Impact of Intraoperative Infusion and Postoperative PCIA of Dexmedetomidine on Early Breastfeeding After Elective Cesarean Section: A Randomized Double-Blind Controlled Trial

Pharmacologic Analgesia for Cesarean Section: An Update in 2024

PURPOSE OF THE REVIEW

With the increasing prevalence of cesarean section globally, the importance of perioperative analgesia for cesarean section is becoming increasingly evident. This article provides an overview and update on the current status of cesarean section worldwide and associated analgesic regimens.

RECENT FINDINGS

Some recent studies unveiled potential association of neuraxial analgesia might be associated with children's autism, pharmacologic analgesia in obstetric will potentially gain some more attention. Various commonly used techniques and medications for analgesia in cesarean section are highlighted. While neuraxial administration of opioid remains the most classic method, the use of multimodal analgesia, particularly integration of nonsteroidal anti-inflammatory drugs, acetaminophen, peripheral nerve blocks has provided additional and better options for patients who are not suitable for intrathecal and neuraxial techniques and those experiencing severe pain postoperatively. Optimal pain management is crucial for achieving better clinical outcomes and optimal recovery, and with the continuous development of medications, more and better pharmacologic regimen will be available in the future.

Effect of intraoperative dexmedetomidine on recovery of gastrointestinal function after caesarean section undergoing spinal and epidural anesthesia: A randomized, double blind, placebo-controlled clinical trial

OBJECTIVE

Gastrointestinal dysfunction after cesarean section negatively affects postoperative recovery. Dexmedetomidine has been shown to improve postoperative gastrointestinal function in patients undergoing lumbar spinal fusion surgery and laparoscopic gastrectomy, but its role in cesarean section has not been fully elucidated. The study aimed to investigate the effect of dexmedetomidine on gastrointestinal function after cesarean section.

STUDY DESIGN

220 pregnant women who underwent elective cesarean section were randomized into group D and group S. Group D patients received a loading dose of 0.5 μg/kg of dexmedetomidine for 10 mins followed by a maintenance dose of 0.5 μg/kg/h intravenously immediately after the umbilical cord was cut intraoperatively, whereas the other group (group S) received an equivalent quantity of normal saline as loading and maintenance dose IV by infusion pump. The primary outcome was time to first flatus after surgery (hours). Secondary outcomes included time to first feces and first bowel sounds (hours), incidence rates of postoperative gastrointestinal complications, and the length of postoperative hospital stay (days).

RESULTS

Modified intention-to-treat analysis showed that patients in Group D had a significantly shorter time to first flatus (21 [16 to 28.25] vs. 25 [18 to 32.25] h; P = 0.014), time to first feces (45.5 [35.75 to 55.25] vs. 53 [40 to 60] h; P = 0.019), and time to first bowel sounds (P = 0.010), a lower incidence of abdominal distension (21[20.6 %] vs. 36[34.3 %], P = 0.027), shorter length of postoperative hospital stay (P = 0.010) compared to patients in Group S.

CONCLUSION

Intraoperative dexmedetomidine infusion reduces the time to first flatus, the incidence of abdominal distension, and shortens the length of hospital stay, promoting gastrointestinal function after cesarean section.

Recent insights into the effect of endoplasmic reticulum stress in the pathophysiology of intestinal ischaemia‒reperfusion injury

Intestinal ischaemia‒reperfusion (I/R) injury is a surgical emergency. This condition is associated with a high mortality rate. At present, there are limited number of efficient therapeutic measures for this injury, and the prognosis is poor. Therefore, the pathophysiological mechanisms of intestinal I/R injury must be elucidated to develop a rapid and specific diagnostic and treatment protocol. Numerous studies have indicated the involvement of endoplasmic reticulum (ER) stress in the development of intestinal I/R injury. Specifically, the levels of unfolded and misfolded proteins in the ER lumen are increased due to unfolded protein response. However, persistent ER stress promotes apoptosis of intestinal mucosal epithelial cells through three signalling pathways in the ER, impairing intestinal mucosal barrier function and leading to the dysfunction of intestinal tissues and distant organ compartments. This review summarises the mechanisms of ER stress in intestinal I/R injury, diagnostic indicators, and related treatment strategies with the objective of providing novel insights into future therapies for this condition.

