Medicine Might Help Shield Injection Drug Abusers From HIV

Study found 70 percent drop in new infections among addicts who adhered closely to tenofovir treatment

By Robert Preidt

HealthDay Reporter

WEDNESDAY, June 12 (HealthDay News) -- An antiviral drug may help protect injection drug users from HIV infection, a new study finds.

The study of more than 2,400 injection drug users recruited at 17 drug treatment clinics in Thailand found that daily tablets of tenofovir reduced the risk of HIV infection by nearly 49 percent, compared to inactive placebo pills.

One expert said an intervention to help shield injection drug users from HIV -- the virus that causes AIDS -- is much needed.

"This is an important study that opens up an additional option for preventing HIV in a hard-to-reach population," said Dr. Joseph McGowan, medical director at the Center for AIDS Research & Treatment at North Shore University Hospital in Manhasset, N.Y.

He noted that "HIV infections continue to occur at high rates, with over 2.5 million worldwide and 50,000 new infections in the U.S. each year. This is despite widespread knowledge about HIV infection and the way it is spread, through unprotected sex and sharing needles for injecting drugs."

The participants included in the new study were followed for an average of four years. During that time, 17 of the more than 1,200 patients taking tenofovir became infected with HIV, compared with 33 of an equal number of patients taking a placebo, according to the study published online June 12 in The Lancet.

Further analyses of the results showed that the protective effect of tenofovir was highest among those who most closely followed the drug's prescribed regimen. In this group, the risk of HIV infection was reduced by more than 70 percent, said study leaders Dr. Kachit Choopanya and Dr. Michael Martin, chief of clinical research for the Thailand Ministry of Public Health--U.S. Centers for Disease Control and Prevention Collaboration.

Prior research has shown that preventive use of antiviral drugs cuts the risk of sexual transmission of HIV in both heterosexual couples and men who have sex with men, and also reduces mother-to-child transmission of HIV. But this is the first study to show that this approach might also be effective among injection drug users.

Worldwide, injection drug use is believed to cause one in 10 new HIV infections. But rates of infection associated with injection drug use are far higher in some areas of the world, such as eastern Europe and central Asia. In these regions, up to 80 percent of new HIV infections are caused by injection drug use.

According to McGowan, tenofovir is no "silver bullet" that would, on its own, eliminate the risk of HIV infection for drug abusers. But it could be a key ingredient in reducing the odds.

"Adoption of this strategy, not as a stand-alone, but in conjunction with needle exchange, counseling, opiate substitution, social support and mental health therapy may enable us to get ahead of this expanding epidemic," McGowan said.

He added that the participants in the study were also provided with what's known as "directly observed therapy," where the drug is administered under the observance of a health care worker. Services like this, along with monthly HIV testing and condom distribution, might not occur in "real life" treatment situations, McGowan said, so outcomes might not be as good as in this clinical trial.

Another expert agreed that adherence to tenofovir therapy is key to success.

Tenofovir "accumulates slowly [in the body], making the case for adherence -- which is strongly associated with the efficacy of the drug," said Victoria Richards, assistant professor of medical sciences at the Frank H. Netter MD School of Medicine at Quinnipiac University, in Hamden, Conn.

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Graphically Speaking: Fracking and Injection Wells

Last week’s National Research Council report on hydraulic fracturing and earthquakes pretty much ends up where a number of scientists are on the correlation between fracking and quakes: that energy development from shale formations poses a low risk for tremors of significance. The report said more attention should be given to injection wells, which are used for waste disposal by a number of industrial enterprises, not just the oil and natural gas industry. AP science writer Seth Borenstein’s take on the report is here.

API, America’s Natural Gas Alliance and the American Exploration & Production Council have produced a couple of informational tools on hydraulic fracturing and seismic activity and underground injection control (UIC) wells that are especially timely with release of the council’s report. 

Highlights from the fracking document:

Hydraulic fracturing is done with a mixture of more than 99.5 percent water and sand. The other one-half of 1 percent is chemical – including anti-bacterials and lubricants. See the FracFocus.org site for more on fracking fluids.Fracturing that occurs thousands of feet below the surface (and below groundwater aquifers) is carefully mapped with sophisticated equipment to optimize recovery of the oil and/or natural gas and to monitor the well itself. In other words, microseismic activity associated with fracking is thoroughly understood.

One study of several thousand shale fracture treatments across North America showed the largest micro-quake measured about 0.8 or about 2,000 times less energy than a magnitude 3.0 earthquake. The chart below shows that most of the micro-quakes in this study were 10,000 to 1 million times smaller than a 3.0 earthquake, which is roughly equivalent to the passing of a nearby truck:

Highlights from the UIC document:

The U.S. has about 151,000 Class II UIC wells used by the oil and natural gas industry, of which only a handful are being studied for possible links to earthquakes. These wells are a subset of more than 800,000 injection wells nationwide used to dispose of a variety of industrial wastes and for development of various minerals and geothermal energy sources. Here’s a map that shows the state-by-state well distribution:

Injection wells are regulated by EPA under the Safe Drinking Water Act. In many cases EPA has delegated authority for the UIC program to the states, with 39 states having primary authority over 95 percent of all UIC Class II wells.Literature published in the past five years shows that less than 40 incidents of seismic activity felt on the surface were associated with Class II injection wells.

Injection wells pump fluids into deep rock formations (see graphic). It’s unusual, but in some cases a quake can occur when a number of geological and operational factors come together – especially the presence of hard, dense and brittle crystalline “basement rock.”  These quakes are almost always small, below the level that would be felt on the surface.

For more information, check out the Energy From Shale website.

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