The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

Second Hand (S)-albuterol:RT Exposure Risk Following Racemic Albuterol.

Bettye Carnathan,RRT, Barbara Martin, PA-C, Gene Colice MD, Washington Hosp Ctr., Washington,DC

Racemic albuterol (RAC), a 50:50mix of (R)-albuterol[R] and (S)-albuterol [S], is commonly used by RTs. R confersall of the bronchodilatory effects, while S demonstrates proinflammatory propertiesin in vitro and in vivo models. S is metabolized 10-fold moreslowly, resulting in higher plasma levels that remain in circulation much longerafter RAC administration. RTs have a higher rate of developing asthma afterentering their profession (7.4 vs 2.4%, respectively; Christiani, 1993). Whetherexposure to nebulized medications such as RAC contribute to this, or some otheroccupational hazard is responsible, is unknown. This study was designed to determineif S and R are detectable in the plasma of RTs. Eligible subjects (at least18 years old; no asthma or other lung disease; at least 4 hrs of RAC exposureon each of 4 study days) began the study after a 2-day work holiday. Blood wasdrawn for S and R levels at baseline, 2, 4, and 8 hrs after exposure on Days1 and 4. Subjects (n=12; mean age 38 yrs) nebulized deliveredwere exposed toapproximately 31 mg of RAC by nebulization or MDI (range 22-43 mg) for 4.3 hours(range 3.2-5.5 hours) each day. At baseline on Day 1, On Day 1,mean levels ofR and S were below the limit of quantification (BLQ, <2 pg/mL) at baseline,but were detectable after 2 hrs and increased over the 8-hr period. S levelswere 1.6-2.5-fold higher than R (Table). On Day 4, approximately 2416 hrs afterthe last exposure, baseline levels of S, but not R, were detectable (3.7 pg/mL).Peak flow improved or remained unchanged in most subjects, but decreased in3/12 subjects by an average of 30 mL. R- and S-albuterol are detectable in RTsfollowing administration of RAC. S achieves higher plasma levels that remainin the systemic circulation for a longer period of time.

Day 1Mean R-albuterolLevel (pg/mL)MeanS-albuterol Level (pg/mL)S:R ratio
2 hours6.6 (1.2)9.8 (1.5)1.6 (0.2)
4 hours9.6 (3.1)13.8 (3.1)1.8 (0.2)
8 hours10.0 (1.2)19.6 (3.7)2.1 (0.1)
BaselineBLQ3.7 (0.8)2.1 (1.1)
2 hours5.4 (0.5)11.2 (0.7)2.2 (0.1)
4 hours5.8 (0.8) 13.6 (1.6)2.4 (0.1)
8 hours8.6 (1.2)19.9 (2.4) 2.5 (0.2)


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