The medical marijuana drug Sativex, which could be approved in the United States in the coming years as a treatment for pain relief, has little potential for abuse, experts say.

The British pharmaceutical company GW Pharmaceuticals is currently testing the drug, which is delivered as a mouth spray and called Sativex, in clinical trials. The company plans to seek U.S. Food and Drug Administration approval for the drug as a treatment for cancer pain when the trials are completed, likely sometime in 2014, a spokesperson for GW Pharmaceuticals told MyHealthNewsDaily.

The active ingredients in Sativex, known as cannabinoids, are derived from the cannabis plant. It is the first marijuana-based drug to be made by extracting the compounds from the plant, rather than synthesizing them. Two other drugs, Marinol and Cesamet, based on synthetic cannabinoids, were approved by the FDA in the 1980s.

Because the drug contains THC, the ingredient primarily responsible for marijuana's "high," it's possible people would use the drug for recreational rather than medical purposes.

"There is no doubt in my mind that there will be people that abuse it," said Dr. Jeffrey Bernstein, director of the Florida Poison Information Center at the University of Miami Miller School of Medicine.

However, because the drug is delivered through ingestion, rather than smoking, it would take much longer to have an effect — at least an hour, compared with the minutes it takes to get high after smoking marijuana, said Margaret Haney, a professor of clinical neurobiology at Columbia University. This means drug users seeking a high would be less likely to abuse it. "Smoking is a really effective way to get a chemical into the brain," Haney said. The mouth spray "is a far safer administration,"she said.

And Marinol and Cesamet, which are also administered orally, have a low rate of abuse. "We don’t see a lot of problems from [those]," Bernstein said.

Not the same high
GW Pharmaceuticals intends to market Sativex in the United States for treatment of cancer pain. The drug is already approved in United Kingdom, Spain, Canada and New Zealand to treat muscle spasms due to multiple sclerosis, according to the company website.

Patients can adjust the dose of Sativex to prevent it from entering the blood too rapidly, allowing them to experience symptom relief without the marijuana high, according to GW Pharmaceuticals.

In addition, while marijuana is a hodgepodge of about 64 different substances, Sativex is composed mainly of two ingredients: THC and another cannabinoid called CBD. The latter component is thought to ameliorate some of the side effects of THC, including the high that marijuana users feel, said Dr. Armando Villarreal, an assistant professor of neurosurgery and pain management at the University of Rochester Medical Center in New York.

And for habitual marijuana users, the cultural and ritualistic practices that go along with smoking pot, such as passing a joint, may be an important part of the experience, Bernstein said. These rituals cannot be replicated with the spray. "A lot of people that smoke marijuana would rather smoke it," he said.

Unlikely overdose
Unlike drugs such as painkillers, which come with a risk of death if people take too much, patients who "overdose" on the marijuana spray would be at little risk for acute health problems, Haney said.

"What could happen is the person could get very uncomfortably intoxicated," Haney said. But in terms of other serious health effects, "there's none that I know of," Haney said.

"Marijuana, in the scheme of things, is a relativity safe drug," Bernstein said. "Even as a smokeable drug of abuse, it's relatively safe…compared to cocaine or heroin."

However, Villarreal noted that for people with psychiatric disorders, smoking marijuana has been shown to make the patients' mental problems worse. It's possible Sativex may also cause this problem in some patients, he said.

Could it help patients?
So far, the studies that have been conducted do not provide enough evidence to say Sativex is effective in improving pain symptoms, Villarreal said.

Sativex has mainly been tested as a drug to treat pain caused by damaged nerves. If the drug is approved by the FDA, Villarreal speculated, its use could be restricted to certain pain patients. Those with cancer pain that is not caused by damaged nerves may not be candidates for the drug, Villarreal said.

About 1 in 11 people who try pot end up addicted to it, Haney said. It would be interesting to study whether Sativex could help people in dependent marijuana users quit the drug, she said.

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Smoking a joint a day for up to seven years didn't cause a reduction in lung capacity, a new study shows.

