What Are Neuropathy Pain Medicines?
There are many different types of pain, and all pain is propagated along nerves. Nerves pass on pain signals from pain receptors (nociceptors) where the signal is provoked and initiated, ultimately to the brain, where all pain is perceived. In between are all of the peripheral and spinal nerves. Where neuropathy is involved will affect how the pain is perceived. The type of neuropathy and the pain syndromes caused are the basis for a rational medication approach. When the protocol individualized for a patient involves multiple drugs, this is referred to as “rational polypharmacology,” and is best prescribed by specialists trained in pain management.
Medication can affect nerves in many ways.
- Medications can be used to lessen the severity of pain signal transmission, or at least slow them down. Anticonvulsants such as gabapentin and pregabalin are used in this respect.
- Medication can be used to raise the pain threshold of nociceptors, making them harder to fire off. Botulinum A toxin is a drug that can do this.
- Antispasmodics are used when muscle spasms result from overtaxing muscle fibers, as happens when a patient “splints” themselves away from painful postures using infrequently used muscles constantly until they become hypoxic, acidotic, and cramp.
- Non-steroidal anti-inflammatories (NSAIDs), such as ibuprofen, celecoxib, and other COX inhibitors, interfere with cyclooxygenase (COX) manufacture of a powerful pain mediator, prostaglandin. When COX-1 or COX-2 reactions are diminished, there is less prostaglandin and less pain.
- Some antidepressants prevent the re-uptake of serotonin and norepinephrine, neurotransmitters whose constant levels will help reduce pain due to their inhibitory properties. The tricyclic antidepressants (amitriptyline) and the SSNRIs (selective serotonin and norepinephrine reuptake inhibitors, such as duloxetine and venlafaxine) do this.
- Ziconotide, made from a snail toxin, has the ability to stop chronic pain, including that of neuropathy, at the spinal level. It must be placed directly into the spinal fluid, so its delivery involves an implantable pump that requires periodic refilling.
- Narcotics, which offer the benefits of the most potent pain relief, but the disadvantages of tolerance build-up and addiction, are reserved for those in whom no other protocols are helpful. Alternately, they can be used sparingly in those who do benefit from conservative medications, but who “break through” with occasional pain spikes that impair their functionality.
Rational polypharmacology often takes advantage of the dual approach for both peripheral and central control of neuropathic pain.
Diagnosis for Neuropathy Pain
Medications used in the treatment for the pain due to neuropathy can include narcotics. Narcotics have both helped and plagued countless generations of people who have pain. The nature of the opioid molecule, based on its ability to fit into some pain receptors on neurons, others on another type of nerve, “glia,” creates a situation in which the longer narcotics are used, the more is needed to achieve the same analgesic effect. This is called “tolerance.”
It also causes a dependence, which is different from addiction:
- Dependence is the emergence of unpleasant symptoms when opioid maintenance that is long-standing is interrupted abruptly or when dosages are reduced.
- Addiction is the reckless behavior to get the opioid medication any way possible, including via criminal diversion, doctor-shopping, or other illicit activities.
Therefore, all persons with addiction have dependence, but not all persons who become dependent on opioids become addicted. 15% of the population have a genetic tendency toward addiction, and because of these 15% testing must be done to ensure that a person being treated for pain is taking the medications prescribed and only the medication prescribed–compliantly and from only one prescriber.
Drug screens are considered a necessary part of any pain management that involves drugs with dependence, tolerance, or addictive potential. A drug screen that indicates absence of a prescribed drug means the patient is diverting it–usually by selling it or simply getting it for someone else; a drug screen that indicates a different type of opioid instead of the one prescribed means the patient is still seeking pain relief, but is probably selling an expensive prescribed medication and buying a different, less expensive, non-prescribed medication illegally. Drug screens also indicate the presence of other substances, such as marijuana, as well as cocaine, amphetamines, and other drugs of abuse.
The Legal Requirement
Drug screens were initially implemented due to the opioid/overdose crisis, but there is no legal requirement that a physician get periodic drug screens. The standard of care, however, includes them as part of pain management because of the dangers that opioids create.
Even without the legal requirement, the prudent doctor will get them to protect the patient him- or herself. The doctor-patient relationship is solely for patient wellness, and drug abuse and diversion interfere with that objective. A doctor so forewarned can intervene on the patient’s behalf with co-therapy involving rehabilitation, psychological therapy, medication weaning and/or substitution, and family interaction. A drug screen that indicates drug abuse of illicit drugs such as cocaine and methamphetamines can warn the doctor of a potentially lethal combination at work within his or her patient.
