1.Research progress in pharmacokinetics and therapeutic drug monitoring of tyrosine kinase inhibitors in the treatment of gastrointestinal stromal tumors
Qiongye HUANG ; Yang ZHAO ; Yi LIU ; Yongqing WANG ; Luning SUN
China Pharmacy 2024;35(7):890-895
Tyrosine kinase inhibitors (TKIs) represent a class of small-molecule targeted drugs that improve the survival time of patients with gastrointestinal stromal tumor (GIST). Imatinib, sunitinib, regorafenib, ripretinib, and avapritinib are commonly used TKIs in the clinical treatment of various types of GIST. This article provides a comprehensive review of the pharmacokinetics and therapeutic drug monitoring (TDM) of these five drugs, finding that there is significant individual variability in the pharmacokinetics of these drugs. Among them, the absorption of imatinib, regorafenib, and avapritinib are influenced by food intake. Imatinib should be taken with meals and 200 mL of water, regorafenib is taken with a low-fat meal, while avapritinib is taken on an empty stomach. TKIs are mainly metabolized by cytochrome P450 3A4 (CYP3A4), and when used in combination with CYP3A4 inducers or inhibitors, drug exposure levels will significantly change; apart from metabolic enzymes, the exposure levels of TKIs are also influenced by interactions with the transporter proteins P-glycoprotein and breast cancer resistance protein. Currently, research on TDM for TKIs is still in the exploratory stage, with a substantial amount of literature reporting the effective concentrations of imatinib, sunitinib and regorafenib. However, the precise relationship between exposure levels and efficacy/ toxicity needs further exploration. Currently, there is a lack of research on the correlation between exposure levels and efficacy/ toxicity of ripretinib and avapritinib. It is recommended to implement TDM in patients taking these drugs and explore their therapeutic window in combination with pharmacokinetic models. The commonly used methods for clinical TDM of TKIs include immunoassay, chromatography, and surface-enhanced Raman spectroscopy, providing a technical basis for clarifying the therapeutic window of TKIs.
2.Arthroscopic long head of the biceps tendon transposition for augmented repair of massive rotator cuff tear
Kai DING ; Yujing YAO ; Zhipeng LI ; Lei WANG ; Changyuan GU ; Hao SHU ; Luning SUN
Chinese Journal of Tissue Engineering Research 2024;28(35):5675-5680
BACKGROUND:Transposition of the long head of biceps tendon is a commonly surgical method for massive rotator cuff tears.Currently,there are a few reports on the clinical efficacy of the transposition of the long head of biceps tendon and there is no consensus on the influencing factors for retearing. OBJECTIVE:To observe the outcome of arthroscopic long head of the biceps tendon in the treatment of massive rotator cuff tear. METHODS:The clinical data of 28 patients with massive rotator cuff tears,aged(61.79±10.50)years,admitted at Jiangsu Province Hospital of Chinese Medicine from March 2019 to May 2022 were retrospectively analyzed.All patients underwent arthroscopic long head of the biceps tendon.Patients were assessed for visual analog scale scores,University of California at Los Angeles scores,American Shoulder and Elbow Surgeons scores,Constant-Murley scores,and shoulder range of motion before and 1 year after operation.MRI of the shoulder joint was performed for observing the integrity of the repaired structure at 1 year after operation.Twenty-three patients(5 of 28 lost to follow-up)were categorized into the intact tendon group(n=18)and the tendon retear group(n=5)according to the Sugaya typing at 1 year after operation;the patients were divided into the normal group(n=8),the degeneration group(n=9),and the partial tear group(n=6)according to the intraoperative quality of the long head of the biceps tendon.Differences in the above indexes were compared between groups. RESULTS AND CONCLUSION:When followed up at 1 year after surgery,the range of motion,visual analog scale scores,University of California at Los Angeles scores,American Shoulder and Elbow Surgeons scores,Constant-Murley scores of the shoulder were significantly improved compared with preoperative data(P<0.05).There was a significant difference in Goutellier grading between intact tendon and tendon retear groups(P<0.05),while no significant difference was observed in the other influencing factors(P>0.05).There were no significant differences in visual analog scale scores,University of California at Los Angeles scores,American Shoulder and Elbow Surgeons scores,Constant-Murley scores,and shoulder range of motion at 1 year after operation among the normal,degeneration,and partial tear groups(P>0.05).MRI findings indicated that the sutured tendon healed well in 18 patients,with a healing rate of 78%.Arthroscopic long head of the biceps tendon for augmented repair can provide a reliable repair for massive rotator cuff tear that is refractory,significantly alleviate the pain of the shoulder joint,and restore the function of the shoulder joint.
