02:16 PM ET 09/23/98



Synthetic marijuana-like drug eases pain - study



         

            By Patricia Reaney

            LONDON, Sept 23 - American researchers have shown

that a synthetic drug that mimics the main active ingredient in

marijuana works like morphine to reduce pain, they said on

Wednesday.

            In a letter to the science journal Nature, Dr Ian Meng and

researchers from the University of California in San Francisco

explained how compounds in marijuana, known as cannabinoids,

affect cells in an area of the brain that controls pain.

            Marijuana has been touted as a pain killer for a variety of

medical conditions but studies of humans have produced

inconsistent results and its use for medicinal purposes is still

controversial.

            Meng's finding from his research on rats raises the

possibility that marijuana-like drugs could be used to treat

pain.

            ``These results indicate that the marijuana-like drug can

reduce pain by affecting the same pain modulating neurons (brain

cells) as morphine, but through separate mechanisms,'' Meng

said.

            Unlike morphine and other opiates which can cause nausea and

respiratory depression, marijuana increases appetite without

uncomfortable or serious side effects. The addiction potential

of marijuana is also much lower.

            ``The implications for future development or treatment would

be looking at different combinations of therapies, a lower dose

of morphine combined with a low dose of cannabinoid,'' Meng said

in a telephone interview.

            ``Perhaps you could eliminate the nausea or at least reduce

it and increase the pain-killing effects,'' he added.

            The research is the latest study into the medicinal

properties of marijuana. It follows a report by the National

Institute of Mental Health in the United States in July that

showed cannabinoids could protect the brain from the damage

caused by injuries and stroke.

            Meng and his colleagues tested the effects of the synthetic

drug on a region of the brain called the rostral ventromedial

medulla (RVM). By measuring the time it took for rats to move

their tails away from a heat source they showed the

pain-relieving effects of cannabinoids.

            Rats given the drug kept their tails on the heat much longer

than rats which didn't receive it.

            In a second experiment the researchers tested the effect of

the drug on the neurons in the RVM of anesthetized rats and

found it produced the same changes as morphine, but in a

different way.

            Some sufferers of arthritis have used marijuana to relieve

their symptoms. Cancer patients also claim it alleviates the

nausea from chemotherapy treatments and medical evidence has

shown it increases the appetite of AIDS sufferers with wasting

diseases.

 

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