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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Guaifenesin 400mg And Dextromethorphan Hbr 20mg
Brand Name
Pharbinex-dm
Generic Name
Guaifenesin 400mg And Dextromethorphan Hbr 20mg
Active Ingredient
DextromethorphanCategory
Expectorant [EPC]
Salt Form
Hydrobromide
Variants
2
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Pharbinex-dm, you must consult a qualified healthcare professional.
Detailed information about Pharbinex-dm
Dextromethorphan is a widely used antitussive (cough suppressant) medication designed to provide temporary relief from non-productive coughs. It belongs to a class of drugs that act on the cough center in the brain to elevate the cough threshold.
For the treatment of non-productive cough, the typical adult dosage ranges are as follows:
Pediatric dosing must be calculated carefully based on age and weight. According to the American Academy of Pediatrics (AAP), OTC cough medications should be used with caution in children.
No specific dose adjustments are provided in the standard labeling; however, patients with severe renal disease should use caution as metabolites are cleared through the kidneys.
Since Dextromethorphan is extensively metabolized by the liver, individuals with hepatic impairment may require lower doses or longer dosing intervals to prevent drug accumulation.
Older adults should start at the lower end of the dosing range due to a higher likelihood of decreased hepatic or renal function and potential sensitivity to central nervous system (CNS) effects.
Dextromethorphan can be taken with or without food. If using the liquid form, always use the provided measuring device (cup or syringe) to ensure an accurate dose; household spoons are not reliable. Extended-release formulations should be shaken well before use and swallowed without crushing or chewing the granules. Store at room temperature away from moisture and heat.
If you miss a dose, take it as soon as you remember. If it is nearly time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up.
Signs of overdose include extreme drowsiness, blurred vision, confusion, hallucinations, and respiratory depression (slowed breathing). In the event of a suspected overdose, contact a poison control center or seek emergency medical attention immediately.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance.
At standard therapeutic doses, Dextromethorphan is generally well-tolerated. However, some patients may experience:
Dextromethorphan should only be used for dry, non-productive coughs. If a cough persists for more than 7 days, returns, or is accompanied by fever, rash, or persistent headache, a healthcare provider should be consulted as these may be signs of a more serious condition.
No FDA black box warnings for Dextromethorphan.
Dextromethorphan is generally classified as Pregnancy Category C. While animal studies have not shown clear evidence of teratogenicity at therapeutic doses, there are no adequate, well-controlled studies in pregnant humans. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, particularly in the first trimester.
It is not known whether dextromethorphan or its metabolites are excreted in human milk. Because many drugs are excreted in breast milk, caution should be exercised. Most experts consider occasional therapeutic doses to be compatible with breastfeeding, but long-term use should be avoided.
Dextromethorphan is FDA-approved for children 4 years and older. However, the FDA and manufacturers have warned against its use in infants and toddlers under age 4 due to the risk of life-threatening respiratory depression and lack of proven efficacy in that age group.
Dextromethorphan acts primarily as an agonist at Sigma-1 receptors in the cough center of the medulla. It also functions as an uncompetitive antagonist at the N-methyl-D-aspartate (NMDA) receptor complex. Unlike opioid antitussives, it does not bind significantly to mu-opioid receptors, which explains its lack of analgesic effects at therapeutic doses. It also has minor activity as a serotonin and norepinephrine reuptake inhibitor.
The antitussive effect of a single dose usually lasts for 3 to 6 hours for immediate-release forms and up to 12 hours for extended-release forms. It increases the threshold for the cough reflex without significantly inhibiting ciliary activity in the respiratory tract.
| Parameter | Value |
|---|---|
| Bioavailability | Highly variable (extensive first-pass) |
| Protein Binding | ~7% |
Common questions about Pharbinex-dm
Dextromethorphan is primarily used for the temporary relief of a dry, non-productive cough caused by minor throat and bronchial irritation. This irritation often occurs during the common cold or after inhaling environmental irritants. It works by acting on the brain's cough center to raise the threshold required to trigger a cough. It is important to note that it does not treat the underlying cause of the cough, such as a viral infection. Healthcare providers recommend it only for coughs that do not produce mucus or phlegm.
Most individuals taking Dextromethorphan at recommended doses experience few to no side effects. When they do occur, the most common symptoms include mild dizziness, drowsiness, and gastrointestinal issues like nausea or stomach upset. Some patients may also report a slight feeling of nervousness or restlessness, particularly children. These effects are usually temporary and resolve once the medication is discontinued. If side effects persist or become bothersome, you should contact your healthcare provider for guidance.
It is strongly advised to avoid alcohol while taking Dextromethorphan. Both substances act as central nervous system depressants, meaning they can slow down brain activity and respiratory function. Combining them can lead to extreme sedation, severe dizziness, and an increased risk of accidents or falls. Furthermore, the combination can increase the likelihood of nausea and vomiting. Always check the labels of other liquid medications, as some may also contain small amounts of alcohol.
Dextromethorphan is generally considered to have a low risk during pregnancy, but it should only be used when clearly needed. It is officially categorized as Pregnancy Category C, meaning human studies are limited. Most healthcare providers suggest avoiding its use during the first trimester unless the benefits outweigh the potential risks. If you are pregnant or planning to become pregnant, you should consult your doctor before using any cough suppressant. They may recommend non-pharmacological alternatives like hydration or a humidifier first.
