Effect of cigarette smoking on serum hydrocodone levels in chronic pain patients.

Nicotine is reported to have analgesic properties. Patients with chronic pain who smoke could therefore, be expected to require less analgesia than non-smokers because of the possible synergism of the two substances. One hundred healthy patients were studied who had non-radicular low back pain for greater than three months. Each patient failed conservative therapies, which consisted of muscle relaxants, physical therapy and/or NSAIDS. Our study population consisted of two groups of 50 patients. Each group included: I, cigarette smokers; and II, non-smokers. Each patient received 0-40 mg/24hrs of hydrocodone as needed for pain relief for the duration of this four week study. Numeric pain intensity scores (0-10), mean total hydrocodone dosing, and quantitative blood nicotine and hydrocodone levels were assessed at the beginning and end of this study. Patients kept daily diaries and recorded pain scores and self hydrocodone dosing upon awakening, in the afternoon, and at bed time. Parametric and nonparametric statistical analysis was performed using the appropriate test with p < or = 0.05 necessary to reject the null hypothesis There were no differences in demographics between the two groups. Smokers had higher end of study pain scores and required more hydrocodone than non-smokers but had significantly lower serum levels of hydrocodone than non-smokers. The results of this study suggest that cigarette smoking adversely affects serum hydrocodone levels. Prescribing physicians should be aware that in some cigarette smokers, serum hydrocodone levels might not be detectible.