A Pilot Study of the Maternal-Fetal Pharmacokinetics of Furosemide in Plasma, Urine, and Amniotic Fluid of Hypertensive Parturient Women Under Cesarean Section.

The third trimester of pregnancy is related to physiological changes that can modify the process of absorption, distribution, metabolism, and excretion and, consequently, the efficacy and toxicity of drugs. However, little is known about furosemide pharmacokinetics and placental transfer in pregnancy. This study evaluated the maternal-fetal pharmacokinetics and distribution to amniotic fluid of furosemide in hypertensive parturient women under cesarean section. Twelve hypertensive parturient women under methyldopa (250 mg/8 h) and/or pindolol (10 mg/12 h) treatment received a 40-mg single oral dose of furosemide 1 to 10 hours before delivery by cesarean section. Blood and urine samples were collected for 12 hours after furosemide administration. At delivery, samples were obtained from maternal and umbilical cord blood (n = 8) to assess the transplacental transfer. Amniotic fluid (n = 4) was collected at the time of delivery. The following furosemide pharmacokinetic parameters were obtained as median (interquartile range): Cmax , 403 ng/mL (229 to 715 ng/mL); Tmax , 2.00 hours (1.50 to 4.83 hours); elimination half-life (t1/2 ), 2.50 hours (1.77 to 2.97 hours); AUC0-12 h , 1366 ng⋅h/mL (927 to 2531 ng⋅h/mL); AUC0-∞ , 1580 ng⋅h/mL (1270 to 2881 ng⋅h/mL); CL/F 25.3 L/h (13.8 to 31.4 L/h); CLR, 2.50 L/h (1.77 to 2.97 L/h); CLNR, 22.7 L/h (12.1 to 25.6 L/h); and Vd /F 82.8 L (34.4 to 173 L). The transplacental transfer of furosemide was 0.43 (0.10 to 0.73), and the amniotic fluid concentration was 11.0 ng/mL (5.51 to 14.6 ng/mL). From a clinical point of view, these results suggest that substrates of uridine diphosphate-glucuronosyltransferase isoenzymes such as furosemide may have increased clearance during pregnancy and could require dose adjustment in this population.

No Requirement for Targeted Theophylline Levels for Diuretic Effect of Aminophylline in Critically Ill Children.

OBJECTIVES: To determine the relationship between theophylline trough levels and urine output in critically ill children administered aminophylline as adjunctive diuretic therapy. DESIGN: Retrospective cohort study. SETTING: The PICU of a tertiary care children's hospital. PATIENTS: A mixed population of medical/surgical including postoperative cardiothoracic surgery patients less than 18 years old. INTERVENTIONS: Electronic medical records of all PICU patients admitted from July 2010 to June 2015 were reviewed, and patients who received aminophylline as diuretic therapy were identified. MEASUREMENTS AND MAIN RESULTS: Patient cohort data including demographics, daily aminophylline, furosemide and chlorothiazide dosing, theophylline trough levels, fluid intake, urine output and total fluid balance, blood urea nitrogen, and creatinine levels were abstracted. Multivariate analysis based on a generalized estimating equations approach demonstrated that aminophylline administration, when analyzed as a categorical variable, was associated with an increase in urine output and decreased fluid balance. However, aminophylline dosing, when analyzed as a continuous variable, was associated with neither an increase in urine output nor decreased fluid balance. Theophylline trough levels were not correlated with urine output at 24 hours (p = 0.78) and were negatively correlated with urine output at 48 hours (r = 0.078; p < 0.005). CONCLUSIONS: Aminophylline administration provided a measure of increased diuresis, regardless of dosage, and theophylline trough levels. Therefore, achieving a prescribed therapeutic trough level may not be necessary for full diuretic effect. Because, as opposed to the diuretic effect, the side effect profile of aminophylline is dose-dependent, low maintenance dosing may optimize the balance between providing adjunctive diuretic effect while minimizing the risk of toxicity.