Effects of dexmedetomidine combined with etomidate on postoperative cognitive function in older patients undergoing total intravenous anaesthesia: a randomized, double-blind, controlled trial

BACKGROUND

Etomidate has been advocated for anesthesia in older and critically ill patients because of its hemodynamic stability. Clinical studies have shown that dexmedetomidine has neuroprotective and anti-inflammatory properties and improves postoperative cognitive dysfunction in older patients. The present study was to evaluate the effects of the combination of etomidate and dexmedetomidine with different anaesthesia time on postoperative cognitive function in older patients.

METHODS

A total of 132 older patients undergoing ureteroscopic holmium laser lithotripsy were randomly divided into EN group and ED group equally. Patients whose surgery time was less than or equal to 1 h in each group were allocated to short-time surgery group (EN1 group and ED1 group), and whose surgery time was more than 1h were allocated to long-term surgery group (EN2 group and ED2 group). The primary outcome was the score of the Mini-Mental State Examination. The secondary outcomes were State-Trait Anxiety Inventory scores, Riker sedation agitation scores, Zung Self-Rating Depression Scale scores, the memory span for Arabic numerals, the plasma concentrations of S-100 calcium-binding protein B and neuron specific enolase, the time to spontaneous respiration, recovery, and extubation.

RESULTS

The MMSE scores at t2-3 were higher in ED1 and ED2 groups than in EN1 and EN2 groups (p<0.05). Compared with ED1 and ED2 groups, the ZSDS scores, the S-AI scores and the T-AI scores at t1-2 were higher in EN1 and EN2 groups (p<0.05), respectively. The recalled Arabic numbers at t1-3 were higher in ED2 group than in EN2 group (p<0.05). The plasma concentration of S-100β at t1-2 in EN1 group and t1-3 in EN2 group were higher than that in ED1 and ED2 groups (p<0.05), respectively. Compared with ED1 and ED2 groups, the plasma concentrations of NSE were higher at t1-3 in EN1 group and t1-4 in EN2 group (p<0.05), respectively.

CONCLUSION

The administration of dexmedetomidine could improve postoperative cognitive dysfunction, emergence agitation, depression and anxiety, attenuate the plasma concentrations of S-100β and NSE in older patients undergoing total intravenous anaesthesia with etomidate.

TRIAL REGISTRATION

Registration number: ChiCTR1800015421, Date: 29/03/2018.

Exploring the Effect of Pain Sensitive Questionnaire on Guiding Intravenous Analgesia After Cesarean Section: A Randomised Double Blind Controlled Trial

Objective

This study investigates the effect of the Pain Sensitivity Questionnaire (PSQ) in guiding patient controlled intravenous analgesia (PCIA) on postoperative analgesia in women undergoing cesarean section.

Methods

A total of 160 women who were to undergo a cesarean section under combined spinal and epidural anaesthesia were included in this study. Women with a preoperative PSQ <4 were randomly divided into a low pain-sensitive control group (LC group), and a low pain-sensitive observation group (LO group), and women with preoperative PSQ >6 were randomly divided into a high pain-sensitive control group (HC group) and a high pain-sensitive observation group (HO group). After the surgery, patients received the pump butorphanol concentration was 3.5 µg·kg-1·h-1 in the LC and HC groups, 3.0 µg·kg-1·h-1 in the LO group and 4.0 µg·kg-1·h-1 in the HO group.To compare the analgesic effects of postoperative PCIA and postoperative recovery in women.

