Correlation between CYP3A4 enzyme and analgesia with fentanyl after gynecological operation

Abstract

Objective To evaluate the correlation between CYP3A4 enzyme and analgesia with fentanyl after gynecological operation. Methods One hundred and fifty-nine ASA Ⅰ or Ⅱ patients, aged 30-50 yr, scheduled for elective myomectomy or abdominal total hysterectomy, were enrolled in this study. Anesthesia was induced with midazolam, remifentanil, propofol and succinylcholine and maintained with iv infusion of propofol and remifentanil and intermitent iv injection of atracurium. Venous blood samples were obtained for determination of the plasma 1'-hydroxymidazolam and midazolam concentrations at 1 h after iv injection of midazolam. The ratio of the 1'-hydroxymidazolam concentration to the midazolam concentration was used to reflect the effect of CYP3A4 enzyme. Pain was assessed with visual analog scale (VAS) after consciousness was regained. When VAS score ＞ 4,the patients were given fentanyl 10 μg every 5 min until VAS score ≤ 4 and then PCIA with fentanyl was performed. VAS score was maintained ≤4. The times of successful delivery within 24 h after operation and during the period of 24-28 h after operation and fentanyl consumption within 48 h after operation were recorded. Pearson correlation was used to analyze the data. Results There was no correlation between the effect of CYP3 A4 enzyme and the times of successful delivery or fentanyl consumption, and the correlation coefficients were 0.16, 0.13 and 0.11 respectively ( P ＞ 0.05). Conclusion CYP3A4 enzyme is not the major enzyme metabolizing fentanyl. Key words: Cytochrome P-450 enzyme system; Fentanyl; Analgesia, patient-controlled