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Allegra vs Claritin

5/8/2016 5:37:24 AM
Allegra vs Claritin

Let us discuss the difference between two preparations and try to find out who is the winner in the “pharm-fight” Allegra vs Claritin.

Antihistamines are used to treat the symptoms of seasonal allergic rhinitis (CAP) for more than 55 years; during this time, it has been repeatedly described hypo sensitivities to them or the development of tolerance to their action. According to the results of earlier studies with antihistamines of first generation of efficacy and side effects on the central nervous system of the central nervous system (eg, sedation) is significantly decreased after 3 weeks of treatment. It has been suggested that this is a consequence of modulation H1-receptors, and not changes in the metabolism of antihistamines. Since the first studies in the use of antihistamines obtained significant achievements, and is currently effective elimination of CAP is not accompanied by symptoms of central nervous system disorders, characteristic of antihistamines I generation. However, patients still need a long suppression of symptoms throughout the pollen season. In this regard, it is important to assess whether hypo sensitivities develops in the admission of new antihistamines. We need to compare the efficacy of Allegra and Claritin the treatment of CAP for 2 weeks.

Historically, that the term "antihistamines" refers to agents that block the H1-histamine receptors and drugs acting on the H2-histamine receptors (cimetidine, ranitidine, famotidine, etc..), Called H2-histamine blockers. The first is used for the treatment of allergic diseases, the latter used as ant secretory agents.

Histamine, the major mediator of various pathological and physiological processes in the body have been chemically synthesized. Subsequently, it was isolated from the tissues of animals and humans (Windaus A., Vogt W.). Still later identified his functions. Gastric secretion, neuromediatory function in the central nervous system, allergic reactions, inflammation, etc. After nearly 21 years, in 1936, the first material having antihistamine activity were created. And in 61 years proved the heterogeneity of receptors in the body histamine, and is divided into three subtypes: H1, H2 and H3, which differ in structure, localization and physiological effects arising at their activation and blockade. Since that time the active period of synthesis and clinical testing of various antihistamines.

Numerous studies have shown that histamine acting on the receptors of the respiratory system, eyes and skin, it causes the characteristic symptoms of allergies and antihistamine drugs that selectively block the H1-type receptors, their ability to prevent and arrest.

The chemical structure of most of them relate to a fat-soluble amines which possess a similar structure. Nucleus (R1) is represented by an aromatic and / or heterocyclic group and is connected by means of a nitrogen molecule, oxygen or carbon (X) with an amino group. The kernel determines the severity of antihistamine activity and some of the properties of matter. Knowing its composition, can predict the strength of the drug and its effects, such as the ability to penetrate the blood-brain barrier.

Antihistamines block the action of histamine at H1 receptors by a mechanism of competitive inhibition, their affinity for these receptors is considerably lower than that of histamine. Therefore, drugs capable of data not displace histamine bound to the receptor, they only block the unoccupied receptors or released. Accordingly, the H1-blockers are most effective for the prevention of allergic immediate type reactions, and prevent the release of histamine in the new portions of the case, which developed reaction.

There are several classifications of antihistamines, although none of them is not universally accepted. According to one of the most popular classifications antihistamines creation time is divided into first- and second-generation. the first generation of drugs (not Claritin) is also called sedative (on the dominant side effect) as opposed to the non-sedating second generation drugs. At the present time, and decided to allocate the third generation: it is treated fundamentally new means - active metabolites, exhibiting, in addition to the highest anti-histamine activity, the absence of sedation and the characteristic of the second-generation drugs cardio toxicity.

Antihistamines are the first generation (sedatives). All of them are readily soluble in fats and, in addition to the H1-histamine, also block cholinergic, muscarinic receptors and serotonin. As competitive blockers, they reversibly bind to the H1-receptors, which makes use of relatively high doses. For these, the most characterized by the following pharmacological properties.

    Sedation is determined by the fact that the majority of first generation antihistamines, easily soluble in lipids, well penetrate the blood-brain barrier and bind to brain H1-receptors. Perhaps their sedative effect develops of blocking central serotonin and acetylcholine receptors. The degree of manifestation of the first generation sedating effect varies in different products and in different patients from mild to severe, and is enhanced when combined with alcohol and psychotropic drugs. Some of them are used as hypnotics. Occasionally, instead of sedation occurs psychomotor agitation (often in doses of Allegra in children and in high toxic in adults). Because of the sedation, most drugs cannot be used during the performance of work requiring attention. All first-generation drugs potentiate the action of sedatives and hypnotic drugs, narcotic and non-narcotic analgesics, monoamine oxidase inhibitors and alcohol.
    The anxiolytic effect, characteristic of hydroxyzine, may be due to the suppression of activity in certain areas of the subcortical region of CNS.

Moreover, many of the qualities, which were discussed, allowed to take the "old" antihistamines their niche in the treatment of certain pathologies (migraine, sleep disorders, extrapyramidal disorders, anxiety, motion sickness, etc.) Are not associated with allergies. Many first-generation antihistamines is part of the combined drugs used for colds, as a soothing, hypnotic, and other components.