Cigarette smoking and heavy coffee drinking affect therapeutic response to olanzapine

Introduction/Objective. Considering relatively complex pharmacokinetic profile of olanzapine, it is expected that certain medications and some compounds, found in food and drink, can induce or inhibit its metabolism. The aim of our study was to investigate the influence of cigarette smoking and heavy coffee consumption on the clinical response to olanzapine. Methods. The phase IV, open-labeled, four-week-long prospective clinical trial included 108 adult patients diagnosed with schizophrenia. According to cigarette smoking (n = 52) and coffee drinking (n = 55), four subgroups were defined: non-smokers, non-heavy coffee consumers (group 1), non-smokers, heavy coffee consumers (group 2), smokers, non-heavy coffee consumers (group 3) and smokers and heavy coffee consumers (group 4). Positive and Negative Syndrome Scale (PANSS) and Global Assessment of Functioning (GAF) scales were used for therapeutic response evaluation. Results. Baseline and final GAF scores were 33.3 ± 5.0 and 61.5 ± 9.6, respectively, and PANSS scores were 100.7 ± 3.9 and 85.5 ± 5.4, respectively. The changes of GAF and PANSS scores from the baseline to the study end were 115.1 ± 35.7 and -19.6 ± 3.1, respectively (group 1), 91.1 ± 30.8 and -15.3 ± 2.9, respectively (group 2), 76.1 ± 29.8 and -13.4 ± 4.4, respectively (group 3), and 64.7 ± 29.3 and -11.3 ± 3.22, respectively (group 4), making significant subgroup differences for both scale scores (p < 0.001). Cigarette smoking and heavy coffee drinking significantly and independently diminished improvement in both GAF and PANSS total score (p < 0.001). Changes of body mass index from the baseline significantly influenced the change of PANSS total score only (p = n.s.), in a negative direction (r = -0.454, p < 0.001). Conclusion. Smoking and heavy coffee drinking influenced effects of olanzapine in patients with schizophrenia treated in routine practice