reduces gastrointestinal secretion of fexofenadine, which may cause a clinically significant increase in the plasma concentrations of this drug.
Cases of drowsiness in patients who have used this medicine have been reported and you should avoid driving cars and operating machinery while on therapy with this medicine.
Concomitant use with antacids containing magnesium or aluminum should be avoided because antacids reduce concentration and effectiveness of Fexal.
Patients with impaired renal function usually have prolonged elimination half-life of this drug (up to 70%), which increases the risk of side effects. It is therefore necessary to reduce the dose in patients with renal impairment.
The effects of this medicine can be enhanced in patients over 65 years of age, and that's why it should be used with extra precautions in such patients.
Although this medicine is used to treat urticaria, it can sometimes cause urticaria as an adverse effect. If you notice any changes in your skin (redness, itching, edema, etc.), stop taking this medication and contact your physician.
Fexal, Pregnancy and Breastfeeding
FDA Pregnancy Category: C.
There are not enough clinical trials to support use of this medicine during pregnancy. Limited data from studies conducted in rabbits and rats did not reveal teratogenic effects. Fexal should not be used during pregnancy unless your doctor considers it necessary.
It is assumed that the active substance - fexofenadine is excreted in breast milk, although this has not been confirmed yet. For this reason, the use of Fexal during breastfeeding should be avoided.
The usual dose for patients over 12 years of age is 60 mg twice daily (or 120 mg once daily) or 180 mg once daily. The maximum daily dose is 180 mg.
The usual dose in patients aged 6-11 years, as well as in patients with impaired renal function, is 30 mg twice daily.
Swallow the tablet with a full glass of plain water (do not use mineral water as it may contain magnesium). After you take a pill, do not take orange juice, grapefruit, apple or other fruit in the next few hours because it can reduce the effectiveness of this drug.
In addition to the interactions with erythromycin, ketoconazole, and antacids, Fexal may also interact with following drugs:
- Quinapril - ACE inhibitor used to treat cardiovascular diseases. Quinapril binds to Fexal in the stomach, and reduces its effectiveness. For this reason, quinapril should be taken 4 hours before or after taking Fexal.
- Dronedarone - antiarrhythmic. Dronedarone increases the concentration of Fexal in the blood and therefore increases the risk of side effects.
- Eltrombopag - medicine used to treat idiopathic thrombocytopenic purpura. Eltrombopag increases the concentration of fexofenadine in the blood.
- Rifampin and rifabutin - medicines used to treat tuberculosis. These drugs reduce the concentration of Fexal in the blood, and reduce its effectiveness.
In one clinical study conducted in US, the following adverse effects have been reported:
- Poor digestion (dyspepsia).
- Painful menstrual periods.
- Back pain.
- Upper respiratory tract infections.
In addition, the occurrence of urticaria, tachycardia, palpitations, insomnia, nightmares and nervousness have also been reported.
Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.
If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.