3.Analysis of risk factors and their warning effectiveness for meniscus tear secondary to delayed anterior cruciate ligament reconstruction
Kai DING ; Yujing YAO ; Zhipeng LI ; Lei WANG ; Changyuan GU ; Hao SHU ; Luning SUN
Chinese Journal of Trauma 2024;40(3):229-235
Objective:To investigate the risk factors and their warning effectiveness for meniscus tear secondary to delayed anterior cruciate ligament (ACL) reconstruction.Methods:A retrospective cohort study was conducted to analyze the clinical data of 114 patients (114 knees) with ACL injury, who were admitted to Affiliated Hospital of Nanjing University of Chinese Medicine from December 2018 to December 2023, including 78 males and 36 females, aged 11-50 years [29(21, 35)years]. The patients were divided into tear group ( n=46) and non-tear group ( n=68) according to whether combined with meniscus tear or not during the surgery. Gender, age, duration of disease, smoking history, Body Mass Index (BMI), cause of injury, mechanism of injury, side of the injury, Beighton score, difference of KT-2000 examination, Tegner activity scale of the knee joint, anterior tibial translation sign, medial posterior tibial slope angle, lateral posterior tibial slope angle, and pivot shift grading of the patients in the two groups were recorded. Correlations between the above-mentioned indicators and occurrence of meniscus tear secondary to delayed ACL reconstruction were assessed. In the meantime, the independent risk factors were determined by univariate and multivariate binary logistic regression analysis. Receiver operating characteristic (ROC) curve and area under curve (AUC) were used to evaluate the warning effectiveness of each risk factor for meniscal tear secondary to delayed ACL reconstruction. Results:Univariate analysis showed correlation of duration of disease, BMI, Tegner activity scale of the knee joint, medial posterior tibial slope angle, lateral posterior tibial slope angle and high-grade pivot shift with occurrence of meniscus tear secondary to delayed ACL reconstruction ( P<0.01). The results of multivariate binary logistic regression analysis showed that the duration of disease ≥14.5 weeks ( OR=1.20, 95% CI 1.05, 1.38, P<0.01), BMI≥26.9 kg/m 2 ( OR=1.36, 95% CI 1.03, 1.81, P<0.05), Tegner activity scale of the knee joint ≥4 points ( OR=2.29, 95% CI 1.18, 4.46, P<0.05), medial posterior tibial slope angle ≥11.2° ( OR=2.27, 95% CI 1.06, 4.89, P<0.05) and high-grade pivot shift ( OR=0.03, 95% CI 0.01, 0.03, P<0.05) were significantly correlated with occurrence of meniscus tear secondary to delayed ACL reconstruction. Results of ROC curve analysis showed that the medial posterior tibial slope angle (AUC=0.86, 95% CI 0.80, 0.93) and duration of disease (AUC=0.85, 95% CI 0.77, 0.92) had good warning value, BMI (AUC=0.78, 95% CI 0.69, 0.87) and Tegner activity scale of the knee joint (AUC=0.73, 95% CI 0.64, 0.83) had ordinary warning value, and the warning value of high-grade pivot shift (AUC=0.60, 95% CI 0.49, 0.71) was the lowest. The combination of the risk factors revealed superior warning effectiveness for meniscus tear second to delayed ACL reconstruction (AUC=0.97, 95% CI 0.96, 1.00). Conclusions:The duration of disease ≥14.5 weeks, BMI ≥26.9 kg/m 2, Tegner score ≥4 points, medial posterior tibial slope angle ≥11.2°and high-grade pivot shift are independent risk factors for meniscus tear secondary to delayed ACL reconstruction. The medial posterior tibial slope angle and duration of disease have good warning value, BMI and Tegner scores have ordinary warning value and high-grade pivot shift has the lowest warning value. The combination of the above risk factors has better warning effectiveness for meniscus tear secondary to delayed ACL reconstruction.
