Dextromethorphan

Today's med: Dextromethorphan (deks troe meth OR fan) 

(brand names: Robitussin, Vick's DayQuil Cough, Creo-Terpin, Creomulsion, Delsym, Father John's, Nycoff, Robafen Cough, Scot-Tussin, Silphen-DM, Triaminic Cough)

Snapshot:

          Use: Cough

·        Action: antitussive

·        SE: severe dizziness, anxiety, restless feeling, or nervousness

·        CI:  (allergic reaction), atopic children, who are especially susceptible to allergic reactions

·        I: MAOIs,  SSRI (potential for serotonin syndrome),  grapefruit juice 

Drug Class: Antitussive, N-Methyl-D-Asparate Receptor Antagonist

Other Drugs in this class: Dextromethorphan/Quinidine,Dextromethorphan/Guaifenesin,

Promethazine/Dextromethorphan,Acetaminophen/Dextromethorphan/Phenylephrine,

Dextromethorphanhydrobromide,Acetaminophen/Dextromethorphan/Guaifenesin/Phenylephrine,

Acetaminophen/Dextromethorphan,Chlorpheniramine/Dextromethorphan,Acetaminophen/Dextromethorphan/Doxylamine,Dextromethorphan/Phenylephrine,Acetaminophen/Chlorpheniramine/Dextromethorphan/Phenylephrine,Pseudoephedrine/Guaifenesin/Dextromethorphan,Acetaminophen/Dextromethorphan/Diphenhydramine,Acetaminophen/Dextromethorphan/Guaifenesin/Pseudoephedrine,Brompheniramine/Pseudoephedrine/Dextromethorphan,Guaifenesin/Phenylephrine/Dextromethorphan,Dextromethorphan/Chlorpheniramine/Phenylephrine,Brompheniramine/Phenylephrine/Dextromethorphan,Acetaminophen/Dextromethorphan/Guaifenesin,Triprolidine/Pseudoephedrine/Dextromethorphan,Acetaminophen/Dextromethorphan/Chlorpheniramine,Dextromethorphan/Doxylamine,Dextromethorphan/Pseudoephedrine/Chlorpheniramine,Benzocaine/Dextromethorphan,Acetaminophen/Dextromethorphan/Doxylamine/Phenylephrine,Acetaminophen/Dextromethorphan/Doxylamine/Pseudoephedrine,Dexbrompheniramine/Dextromethorphan/Phenylephrine,Dexbrompheniramine/Dextromethorphan/Pseudoephedrine,Dextromethorphan/Pseudoephedrine/Pyrilamine,Pyrilamine/Phenylephrine/Dextromethorphan,Aspirin/Dextromethorphan/Phenylephrine,Aspirin/Doxylamine/Phenylephrine/Dextromethorphan,Menthol/Benzocaine/Dextromethorphan

Indications: Symptomatic relief of coughs caused by the common cold or inhaled irritants

Use: Unlabeled: N-methyl-D-aspartate (NMDA) antagonist

Action: Decreases the sensitivity of cough receptors and interrupts cough impulse transmission by depressing the medullary cough center through sigma receptor stimulation; structurally related to codeine

Contraindications: Concurrent administration with or within 2 weeks of discontinuing an MAO inhibitor

Adverse Effects: Central nervous system: Confusion, excitement, irritability, nervousness, serotonin syndrome

Warnings:

Concurrent drug therapy issues:

• Serotonin syndrome: Symptoms of agitation, confusion, hallucinations, hyper-reflexia, myoclonus, shivering, and tachycardia may occur with concomitant proserotonergic drugs (ie, SSRIs/SNRIs or triptans); especially with higher dextromethorphan doses.

Special populations:

• Debilitated patients: Use with caution in patients who are sedated, debilitated or confined to a supine position.

• Neonates: Some products may contain sodium benzoate which has been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; in vitro and animal studies have shown that benzoate, a metabolite of benzyl alcohol, displaces bilirubin from protein binding sites; avoid use of products containing sodium benzoate in neonates.

• Pediatrics: Use with caution in atopic children. Not for OTC use in children <4 years of age.

