Dextromethorphan (DXM) Injectable opiates Red Discussion: Dextromethorphan (DXM) & Injectable opiates

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Dextromethorphan (DXM) & Injectable opiates​

Dextromethorphan (DXM) is a medication commonly found in over-the-counter cough suppressants. Its primary use is to alleviate coughing, but it also has psychoactive properties that can lead to misuse.

DXM acts on sigma-1 receptors in the brain, which are involved in modulating neurotransmission and have a role in cough suppression. This reduces the cough reflex. At higher doses, DXM blocks NMDA (N-methyl-D-aspartate) receptors. NMDA receptors are critical for synaptic plasticity and memory function. Their blockade can lead to dissociative effects, similar to those produced by ketamine or phencyclidine (PCP).

DXM inhibits the reuptake of serotonin, increasing its levels in the brain. This can produce mild euphoria and has the potential to cause serotonin syndrome if taken with other serotonergic agents. DXM also inhibits the reuptake of norepinephrine, which can contribute to increased alertness and energy.

DXM is metabolized in the liver by the enzyme cytochrome P450 2D6 (CYP2D6) into its active metabolite, dextrorphan (DXO), which also has NMDA antagonist properties. The activity of CYP2D6 varies between individuals, leading to different levels of sensitivity and risk for side effects.


Injectable opiates, also known as opioids when considering both natural and synthetic derivatives, are a class of drugs that bind to opioid receptors in the brain, spinal cord, and other parts of the body. These drugs are used primarily for pain relief, but they also have significant potential for misuse and addiction.

Opioid Receptors:

• Mu Receptors (μ): The primary target for most opioids, responsible for analgesia, euphoria, respiratory depression, and physical dependence.
• Delta Receptors (δ): Contribute to analgesia and can modulate mood and emotional responses.
• Kappa Receptors (κ): Involved in analgesia, dysphoria, and hallucinations.

When opioids bind to these receptors, they inhibit the release of neurotransmitters like substance P and glutamate, which are involved in the transmission of pain signals. This binding also triggers the release of dopamine in the brain’s reward pathways, leading to feelings of euphoria, which can contribute to their addictive potential.

Examples of Injectable Opiates

• Morphine: Binds primarily to mu receptors, providing strong analgesic and euphoric effects.
• Heroin (Diacetylmorphine): Rapidly crosses the blood-brain barrier and is converted to morphine, producing intense euphoria and analgesia.
• Fentanyl: Highly potent mu receptor agonist, approximately 50-100 times more potent than morphine.
• Hydromorphone (Dilaudid): Similar to morphine but more potent, providing effective analgesia and euphoria.
• Oxymorphone: Potent mu receptor agonist, used for its strong analgesic effects.

Opioids are primarily metabolized in the liver by enzymes such as cytochrome P450.


Combining DXM with injectable opiates can lead to a range of significant and potentially dangerous effects due to their overlapping and synergistic impacts on the central nervous system.

1. Enhanced CNS Depression: Both substances can cause central nervous system (CNS) depression, leading to dizziness, drowsiness, and impaired cognitive and motor functions. When combined, these effects can be more pronounced, increasing the risk of accidents and injuries. Patients may experience severe sedation and impaired judgment.
2. Respiratory Depression: Both DXM and injectable opiates can cause respiratory depression by suppressing the brainstem's respiratory centers. When used together, this effect can be significantly amplified, increasing the risk of life-threatening respiratory failure. This is a primary concern in overdose situations.
3. Increased Risk of Overdose: Due to the combined depressant effects on the CNS and respiratory system, there is a significantly increased risk of overdose when DXM and injectable opiates are used together. This is particularly true if higher doses of either substance are taken, or if the individual has a low tolerance to one or both substances.
4. Additional Side Effects: Other side effects can include nausea, vomiting, constipation, and urinary retention. Long-term use or misuse of this combination can lead to tolerance, dependence, with an increased risk of withdrawal symptoms upon cessation.
5. Metabolic Interactions: Individual variations in drug metabolism, especially involving the cytochrome P450 enzymes, can alter the effects of these drugs. For instance, DXM is metabolized by CYP2D6, and individuals with different levels of this enzyme may experience varying intensities of effects.
6. Serotonin Syndrome: Combining DXM with opioids like morphine can increase the risk of serotonin syndrome. This is a rare but serious condition characterized by symptoms such as confusion, hallucinations, seizures, extreme changes in blood pressure, increased heart rate, fever, excessive sweating, shivering, muscle stiffness, tremor, incoordination, nausea, vomiting, and diarrhea. Severe cases can result in coma or death.

The combination of DXM and injectable opiates poses significant health risks, particularly due to their synergistic effects on the respiratory and central nervous systems.

All things considered, we recommend avoiding this combination under any conditions.