Method establishment and clinical practice for concentration determination of caffeine and its metabolites in urine / 中国药房

OBJECTIVE To establish a method for concentration determination of caffeine and its three metabolites， theophylline， paraxanthine and theobromine in urine， and apply it in clinical practice. METHODS Using caffeine-13C3-d3 as internal standard （IS）， and the urine samples were protein precipitated with acetonitrile； HPLC-MS/MS method was adopted to determine the concentrations of caffeine and its three metabolites. The determination was performed on Waters ACQUITY UPLC® BEH HILIC column with mobile phase consisting of 60 mmol/L ammonium acetate （A）-acetonitrile （B） （gradient elution） at the flow rate of 0.5 mL/min. The column temperature was set at 38 ℃ ， and the sample size was 2 μL. The electrospray ionization detection was operated in a positive mode by multiple reaction monitoring. The detection ions for quantitative analysis were m/z 195.1→110.0 for caffeine， m/z 181.1→124.0 for theophylline， m/z 181.1→124.0 for paraxanthine， m/z 181.1→138.0 for theobromine， and m/z 198.1→ 140.1 for IS. The above method was used to determine the concentrations of caffeine and its three metabolites in the urine of 19 infants with apnea of prematurity （AOP）. RESULTS The linear ranges of mass concentration of caffeine， theophylline， paraxanthin and theobromine were 0.200-200， 0.050-50.0，0.050 0-50.0， and 0.100-100 μg/mL， respectively. The lower limits of quantification were 0.200， 0.050， 0.050 and 0.100 μg/mL （r＞0.990）， respectively. RSDs of intra-day and intra- day precision were not above 10.37%， and matrix factors were 85.68%-109.90%； extraction recoveries were 93.53%-109.40% （RSD≤15%）， and RSDs of stability tests were all lower than 15%. The concentrations of caffeine and its three metabolites in the urine of 19 cases were （27.346±7.951）， （0.351±0.223）， （0.428±0.395） and （0.472±0.374） μg/mL， respectively. CONCLUSIONS The established HPLC-MS/MS method is simple， sensitive and can be used for the determination of caffeine and its three metabolites in urine samples of AOP.

Development of Physiologically Based Pharmacokinetic Model and Assessment of the Impact of Renal Underdevelopment in Preterm Infants on the Pharmacokinetics of Aminophylline

Objective:To develop a physiologically based pharmacokinetic (PBPK) model for individualization of the dosing regimen considering the physiological requirements of these preterm neonates. Methods: The study comprised preterm newborns with fewer than 34 weeks of gestation and six apneic episodes in 24 h. A PBPK model was created using PK-SIM (version 9, update 1, GitHub, San Francisco, CA, USA). A PBPK model is built using a typical loading dosage of 5 mg/kg and a maintenance dose of 1.5 mg/kg. Based on the verified base model, a PBPK model representing renal underdevelopment based on nRIFLE/pRIFLE categorization was developed. Results: The PK parameters of Aminophylline were computed using the PBPK model. As per the model prediction, T1/2 and area under the curve reduced as postnatal age increased, and in the event of renal underdevelopment, even while Cmax for patients under R (RISK), I (injury) was within the therapeutic range; it was greater compared to preterm without any renal complications. Mean Cmax (mol/L) was 59.53 and for R, I, and F (FAILURE) categories the values were 83.04, 99.69, and 126.98, respectively. Conclusion: The model was created using appropriate drug, study subject, and dosage protocol inputs. The established PBPK model could help in individualizing aminophylline dose in preterm babies.

Recent research on gene polymorphisms related to caffeine therapy in preterm infants with apnea of prematurity / 中国当代儿科杂志

Apnea of prematurity (AOP) is one of the common diseases in preterm infants. The main cause of AOP is immature development of the respiratory control center. If AOP is not treated timely and effectively, it will lead to respiratory failure, hypoxic brain injury, and even death in severe cases. Caffeine is the first choice for the treatment of AOP, but its effectiveness varies in preterm infants. With the deepening of AOP research, more and more genetic factors have been confirmed to play important roles in the pathogenesis and treatment of AOP; in particular, the influence of single nucleotide polymorphism on the efficacy of caffeine has become a research hotspot in recent years. This article reviews the gene polymorphisms that affect the efficacy of caffeine, in order to provide a reference for individualized caffeine therapy. Citation.