Because most patients who become addicted and break the law are truly in need of pain relief, it is not simply an either-or case of patient vs. law-breaker. When illegal actions occur, they typically occur in real patients who need real pain relief. This is what gives the patient’s doctor an advantage toward patient well-being when drug screens are used. Identifying these patients also can indicate when a patient is being under-treated; inadequate pain relief can sometimes drive addictive behavior. If a patient is being inadequately treated for pain, knowing this is an important part of pain management.
Management of Neuropathy Pain Medications
Using medication in the treatment of pain due to neuropathy is usually a protocol referred to as “rational polypharmacology.” Pain from neuropathy is complex, and so are the protocols individualized for each patient. A physician must not only be knowledgeable of the different medications used for different strategies, but must be aware of the augmenting properties of combining medications, including both beneficial and harmful effects.
Many drugs affect cardiac function, impacting blood pressure, heart rate, respiration, and electrolyte balance. Many drugs, especially those that manipulate neurotransmitters (the selective serotonin norepinephrine re-uptake inhibitors), can cause emotional changes and even provoke thought of suicide.
Drug-drug interaction is important to consider in any use of multiple medications. Two medications with sedating properties will have more than just twice the sedation. This can impact a person’s driving, employment, or functioning in general.
Side effects can emerge that are specific for the drug. Methadone, for instance, requires an electrocardiogram (ECG) to watch for a particular arrhythmia seen when it is used for either pain management or rehabilitation.
The benzodiazepines can cause an overdose when mixed with narcotics or initiate a seizure when stopped abruptly. Physicians know not to stop them abruptly, but this offers no protection from a patient simply running out of them; the education of the patient regarding this danger must be part of the management and treatment.
Other medications besides the opioids are potentially addictive. Barbiturates, anti-anxiety medications, and even some antispasmodic medications can be, so this is part of the patient’s education, as well.
The management and treatment of neuropathic pain, whether using only one medication or combinations of pain medications, require effective communication between the patient and his or her doctor. Immediate notification of side effects can sometimes make possible a life-saving medical intervention.
Prevention of Neuropathy with Pain Medicines
Pain medicines used for neuropathy are powerful and each has a risk-vs-benefit profile that is individualized for each patient. There are many pitfalls that can emerge in using them, and prevention of the ill-effects of pain medication is just as much a part of therapy as the beneficial effects of the pain relief they provide.
Pitfalls in Using Pain Medication
Monotherapy (one medication at a time) simply presents concern for side effects and dosing. When multiple medications are used, the drug-drug interaction between/among them can prove fatal if not monitored very closely. There is value to what is called rational polypharmacology, tweaking several medication dosages and combinations of them to get a “designer” effect for an individual patient; such personalized protocols develop over time as the physician and patient sort out the benefits vs. the side effects.
Preventing the Pitfalls in Using Pain Medication
- Any sedating drugs will be potentiated by narcotics, including the antidepressants and anticonvulsants used for neuropathic pain. Mixing a narcotic with alprazolam, for example, can be fatal if not supervised scrupulously. This particular combination is especially noteworthy due to the fact that both the narcotic and the short-acting alprazolam are very addictive. In patients in which this poses danger, a longer-acting anxiety benzodiazepine should be used, because the rapid-acting ones give the brain a surge of the neurotransmitter dopamine which increases its addictive properties.
- Methadone causes cardiac rhythm disturbances, so chronic use requires intermittent ECGs to monitor heart rate and rhythm.
- The acetaminophen in combination with an opioid augments the pain relief of both, which is a benefit purposely designed in these drugs. Oxycodone/acetaminophen, hydrocodone/acetaminophen, and other combinations require arithmetic to ensure the acetaminophen total per day does not exceed 2,000 mg, which can cause liver toxicity.
- Switching a patient from one narcotic to another must take into account the potency equivalence of each so that under-treatment or overdose won’t occur.
- Rather than taking many short-acting opioids on a chronic basis, a longer-acting one is safer in regards to addiction. As with the benzodiazepines, shorter-acting opioids give a “rush” due to a spike in dopamine, which can provoke addiction in predisposed individuals. The short-acting opioids, with chronic use, should be reserved for “breakthrough” pain that occasionally occur with long-term opioid maintenance.
- It makes no sense to use two short-acting opioids. It only increases the addictive potential. If one opioid is needed for maintenance and another for breakthrough pain, it should be a regimen of long-acting with short-acting, respectively.
- Drug screens are seen as obtrusive. Even insulting to patients but they are necessary to prevent the dangerous behaviors that they readily identify. It is not for law enforcement, but for patient safety and well-being.