Antidepressants should be first-line approach for nerve tissue pain

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Antidepressants should be first-line approach for nerve tissue pain

21 Jul 2005 Medical News Today

New reviews of previous studies confirm that older-style

antidepressants, as well as anticonvulsant drugs, can help ease the

disabling pain caused by nerve tissue damage.

Often felt as a burning, tingling or stabbing sensation, neuropathic

pain can result from nerve injuries or from conditions including

chronically high blood sugar, complications from shingles or some

cancer treatments.

For many years antidepressants, which are believed to work by

dampening pain signals, have been the first-line drugs for

neuropathic pain. " It is usual to start with an antidepressant like

amitriptyline, and if this fails then try an anticonvulsant, " says

Phil Wiffen, a researcher at Churchill Hospital in Oxford,

England. " The results of these meta-analyses suggest this is probably

still the best approach to take. "

Wiffen led several systematic evidence reviews on the effect of

various antidepressants and anticonvulsives on pain, appearing in the

current issue of the Cochrane Library, a publication of The Cochrane

Collaboration, an international organization that evaluates medical

research. Systematic reviews draw evidence-based conclusions about

medical practice after considering both the content and quality of

existing medical trials on a topic.

Wiffen and Tiina Saarto, M.D., analyzed 50 trials of 19

antidepressants, which involved more than 2,500 study participants.

They found that tricyclic anti-depressants, particularly

amitriptyline, can help ease the two most common types of neuropathic

pain: from diabetes and shingles. The researchers recommend more

studies of the effects of other antidepressants such as the newer

selective serotonin reuptake inhibitors (SSRIs) and selective

Norepinephrine Reuptake Inhibitors (SNRIs), as well as alternative

medicines such as St. 's Wort, before they can be recommended for

neuropathic pain.

These results on tricyclics may be encouraging but " antidepressants

do not cure or totally eliminate all pain, " says Dennis C. Turk,

Ph.D., at the University of Washington.

" The amount of pain reduction is moderate at best. Typically the pain

reduction averages around 40 percent in 50 percent of treated

patients, " Turk says. " This means that a significant proportion of

patients do not obtain even moderate reductions in pain and even

those who do continue to experience significant pain. "

The findings on anticonvulsants are similarly both encouraging and

sobering. Originally developed to treat epilepsy, anticonvulsants

have been used to treat pain since the 1960s, and are believed to

work by quieting abnormal firings of nerves in the brain and central

nervous system.

Anticonvulsant drugs currently used for neuropathic pain are:

carbamazepine, gabapentin, clonazepam, gabapentin, lamotrigine,

oxcarbazepine, phenytoin, valproate and, most recently, pregabalin.

To evaluate the effectiveness of carbamazepine, Wiffen and colleagues

examined 12 studies, which included more than 400

participants. " There is evidence to show that carbamazepine is

effective but trials are small, " write Wiffen and colleagues.

Gabapentin is a newer drug that is becoming so popular that it has

reaped more than $2 billion in yearly sales in recent years, mostly

for neuropathic pain treatment. After examining 15 studies of

gabapentin that consisted of nearly 1,500 participants, the

researchers found its effectiveness to be comparable to

carbamazepine.

Gabapentin has fewer side effects than carbamazepine so it may be a

good choice for some, but it's more expensive, and cheaper treatments

are equally effective.

" Gabapentin is not superior to carbamazepine, " Wiffen says. " It

works, but so do carbamazepine and tricyclic antidepressants, which

are far more affordable.

In their general analysis of anticonvulsants, Wiffen and colleagues

examined 23 trials consisting of more than 1,000 patients. These

results of these studies were conflicting, suggesting the need for

more studies of the effectiveness of each anticonvulsant, along with

comparison studies of anticonvulsants and antidepressants, according

to the researchers.

" The evidence here does not support the use of anticonvulsants as

first-line remedies, " write Wiffen and colleagues, adding that

tricyclic antidepressants should be the first choice.

Turk says the newer antidepressants, the SSRIs and SNRIs - are worth

trying even though the jury is still out on their effectiveness for

neuropathic pain, but the side effects are more manageable.

" Neuropathic pain can be extremely severe, disabling, and

recalcitrant to treatment, " Turk says. " It is therefore reasonable to

try patients on antidepressants and combinations of antidepressants

with other drugs in what has come to be known as 'rational

polypharmacy.' "

FOR MORE INFORMATION

Health Behavior News Service: 202-387-2829 or http://www.hbns.org.

Interviews: Contact Phil Wiffen at 44-186-522-5762 or

phil.wiffen@...

To receive a full copy of the review or to arrange an interview with

an author, contact Lampam at 44-124-377-0668

Wiffen P, S. et al. Anticonvulsant Drugs for Acute and

Chronic Pain; Saarto T & Wiffen, PJ. Anitdepressants for Neuropathic

Pain; Wiffen PJ, McQuay HJ, RA. Carbamazepine for Acute and

Chronic Pain; Wiffen PJ, McQuay HJ, RA. Gabapentin for Acute

and Chronic Pain (Reviesw) The Cochrane Database of Systematic

Reviews 2005, Issue 3

The Cochrane Collaboration is an international nonprofit, independent

organization that produces and disseminates systematic reviews of

health care interventions and promotes the search for evidence in the

form of clinical trials and other studies of interventions. Visit

http://www.cochrane.org for more information.

Center for the Advancement of Health

http://www.cfah.org