Hildebrandt R, Weitzel H K, Gundert-Remy U
Department Obstetrics and Gynecology, University Hospital Klinikum Benjamin Franklin, Free University Berlin, Fed. Rep. of Germany.
J Perinat Med. 1997;25(2):173-9. doi: 10.1515/jpme.1997.25.2.173.
The effect of tocolytic treatment with fenoterol on plasma potassium concentrations was studied in 83 pregnant women on intravenous tocolytic therapy. Plasma concentrations of fenoterol and potassium were measured simultaneously, the time interval between initiation of therapy and taking the blood sample varying from 2 hours to 100 days. In a subset of 13 patients this blood sample was taken after two hours of therapy and pretreatment potassium concentrations were measured also. Pretreatment potassium concentrations were normal in these 13 patients and declined to 2.88 mmol/L (median) fenoterol concentrations being 320 ng/L through 1164 ng/L. Potassium concentrations measured later than 24 hours after initiation of therapy were all in the normal range corresponding fenoterol concentrations varying from 200 ng/L to 2504 ng/L. The multivariate statistical model for the description of all data showed that the duration of treatment was the only variable which explained the data to a significant extent. This might indicate that tolerance to the potassium lowering effect of fenoterol had developed within 24 hours after initiation of therapy. In the subset of 13 patients pretreatment potassium concentrations were found to be more important in explaining potassium concentrations than fenoterol concentrations at two hours. As we did not observe any adverse events in patients with low potassium concentrations and potassium concentrations were normal within 24 hours, we conclude that hypokalaemia due to fenoterol in the treatment of premature labor is not of clinical concern.
在83名接受静脉内宫缩抑制治疗的孕妇中，研究了用非诺特罗进行宫缩抑制治疗对血浆钾浓度的影响。同时测量了非诺特罗和钾的血浆浓度，治疗开始至采集血样的时间间隔从2小时到100天不等。在13名患者的亚组中，在治疗两小时后采集该血样，并也测量了治疗前的钾浓度。这13名患者治疗前的钾浓度正常，降至2.88 mmol/L（中位数），非诺特罗浓度为320 ng/L至1164 ng/L。在开始治疗24小时后测量的钾浓度均在正常范围内，相应的非诺特罗浓度为200 ng/L至2504 ng/L。描述所有数据的多变量统计模型表明，治疗持续时间是唯一能在很大程度上解释数据的变量。这可能表明在开始治疗后24小时内已产生了对非诺特罗降钾作用的耐受性。在13名患者的亚组中，发现治疗前的钾浓度在解释两小时时的钾浓度方面比非诺特罗浓度更重要。由于我们在低钾浓度患者中未观察到任何不良事件，且钾浓度在24小时内正常，我们得出结论，在早产治疗中因非诺特罗引起的低钾血症并非临床关注问题。
