Pharmacologic Management Of Chronic Non-Cancerous Pain In Adults

Published by Kyle Gallardo on May 15, 2023

Introduction:

Chronic non-cancer pain is a significant public health issue that affects a large number of adults worldwide. Pharmacological management is one of the primary approaches used to address chronic pain, and various medications are available to alleviate symptoms and improve the quality of life for patients. However, the management of chronic pain can be challenging, as it often requires a multifaceted and individualized approach. Healthcare providers must consider the underlying mechanisms of pain, patient characteristics, and the potential side effects of medications when developing a treatment plan. This may include non-opioid analgesics, such as NSAIDs and acetaminophen, anti-seizure medications, antidepressants, opioids, adjuvant medications, and infusion therapies. Non-pharmacological interventions, such as physical therapy and cognitive behavioral therapy, should also be considered as part of a comprehensive pain management plan. This summary will provide an overview of pharmacological management options for chronic non-cancer pain in adults, including the benefits, risks, and limitations of various medications.

Pharmacological Management:

When selecting pharmacologic therapy for chronic pain, it is important to consider the underlying mechanism of the pain. For neuropathic pain, which is caused by nerve damage or dysfunction, drugs that target the nervous system are often effective. For neoplastic or centralized pain, which arises from changes in the central nervous system, drugs that modulate the perception of pain may be more appropriate.
In general, drug selection for chronic pain should take into account the patient’s medical history, co-morbidities, and medications they are currently taking. The selection of analgesic drugs should be based on the severity of the pain, the patient’s response to previous therapies, and the potential for adverse effects.
For neuropathic pain, anticonvulsants, antidepressants, and some opioids may be effective. Anticonvulsants such as gabapentin and pregabalin work by blocking the transmission of pain signals in the CNS. Tricyclic antidepressants, selective serotonin reuptake inhibitors, and serotonin-norepinephrine reuptake inhibitors can also be effective in treating neuropathic pain by increasing levels of neurotransmitters in the CNS. Some opioids, such as tramadol, can also be effective in treating neuropathic pain, but their use should be carefully monitored due to the risk of addiction and overdose.

For neoplastic or centralized pain, drugs that modulate the perception of pain may be more appropriate. These drugs include non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants, and anticonvulsants. NSAIDs work by reducing inflammation, which can contribute to pain. Antidepressants and anticonvulsants can help to modulate the perception of pain by altering the way that pain signals are processed in the CNS.

Non-Opioid Analgesics:

Non-opioid analgesics are an important class of medications used in the treatment of acute and chronic pain. They are effective in reducing pain and inflammation and are often used as first-
line therapy before opioids are considered. Two common non-opioid analgesics are non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen.
NSAIDs work by inhibiting the production of prostaglandins, which are responsible for inflammation and pain. There are several types of NSAIDs available, including aspirin, ibuprofen, and naproxen. These drugs are effective in treating mild to moderate pain, such as headaches, menstrual cramps, and muscle aches. They are also used to treat inflammatory conditions such as arthritis. NSAIDs are available over-the-counter or in prescription strength and can be taken orally, topically, or injected.
Acetaminophen is another non-opioid analgesic commonly used for pain relief. It works by blocking the production of prostaglandins in the brain, which reduces pain and fever. Unlike NSAIDs, acetaminophen does not have anti-inflammatory effects. It is often used to treat mild to moderate pain, such as headaches, menstrual cramps, and toothaches. Acetaminophen is available over-the-counter or in prescription strength and can be taken orally or rectally.
While NSAIDs and acetaminophen are effective in treating many types of pain, they are not without risks. NSAIDs can cause gastrointestinal side effects, such as stomach ulcers and bleeding, and can also affect kidney function. Acetaminophen can cause liver damage if taken in large doses. It is important to take these medications as directed and to talk to a healthcare provider before taking them if you have a history of gastrointestinal or liver problems.

