Allegra-D Adverse Reactions

abdominal pain
agitation
anaphylactoid reactions
angina
angioedema
anorexia
anxiety
arrhythmia exacerbation
back pain
dizziness
drowsiness
dyspepsia
dysuria
excitability
headache
hypertension
infection
insomnia
myocardial infarction
nausea/vomiting
palpitations
photophobia
pruritus
QT prolongation
rash (unspecified)
restlessness
seizures
sinus tachycardia
stroke
supraventricular tachycardia (SVT)
throat irritation
tremor
urticaria
ventricular tachycardia
xerostomia

Allegra-D Adverse Reactions

In one clinical trial, adverse events of Allegra-D® were similar to those reported either in patients receiving fexofenadine 60 mg alone or in patients receiving pseudoephedrine 120 mg alone. The adverse event discontinuation rate was 3.7% for fexofenadine; pseudoephedrine, 0.5% for fexofenadine, and 4.1% for pseudoephedrine.

The most commonly reported adverse experiences with the recommended daily dosage of fexofenadine; pseudoephedrine (Allegra-D®) compared to fexofenadine or pseudoephedrine alone were headache (13.0% vs 11.5% vs 17.4%), insomnia (12.6% vs 3.2% vs 13.3%), and nausea/vomiting (7.4% vs 0.5% vs 5.0%). Many of the adverse events occurring in the Allegra-D® group were adverse events also reported predominantly in the pseudoephedrine group and are consistent with the pharmacology of sympathomimetic amines, such as insomnia, headache, nausea, dry mouth, dizziness, agitation, nervousness, anxiety, and palpitations. Anticholinergic side effects are minimal with fexofenadine compared to most other H-blockers; however, some patients experience xerostomia or dry mouth (2.8% with Allegra-D® vs 0.5% with fexofenadine alone). Other adverse experiences which exceeded 1% in the Allegra-D® group compared to fexofenadine or pseudoephedrine alone included: dyspepsia (2.8% vs 0.5% vs 0.9%), throat irritation (2.3% vs 1.8% vs 0.5%), dizziness (1.9% vs 0.0% vs 3.2%), agitation (1.9% vs 0.0% vs 1.4%), back pain (1.9% vs 0.5% vs 0.5%), palpitations (1.9% vs 0.0% vs 0.9%), nervousness or excitability (1.4% vs 0.5% vs 1.8%), anxiety (1.4% vs 0.0% vs 1.4%), upper respiratory infection (1.4% vs 0.9% vs 0.9%), and abdominal pain (1.4% vs 0.5% vs 0.5%). CNS effects such as anxiety, restlessness, headache, lightheadedness, dizziness, insomnia, tremor, seizures, and psychological disturbances including fear, hallucinations and psychosis have been reported during therapy with pseudoephedrine. Elderly patients appear to be more sensitive to the CNS stimulation effects of pseudoephedrine.

Fexofenadine is a metabolite of terfenadine. Terfenadine has been associated with QT prolongation and ventricular tachycardias (torsades de point) and was withdrawn from the U.S. market after ten years of post-marketing experience. Premarketing trials with fexofenadine in greater than 900 patients demonstrated no significant prolongation of the QT interval at doses of 60 - 240 mg PO twice daily. One case report documented ventricular tachycardia associated with QT prolongation during therapy with fexofenadine in a patient with a history of prolonged QT interval. No cases of cardiac arrhythmias are reported in the fexofenadine or Allegra-D® product information. No QT prolongation was evident the maximum fexofenadine dosage studied (400 mg twice daily for seven days in healthy subjects). As with other sympathomimetics, cardiovascular adverse effects may occur during pseudoephedrine therapy including angina, cardiac arrhythmias (or arrhythmia exacerbation), hypertension, myocardial infarction, or stroke; these effects generally occur at excessive dosage or in patients at higher risk (see Contraindications). Pseudoephedrine and phenylephrine appear to have a lower propensity to cause hypertension and potential sequelae (e.g., stroke, hypertensive crisis, intracranial bleeding) compared to ephedrine or phenylpropanolamine. Well-controlled hypertensive patients receiving pseudoephedrine at recommended doses (240 mg/day PO) do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure (especially systolic hypertension) has been reported in some patients. Although infrequent, cardiac arrhythmias (< 2%) secondary to pseudoephedrine may occur in the general population at therapeutic doses and include palpitations, premature ventricular contractions (PVCs), supraventricular tachycardia (SVT), and sinus tachycardia.

Drowsiness and/or sedation is a frequent adverse reaction to most H₁-blockers, however, H₁-blockers vary in their ability to produce drowsiness, and this side effect does not correlate with peripheral antihistamine potency. Fexofenadine is a nonsedating antihistamine which does not readily cross the blood-brain barrier. The incidence of drowsiness was 1.3% in patients receiving fexofenadine monotherapy (vs placebo 0.9%). Patients should be warned about undertaking hazardous tasks (add: driving or operating machinery to cautions) while taking fexofenadine; pseudoephedrine, although the risk is relatively low.

Ocular effects can occur with the use of pseudoephedrine. These can include increased intraocular pressure and photophobia.

Pseudoephedrine also can produce GI and GU effects such as nausea, anorexia, and dysuria.

Events that have been reported during controlled clinical trials involving seasonal allergic rhinitis and chronic idiopathic urticaria patients with frequencies < 1%, similar to placebo, and have been rarely reported during post-marketing surveillance of fexofenadine include: insomnia, nervousness (restlessness), and sleep disorders or paranoia. In rare cases, rash (unspecified), urticaria, pruritus and hypersensitivity reactions (anaphylactoid reactions) with manifestations such as angioedema, chest tightness, dyspnea, flushing and systemic anaphylaxis have been reported.

[ Last revised: 4/17/2003 12:13:00 PM ]

References
_{. Levander S, Hagermark O, Stahle M. Peripheral antihistamine and central sedative effects of three H₁-receptor antagonists. Eur J Clin Pharmacol 1985;28:523 - 9.}

. Coates ML, et al. Does pseudoephedrine increase blood pressure in patients with controlled hypertension? J Fam Pract 1995;40:22 - 6.

. Giraud T. QT lengthening and arrhythmias associated with fexofenadine. Lancet 1999;353:2072 - 3.

. Chua SS, Benrimoj SI. Non-prescription sympathomimetic agents and hypertension. Med Toxicol Adverse Drug Exp 1988;3:387 - 417.

. Beck RA, Mercado DL, Seguin SM, et al. Cardiovascular effects of pseudoephedrine in medically controlled hypertensive patients. Arch Intern Med 1992;152:1242 - 5.

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