Module 3 - Pain Management Flashcards
What are some common sources of pain in cancer patients, both from the cancer itself and therapeutic interventions?
In cancer patients, pain can stem from the cancer itself and therapeutic interventions. The cancer can cause pain through direct invasion of surrounding tissues, such as nerves, muscles, and visceral organs, and through metastatic invasion at distant sites. Bone metastases are particularly common, causing pain in up to 50% of patients. Cancer can also induce neuropathic pain through nerve infiltration and visceral pain through infiltration, obstruction, and compression of visceral structures.
What factors influence the incidence and intensity of cancer-induced pain among patients with cancer?
The incidence and intensity of cancer-induced pain depend on the type of cancer and the stage of disease progression. Among patients with advanced disease, approximately 75% experience significant pain. Of these, 40% to 50% report moderate to severe pain, and 25% to 30% report very severe pain.
Which therapeutic interventions commonly lead to pain in cancer patients, and what are some examples of pain syndromes caused by these interventions?
Therapeutic interventions, including chemotherapy, radiation, and surgery, often cause significant pain in at least 25% of cancer patients. For example, chemotherapy can lead to painful mucositis, diffuse neuropathies, and aseptic necrosis of joints. Radiation therapy can result in osteonecrosis, chronic visceral pain, and peripheral neuropathy due to nerve fibrosis. Surgery can induce various pain syndromes, including phantom limb syndrome and postmastectomy syndrome.
What is the first step in the management of cancer pain, and why is it crucial?
The first step in the management of cancer pain is conducting a comprehensive assessment. This step is crucial because it helps determine the nature of the pain and provides a foundation for selecting appropriate treatment modalities.
What is the preferred initial approach for managing cancer pain, and what is usually tried first?
The preferred initial approach for managing cancer pain is the use of analgesic drugs. Typically, analgesic drugs are tried first.
What are some alternative modalities that can be implemented if analgesic drugs are ineffective in managing cancer pain?
If analgesic drugs prove ineffective in managing cancer pain, alternative modalities can be implemented, including radiation therapy, surgery, and nerve blocks.
What should be done when relief from pain has been achieved, and how should the process continue?
When relief from pain has been achieved, the effective intervention should be continued, accompanied by frequent reassessments. The process should continue with active involvement from the patient and their family.
What should be the course of action if severe pain returns or new pain develops during the management of cancer pain?
If severe pain returns or new pain develops, a new comprehensive assessment should be performed, followed by appropriate interventions and reassessment.
What are the three main types of analgesic drugs used in the treatment of cancer pain?
The three main types of analgesic drugs used in the treatment of cancer pain are:
Nonopioid analgesics (including nonsteroidal anti-inflammatory drugs [NSAIDs] and acetaminophen).
Opioid analgesics (such as oxycodone, fentanyl, and morphine).
Adjuvant analgesics (including medications like amitriptyline, carbamazepine, and dextroamphetamine).
What is the primary modality for treating cancer pain, and how effective are these drugs in relieving pain?
The primary modality for treating cancer pain is drug therapy, specifically the use of analgesic drugs. When used properly, these agents can relieve pain in 90% of patients, making them highly effective in managing cancer-related pain.
How do the abilities to relieve pain differ among nonopioid analgesics, adjuvant analgesics, and opioids?
The abilities to relieve pain differ among these analgesic classes. Nonopioid and adjuvant analgesics have a ceiling to how much pain relief they can achieve. In contrast, there is no ceiling to the relief that opioids can provide.
How is the selection of analgesics determined, and what guided the creation of the World Health Organization’s (WHO) drug selection ladder?
The selection of analgesics is based on pain intensity and pain type. The World Health Organization (WHO) devised a drug selection ladder to guide drug selection. It consists of three steps:
The first step, for mild to moderate pain, includes nonopioid analgesics such as NSAIDs and acetaminophen.
The second step, for more severe pain, adds opioid analgesics of moderate strength like oxycodone and hydrocodone.
The top step, for severe pain, substitutes powerful opioids like morphine and fentanyl for the weaker ones. Adjuvant analgesics, especially effective against neuropathic pain, can be used at any step of the ladder.
What is the role of adjuvant analgesics in pain management, and for which type of pain are they particularly effective?
Adjuvant analgesics are medications that can be used in pain management and are especially effective against neuropathic pain. They can be employed at any step of the World Health Organization’s (WHO) drug selection ladder.
Why the Drug Is Not Recommended:
Drug Class: Pure Opioid Agonists
Drug: Meperidine
A toxic metabolite accumulates with prolonged use.
Why the Drug Is Not Recommended:Drug Class: Pure Opioid Agonists
Drug: Codeine
Maximal pain relief is limited due to dose-limiting side effects.
