Volume 12, Number 1
Smoking Any Substance Raises Risk of Lung Infections
By Michael D. Mueller
NIDA NOTES Staff Writer
Smoking any substance- tobacco, marijuana, or "crack," a smokable
form of cocaine-increases a smoker's risk of developing bacterial pneumonia
and other infections of the lungs, according to the findings of drug abuse,
smoking and health, and AIDS researchers.
Although some drugs seem to have specific damaging effects when smoked,
smoking anything appears to damage or paralyze the cilia, the hair-like
projections in the lungs that sweep out microbes and other matter that can
cause disease, according to NIDA-funded studies. Damaging the lung's cilia,
the respiratory system's first line of defense, can have severe consequences
for people with weak immune systems, the studies note.
A NIDA workshop held in August 1995 examined current research at that
time on the cardio-pulmonary complications of crack cocaine use. In a report
summarizing the major findings presented at the workshop, Dr. Pushpa V.
Thadani, a pharmacologist in NIDA's Division of Basic Research, notes that
smoking cocaine appears to weaken the crack smoker's natural resistance
to infection in the lungs.
"Pulmonary alveolar macro-phages-cells that protect the lungs from
infectious agents-are exposed to the highest concentrations of cocaine,"
says Dr. Thadani. NIDA-funded studies show that alveolar macrophages from
crack cocaine smokers are less active than are alveolar macrophages from
nonsmokers in destroying Staphylococcus aureus, a common cause of bacterial
lung infection. Preliminary findings also indicate that alveolar macro-phages
of cocaine smokers are more susceptible to HIV-related infections than are
alveolar macrophages of people who do not smoke cocaine.
"Much remains unknown about the effects of crack smoking on the
alveolar macrophages and other cells of defense in the lungs," says
Dr. Thadani. "However, it appears that there are profound effects,
and this needs to be further explored," she says.
Smoking anything appears to damage
or paralyze the cilia, the hair-like projections in the lungs that sweep
out microbes and other matter that can cause disease.
Dr. Donald P. Tashkin, a professor of medicine at the University of California
at Los Angeles School of Medicine, and his colleagues recently examined
the effects that habitual smoking of tobacco, marijuana, and/or cocaine
has on the lining of the lung's air passages. The NIDA-funded study included
53 nonsmokers, 14 smokers of crack cocaine only, 40 smokers of marijuana
only, and 31 regular tobacco smokers. In addition, there were 16 smokers
of both cocaine and marijuana, 12 smokers of cocaine and tobacco, and 44
smokers of both marijuana and tobacco. Thirty-one patients smoked all three
The researchers found that smoking either marijuana or tobacco produces
significant damage to the cilia in the lining of the airways. Among smokers
of both marijuana and tobacco, it appears that the effects of marijuana
add to the effects of tobacco, and vice versa. "The damage to the ciliated
cells in the lining of the airways caused by smoking tobacco, and/or marijuana
weakens the ability of the lungs to remove inhaled particles, making the
lungs more vulnerable to infection," says Dr. Tashkin.
Cocaine smokers had fewer significant abnormalities than marijuana or
tobacco smokers did- but more abnormalities than were detected among nonsmokers,
Dr. Tashkin says. Among people who smoke both tobacco and cocaine, cocaine
smoking appears to produce injury to the mucosal lining of the airways beyond
that caused by smoking tobacco alone.
A NIDA-supported study by Dr. Waleska T. Caiaffa and her colleagues at
Johns Hopkins University in Baltimore compared the medical records of 40
HIV-positive injecting drug users (IDUs) who had suffered from one bout
of bacterial pneumonia with those of 197 HIV-positive IDUs with no history
of bacterial pneumonia. The study found that HIV-positive IDUs who smoked
illicit drugs were almost twice as likely to develop bacterial pneumonia
as were their counterparts who did not smoke illicit drugs. This association
was independent of age, degree to which the natural immune system had been
suppressed, and cigarette smoking. Among the 77 HIV-positive IDUs who reported
smoking drugs, 87.9 percent indicated that they had smoked marijuana, 25.9
percent said that they had used cocaine, and 9.1 percent admitted smoking
Smoking is a serious issue among AIDS patients, according to several
NIDA-supported studies. The health effects of smoking illicit drugs are
above and beyond those caused by smoking cigarettes, the studies note. People
with AIDS often die of pneumonia and other lung problems, and smoking tobacco
and/or illicit drugs increases the risks for these diseases.
"The effect that smoking has on the lungs is more serious than most
people realize. Smoking anything is bad for your health, especially if your
immune system has been weakened," says Dr. Tashkin.
Caiaffa, W.T.; Vlahov, D.; Graham, N.M.; Astemborski, J.; Solomon, L.;
Nelson, K.E.; and Munoz, A. Drug smoking, Pneumo-cystis carinii pneumonia,
and immunosuppression increase risk of bacterial pneumonia in human immunodeficiency
virus-seropositive injection drug users. Am. J. of Respiratory and Critical
Care Medicine 150:1493-1498, 1994.
Fligiel, S.E.; Roth, M.D.; Kleerup, E.C.; Barsky, S.H.; Simmons, M.S.;
and Tashkin, D.P. Tracheobronchial histopathology in habitual smokers of
cocaine, marijuana, and/or tobacco. Chest, in press.
Thadani, P.V., et al. NIDA conference report on cardiopulmonary complications
of "crack" cocaine use: Clinical manifestations and pathophysiology.
Chest 110:1072-1076, 1996.
From NIDA NOTES, January/February, 1997
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