Chlorphenamine

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Chlorphenamine Systematic (IUPAC) name 3-(4-chlorophenyl)-N,N-dimethyl- 3-pyridin-2-yl-propan-1-amine Identifiers CAS number 132-22-9 ATC code R06AB04 PubChem 2725 DrugBank DB01114 ChemSpider 2624 Chemical data Formula C16H19ClN2  Mol. mass 274.788 g/mol Physical data Solubility in water 0.55 g/100 mL, liquid mg/mL (20 °C) Pharmacokinetic data Bioavailability 25 to 50% Protein binding 72% Metabolism Hepatic (CYP2D6) Half life 21-27 hours Excretion Renal Therapeutic considerations Pregnancy cat. A(AU) B(US) Legal status Pharmacist Only (S3)(AU) GSL(UK) OTC(US) (for oral forms) Routes Oral, IV, IM, SC

Chlorphenamine 4mg, in the UK

Chlorphenamine (INN) or chlorpheniramine (USAN, former BAN), commonly marketed as its salt chlorphenamine maleate (CPM; Chlor-Trimeton, Piriton, Chlor-Tripolon), is a first-generation alkylamine antihistamine used in the prevention of the symptoms of allergic conditions such as rhinitis and urticaria. Its sedative effects are relatively weak compared to other first-generation antihistamines. Chlorpheniramine is one of the most commonly used antihistamines in small-animal veterinary practice as well. Although not generally approved as an antidepressant or anti-anxiety medication, chlorpheniramine appears to have these properties as well (see below).

Chlorpheniramine is part of a series of antihistamines including pheniramine (Naphcon) and its halogenated derivatives and others including fluorpheniramine, dexchlorpheniramine (Polaramine), brompheniramine (Dimetapp), dexbrompheniramine (Drixoral) deschlorpheniramine, dipheniramine (also known as triprolidine with the trade name Actifed), and iodopheniramine.

The halogenated alkylamine antihistamines all exhibit optic isomerism and chlorpheniramine in the indicated products is racemic chlorpheniramine maleate whereas dexchlorpheniramine (Polaramine) is the dextrorotary (right-handed) stereoisomer.

Also known as "Comakin" in Taiwan and parts of Asia.^{[citation needed]}

[edit] Serotonergic and Norepinephrinergic Hypothesis

In addition to being an H-1 histamine receptor antagonist, chlorpheniramine has been hypothesized to work as a Serotonin-norepinephrine reuptake inhibitor or SNRI ^[1], although extensive clinical trials of its psychiatric properties in humans have not been conducted. Limited clinical evidence suggests that it is comparable to several antidepressant medications in its ability to inhibit the reuptake of serotonin and possibly also norepinephrine (noradrenaline).

[edit] Combination medications

Chlorpheniramine is often combined with phenylpropanolamine to form an allergy medication with both antihistamine and decongestant properties. Brand names include Demazin, Allerest 12 Hour, Codral Nighttime, Chlornade, Contac 12 Hour, A. R. M. Allergy Relief, Ordrine, Ornade Spansules, Teldrin, Triaminic, and Tylenol Cold/Allergy.

Chlorpheniramine is combined with a narcotic (hydrocodone) in the product Tussionex which is indicated for treatment of cough and upper respiratory symptoms associated with allergy or cold in adults and children 6 years of age and older^[2]. This combination is manufactured as a time-released formula, which allows for administration every 12 hours versus the more common 4 to 6 hour regimen for other narcotic cough suppressants. See Pennkinetic Technology by Celltech.

[edit] Off-label uses

Chlorphenamine can be effective as a mild anxiolytic.^[3] It inhibits norepinephrine and serotonin reuptake, but serotonin reuptake less so. These qualities make it a mild Serotonin-norepinephrine reuptake inhibitor.^[4]

[edit] See also

• Diphenhydramine
• Coricidin
• Dexchlorpheniramine

[edit] References

1. ^ Hellbom, E. (2006). Chlorpheniramine, selective serotonin-reuptake inhibitors (SSRIs) and over-the-counter (OTC) treatment. Medical Hypotheses, 66(4), 689 - 690.
2. ^ "UCB :: Tussionex™ (Respiratory Disease)." 2007. UCB, Inc.. 11 Jul 2008 <http://www.ucb-group.com/products/860.asp>.
3. ^ Bruce G. Charlton, Self-management of psychiatric symptoms using over-the-counter (OTC) psychopharmacology: the S-DTM therapeutic model - self-diagnosis, self-treatment, self-monitoring. Medical Hypotheses 2005; 65: 823-828.
4. ^ Edward F. Domino, History of Modern Psychopharmacology: A Personal View With an Emphasis on Antidepressants. Psychosomatic Medicine 1999; 61:591-598.