4.Relationship between ripretinib concentration and the prognosis of advanced gastrointestinal stromal tumors in China: a multicenter study
Hao XU ; Xiaofeng SUN ; Haoran QIAN ; Ming WANG ; Xin WU ; Ye ZHOU ; Feng WANG ; Luning SUN ; Yongqing WANG ; Fengyuan LI ; Qiang ZHANG ; Zekuan XU
Chinese Journal of Gastrointestinal Surgery 2024;27(11):1133-1140
Objective:To investigate the prognosis and safety of ripretinib in the treatment of patients with advanced gastrointestinal mesenchymal stromal tumors (GISTs) and to analyze the relationship between blood concentrations of this drug and prognosis.Methods:In this retrospective study, we investigated the effects of ripretinib in patients with advanced GISTs. The inclusion criteria comprised: (1) daily oral administration of ripretinib scheduled; and (2) uninterrupted treatment for at least 1month, with a stable and relatively fixed daily dosage maintained for a minimum of 2 weeks. Exclusion criteria comprised concurrent use of other tyrosine kinase inhibitors and presence of significant organ dysfunction. We retrospectively identified 79 patients with advanced GISTs who had received ripretinib across seven medical centers, namely Jiangsu Provincial Hospital, Jiangsu Cancer Hospital, Nanjing Drum Tower Hospital Affiliated to Nanjing University, Sir Run Run Shaw Hospital of Zhejiang University, Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and the General Hospital of the People's Liberation Army, from 1 June 2021 to 31 March 2024. The cohort included 48 men and 31 women, 19 of whom had received ripretinib as second-line, 13 as third-line, and 47 as fourth-line therapy. Two peripheral venous blood samples were obtained from each participant and high-performance liquid chromatography-tandem mass spectrometry used to determine peak (Cmax) and trough (Cmin) concentrations of ripretinib. Machine learning methodologies, specifically the K-nearest neighbor algorithm combined with the Gridsearch CV strategy, were employed to establish the threshold for Cmin. We analyzed adverse reactions, treatment efficacy, median progression-free survival (mPFS), and the relationship between drug blood concentration and selected clinical parameters.Results:In the entire cohort, the Cmin and Cmax of ripretinib were 467 ± 360 μg/L and 986 ± 493 μg/L, respectively. Notably, female patients and individuals in the high-dose group exhibited significantly higher values for both Cmin and Cmax (both P<0.05). However, variations in drug concentrations associated with the line of ripretinib therapy, treatment efficacy, disease progression, and presence of selected specific genetic mutations were not significantly associated with values of Cmin and Cmax ( P>0.05). Among the 79 patients with advanced GISTs receiving ripretinib, reported adverse reactions included alopecia (53, 67.09%), hand–foot syndrome (24, 30.38%), fatigue (22, 27.85%), and myalgia (21, 26.58%). Two patients (2.53%) had grade III complications, both classified as hand–foot syndrome. The correlation between Cmax and adverse reactions was not statistically significant ( P > 0.05). By the time of the latest follow-up, five deaths (6.3%) had occurred within the cohort. The mPFS for the group was 16.3 months, with a mPFS of 14.4 months for those receiving standard dosage and 7.0 months for those receiving escalating dosage. Among the 65 patients treated with standard doses of ripretinib, those with Cmin exceeding a threshold of 450 μg/L exhibited a significantly longer mPFS (18.0 months vs.13.7 months; P < 0.05). Conclusion:In China, patients with advanced GISTs exhibit a notable tolerance to ripretinib, with no evidence for a correlation between adverse reactions and Cmax for the drug. Additionally, a Cmin exceeding 450 μg/L may be associated with an extended mPFS.