Dextromethorphan typically begins to work within 15 to 30 minutes after oral administration. The peak effect of the medication is usually reached within 2 to 3 hours for immediate-release formulations. For extended-release versions, the onset may be slightly slower, but the effects are designed to last for up to 12 hours. If you do not feel any relief from your cough after several doses, do not increase the amount you take. Instead, contact a medical professional to ensure there isn't a more serious underlying issue.
Yes, for the vast majority of people using Dextromethorphan for a short-term cough, the medication can be stopped abruptly without any issues. It does not require a tapering period when used as directed on the OTC label. However, if the drug has been used at high doses for a long period or misused, sudden discontinuation might cause mild withdrawal symptoms like anxiety or restlessness. If you have been taking it for longer than 7 days, you should speak with your doctor. Always follow the duration of use instructions provided on the packaging.
If you miss a dose of Dextromethorphan, take it as soon as you realize it is missing. However, if it is almost time for your next scheduled dose, you should skip the missed one and continue with your regular timing. You should never take two doses at once to make up for a missed one, as this increases the risk of side effects and overdose. Maintaining a consistent schedule helps keep the cough threshold elevated effectively. If you frequently forget doses, setting a timer on your phone may be helpful.
There is no clinical evidence to suggest that short-term use of Dextromethorphan causes weight gain. The medication is not associated with metabolic changes or increased appetite that typically lead to weight fluctuations. If you notice weight gain while taking a cough syrup, it is more likely due to other factors, such as inactivity while sick or the sugar content in certain liquid formulations. For those concerned about sugar intake, sugar-free versions of dextromethorphan are often available. If weight changes persist, discuss them with your healthcare provider.
Dextromethorphan can interact with many other drugs, some of which can cause serious safety concerns. It should never be taken with MAO inhibitors, and caution is required when combining it with antidepressants like SSRIs due to the risk of serotonin syndrome. Many other OTC multi-symptom cold medicines also contain dextromethorphan, so taking them together could lead to an accidental overdose. Always read the active ingredient list on all your medications. Consult a pharmacist or doctor to perform a full drug interaction check before starting treatment.
Yes, Dextromethorphan is widely available as a generic medication and is often much less expensive than brand-name versions. Generic versions are required by the FDA to have the same active ingredient, strength, and dosage form as the brand-name products. You can find it as a standalone ingredient or as part of combination products for cold and flu relief. Whether you choose a brand name or a generic, the cough-suppressing efficacy remains the same. Look for 'Dextromethorphan HBr' on the 'Drug Facts' label of the packaging.
Other drugs with the same active ingredient (Dextromethorphan)
> Warning: Stop taking Dextromethorphan and call your doctor immediately if you experience any of these.
Dextromethorphan is intended for short-term use (usually less than 7 days). Prolonged use or misuse can lead to psychological dependence and a phenomenon known as "dexing" or "robotripping," which involves dissociative states similar to ketamine or PCP. Long-term high-dose use may result in cognitive impairment and persistent neurological disturbances.
No FDA black box warnings currently exist for Dextromethorphan when used at recommended therapeutic doses. However, the FDA has issued safety communications regarding its potential for abuse among teenagers and the risks of serious breathing problems in young children.
Report any unusual symptoms to your healthcare provider.
No routine lab monitoring is required for short-term OTC use. However, if used long-term or for off-label indications, healthcare providers may monitor liver function and neurological status.
Dextromethorphan may cause drowsiness or dizziness. Patients should determine how they react to the medication before driving, operating heavy machinery, or performing tasks that require mental alertness.
Alcohol can increase the sedative effects of Dextromethorphan. Combining the two can lead to excessive drowsiness, impaired motor coordination, and increased risk of respiratory depression.
For standard cough suppression, the drug can be stopped abruptly without tapering. However, if the drug has been misused at high doses for a long period, withdrawal symptoms like anxiety and tremors may occur.
> Important: Discuss all your medical conditions with your healthcare provider before starting Dextromethorphan.
Dextromethorphan may cause false-positive results in some urine drug screens for phencyclidine (PCP) or opioids. Always inform laboratory staff if you have taken dextromethorphan before a drug test.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking.
There is no established cross-sensitivity between dextromethorphan and other common drug classes like penicillins or NSAIDs; however, patients sensitive to other morphinan derivatives should exercise caution.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Dextromethorphan.
Clinical studies have not identified significant differences in responses between the elderly and younger patients. However, due to the higher prevalence of polypharmacy (taking multiple medications) in the elderly, the risk of drug-drug interactions is significantly higher.
No specific GFR-based adjustments are provided. However, since the kidneys excrete the metabolites, patients with a GFR < 30 mL/min should be monitored for increased side effects.
In patients with Child-Pugh Class B or C hepatic impairment, the half-life of dextromethorphan may be significantly prolonged. Dose reductions of 50% or longer intervals between doses are often recommended by clinical pharmacologists.
> Important: Special populations require individualized medical assessment.
| Tmax | 2 - 3 hours |
| Metabolism | Hepatic (CYP2D6, CYP3A4) |
| Excretion | Renal (>90%) |
Dextromethorphan is a morphinan-class antitussive. It is often grouped with other cough suppressants like benzonatate or codeine, though its mechanism is distinct from both.