Effects of `Crack' Cocaine on Pulmonary Alveolar Permeability

¹ From the Department of Medicine, University of Southern California School of Medicine, Los Angeles
² From the Department of Radiology, UCLA School of Medicine, University of Southern California School of Medicine, Los Angeles
³ From the Departments of Medicine, Physiology, and Biophysics and the Will Rogers Institute Pulmonary Research Center, University of Southern California School of Medicine, Los Angeles

Background: Lung clearance of ^99mTc-labeled diethylenetriamine pentaacetate (DTPA) is a sensitive test of altered alveolar epithelial permeability that has been found to be increased in smokers of tobacco, as well as a small number of healthy smokers of crack cocaine, suggesting the possibility of subclinical crack-related lung injury.

Study objective: To evaluate further whether habitual smoking of cocaine alone alters alveolar permeability, whether crack smoking adds to or potentiates the effects of tobacco and/or marijuana, and whether experimental cocaine smoking acutely alters DTPA lung clearance.

Design: Observational cohort study (habitual cocaine smoking) and single-blind crossover study (experimental cocaine administration).

Subjects: Fourteen habitual smokers of cocaine alone (CS), 19 smokers of cocaine and tobacco (CTS), 3 smokers of cocaine and marijuana, 12 smokers of cocaine, tobacco, and marijuana (CMTS), and 5 smokers of marijuana plus tobacco (MTS). Results obtained in the crack-smoking subjects were compared with data previously obtained in 10 nonsmokers (NS), 9 smokers of tobacco alone (TS), 10 smokers of marijuana alone (MS), and 4 additional MTS.

Methods: Subjects underwent measurements of DTPA radioaerosol lung clearance after refraining from marijuana and/or cocaine for > 12 h and from tobacco for >2 h. Ten of the 48 crack users were tested on two days 1 to 2 weeks apart within 2 h of experimental smoking of three physiologically active or inactive doses (total 98.8±15.5 or 8.5±2.5 mg, respectively) of cocaine base. Lung clearance half-times (T) were computed from time-activity curves for each lung.

Results: T values for each lung in CS and MS were comparable to those of NS, while TS, MTS, CTS, and CMTS had significantly shorter clearance rates than NS (p<0.01; three-way analysis of variance). No additive or interactive effects on T were noted among tobacco, cocaine, and/or marijuana. No acute effect of experimental cocaine smoking on T was noted.

Conclusion: Whereas regular smoking of tobacco alone or with other substances increases alveolar epithelial permeability, habitual smoking of cocaine and/or marijuana has no measurable effect on alveolar permeability in the absence of tobacco nor any additive effect to that of tobacco alone.

Key Words: alveolar epithelial permeability • crack cocaine • DTPA lung clearance • marijuana • tobacco

Submitted on September 25, 1996
Accepted on January 8, 1997

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