5.Predictive value of preoperative blood inflammatory markers for recurrence risk of basal cell carcinoma
Ruixue SUN ; Xiaoxiao LIU ; Xinyi YUE ; Dongmei YANG ; Luning REN ; Fei WANG ; Hongyang DU
Tianjin Medical Journal 2024;52(12):1274-1277
Objective To investigate the predictive value of preoperative blood inflammatory markers for the recurrence risk in patients with basal cell carcinoma(BCC).Methods A total of 225 patients with BCC were divided into the high-risk recurrence group(155 cases)and the low-risk recurrence group(70 cases).General information and preoperative hematological indicators were collected in the two groups of patients.The neutrophil-to-lymphocyte ratio(NLR),lymphocyte-to-monocyte ratio(LMR),systemic inflammation marker(SIM)and platelet-to-lymphocyte ratio(PLR)were calculated.Receiver operating characteristic(ROC)curves were used to determine the predictive value of hematological markers with statistically significant differences between the two groups for BCC recurrence and to establish optimal cutoff values.Univariate and multivariate Logistic regression analyses were conducted to identify factors influencing BCC recurrence.A multivariate Logistic regression model was established to predict the recurrence risk of BCC.Area under the curve(AUC)and the Hosmer-Lemeshow test were used to evaluate the prediction efficiency and goodness-of-fit of the model.Results ROC analysis identified that optimal cutoff values for LMR and SIM were 5.12 and 0.86,respectively.Univariate Logistic regression analysis showed that LMR,SIM,ulceration at the primary tumor site,UV exposure and tumor maximum diameter were factors influencing BCC recurrence.Multivariate Logistic regression revealed that SIM≥0.86,tumor maximum diameter≥2.0 cm and UV exposure were risk factors for BCC recurrence,while LMR≥5.12 had a protective effect.The Logistic prediction model for BCC recurrence risk was Logit(P)=-1.598-1.517×LMR+1.323×SIM+2.406×UV exposure+3.465×tumor maximum diameter,with good model fit(P=0.725)and an AUC of 0.869(95%CI:0.822-0.917)for predicting BCC recurrence risk.Conclusion Monitoring preoperative LMR and SIM levels can assist in assessing the risk of recurrence in BCC patients and provide important guidance for clinical decision-making.
6.Relationship between ripretinib concentration and the prognosis of advanced gastrointestinal stromal tumors in China: a multicenter study
Hao XU ; Xiaofeng SUN ; Haoran QIAN ; Ming WANG ; Xin WU ; Ye ZHOU ; Feng WANG ; Luning SUN ; Yongqing WANG ; Fengyuan LI ; Qiang ZHANG ; Zekuan XU
Chinese Journal of Gastrointestinal Surgery 2024;27(11):1133-1140
Objective:To investigate the prognosis and safety of ripretinib in the treatment of patients with advanced gastrointestinal mesenchymal stromal tumors (GISTs) and to analyze the relationship between blood concentrations of this drug and prognosis.Methods:In this retrospective study, we investigated the effects of ripretinib in patients with advanced GISTs. The inclusion criteria comprised: (1) daily oral administration of ripretinib scheduled; and (2) uninterrupted treatment for at least 1month, with a stable and relatively fixed daily dosage maintained for a minimum of 2 weeks. Exclusion criteria comprised concurrent use of other tyrosine kinase inhibitors and presence of significant organ dysfunction. We retrospectively identified 79 patients with advanced GISTs who had received ripretinib across seven medical centers, namely Jiangsu Provincial Hospital, Jiangsu Cancer Hospital, Nanjing Drum Tower Hospital Affiliated to Nanjing University, Sir Run Run Shaw Hospital of Zhejiang University, Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and the General Hospital of the People's Liberation Army, from 1 June 2021 to 31 March 2024. The cohort included 48 men and 31 women, 19 of whom had received ripretinib as second-line, 13 as third-line, and 47 as fourth-line therapy. Two peripheral venous blood samples were obtained from each participant and high-performance liquid chromatography-tandem mass spectrometry used to determine peak (Cmax) and trough (Cmin) concentrations of ripretinib. Machine learning methodologies, specifically the K-nearest neighbor algorithm combined with the Gridsearch CV strategy, were employed to establish the threshold for Cmin. We analyzed