The effect of mechanical or electrical stimulation on apnea length in mice

Premature birth is a leading cause of infant mortality which is often attributed to irregular breathing and apnea of prematurity. A common treatment for apnea is caffeine to stimulate the brain's respiratory center. However, caffeine's long term effect on infant development is not fully comprehended. We hypothesized that noninvasive localized body stimulation regularizes breathing pattern. We investigated the impact of electrical or mechanical stimulation on breathing in mice. After the mice were ventilated for 28 s to induce apnea, mice were taken off the ventilator while receiving mechanical, electrical, or no stimulation in a randomized order. Both stimuli targeted the diaphragm area through a custom-built belt with vibrating motors or adhesive electrodes. After each apnea cycle, the time to take the first breath (T) was recorded. The electrical stimulation given at 4.5, 8.3, 16.7 V (pulse rate = 3 Hz, pulse width = 120 μs) showed no reduction in T. Electrical stimulation at pulse rates of 10 or 20 Hz (16.7 V, pulse width 260 μs) showed a detrimental effect increasing T by ~ 7% compared to control values (p = 0.005, p = 0.038 respectively). High and medium intensity mechanical stimulations significantly reduced T by 11.74 (p<10⁻¹³) and by 17.08% (p<10⁻⁸), respectively. Further reducing the amplitude of vibrations did not affect T. When the probe was attached to the ankles, only the high intensity vibrations resulted in a decrease in T (p<10⁻¹³). Mechanical vibrations, applied at various intensities and locations, could be used to treat irregular breathing and apnea in infants.

Clinical Pharmacokinetics of Caffeine in Korean Preterm Infants with Apnea of Prematurity

PURPOSE: Caffeine shows wide interindividual pharmacokinetic (PK) variation, and therapeutic drug monitoring (TDM) may be needed. The PK profile of caffeine in Korean preterm neonates was investigated, and factors influencing the clearance of caffeine were analyzed. METHODS: Fifty-nine preterm neonates receiving caffeine for apnea of prematurity were enrolled in the study (gestational age, 29.5±2.2 weeks and birth weight [BW], 1,318±358 g). Caffeine (20 mg/kg) was intravenously administered to each neonate as a loading dose, followed by a maintenance dose of 5-10 mg/kg/d. A total of 190 serum concentrations were measured for population PK analysis and modeling using nonlinear mixed-effects model (NONMEM®) software. RESULTS: The mean serum concentration of caffeine was 15.4±4.5 mg/L (range 7.8-33.0 mg/L). High serum concentrations (>20 mg/L) were noted in 36 samples (29%). At the first measurement of serum caffeine, the mean postmenstrual age was 33.9±2.3 weeks, mean BW was 1,802±471 g, mean duration of treatment was 7.4±9.4 days, and mean sampling time after the last dose was 21.8±2.1 hours. In the population PK analysis, the clearance was 0.033 L/h and volume of distribution was 0.371 L. Typical clearance was calculated as 0.0293×(BW/70)1.33. Among the subjects receiving 5 mg/kg/d caffeine, the most significant risk factor associated with high serum concentrations (>20 mg/L) was low BW (P=0.024). CONCLUSION: BW was the only covariate that influenced caffeine clearance in preterm neonates. Preterm neonates with low BW should be carefully monitored for apnea and adverse reactions in addition to undergoing TDM.

Efficacy comparison of aminophylline combined with naloxone and caffeine citrate in prevention of apnea of prematurity / 中华实用儿科临床杂志