Results

Wound pain and uterine contraction pain VAS scores at rest and activity were significantly lower in the LC group than in the LO group at 4 and 8 h postoperatively (P<0.05). Similarly, wound pain and uterine contraction pain VAS scores at rest and activity were significantly lower in the HO group than in the HC group at 8, 12, and 24 h postoperatively (P<0.05). The Ramsay scores were significantly higher in the LC than in the LO groups at 4, 8, 12, 24, and 48 h postoperatively (P<0.05), but there was no statistically significant difference between the Ramsay scores in the HC group and the HO group. There was no statistical difference in any of the post-operative recoveries (P>0.05).

Conclusion

Compared to the weight-based postoperative PCIA, the PSQ-based postoperative PCIA has better analgesic effects and can improve maternal satisfaction with postoperative analgesia.

An optimization for postpartum depression risk assessment and preventive intervention strategy based machine learning approaches

BACKGROUND

Postpartum depression (PPD) is one of the most common psychiatric disorders for women after delivery. The establishment of an effective PPD prediction model helps to distinguish high-risk groups, and verifying whether such high-risk groups can benefit from drug intervention is very important for clinical guidance.

METHODS

We collected data of parturients that underwent a cesarean delivery. The Control group was divided into a training cohort and a testing cohort. Six different ML models were constructed and we compared their prediction performance in the testing cohort. For model interpretation, we introduced SHapley Additive exPlanations (SHAP). Then, training cohort, ketamine group and dexmedetomidine (DEX) group were classified as high or low risk for PPD by the model. A 1:1 propensity score matching (PSM) was performed to compare the incidence of PPD between two groups in different risk cohorts.

RESULTS

Extreme gradient enhancement (XGB) had the best recognition effect, with an area under the receiver operating characteristic curve (AUROC) of 0.789 (95 % CI 0.742-0.836) in the training cohort and 0.744 (95 % CI 0.655-0.823) in the testing cohort, respectively. A threshold of 21.5 % PPD risk probability was determined. After PSM, the results showed that the incidence of PPD in the two intervention groups was significantly different from the control group in the high-risk cohort (P < 0.001) but not in the low-risk cohort (P > 0.001).

CONCLUSION

Our study demonstrated that the XGB algorithm provided a more accurate in prediction of PPD risk, and it was beneficial to receive early intervention for the high-risk groups distinguished by the model.

A Comparison of Ultrasound Imaging Texture Analyses During the Early Postpartum With the Mode of Delivery

BACKGROUND

Breastfeeding is beneficial to infants. However, cesarean section is reported to be a risk factor for unsuccessful breastfeeding.

RESEARCH AIMS

(1) To extract discriminating data from texture analysis of breast ultrasound images in the immediate postpartum period; and (2) to compare the analysis results according to delivery mode.

METHODS

A cross-sectional, prospective non-experimental design with a questionnaire and observational components was used. Participants (N = 30) were women who delivered neonates at a center from September 2020 to December 2020. The participants underwent ultrasound examination of bilateral breasts 7-14 days after delivery. Ultrasound images were collected for texture analysis. A questionnaire about breastfeeding patterns was given to the participants on the day of the ultrasound examination.

RESULTS

No significant differences were found in texture analysis between the breasts of participants who had undergone Cesarean section and vaginal deliveries. The mean volume of total human milk produced in 1 day was significantly greater in the vaginal delivery group than in the cesarean section group (M = 350.87 ml, SD = 183.83 vs. M = 186.20 ml, SD = 184.02; p = .017). The pain score due to breast engorgement measured subjectively by participants was significantly lower in the vaginal delivery group than in the cesarean section group (M = 2.8, SD = 0.86 vs. M = 3.4, SD = 0.63; p = .047).

CONCLUSION

Texture analysis of breast ultrasound images did not demonstrate difference between the cesarean section and vaginal delivery groups in the immediate postpartum period; nevertheless, cesarean section was independently associated with less successful breastfeeding.

