Description of the medicine
Allegra is an H1 antihistamine with a fast and efficient anti-allergic action. It is used for the treatment of hay fever, allergic rhinitis and hives. Allegra was manufactured by the Sanofi-Aventis laboratory as a replacement of terfenadine (an antihistamine with serious cardiac adverse effects).
As the other antihistamines, Allegra is used as a race-mate (one that has equal amounts of left- and right-handed enantiomers of a chiral molecule). Allegra consist of piperidine-4-carboxylate and 4-bromophenyl acetonitrile compounds. First two of them are introduced as phenyl esters through the Grignard reaction. The other compounds are synthesized by double alkylation of the nitrile derived carbanion with iodomethane. The nitrite group is now the hydrolyzed form of carboxylic acid. The aryl bromide is eliminated by lithiation with n-butyllithium and organolithium compounds. This reaction results in the formation of Allegra.
Allegra is quickly absorbed after the intake and achieves maximum plasma in about 2 hours. The bioavailability is unknown. Allegra is usually excreted in the feces (however, 1/10 of the dosage can be found in urine). The half-life of Allegra is about 13 hours. Allegra is used for the treatment of hay fever and different allergic reactions. It alleviates allergic symptoms, including displacement of histamine from the H1 receptor.
Allegra was designed as a replacement of terfenadine which had to be removed from the market due to the severe adverse effects. This substance has the same biological activity as terfenadine, but has much less adverse effects. It doesn’t have any anticholinergic or alpha-receptor blocking action. Unlike terfenadine, Allegra doesn’t block the potassium channels in the cardiac muscle cells. Allegra was created by Sepracor and approved in the US (1996). The patents for the release of Allegra and related products belong to the French drug company, Sanofi-Aventis and Albany Molecular Research Inc.
Diseases cured by Allegra
Seasonal allergic rhinitis
In a double-blind multicenter study, about six hundred patients suffering from seasonal allergic rhinitis received 14 days of Allegra or placebo. They took various dosages of Allegra (60, 120 or 240 mg) or placebo two times a day. The drug effect was assessed by the patients 12 hours after the intake. All Allegra dosages compared to placebo caused a great reduction of unpleasant symptoms. The maximum dose were just as effective as the lowest one (60 mg 2 times a day).
Another two-week was carried out with about 600 patients suffering from allergic rhinitis. The patients took 40-120 mg of Allegra 2 times a day. Once again, Allegra had much better effect than placebo. About 800 patients with seasonal allergic rhinitis were had to assess the effect of Allegra compared to the placebo. Allegra resulted much more efficient than placebo.
About two hundred patients with chronic idiopathic urticaria were assessed for 14 days. They took Allegra or placebo. 4 various doses of Allegra (60-240 mg) were used. This therapy resulted in a great reduction in itching, lower impairment of daytime activities and normal sleep. Two higher daily dosages (180 or 240 mg) were much more efficient than placebo.
The common dosage is 120 mg a day. Allegra comes in the form of tablets (in the dosage of 60 to 180 mg). The medicine must be prescribed by your doctor. If you have seasonal allergic rhinitis, you should take a 120 mg dose once a day, while for urticaria you must take a 180 mg dose. Kids under the age of 12, pregnant and breastfeeding women must avoid taking Allegra. Patients with renal dysfunction should to reduce the dosage and increase the interval between the intakes. Older patients must take a lower dosage as well.
Studies have shown that patients treated with Allegra had no more side effects than those getting placebo. According to the manufacturer, only about 1% of about 2500 people experienced:
head pain or stiff neck
Patients receiving placebo often note the same symptoms. Only influenza-like symptoms (2.5%) and dysmenorrhea (1.5%) were noted in the treated patients, but they doesn’t seem related to the treatment with Allegra. As any modern H1 antihistamine, it overcomes only a small part of the blood-brain barrier. For this reason, the drug has a very low sedative effect.
Rare adverse effects are:
pain in the throat
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