ATC Group: S01G Decongestants and antiallergics

Alcaftadine is an H₁ histamine receptor antagonist and inhibitor of the release of histamine from mast cells. Decreased chemotaxis and inhibition of eosinophil activation has also been demonstrated.

Azelastine, a phthalazinone derivative is classified as a potent long-acting anti-allergic compound with selective H₁ antagonist properties. An additional anti-inflammatory effect could be detected after topical ocular administration. Data from in vivo (pre-clinical) and in vitro studies show that azelastine inhibits the synthesis or release of the chemical mediators known to be involved in early and late stage allergic reactions e.g. leukotriene, histamine, PAF and serotonin.

Brimonidine is an alpha₂-adrenergic receptor agonist that is 1000-fold more selective for the alpha₂-adrenoceptor than the alpha₁-adrenoreceptor. This selectivity results in no mydriasis and the absence of vasoconstriction in microvessels associated with human retinal xenografts.

Sodium cromoglicate (Cromoglicic acid) inhibits the activation of many of the cell types involved in the development and progression of asthma. Thus, sodium cromoglicate inhibits the release of inflammatory mediators including cytokines from mast cells and reduces the chemotactic activity of eosinophils and neutrophils.

Emedastine is a potent selective and topically effective histamine H₁ antagonist. In vivo topical ocular administration of emedastine produces a concentration-dependent inhibition of histamine-stimulated conjunctival vascular permeability.

Epinastine is a topically active, direct H₁-receptor antagonist and an inhibitor of the release of histamine from the mast cell. Epinastine is selective for the histamine H₁-receptor and has affinity for the histamine H₂receptor. Epinastine also possesses affinity for the α₁, α₂, and 5-HT₂–receptors.

Ketotifen is a histamine H₁-receptor antagonist. In vivo animal studies and in vitro studies suggest the additional activities of mast cell stabilisation and inhibition of infiltration, activation and degranulation of eosinophils.

Levocabastine is a potent, fast-acting and highly selective histamine H1-antagonist with a sustained duration of action.

Lodoxamide is a mast cell stabiliser that inhibits the in vivo Type I immediate hypersensitivity reaction in animals and man.

Naphazoline is a sympathomimetic amine with pronounced alpha adrenergic activity and as a consequence has vasoconstrictor activity.

Nedocromil is a non-steroidal agent, which has anti-inflammatory properties when administered topically in the lung. In the treatment of bronchial asthma, nedocromil sodium reduces bronchospasm, cough and bronchial hyperreactivity and improves objective measurements of lung function.

Olopatadine is a potent selective antiallergic/antihistaminic agent that exerts its effects through multiple distinct mechanisms of action.

Oximetazoline is an imidazoline derivative. It exhibits sympathomimetic activity and specifically stimulates the α-adrenergic receptors of the sympathetic system. When administered topically to the nose it causes vasoconstriction of the expansed arterioles of the mucosal nose and a concurrent reduction in blood flow. It also reduces the hypersecretion of the nasal mucosa, ultimately contributing to the decongestion of the nasal mucosa.

Phenylephrine is a sympathomimetic agent with mainly direct effects on adrenergic receptors. It has predominantly alpha adrenergic activity and is without stimulating effects on the central nervous system. The sympathomimetic effect of phenylephrine produces vasoconstriction which in turn relieves nasal congestion.

Tetryzoline is an alpha adrenergic receptor agonist, which is used in form of nasal solution or spray for decongestion of nasal and nasopharyngeal mucosa.

Xylometazoline acts directly on α-adrenoreceptors but does not act on β-receptors. When used topically as a nasal decongestant, xylometazoline acts rapidly and provides long-lasting relief. Onset of action is within minutes, the decongestant effect being prolonged and lasting for up to 10 hours.