Opioids:

Opioids are a class of medications that are commonly used in the treatment of chronic pain. They work by binding to specific receptors in the brain and spinal cord to block pain signals. However, opioids are associated with a range of potential risks and adverse effects, including addiction, overdose, and respiratory depression. Therefore, their use should be carefully considered and closely monitored.
When prescribing opioids for chronic pain, healthcare providers must consider a variety of factors, including the patient’s pain severity, medical history, current medications, and risk factors for addiction and overdose. They must also carefully balance the potential benefits of opioids with the potential risks and adverse effects.
Tramadol is a synthetic opioid that is commonly used in the treatment of moderate to severe pain. It works by binding to opioid receptors in the brain and spinal cord and by inhibiting the reuptake of serotonin and norepinephrine. Tramadol is generally considered to have a lower risk of dependence and addiction compared to other opioids, but it can still be habit-forming and should be used with caution. Common side effects of tramadol include nausea, constipation, dizziness, and drowsiness.
Tapentadol is another synthetic opioid that is used in the treatment of moderate to severe pain. It works by binding to both opioid receptors and inhibiting the reuptake of norepinephrine. Tapentadol is considered to have a lower risk of respiratory depression compared to other opioids, but it can still cause drowsiness, dizziness, nausea, and constipation.
Buprenorphine is a partial opioid agonist that is used in the treatment of opioid addiction and chronic pain. It works by binding to opioid receptors in the brain and spinal cord, but it has a ceiling effect that limits its ability to produce euphoria and respiratory depression. Buprenorphine is considered to have a lower risk of abuse and dependence compared to other opioids, and it may be particularly useful in the treatment of chronic pain in patients with a history of substance abuse or dependence. However, it can still cause side effects such as nausea, constipation, and dizziness.
Overall, opioids can be an effective treatment option for chronic pain, but their use should be carefully considered and closely monitored due to the potential risks and adverse effects. Tramadol, tapentadol, and buprenorphine are three opioids that may be particularly useful in the treatment of chronic pain due to their lower risk of addiction and respiratory depression. However, patients and healthcare providers should work together to develop a comprehensive treatment plan that addresses the individual patient’s needs and minimizes the potential risks and adverse effects of opioid therapy.

Antidepressants:

Antidepressants are commonly used in the treatment of chronic pain, particularly neuropathic pain, and pain with a significant emotional component. Several classes of antidepressants are used for pain management, including tricyclic antidepressants (TCAs) and serotonin-norepinephrine reuptake inhibitors (SNRIs).
TCAs work by blocking the reuptake of serotonin and norepinephrine in the brain, which increases the levels of these neurotransmitters and can help to reduce pain. TCAs are effective in treating neuropathic pain, fibromyalgia, and chronic headaches. However, they can have side effects such as sedation, dry mouth, and constipation. Some commonly used TCAs for pain management include amitriptyline, nortriptyline, and desipramine.
SNRIs work by blocking the reuptake of serotonin and norepinephrine, which can also help to reduce pain. SNRIs are effective in treating neuropathic pain, fibromyalgia, and chronic headaches. They are generally better tolerated than TCAs, with fewer side effects. Some commonly used SNRIs for pain management include duloxetine, milnacipran, and venlafaxine.
Duloxetine is FDA-approved for the treatment of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain. It has been shown to reduce pain intensity and improve physical function in patients with these conditions. Milnacipran is FDA-approved for the treatment of fibromyalgia and has also been shown to be effective in reducing pain and improving the quality of life in patients with this condition. Venlafaxine is not FDA-approved for pain management, but it is effective in reducing pain intensity in patients with neuropathic pain and fibromyalgia.

Anti-seizure Medications:

Anti-seizure medications, also known as anticonvulsants, are a class of medications that are commonly used in the treatment of seizures and epilepsy. However, they are also used in the
treatment of chronic pain, particularly neuropathic pain. Two commonly used anticonvulsants for pain management are gabapentin and pregabalin.
Gabapentin and pregabalin work by blocking the transmission of pain signals in the central nervous system. They are often used to treat neuropathic pain, which is caused by damage or dysfunction of the nervous system. Gabapentin and pregabalin are effective in reducing pain intensity and improving quality of life in patients with neuropathic pain.
Other anticonvulsants that are used in pain management include carbamazepine, oxcarbazepine, and topiramate. These medications work by reducing the excitability of nerve cells in the central nervous system, which can help to reduce pain. However, they are less commonly used than gabapentin and pregabalin for pain management.
Anticonvulsants are generally well-tolerated, but they can have side effects. The most common side effects of gabapentin and pregabalin include dizziness, drowsiness, and weight gain. In rare cases, these medications can cause serious side effects such as Stevens-Johnson syndrome or anaphylaxis. Patients should be closely monitored for these side effects.

