Painkiller Drug Development Is Booming, New Report Shows - But Pharmas Should Do

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Painkiller Drug Development Is Booming, New Report Shows - But

Pharmas Should Do Comparative Testing, Suggests Queen's

Anesthesiologist

http://www.medicalnewstoday.com/medicalnews.php?newsid=64147

The number of new drugs being developed to relieve neuropathic pain -

a chronic, devastating condition affecting three to eight per cent

of the population - has quadrupled over the past year and a half, a

Queen's University study shows.

But under present regulations, pharmaceutical companies are not

required to test their products against currently used neuropathic

pain drugs, notes Dr. Ian Gilron, Director of Clinical Pain Research

for Queen's Departments of Anesthesiology, and Pharmacology &

Toxicology, and an anesthesiologist at Kingston General

Hospital. " We would like to see more comparative drug trials,

whenever possible, so that the increased value of new drugs is

clearly shown. "

His review, co-authored with Dr. Terence Coderre of McGill

University, will be published in the March 2007 issue of the journal

Expert Opinion in Emerging Drugs.

" We were surprised to discover how rapidly this area has mushroomed

in a period of less than two years, " says Dr. Gilron. His survey of

recent submissions to Investigational Drugs (IDdb) and

Pharmaprojects databases revealed that the number of new drugs under

development to treat neuropathic pain has jumped from 13 to 48.

Defined as " pain caused by a lesion of the nervous system, "

neuropathic pain is a condition that has puzzled health care workers

for years because it is often experienced in areas of the body that

appear to be uninjured. Generally longstanding, severe, and

resistant to over-the-counter painkillers, it may result from a wide

variety of causes, including degenerative spinal disease, diabetes,

cancer and infectious diseases that affect the brain, spinal cord

and/or peripheral nerves.

" What's particularly exciting is the emergence of entirely new types

of drugs to combat this unique pain condition, " says Dr.

Gilron. " With so much work in basic science happening today, and the

recognition now that this is such a prevalent public health problem,

scientists in both universities and industry are able to apply the

new knowledge. "

Traditionally, the drugs used to treat neuropathic pain have been

anti-depressants, anti-convulsants, and sometimes opioids like

morphine. On average they reduce pain intensity by 20 to 40 per

cent.

New developments now under way include:

• vanilloids, such as capsaicin, extracted from hot chili peppers,

that actually burn when applied to the skin and eventually exhaust

the nerve's ability to transmit pain;

• cannabinoids, derived from chemical components found in marijuana

or cannabis; and

• combinations of drugs, where the combined effect is better than

either drug, when used alone.

Still in an experimental stage are pain-inhibiting treatments

derived from gene therapy. " We're not aware of any clinical trials

in this area, but the scientific basis is certainly there, " says

Dr.Gilron, noting that his study captured only those drugs disclosed

in the public domain. Industry is not required to make public its

pre-marketing testing, as long as other regulations are being met.

Of the new drugs identified in the review, 10 were in Phase 1

clinical trials (testing for toxicity and tolerability); 30 were in

Phase II trials (looking at effectiveness in a target population);

and eight had entered Phase III (the " pre-marketing " stage which is

usually much larger and placebo-controlled).

" Although it's likely that only a handful of these drugs will be on

the market in less than five years, it indicates there's a lot of

potential, and that the pipeline is getting fatter! " says Dr.Gilron.

The fact that regulatory agencies currently don't require such

clinical trials to include " active comparators " (determining whether

the drug being tested works better than those already on the market)

makes optimal treatment selection more difficult for prescribing

doctors, he comments.

The study recommends that, whenever possible, drug trials should

include comparative evaluations throughout the development process.

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