adverse reactions, treatment efficacy, median progression-free survival (mPFS), and the relationship between drug blood concentration and selected clinical parameters.Results:In the entire cohort, the Cmin and Cmax of ripretinib were 467 ± 360 μg/L and 986 ± 493 μg/L, respectively. Notably, female patients and individuals in the high-dose group exhibited significantly higher values for both Cmin and Cmax (both P<0.05). However, variations in drug concentrations associated with the line of ripretinib therapy, treatment efficacy, disease progression, and presence of selected specific genetic mutations were not significantly associated with values of Cmin and Cmax ( P>0.05). Among the 79 patients with advanced GISTs receiving ripretinib, reported adverse reactions included alopecia (53, 67.09%), hand–foot syndrome (24, 30.38%), fatigue (22, 27.85%), and myalgia (21, 26.58%). Two patients (2.53%) had grade III complications, both classified as hand–foot syndrome. The correlation between Cmax and adverse reactions was not statistically significant ( P > 0.05). By the time of the latest follow-up, five deaths (6.3%) had occurred within the cohort. The mPFS for the group was 16.3 months, with a mPFS of 14.4 months for those receiving standard dosage and 7.0 months for those receiving escalating dosage. Among the 65 patients treated with standard doses of ripretinib, those with Cmin exceeding a threshold of 450 μg/L exhibited a significantly longer mPFS (18.0 months vs.13.7 months; P < 0.05). Conclusion:In China, patients with advanced GISTs exhibit a notable tolerance to ripretinib, with no evidence for a correlation between adverse reactions and Cmax for the drug. Additionally, a Cmin exceeding 450 μg/L may be associated with an extended mPFS.
7.Effects of Serum Containing Wenjing Tongluo Decoction on Mouse Chondrocyte Injury and IκB-ζ/HIF-1α/LDHA Axis
Wei WEI ; Chenjian PENG ; Renjun GU ; Xiwu YAN ; Jiapeng YE ; Guicheng HUANG ; Luning SUN
Journal of Nanjing University of Traditional Chinese Medicine 2024;40(5):469-478
OBJECTIVE To study the effects and mechanisms of serum containing Wenjing Tongluo Decoction on interleukin-1β(IL-1β)-induced mouse primary chondrocyte injury.METHODS The IL-1β-induced primary chondrocyte injury model was estab-lished,and the mRNA expression of inflammatory factors IL-1β,IL-6,TNF-α,cartilage degradation-related proteases matrix metal-loproteinase 3(MMP3),MMP9,MMP13,ADAM metallopeptidase containing thrombospondin 1 motif 4(ADAMTS4),and glycoly-sis-related enzymes lactate dehydrogenase A(LDHA),M2 pyruvate kinase(PKM2),reduced coenzyme Ⅱ oxidase 2(NOX2)and re-duced coenzyme Ⅱ oxidase 4(NOX4)in the cells was detected;the intracellular MMP3,MMP13,P65,IκB-ζ,hypoxia-inducible factor 1α(HIF-1α)and LDHA protein expression levels were determined;the concentrations of nitric oxide(NO),malondialdehyde(MDA)and lactic acid in the cell supernatant were further detected,and the ratio of the reduced state(NADH)and oxidized state(NAD+)of intracellular coenzyme Ⅰ(NAD),as well as intracellular reactive oxygen species(ROS)levels were assayed.RESULTS Serum containing Wenjing Tongluo Decoction significantly inhibited the mRNA expression of IL-1β,IL-6,and TNF-α in IL-1β chondrocytes(P<0.01),reduced the NO concentration in the cell supernatant(P<0.05,P<0.01),and downregulated the protein ex-pression of IκB-ζ(P<0.05)and P65(P<0.05,P<0.01).Serum containing Wenjing Tongluo Decoction significantly downregulated the mRNA expression of MMP3,MMP9,MMP13 and ADAMTS4(P<0.01),and inhibited the protein expression of MMP13(P<0.05,P<0.01)and MMP3(P<0.05).In terms of oxidative stress,it significantly suppressed the production of ROS in chondrocytes,increased the NADH/NAD+ratio,reduced the MDA concentration in the supernatant,and downregulated the expression of HIF-1α protein(P<0.01).The serum containing Wenjing Tongluo Decoction significantly reduced the lactic acid concentration,downregulated the expression of LDHA,PKM2,NOX2 and NOX4,and reduced the level of intracellular glycolysis(P<0.05,P<0.01).CONCLU-SION The serum containing Wenjing Tongluo Decoction can alleviate IL-1β-induced mouse primary chondrocyte injury by inhibiting inflammation,cartilage degradation,oxidative stress and glycolysis,which may be related to the regulation of IκB-ζ/HIF-1α/LDHA axis.