Periodically smoking marijuana doesn't appear to hurt lung capacity, the largest study ever conducted on pot smokers has found.

Even though most marijuana smokers tend to inhale deeply and hold the smoke in for as long as they can before exhaling, the lung capacity didn't deteriorate even among those who smoked a joint a day for seven years or once a week for 20 years, according to the study published Tuesday in JAMA, the journal of the American Medical Association.

In recent years, studies on marijuana smoking and its effects on lung function have been contradictory. While most studies have shown no effects on the lungs from smoking cannabis, others have shown adverse effects, and still others have shown improvement in lung function. Researchers at the University of California, San Francisco, and University of Alabama at Birmingham knew tobacco smoking causes lung damage and leads to respiratory issues such as chronic obstructive pulmonary disease (COPD), but they wanted to be clear whether smoking marijuana, had similar effects.

They measured lung function multiple times in more than 5,100 men and women during a 20-year period. In fact, the research shows, some people who regularly smoke marijuana can have a slight improvement in lung function.

Experts say that people shouldn’t simply take the news as green light to get high, but should also consider other factors.

“Marijuana is a complicated substance, and for people who are thinking about what they’ve done in the past or are thinking about using marijuana or believing it can help medically, their decision should not be based on lung consideration,” says study co-author Dr. Stefan Kertesz, a researcher and primary care doctor at University of Alabama at Birmingham and the Birmingham VA Medical Center.

“It’s not a decision about lung health, it’s all the other issues: the risk of addiction, an increase in the chance of having accidents and social functioning.”

Researchers reached their findings by using data from the Coronary Artery Risk Development in Young Adults, collecting repeated measurements of lung function and smoking from March 1985 to August 2006.  More than half of the participants, or 54 percent, said they were current marijuana smokers, cigarette smokers or both when the study began. The average marijuana use was only a joint or two a few times a month — typical for U.S. marijuana users, Kertesz said.

The authors calculated the effects of tobacco and marijuana separately, both in people who used only one or the other, and in people who used both. They also considered other factors that could influence lung function, including air pollution in cities studied.

The analyses showed pot didn't appear to harm lung function, but cigarettes did. Cigarette smokers' test scores worsened steadily during the study.

Researchers measured how well participants could blow air in and out. A healthy adult can exhale about a gallon of air in one second. Although their study focused on lighter smokers, they found some people who smoked more than a joint a day for seven years, could exhale slightly more air than that.

Kertesz says that extra strength may come from the habit of deeply inhaling, holding and slowly exhaling marijuana smoke.

“It’s a tiny increase; it’s not a big increase to lung health,” he says. “So be careful not to say that, ‘Oh, wow! Lungs work better on marijuana.’ That would be totally inaccurate.” 

Authors say there weren't enough heavy users (those who smoked two or more joints a day) among those in the study to draw firm conclusions on that group.

Dr. Donald Tashkin, who has studied the relationship between marijuana smoking and lung function for more than 30 years as a professor of medicine at UCLA, says the study confirms what other research has also concluded.

“This is a well-done study involving more subjects than in the past,” says Tashkin, who is not affiliated with the new study. “The public should take away it’s a confirmatory study, but larger and longer than previous studies demonstrating, once again, that smoking marijuana does not impair lung function, unlike tobacco.”

Tashkin says scientists have a theory that lung capacity is not affected in marijuana smokers because the chemical THC in marijuana has immunosuppressant properties that interfere with the development of respiratory issues such as COPD. He says this indicates there will be lower rates of COPD, but marijuana smokers are still at risk for chronic bronchitis, which means they tend to have increased cough and mucus. The study didn't look at the risk of lung cancer.

And Tashkin cautions about drawing overall conclusions from the new work: “We’re only talking about one end point. We’re not looking at lung cancer, chronic bronchitis symptoms. We are not looking at other effects, behavioral effects. We are looking at lung function.”

The Associated Press contributed to this report.

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