Pulmonary elimination rate of inhaled 99m Tc-sestamibi radioaerosol is delayed in healthy cigarette smokers

Aim - To explore inhaled technetium-99m-labelled hexakis-methoxy-isobutyl isonitrile (99mTc-sestamibi) for quantifying pulmonary P-glycoprotein(P-gp) expression. Methods - The elimination rate from the lungs of 99mTc-sestamibi was recorded scintigraphically for 30min following inhalation as an aerosol in healthy smokers, nonsmokers and patients with lung disease. Results - 99m Tc-sestamibi elimination rates [%min-1 (SD; P vs. healthy nonsmokers)] were: healthy nonsmokers, 0.43 (0.083); healthy smokers,0.19 (0.056; P < 0.001); chronic obstructive pulmonary disease patients, 0.26 (0.077; P < 0.001). Elimination rates in three patients with interstitial lung disease were not accelerated. Cconclusion - Cigarette smoke upregulates lung P-gp. 99mTc-sestamibi elimination in normal smokers could be used to test new P-gp modulators. The findings also have implications for inhaled drug delivery