Medication Summary
Tricyclic antidepressants, such as amitriptyline (10-100 mg qhs), may be helpful at low doses. Antiepileptics, such as gabapentin (300-3600 mg/d in 3-4 divided doses) also can be tried. Opiates, especially methadone and steroids, can be considered as well. Mexiletine, a class 1b antiarrhythmic, at 200 mg bid, has been used for the management of significant neuropathic pain due to neoplastic plexus infiltration. [27] Low- (0.1 g/kg/d) and higher-dose (0.2-2 g/kg/d) intravenous immunoglobulin therapy has, in limited cases, been successfully used for idiopathic brachial and lumbosacral plexopathy. However, its effectiveness in neoplastic plexopathy is unproven. A single dose (500 mg or 1 g) of intravenous magnesium sulfate has been used with success in a small sample of patients with neuropathic pain due to neoplastic plexopathy. [28]
Tricyclic antidepressants
Class Summary
These agents have central and peripheral anticholinergic effects, as well as sedative effects, and block the active reuptake of norepinephrine and serotonin.
Amitriptyline (Elavil)
Analgesic for certain chronic and neuropathic pain.
Analgesics
Class Summary
Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who experience pain.
Morphine sulfate (Astramorph, MS Contin, MSIR)
Generally used for short-term, acute pain, moderate to severe in nature, as well as for chronic pain (eg, that associated with cancer). Morphine sulfate is available in immediate (3-4 h duration) and extended-release preparation (12 h). Switch over to long-acting preparations (MS Contin) once the pain is controlled with short-acting preparation (MS IR). Morphine can produce drug dependence and has the potential to be abused. Tolerance may develop with repeat exposure. Abrupt cessation of the drug or a sudden reduction in dose with prolonged use may result in withdrawal symptoms. Physical dependence is not of paramount importance in terminally ill patients.
Methadone (Dolophine)
Used in the management of severe pain. Methadone inhibits ascending pain pathways, diminishing the perception of and response to pain.
Muscle relaxants
Class Summary
These agents inhibit events involved in muscle contraction.
Methocarbamol (Robaxin)
Reduces nerve impulse transmission from the spinal cord to skeletal muscle.
Antiepileptics
Class Summary
Antiepileptics are used to manage severe muscle spasms and to provide sedation in neuralgia.
Pregabalin (Lyrica)
Structural derivative of GABA. The mechanism of action is unknown. Pregabalin binds with high affinity to the alpha2 -delta site (a calcium channel subunit). In vitro, it reduces the calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function. Pregabalin is FDA approved for neuropathic pain associated with diabetic peripheral neuropathy or postherpetic neuralgia and as an adjunctive therapy in partial-onset seizures.
Gabapentin (Neurontin)
Has anticonvulsant properties and antineuralgic effects; however, the exact mechanism of action is unknown. Gabapentin is structurally related to GABA but does not interact with GABA receptors.
