These are the active enantiomer (levocetirizine, desloratadine) or metabolite (fexofenadine) derivatives of second-generation drugs intended to have increased efficacy with fewer adverse drug reactions. Indeed, fexofenadine is associated with a decreased risk of cardiac arrhythmia compared to terfenadine. However, there is little evidence for any advantage of levocetirizine or desloratadine, compared to cetirizine or loratadine respectively. Antihistamine - SystemicSee also:

Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H₁-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H₂-receptor antagonists, Antihistamine - H₃- and H₄-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - Third-generation H₁-receptor antagonists

Acetylcholine receptors, of which muscarinic receptors are a subdivision, are widely distributed in both the central nervous system and the autonomic nervous system. The autonomic nervous system is anatomically distinct from the somatic nervous system. The autonomic nervous system controls various involuntary actions, such as heart rate, pupil dilation, sweating, salivation, urination and defecation, digestion, and so on. These actions are known as involuntary, that is to say that the conscious mind is unaware of these actions, or unable to influence them. It is the autonomic nervous system a ...

See also:

Muscarinic acetylcholine receptor, Muscarinic acetylcholine receptor - Context, Muscarinic acetylcholine receptor - Physiology, Muscarinic acetylcholine receptor - The Form of Muscarinic Receptors, Muscarinic acetylcholine receptor - Variety of Receptor Forms, Muscarinic acetylcholine receptor - Receptor Subtype m1, Muscarinic acetylcholine receptor - m2, Muscarinic acetylcholine receptor - m3, Muscarinic acetylcholine receptor - m4, Muscarinic acetylcholine receptor - m5

Read more here: » Muscarinic acetylcholine receptor: Encyclopedia II - Muscarinic acetylcholine receptor - Context

In allergic reactions an allergen (a type of antigen) interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H1-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, bronchoconstriction, increases vascular permeabili ...

See also:

Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H₁-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H₂-receptor antagonists, Antihistamine - H₃- and H₄-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - Pharmacology

There has been a notable increase in the commonness of allergies in the past decades, and there are multiple hypotheses explaining this phenomenon. Allergy - The hygiene hypothesis. One theory that has been gaining strength is the "hygiene hypothesis". This theory maintains that since children in more affluent countries are leading a cleaner and cleaner life (less exposure to dirt, extra use of disinfectants, etc), their immune systems have less exposure to parasites and other pathogens than children in ot ...

See also:

Allergy, Allergy - History, Allergy - Signs and symptoms, Allergy - Diagnosis, Allergy - Skin test, Allergy - Problems with skin test, Allergy - Total IgE count, Allergy - Treatment, Allergy - Immunotherapy, Allergy - Chemotherapy, Allergy - Alternative therapies, Allergy - Pathophysiology, Allergy - Acute response, Allergy - Late-phase response, Allergy - Basis of the allergic response, Allergy - Genetic Basis, Allergy - Relationship with parasites, Allergy - Basis of increasing prevalence, Allergy - The hygiene hypothesis, Allergy - Increasing use of chemicals, Allergy - Common allergens

Read more here: » Allergy: Encyclopedia II - Allergy - Basis of increasing prevalence

Muscarinic acetylcholine receptors belong to a class of metabotropic receptors which use G proteins as their signalling mechanism. There are known to be a large number of these G protein-coupled receptors for neuroreceptors, hormones, and other substances. G proteins are also present in taste, and odour detecting cells, in the retina, and in many other systems. In such receptors, the signalling molecule (the ligand) binds to a receptor which has seven transmembrane regions, in our case the ligand is ACh. This receptor is bound to intracellul ...

See also:

Muscarinic acetylcholine receptor, Muscarinic acetylcholine receptor - Context, Muscarinic acetylcholine receptor - Physiology, Muscarinic acetylcholine receptor - The Form of Muscarinic Receptors, Muscarinic acetylcholine receptor - Variety of Receptor Forms, Muscarinic acetylcholine receptor - Receptor Subtype m1, Muscarinic acetylcholine receptor - m2, Muscarinic acetylcholine receptor - m3, Muscarinic acetylcholine receptor - m4, Muscarinic acetylcholine receptor - m5

Read more here: » Muscarinic acetylcholine receptor: Encyclopedia II - Muscarinic acetylcholine receptor - The Form of Muscarinic Receptors

These are newer drugs that are much more selective for peripheral H1 receptors in preference to the central nervous system histaminergic and cholinergic receptors. This selectivity significantly reduces the occurrence of adverse drug reactions compared with first-generation agents, while still providing effective relief of allergic conditions. Antihistamine - Systemic. acrivastine astemizole cetirizine loratadine mizolastine terfenadine (withdrawn from ...

See also:

Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H₁-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H₁-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H₂-receptor antagonists, Antihistamine - H₃- and H₄-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - Second-generation H₁-receptor antagonists