Drug Class: Opioid Agonist-Antagonists
Drugs: Buprenorphine, Butorphanol, Nalbuphine, Pentazocine
Why the Drugs Are Not Recommended:
they have a ceiling to analgesic effects, can precipitate withdrawal in opioid-dependent patients, and may cause psychotomimetic reactions.
Drug Class: Benzodiazepines
Drugs: Diazepam, Lorazepam (others)
Why the Drugs Are Not Recommended:
Sedation from benzodiazepines limits opioid dosage, and they have no demonstrated analgesic action.
Drug Class: Barbiturates
Drugs: Amobarbital, Secobarbital (others)
Why the Drugs Are Not Recommended:
Sedation from barbiturates limits opioid dosage, and they have no demonstrated analgesic action.
Drug Class: Miscellaneous
Drug: Marijuana
Why the Drug Is Not Recommended:
Side effects (dysphoria, drowsiness, hypotension, and bradycardia) preclude routine use as an analgesic.
What approach does the National Comprehensive Cancer Network (NCCN) recommend for the initial selection of analgesic drugs based on pain intensity, and how does it differ from traditional practice?
The NCCN recommends an approach in which initial drug selection is based on pain intensity. If the patient reports pain in the 4 to 10 range, treatment should start directly with an opioid; no initial trial with a nonopioid is considered necessary. For pain in the 1 to 3 range, treatment usually begins with a nonopioid, but starting with an opioid remains an alternative. This approach differs from traditional practice, where opioid analgesics were typically given only after a trial with nonopioids had failed.
What is the rationale for combining an opioid with a nonopioid in pain management, and under what circumstances can they be administered as a fixed-dose combination?
Combining an opioid with a nonopioid in pain management can be more effective than using either drug alone. When pain is only moderate, opioids and nonopioids can be given as a fixed-dose combination formulation, simplifying dosing. However, when pain is severe, they must be administered separately, as the side effects of the nonopioid would become intolerable as the dosage grows large, limiting how much opioid can be given.
What are the key principles that should guide drug therapy for cancer pain?
The key principles that should guide drug therapy for cancer pain are as follows:
Perform a comprehensive pretreatment assessment to determine pain intensity and the underlying cause.
Individualize the treatment plan.
Use the World Health Organization (WHO) analgesic ladder and National Comprehensive Cancer Network (NCCN) guidelines to inform drug selection.
Prefer oral therapy whenever possible.
Avoid intramuscular (IM) injections whenever possible.
For persistent pain, administer analgesics on a fixed schedule around-the-clock (ATC) and provide additional rescue doses of a short-acting agent if breakthrough pain occurs.
If a particular activity is associated with breakthrough pain (e.g., bathing), provide an “incident dose” of short-acting medication before the procedure.
Evaluate the patient frequently for pain relief and drug side effects.
Nonopioid Analgesics
Nonopioid Analgesics are the first step on the WHO analgesic ladder, including NSAIDs and acetaminophen. They are preferred for mild pain, but exceeding recommended dosages offers no extra benefit.
Acetaminophen has similar pain-relief efficacy to NSAIDs but lacks anti-inflammatory properties. It is discussed separately later.
Nonsteroidal Antiinflammatory Drugs (NSAIDs)
NSAIDs (e.g., aspirin and ibuprofen) provide pain relief, reduce inflammation, and lower fever. They can also cause gastric ulcers, acute renal failure, bleeding, and increased thrombotic event risk.
NSAIDs don’t lead to tolerance, physical dependence, or psychological dependence like opioids.
NSAIDs effectively alleviate mild to moderate pain and can be combined with opioids for greater pain relief.
NSAIDs (e.g., aspirin and ibuprofen) provide pain relief, reduce inflammation, and lower fever. They can also cause gastric ulcers, acute renal failure, bleeding, and increased thrombotic event risk.
NSAIDs don’t lead to tolerance, physical dependence, or psychological dependence like opioids.
NSAIDs effectively alleviate mild to moderate pain and can be combined with opioids for greater pain relief.
NSAIDs inhibit cyclooxygenase (COX), an enzyme with two forms: COX-1 and COX-2. Most NSAIDs inhibit both forms, while some selectively inhibit COX-2 (e.g., celecoxib).
Selective COX-2 inhibitors cause less gastrointestinal (GI) damage but carry a higher risk of thrombotic events, limiting long-term use.
NSAIDs and Platelet Aggregation
Inhibition of platelet aggregation by NSAIDs is a concern during chemotherapy, as anticancer drugs often reduce platelet production, leading to thrombocytopenia (increased bleeding risk).
Nonacetylated salicylates (e.g., magnesium salicylate) are the only conventional NSAID subclass that doesn’t inhibit platelet aggregation and is safe for thrombocytopenic patients.
Aspirin should be avoided as it irreversibly inhibits platelet aggregation, persisting for about 8 days. COX-2 inhibitors are safe for thrombocytopenic patients because they don’t affect platelets.