8.Pharmacokinetics,pharmacodynamics of esomeprazole in critically ill patients
Xian ZHA ; Luning SUN ; Chao CHEN ; Yongqing WANG
Chinese Journal of Clinical Pharmacology and Therapeutics 2024;29(10):1152-1160
AIM:To investigate the pharmacoki-netic/pharmacodynamic(PK/PD)profile of esome-prazole for injection in critically ill patients.METH-ODS:This was a prospective,single-center,open-la-bel study,all patients received intravenous infused esomeprazole 40 mg q12h for stress ulcer prophy-laxis,treatment duration is determined by clini-cians based on patients condition.Forty critically ill patients were enrolled and were divided into single and multiple dose groups according to the timing of blood sample collection.Twenty-one patients in the single-dose group had their blood samples col-lected at 1,3,6,8,and 12 h after the first dose,and 34 patients in the multiple-dose group had their blood samples collected at 0 h before the fifth dose and 1,3,6,and 8,and 12 h after the fifth dose,of which 14 patients had their blood samples collected at both the first dose and the repeated doses.The concentration of esomeprazole was measured by HPLC-MS/MS,and PK parameters were analyzed using noncompartmental analysis.Gastric aspirates were collected for pH measure-ment in fasted patients with gastric tube before the first dose(0 h),and 1,2,4,8,12,14,16,20,24 h after the initiation of drug administration,and the percentage of time with pH≥4 was calculated.All adverse events and serious adverse events during treatment were recorded.RESULTS:Patients in the single-dose group were 67.75 years old(45-69 years)with a BMI(24.05±3.35)kg/m2,and pa-tients in the multiple-dose group were 63.35 years old(24-87 years)with a BMI(24.08±3.29)kg/m2.PK parameters after the first dose were AUC0-t(11.26±6.58)mg·h·L-1,Cmax(3.08±2.06)mg/L,CL(4.13±3.68)L/h,Vd(17.12±6.13)L,t1/2(4.80±3.06)h;PK parameters after multiple doses were AUC0-t(16.70±11.20)mg·h/L,Cmax(3.37±2.59)mg/L,CL(3.94±2.94)L/h,Vd(22.71±17.26)L,t1/2(5.23±3.34)h.Percentage of time with pH≥4 with-in 0 h-24 h after administration was 61.69%,and percentage of time with pH≥4 within 12 h-24 h was up to 100%.Esomeprazole was well tolerated by all patients with no serious adverse events.CONCLU-SION:Compared with healthy volunteers,inject-able esomeprazole showed increased Vd,decreased CL,increased drug exposure and accumulation af-ter repeated administration in critically ill patients.The drug had a favorable safety profile in critically ill patients.
9.Etiology,pathogenesis and animal model building of premature ovarian insufficiency
Zhihui YANG ; Yang HU ; Zheng ZONG ; Xiangming SUN ; Hui SONG ; Yingxiang CHEN ; Beilei XU ; Wenjun ZHANG ; Luning CHEN ; Wenlan LI
Chinese Journal of Comparative Medicine 2024;34(3):149-160
Premature ovarian insufficiency(POI),also known as"ovarian insufficiency",has an incidence of 1%~5%.The incidence has been on the rise in recent years,seriously affecting women's physical and mental health and quality of life.At present,the cause and mechanisms of POI are still unclear,and the method and applications of model construction are also confusing.Most models have some shortcomings in pertinence and stability.The limitations greatly limit research into the clinical diagnosis and treatment of POI.This paper summarizes and discusses the etiology and pathogenesis of POI and the construction of POI animal models to provide a comprehensive reference for those studying POI.
10.Method establishment and clinical practice for concentration determination of caffeine and its metabolites in urine
Xianglong CHEN ; Yang ZHAO ; Qiongye HUANG ; Mingqing XU ; Yue LI ; Chao LU ; Luning SUN ; Yongqing WANG
China Pharmacy 2023;34(18):2233-2237
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.

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