PERT Program

Tip of the Month: September 2004


MANAGEMENT OF NEUROPATHIC PAIN

Pharmacologic therapy is the first-line treatment for the management of neuropathic pain¹. The medication classes used to manage neuropathic pain are topical analgesics, adjuvants, and opioid analgesics.


Topical analgesics are effective for some peripheral neuropathic pain syndromes such as post herpetic neuralgia (PHN), neuropathies seen in diabetes and HIV, and complex regional pain syndrome (CRPS). Topical agents such as capsaicin cream (Zostrix®) are very useful in the management of localized neuropathic pain. Transdermal lidocaine (Lidoderm® patch) has been shown to provide pain relief without systemic side effects or drug interactions. It is easy to use, although it is costly. Up to 3 patches can be applied to the resident’s skin, covering the most painful site, for 12 hours on and 12 hours off.


Adjuvants such as the tricyclic antidepressants (TCAs) and anticonvulsants can be used alone or in conjunction with other analgesics. The TCAs have been the “gold standard” of therapy for many years, however they are known to cause balance problems and cognitive impairment in the elderly, as well as sedation, postural hypotension, and anticholinergic effects (dry mouth, blurred vision, urinary retention, and constipation).² Amitriptyline (e.g., Elavil®) is not recommended for use in older adults because of the high incidence of side effects. Desipramine (e.g., Norpramin®) and nortriptyline (e.g., Pamelor®) have fewer adverse effects and are therefore better tolerated. Analgesic benefit from the TCAs occurs at lower doses than commonly recommended antidepressant doses.³ Titration is done on the basis of pain relief; however, it is recommended that in the frail elderly a TCA be started at the lowest possible dose and increased by only 10mg every other week. It is also suggested that residents receive the dose at bedtime to take advantage of sedating side effects.

Antiepileptic drugs used in the treatment of neuropathic pain include gabapentin (Neurontin®), and less commonly lamotrigine (Lamictyl®) and carbamazepine (Tegretol®). Gabapentin is generally well tolerated but sedation, balance problems, and cognitive impairments can occur, particularly in the elderly. To minimize side effects, start at a low dose (100 mg at bedtime) and increase by 100–200 mg every 7 days. Clinicians and patients sometimes evaluate the drug as ineffective when in fact inadequate doses are used. Although doses of 2400–3600 mg/day are typical in younger adults, geriatric specialists recommend smaller maximum daily doses of 1200–1500 mg. Gabapentin is most effective when it is divided into three doses per day.


Opioid analgesics are also effective in the treatment of neuropathic pain. Long acting opioids such as sustained relief morphine (e.g., MS Contin®), oxycodone (OxyContin®), and transdermal fentanyl (Duragesic®) may be titrated without ceiling to achieve adequate pain relief. As discussed in the May 2004 Tip of the Month on Methadone, the NMDA receptor activity that is unique to methadone may give it an advantage over other opioids for management of neuropathic pain. Remember that with all opioids, most residents become tolerant to the transient side effects of sedation and nausea; however, constipation persists throughout opioid therapy and must be managed prophylactically.


Important guidelines by Galer & Dworkin¹ for the pharmacologic management of neuropathic pain suggest that
  • Patients require individualized dosing to achieve relief from neuropathic pain.
  • Patients should be started on the lowest possible dose and titrate upwards; bear in mind the mantra: Start low and go slow.
  • Pharmacologic agents to control neuropathic pain should be administered around the clock as opposed to prn.
  • When adequate pain management requires more than one medication, titrate only one drug at a time — if you make too many changes at one time, you won’t know which drug caused which side effect.
  • Pharmacologic agents should be titrated every 3 to 14 days depending on the drug, the resident's side-effect history, and the resident’s medical history; residents who have a history of experiencing side effects with other medications are less likely to experience side effects with a slow, gentle increase.
  • Residents who are very sensitive to medications may be resistant to trying a new drug because of the fear of experiencing a side effect. If a low dose of a drug is started and slowly increased, the resident is much less likely to experience side effects.
  • Medications should be initiated in order of safety, efficacy, and side-effect profile, i.e., start with topical agents; if unsuccessful follow with oral agents. For example, an elderly resident with localized severe neuropathic pain in the right thorax due to PHN may experience pain relief from transdermal lidocaine. If pain is not relieved, gabapentin may be initiated at 100 mg/day with titration to effectiveness.

This month's tip provided by Polly Mazanec, MSN, APRN, BC, AOCN, Palliative Care Consultant, University Hospitals of Cleveland, Ireland Cancer Center and Elizabeth Ford Pitorak, MSN, APRN, CHPN, Director of the Hospice Institute, Hospice of the Western Reserve, Cleveland, OH.


Questions or comments? Please feel free to contact the PERT Program.



References

  1. Galer B, Dworkin R. A Clinical Guide to Neuropathic Pain. McGraw- Hill: Minneapolis, 2000.
  2. Nicholson B, Verma S. Comorbidities in chronic neuropathic pain. Pain medicine: The official Journal of the American Academy of Pain Medicine, 5(S1), 2004
  3. Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain , 5th Edition. American Pain Society, 2003.