Acute Rhinitis - Common Cold

The common cold is the most prevalent type of upper respiratory infection

The common cold is caused by the rhinovirus and affects primarily the nasopharyngeal tract

Acute rhinitis is inflammation of the mucous membranes of the nose.

The groups used to manage cold symptoms are antihistamines (H1 blockers), decongestants (sympathomimetic amines), antitussives, and expectorants.

Antihistamines (H1 blockers or antagonists) compete with histamine for receptor sites, preventing the histamine response. When the H1 receptor is stimulated the extravascular smooth muscles are constricted. With stimulation of the H2 receptors an increase of gastric secretion occurs which is a cause of a peptic ulcer. They are not potent enough for anaphylazis.

Most first gen antihistamines cause drowsiness, dry mouth and other anticholinergic symptoms while second gen have lower incidences of these. Benadryl (diphenhydramine) is a first gen.

The second generation antihistamines are frequently called nonsedating antihistamines because they have little sedation. They also have fewer anticholineric responses. These are cetirizine (Zyrtec), fexofenadine (Allegra), and loratadine (Claritin). Azelastine (Astelin) is taken as a nasal spray and has a half life of 22 hours.

Diphenhydramine (Benadryl) can be oral, IM, IV. Well absorbed from GI tract but topical is minimal. It is highly protein bound. It blockes the effects of histamine by competing and occupying H1 receptor sites. Not for those with narrow angle glaucoma. Drowsiness is a major side effect. It is some times used as a sleep aid. Can also be used as antitussive. Can cause CNS depression if taken with other depressants. Common side effects of first generation is drowsiness, dizziness, faituge, and disturbed coordination.

Nasal decongestants (sympathomimetic amines) stimulate the alpha adrenergic receptors, producing vascular constriction of the capillaries within the nasal mucosa. The result is shrinking of the nasal mucous membranes and a reduction in fluid secretion. They can be administered by nasal spray or drops or in tablet, cap, or liquid form. Frequent use can result in tolerance and rebound nasal congestion (rebound vasodilation instead of contriciton).

Systemic decongestants (alpha adrenergic agonists) are avail in tab, cap or liquid form and used for allergic rhinitis. These are ephedrine (Ephedrine) and pseudoephedrine (Sudafed). Ephedrine, phenylephrine, and pseudoephedrine are frequently combined with an antihistamine, analgesic, or antitiussive oral cold remedies. The advantage of systemic decongestants is that they relieve nasal congestion for a longer period than nasal decongestants. Nasal decongests act more promptly and cause fewer side effects.

As with any alpha adrenergic drug (decongestants)