Dextromethorphan


Concise Prescribing Info
Indications/Uses
Cough suppressant.
Dosage/Direction for Use
Adult : PO As dextromethorphan hydrobromide: As conventional preparation: 10-20 mg 4 hourly, or 30 mg 6-8 hourly. As extended-release preparation: 60 mg 12 hourly. Max: 120 mg/day. As loz: Suck not more than 12 loz/day.
Dosage Details
Oral
Cough suppressant
Adult: As dextromethorphan hydrobromide: As conventional preparation: 10-20 mg 4 hourly, or 30 mg 6-8 hourly. As extended-release preparation: 60 mg 12 hourly. Max: 120 mg daily. As loz: Suck not more than 12 loz daily.
Child: >12 years Same as adult dose.
Administration
May be taken with or without food.
Contraindications
Asthma, bronchitis, emphysema or other conditions where persistent or chronic cough occurs. Concomitant use or within 14 days of MAOI or SSRI therapy. Children <12 years.
Special Precautions
Patient with history of drug abuse. Children. Treatment with a cough medicine in children (especially under 12 years old) should be considered carefully due to potential risks and limited evidence on efficacy. Pregnancy and lactation.
Adverse Reactions
Gastrointestinal disorders: Abdominal pain, diarrhoea, gastrointestinal disturbance, nausea, vomiting.
Nervous system disorders: Dizziness, drowsiness, convulsion, psychomotor hyperactivity, somnolence, serotonin syndrome, excitement, nervousness.
Psychiatric disorders: Insomnia, confusional state.
Respiratory, thoracic and mediastinal disorders: Respiratory depression.
Patient Counseling Information
This drug can cause drowsiness or cognitive function impairment, if affected, do not drive or operate machinery.
Overdosage
Symptoms: Mydriasis, nausea, vomiting, CNS depression, excitations, lethargy, nystagmus, psychomotor hyperactivity, serotonin syndrome, somnolence, dizziness, dysarthria, mental confusion, psychotic disorder, respiratory depression. Management: Supportive and symptomatic treatment. May perform gastric lavage. Naloxone may be effective in reversing toxicity.
Drug Interactions
Additive CNS effect when used with antihistamines, psychotropics and other CNS depressants. Increased toxic effect when used with potent CYP2D6 enzyme inhibitors (e.g. fluoxetine, paroxetine, quinidine, terbinafine).
Potentially Fatal: Increased risk of serotonin syndrome (e.g. hyperpyrexia, hallucinations, gross excitation or coma) when concomitantly used with MAOIs or SSRIs.
Food Interaction
Additive CNS effect when used with alcohol.
Lab Interference
False positive phencyclidine, opioids and heroin urine drug screen.
Action
Description: Dextromethorphan, a centrally-acting antitussive agent, depresses the medullary cough centre through sigma receptor stimulation, resulting to decreased sensitivity of cough receptors and interruption of cough impulse transmission.
Onset: 15-30 minutes.
Duration: ≤6 hours.
Pharmacokinetics:
Absorption: Rapidly absorbed from the gastrointestinal tract. Time to peak plasma concentration: 2-3 hours.
Distribution: Widely distributed.
Metabolism: Metabolised in the liver via demethylation by CYP2D6 enzyme to dextrorphan (active); undergoes rapid and extensive first-pass metabolism.
Excretion: Via urine, as unchanged drug and metabolites. Elimination half-life: 2-4 hours (extensive metabolisers); 24 hours (poor metabolisers).
Chemical Structure

Chemical Structure Image
Dextromethorphan

Source: National Center for Biotechnology Information. PubChem Database. Dextromethorphan, CID=5360696, https://pubchem.ncbi.nlm.nih.gov/compound/Dextromethorphan (accessed on Jan. 20, 2020)

Storage
Store between 20-25°C. Protect from light.
ATC Classification
R05DA09 - dextromethorphan ; Belongs to the class of opium alkaloids and derivatives. Used as cough suppressant.
References
Anon. Dextromethorphan. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 02/08/2018.

Anon. Dextromethorphan. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 02/08/2018.

Buckingham R (ed). Dextromethorphan. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 02/08/2018.

Delsym Suspension, Extended-Release (Reckitt Benckiser LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/08/2018.

Dextromethorphan HBr Capsules, Liquid Filled [Humanwell PuraCap Pharmaceutical (Wuhan), Ltd.]. DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 02/08/2017.

Disclaimer: This information is independently developed by MIMS based on Dextromethorphan from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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