Dosage form specific issues:

• Sodium benzoate: Some products may contain sodium benzoate may cause allergic reactions in susceptible individuals.

• Tartrazine: Some products may contain tartrazine.

Other warnings/precautions:

• Abuse/misuse: Healthcare providers should be alert to problems of abuse or misuse. Abuse can cause death, brain damage, seizure, loss of consciousness, and irregular heartbeat.

• Self-medication (OTC use): When used for self medication (OTC) notify healthcare provider if symptoms do not improve within 7 days, or are accompanied by fever, rash or persistent headache. Do not use for persistent or chronic cough (as with smoking, asthma, chronic bronchitis, emphysema) or if cough is accompanied by excessive phlegm unless directed to do so by healthcare provider.

Pregnancy Considerations

Maternal use of standard OTC doses of dextromethorphan when used as an antitussive during the first trimester of pregnancy has not been found to increase the risk of teratogenic effects. Dextromethorphan is metabolized in the liver via CYP2D6 and CYP3A enzymes. The activity of both enzymes is increased in the mother during pregnancy. In the fetus, CYP2D6 activity is low in the fetal liver and CYP3A4 activity is present by ~17 weeks gestation.

Standard Dosing:  Oral: Children:

<4 years: Not for OTC use

4-6 years (syrup): 2.5-7.5 mg every 4-8 hours; extended release is 15 mg twice daily (maximum: 30 mg/24 hours)

6-12 years: 5-10 mg every 4 hours or 15 mg every 6-8 hours; extended release is 30 mg twice daily (maximum: 60 mg/24 hours)

Children >12 years and Adults: 10-20 mg every 4 hours or 30 mg every 6-8 hours; extended release: 60 mg twice daily; maximum: 120 mg/day

Drug interactions: http://www.drugs.com/drug-interactions/dextromethorphan.html

A total of 58 drugs (160 brand and generic names) are known to interact with dextromethorphan.

• 30 major drug interactions (80 brand and generic names)
• 23 moderate drug interactions (65 brand and generic names)
• 5 minor drug interactions (15 brand and generic names)

Show all medications in the database that may interact with dextromethorphan.

Abiraterone Acetate: May increase the serum concentration of CYP2D6 Substrates. Management: Avoid concurrent use of abiraterone with CYP2D6 substrates that have a narrow therapeutic index whenever possible. When concurrent use is not avoidable, monitor patients closely for signs/symptoms of toxicity. Consider therapy modification

Antipsychotics: May enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome.Monitor therapy

CYP2D6 Inhibitors (Moderate): May decrease the metabolism of CYP2D6 Substrates. Monitor therapy

CYP2D6 Inhibitors (Strong): May decrease the metabolism of CYP2D6 Substrates. Consider therapy modification

Darunavir: May increase the serum concentration of CYP2D6 Substrates. Monitor therapy

MAO Inhibitors: May enhance the serotonergic effect of Dextromethorphan. This may cause serotonin syndrome. Avoid combination

Metoclopramide: Serotonin Modulators may enhance the adverse/toxic effect of Metoclopramide. This may be manifest as symptoms consistent with serotonin syndrome or neuroleptic malignant syndrome. Monitor therapy

Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates. Monitor therapy

QuiNIDine: May increase the serum concentration of Dextromethorphan. Management: Avoid concurrent use of these agents when possible, unless the increased psychoactive effects of dextromethorphan are desired. Since codeine activation is also inhibited by quinidine, codeine is unlikely to be suitable as an alternative antitussive. Consider therapy modification

Selective Serotonin Reuptake Inhibitors: May enhance the serotonergic effect of Dextromethorphan. Selective Serotonin Reuptake Inhibitors may increase the serum concentration of Dextromethorphan. Management: Avoid the concurrent use of dextromethorphan and SSRIs, particularly fluoxetine and paroxetine, when possible. The risk for this interaction may persist for several weeks following discontinuation of fluoxetine or paroxetine. Exceptions: FluvoxaMINE.Consider therapy modification

Serotonin Modulators: May enhance the adverse/toxic effect of other Serotonin Modulators. The development of serotonin syndrome may occur. Consider therapy modification

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