Objective To investigate the efficacy and safety of aminophylline,caffeine citrate and aminophylline combined with naloxone in prevention of apnea of prematurity(AOP).Methods Ninety-four infants with a birth weight ＜ 1 500 g and gestational age ＜ 34 weeks admitted to Department of Pediatrics,Tongji Hospital Affiliated to Tongji Medical College,Huazhong University of Science and Technology between Jan.2010 and Jan.2012 were randomly divided into 3 groups.(1) Aminophylline group (n =30):30 infants received a loading dose of 4-5 mg/kg of aminophylline and then maintained by a dose of 2 mg/kg,with intravenous drip q12 h.(2) Caffeine citrate group(n =32):a loading dose of 20 mg/kg of caffeine citrate was followed by a daily maintained dose of 5 mg/kg,with intravenous drip per day.(3) Aminophylline combined naloxone group (observation group,n =32):32 infants were treated with Aminophylline combined with naloxone.After 6 hours of the first dose of aminophylline,a dose of 0.1 mg/kg naloxone was injected,q12 h.Then the two drugs were used alternately.The mortality and incidence of AOP,bronchopulmonary dysplasia(BPD),retinopathy of prematurity (ROP) and brain injury were evaluated,and drug-related side effects were recorded.Results 1.There was no significant difference in gender,gestational age,birth weight,maternal antenatal glucocorticoid application,pregnancy (including multiple pregnancy) and delivery,5 min Apgar score,oxygen therapy,and the application of positive airway pressure as well as pulmonary surfactant among the 3 groups(all P ＞0.05).2.Compared with aminophylline group,the incidence of apnea of caffeine group and observation group were significantly lower (F =6.704,P ＜ 0.05),but there was no significant difference between caffeine group and observation group (P ＞0.05).3.There was no statistically significant difference in mortality,duration of oxygen therapy,the incidence of ROP,brain injury and hearing loss,postmenstrual age,body weight at discharge,the duration and cost of hospitalization among the 3 groups(all P ＞0.05).4.The BPD incidence in caffeine group[9.4％ (3/32 cases)] and observation group [12.5％ (4/32 cases)] were lower than that in Aminophylline group [20.0％ (6/30 cases)],but there was no statistical significance among the 3 groups(P ＞ 0.05).5.No drug-related side effects were recorded in the 3 groups.Conclusions It is safe and effective to use aminophylline combined with naloxone in prevention of AOP,and its efficiency is similar to caffeine citrate.

Plasma Glucose and Insulin Changes during IV Theophyline Therepy in Preterm Infants with Apnea / 대한주산의학회잡지

PURPOSE: The purpose of this study was to evaluate the effects of theophylline in preterm infants with apnea on glucose homeostasis and insulin values. METHOD: In this prospective study, level of glucose and insulin were measured from peripheral blood of 8 neonates(1,450+/-114gm, 31+/-2.1week), who were admitted from April 1, 1997 to July 30, 1997 in Neonatal Intensive Care Unit of Wonkwang University Hospital, for apnea of prematurity(> 20 sec with bradycardia and/or cyanosis) were given aminophylline intravenously. Blood samples were collected at pretreatment, posttreatment 2hours, 1-2days, 3-4days, 5-7days and posttreatment 48hours, and compare to those of the 8 control neonates(1,711+/-232gm, 32+/-1.7week). RESULTS: The results were as follows: 1) Plasma glucose values were significantly higher in the treatment group than those of the control group at 1-2days(104.67+/-20.39mg/dL vs 83.43+/-15.86mg/dL) and 3-4days(111.0+/-32.39mg/dL vs 79.25+/-14.03mg/dL)(p 125mg/dL). 3) The mean posttreatment glucose levels drawn at 48hours after discontinuation of theophylline was significantly decreased to the values of pretreatment values compared to those of the 1-2days and 3-4days(p 125mg/dL) was not noted. So, plasma glucose may not need to be monitored in preterm apneic infants receiving theophylline. But, further studies are need to elucidate the effect of theophylline considering the serum toxic level of theophylline.

Erythropoietin Levels in Premature Infants Following Prolonged Treatment with Theophylline

PURPOSE: Theophylline, an adenosine antagonist commonly used in premature infants to treat apnea, has been shown to decrease erythropoietin levels in adults. We studied the effect of theophylline on serum erythropoietin levels in premature infants with apnea. METHODS: Subject were 12 premature infants with apnea who were admitted to the NICU, Chosun University Hospital. The first dose of theophylline was 5mg/kg, given intravenously, followed by 1 to 2mg/kg per day. Serum levels were maintained between 5 and 12microgram/dl with dosage adjustments. Erythropoietin, hemoglobin, hematocrit, reticulocyte count, erythrocyte indices were obtained on the last day of theophylline treatment and again 1 week later. Erythropoietin levels were determined by radioimmunoassay. Blood transfusions were avoided a week before and during the study period. RESULTS: 1) Hemoglobin and hematocrit levels were decreased at 1 week after the discontinuation of theophylline treatment compared to the last day of theophylline treatment (P<0.05), but reticulocyte count (%) was increased (P<0.05). 2) There was a significant increase in serum erythropoietin levels from 3.31+/-1.53u/l to 6.68+/-2.41u/l (P<0.05). 3) No correlation was found between erythropoietin levels and the number of days on respirator, the number of days of O2 supply, the number of apneic episodes, the number of blood transfusion, the period of theophylline treatment and the theophylline blood levels. CONCLUSIONS: We suggest that prolonged treatment with theophylline might reduce erythropoietin production in premature infants.