Other Adjuvant Medications:

In addition to opioids and non-opioid analgesics, several other adjuvant medications can be used in the treatment of chronic pain. These medications include topical agents, cannabis, botulinum toxin, and others.
Topical agents, such as lidocaine patches and capsaicin cream, can be used to treat localized pain. Lidocaine patches work by numbing the area where they are applied, while capsaicin cream works by depleting the nerve endings of substance P, which is involved in pain transmission. These agents can be particularly useful in treating neuropathic pain and other types of localized pain.

Cannabis has been increasingly used in the treatment of chronic pain, particularly neuropathic pain. The two primary active ingredients in cannabis, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have been shown to have analgesic properties. However, there is limited evidence to support the use of cannabis for chronic pain, and more research is needed to fully understand its safety and efficacy.
Botulinum toxin, commonly known as Botox, has been used in the treatment of chronic pain associated with conditions such as migraines and neuropathic pain. It works by blocking the release of acetylcholine, which is involved in muscle contraction and pain transmission. However, the use of Botox for chronic pain is still considered experimental and more research is needed to determine its effectiveness.
Several adjuvant medications are not recommended for the treatment of chronic pain, including muscle relaxants and benzodiazepines. Muscle relaxants, such as cyclobenzaprine and methocarbamol, can be useful in treating acute musculoskeletal pain, but they are not recommended for long-term use in the treatment of chronic pain. Benzodiazepines, such as diazepam and lorazepam, can have sedative and anxiolytic effects, but they are also not
recommended for long-term use in the treatment of chronic pain due to the risk of dependence and addiction.

Infusions:

Infusion therapies can be a useful treatment option for chronic pain patients who have not responded well to other forms of treatment. Two commonly used infusion therapies for chronic pain are ketamine and lidocaine infusion.
Ketamine infusion is a form of treatment in which ketamine, a dissociative anesthetic, is administered intravenously over several hours. Ketamine is believed to work by blocking N-methyl-D-aspartate (NMDA) receptors in the brain and spinal cord, thereby reducing pain sensitivity. It has also been shown to have anti-inflammatory and neuroprotective effects. Ketamine infusion therapy is effective in the treatment of a variety of chronic pain conditions, including neuropathic pain, fibromyalgia, and complex regional pain syndrome (CRPS). However, it can cause side effects such as hallucinations, dizziness, and nausea, and may be associated with an increased risk of abuse and dependence.
Lidocaine infusion therapy involves the administration of lidocaine, a local anesthetic, intravenously over several hours. Lidocaine is believed to work by blocking sodium channels in the nerves, thereby reducing pain signals. It has also been shown to have anti-inflammatory and anti-hyperalgesic effects. Lidocaine infusion therapy is effective in the treatment of a variety of chronic pain conditions, including neuropathic pain, fibromyalgia, and CRPS. However, it can cause side effects such as dizziness, numbness, and tingling, and may not be effective for all patients.
Infusion therapies can be an effective treatment option for chronic pain patients who have not responded well to other forms of treatment. However, they are typically reserved for patients who have severe or refractory pain that has not responded to other treatments. Before undergoing infusion therapy, patients should be evaluated by a healthcare provider to determine if they are a good candidate for the treatment, and to discuss the potential risks and benefits.

Conclusion:

Pharmacological management of chronic non-cancer pain in adults is a complex and multifaceted process that requires a thorough understanding of the underlying pain mechanism, patient characteristics, and potential side effects of various medications. Non-opioid analgesics, such as NSAIDs and acetaminophen, are often used as first-line treatment options for chronic pain. Anti-seizure medications, antidepressants, and opioids can also be effective for certain types of chronic pain. Adjuvant medications, such as topical agents and cannabis, can also be considered as part of a comprehensive pain management plan. Infusion therapies, such as ketamine and lidocaine, may be used for patients who have not responded well to other forms of treatment. It is important for healthcare providers to work closely with patients to develop an individualized treatment plan that addresses the patient’s unique needs, minimizes potential risks, and maximizes pain relief. Non-pharmacological approaches, such as physical therapy and cognitive behavioral therapy, should also be considered as part of a comprehensive pain management plan.

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