Table 6. Adjuvant Analgesics for End-of-Life Pain Management 56
Drug Class
Agent
Route of Administration
Potential adverse effects
Indications
Antidepressants
Nortriptyline
Oral
Anticholinergic effects
Neuropathic pain
Desipramine Venlafaxine Duloxetine
Oral Oral Oral Oral Oral
Cardiac arrhythmia Nausea, dizziness
Nausea
Anti-epilepsy drugs Gabapentin
Dizziness Dizziness Sedation
Neuropathic pain
Pregabalin
Clonazepam Oral
Corticosteroids
Dexamethasone Oral/IV/Sq
“Steroid psychosis” Neuropathic pain, cerebral edema, spinal cord compression, bone pain, visceral pain
Lidocaine
Lidocaine patch Topical
Erythema (rare)
Neuropathic pain
Lidocaine infusion IV/sq
Perioral numbness, cardiac changes
Intractable neuropathic pain Unrelieved neuropathic pain; need to reduce opioid dose
NMDA antagonists Ketamine
Oral/IV/ intranasal/ topical
Hallucinations
Bisphosphonates
Pamidronate Clondronate Alendronate Zoledronic acid
IV IV
Pain flare, osteonecrosis
Osteolytic bone pain
Cannabinoids
Dronabinol (Marinol®)
Oral
Dizziness, nausea, tachycardia, euphoria
Pain, nausea, loss of appetite, spasticity
Nabilone (Cesamet® and Syndros®)
Oral
Some antidepressant agents appear to exert analgesic properties and may be particularly helpful for neuropathic pain conditions. Tricyclic antidepressants inhibit reuptake of norepinephrine and serotonin, which appears to exert analgesic effects, either directly or indirectly. These agents have been shown to provide clinically relevant effects in a review of analgesic studies conducted in neuropathic pain conditions, primarily diabetic neuropathy and other non-cancer conditions. 57 Potential side effects include cardiac arrhythmias, conduction abnormalities, narrow- angle glaucoma, and clinically significant prostatic hyperplasia. On the other hand, the sleep-enhancing and mood-elevating effects of these antidepressants may benefit some patients. Although little evidence supports an analgesic effect for SSRIs, some newer antidepressants, such as the serotonin-norepinephrine reuptake inhibitors have been shown to be effective in relieving neuropathic pain, including venlafaxine and duloxetine. 58 These have the added advantage of alleviating hot flashes, a common and disturbing symptom, particularly in breast
cancer patients undergoing hormonal therapy. Care must be taken in such situation, however, because duloxetine reduces the bioavailability of tamoxifen, potentially reducing its therapeutic efficacy. 59 The anti-epilepsy drugs gabapentin and pregabalin have undergone extensive testing in many non-cancer neuropathy syndromes, and a recent review concluded that these drugs have a clinically meaningful effect. 57 The most common adverse effects reported by patients are dizziness; some patients also develop fluid retention. Although the data for the efficacy of other anticonvulsants are not as conclusive as those for gabapentin and pregabalin, existing reports suggest potential efficacy. As with most adjuvant analgesics, antiepileptic agents are commonly used in combination with opioid therapy, particularly when pain is moderate to severe. A review of cancer trials found that adjuvant analgesics added to opioids provide additional relief, usually within 4 to 8 days, with the strongest evidence for gabapentin. 60 Corticosteroids can play a valuable role in treating end-of-life pain related to neuropathic pain syndromes,
Book Code: CA23CME
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