Dextromethorphan Hydrobromide
Also known as: Dextromethorphan Hydrobromide, DXM HBr, Dextromethorphan, DXM, DM, Robitussin
Overview
Dextromethorphan Hydrobromide (DXM HBr) is a synthetic compound primarily used as an over-the-counter cough suppressant. It is the dextrorotatory enantiomer of levomethorphan. While primarily known for its antitussive properties, DXM also acts as an NMDA receptor antagonist, which has led to its investigation as an adjunct for perioperative pain management. It works centrally in the medulla to suppress the cough reflex and interacts with opioid and glutamatergic pathways. DXM is available in various forms, including oral tablets, syrups, and lozenges. It is rapidly absorbed after oral administration but has a relatively low bioavailability of approximately 11% due to extensive first-pass metabolism. Research supports its efficacy for cough suppression, while its role in pain management is still being explored.
Benefits
Dextromethorphan Hydrobromide is primarily used for cough suppression. Meta-analyses of placebo-controlled RCTs have shown a modest but statistically significant reduction in cough sensitivity. Studies indicate that DXM can reduce cough sensitivity within 1-2 hours of administration. Additionally, research suggests that DXM may be beneficial in postoperative pain management. Meta-analyses have demonstrated a significant reduction in pain scores at 1, 4-6, and 24 hours postoperatively, as well as a reduction in opioid consumption. These benefits have been observed in both adults and children, making DXM a versatile option for managing cough and potentially pain in various populations. However, the evidence for pain management is still considered moderate and requires further high-quality studies.
How it works
Dextromethorphan Hydrobromide primarily works by acting centrally in the medulla oblongata to suppress the cough reflex. It also functions as an NMDA receptor antagonist, which is believed to contribute to its potential analgesic effects. DXM interacts with the central nervous system (CNS), potentially affecting opioid and glutamatergic pathways. At the molecular level, DXM acts as a sigma-1 receptor agonist and, at higher doses, can inhibit serotonin and norepinephrine reuptake. Its rapid absorption after oral administration allows for relatively quick onset of action, though its bioavailability is limited by first-pass metabolism.
Side effects
Dextromethorphan Hydrobromide is generally considered safe at recommended doses for cough suppression. Common side effects include dizziness, nausea, sedation, and headache, typically occurring in more than 5% of users. Less common side effects (1-5%) may include vomiting, abdominal pain, and confusion. Rare but potentially serious side effects (less than 1%) include severe allergic reactions, serotonin syndrome (particularly when combined with other serotonergic drugs), and hallucinations, which are more likely at supratherapeutic doses. DXM can interact with MAO inhibitors and serotonergic drugs, increasing the risk of serotonin syndrome. It is contraindicated in individuals using MAO inhibitors within 14 days and those with a history of hypersensitivity. Caution is advised in elderly individuals, those with hepatic impairment, and patients taking other CNS-active drugs.
Dosage
For cough suppression in adults, the recommended dosage of Dextromethorphan Hydrobromide is typically 15-30 mg every 4-6 hours as needed, with a maximum daily dose of 120 mg. In perioperative settings, studies have used higher doses, such as 40-90 mg preoperatively, but these should be administered under medical supervision. DXM is available in various forms, including oral tablets, syrups, and lozenges. While absorption is best on an empty stomach, food does not significantly impair it. It is important to adhere to the recommended dosage and not exceed the maximum safe dose to minimize the risk of adverse effects. No specific cofactors are required for its activity.
FAQs
Is Dextromethorphan an opioid?
No, Dextromethorphan is not an opioid, although it is structurally related to opioids. It primarily acts as a cough suppressant and NMDA receptor antagonist, without the same addictive properties as opioids at recommended doses.
Can I take Dextromethorphan with other medications?
Dextromethorphan can interact with certain medications, particularly MAO inhibitors and serotonergic drugs, increasing the risk of serotonin syndrome. Consult a healthcare professional before combining DXM with other medications.
What are the side effects of Dextromethorphan?
Common side effects include dizziness, nausea, sedation, and headache. Less common side effects may include vomiting, abdominal pain, and confusion. Serious side effects are rare but can include allergic reactions and serotonin syndrome.
How often can I take Dextromethorphan for cough?
Dextromethorphan can be taken every 4-6 hours as needed for cough, but do not exceed the maximum daily dose of 120 mg for adults. It is not recommended for chronic cough without medical supervision.
Does Dextromethorphan provide significant pain relief?
At cough-suppressant doses, Dextromethorphan does not provide significant pain relief. However, higher doses have been investigated for perioperative pain management, showing moderate reduction in postoperative pain and opioid use.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4755866/ – This meta-analysis of 21 trials (884-950 patients) evaluated perioperative dextromethorphan for postoperative pain. The study found a significant reduction in pain scores at 1, 4-6, and 24 hours postoperatively, as well as reduced opioid consumption at 24-48 hours. While the study was high-quality, some variability in study design and outcomes was noted.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2432485/ – This meta-analysis of RCTs examined the antitussive efficacy of dextromethorphan in acute cough. The study, involving three placebo-controlled studies, found a modest but significant reduction in cough sensitivity. The quality of the study was moderate, limited by a small sample size and placebo effects.
- https://onlinelibrary.wiley.com/doi/full/10.1002/ppul.26416 – This systematic review assessed objective and self-reported evidence of dextromethorphan's efficacy in children. The review found evidence of antitussive efficacy in children using both objective and subjective measures. The quality of the review was moderate, supporting the use of dextromethorphan in children, but noted a limited number of high-quality pediatric studies.
- https://archive.hshsl.umaryland.edu/server/api/core/bitstreams/cba31b30-1fdc-4adb-bc4a-3f7e154a36b0/content – This source is a presentation regarding the use of dextromethorphan for chronic cough. It provides an overview of the pharmacology, clinical efficacy, and safety considerations of dextromethorphan in treating chronic cough, highlighting its role as a centrally acting cough suppressant.
- https://cdn.clinicaltrials.gov/large-docs/16/NCT02651116/Prot_000.pdf – This is a clinical trial protocol for a study investigating the effects of dextromethorphan on postoperative pain. The protocol outlines the study design, including the dosage, administration, and outcome measures, providing insights into the use of dextromethorphan in pain management research.