Glucose-insulin-potassium alleviates uterine cramping pain following cesarean delivery: A randomized, controlled trial

Objectives

To explore the effect of glucose-insulin-potassium (GIK) therapy on uterine cramping pain (UCP) following cesarean delivery (CD).

Design

Single-center, randomized controlled study.

Setting

Second Affiliated Hospital of Army Medical University, Chongqing, China.

Participants

A total of 140 women, aged 20-40 years, who underwent CD with a transverse incision were randomly assigned to the GIK (P) or control (C) groups in a 1:1 ratio.

Interventions

GIK was intravenously administered to patients in Group P. Patients in Group C received normal saline (NS). After umbilical cord clamping, oxytocin was administered intravenously. The same GIK and NS regimens were administered on postoperative days 1 and 2, followed by oxytocin 10 min later.

Primary and secondary outcome measures

Following oxytocin administration, UCP was assessed using the visual analog scale (VAS), and the maximum VAS score (primary outcome) was recorded.

Results

Patients in Group P had significantly lower maximum VAS scores than those in Group C on postoperative days 1 (38.4 ± 21.1 vs. 52.3 ± 20.8, p < 0.001) and 2 (10 [0,30] vs. 30.5 [8.75,50], p < 0.001). Group P patients also had shorter pain duration on postoperative day 1 (39.6 ± 19.5 min vs. 50.6 ± 18.2 min, p = 0.001). Group P patients had a lower incidence of inadequate analgesia of UCP than Group C on days 1 (45.5% vs. 74.2%, p < 0.001) and 2 (10.6% vs. 47.0%, p < 0.001); the RRs for experiencing inadequate analgesia for UCP postpartum in Group P patients was 0.612 (95% CI: 0.454-0.826, p < 0.001) on day 1 and 0.226 (95% CI: 0.107-0.476, p < 0.001) on day 2. The absolute risk reduction (ARR) was 28.7%; thus number needed to treat (NNT) was 3 after rounding up. A subgroup analysis demonstrated that Group P patients undergoing repeat CD had lower maximum VAS scores for UCP on both postoperative days 1 and 2.

Conclusion

Our findings suggest that GIK can relieve UCP and shorten its duration. Our results provide information to facilitate the development of novel approaches for managing UCP.Clinical Trial Registration: This study was approved by the Medical Ethics Committee of Second Affiliated Hospital of Army Medical University (2020-109-01, 19/11/2020) and registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn, ChiCTR2100041607,01/01/2021).

Efficacy and safety evaluation of dexmedetomidine for postoperative patient controlled intravenous analgesia: A systematic review and meta-analysis

Objective: To investigate the efficacy and safety of dexmedetomidine (DEX) for postoperative patient controlled intravenous analgesia (PCIA). Measurements: Two investigators independently searched Pubmed, Embase, Scopus, Cochrane Library and CBM for randomized controlled trials of DEX for PCIA. Main results: Thirty-seven studies with a total of 5,409 patients were included in this meta-analysis. Compared with analgesics alone, DEX for PCIA reduced pain score at 24 h [mean difference (MD) = -0.70; 95% confidence interval (CI): -0.85, -0.54; p < 0.00001, I ² = 90%] and 48 h postoperatively (MD = -0.43; 95% CI: -0.52, -0.34; p < 0.00001, I ² = 96%). Moreover, DEX reduced analgesics consumption during the first 24 h [standardized mean difference (SMD) = -0.25; 95% CI: -0.34, -0.16; p < 0.00001, I ² = 91%] and the number of resuscitation analgesics administered [odds ratio (OR) = 0.54; 95% CI: 0.44, 0.66; p < 0.00001, I ² = 72%]. Furthermore, DEX improved patient satisfaction (OR = 3.55; 95% CI: 2.36, 5.35; p < 0.00001, I ² = 60%), and reduced incidence of side effects, such as postoperative nausea and vomiting (PONV) (OR = 0.47; 95% CI: 0.39, 0.57; p < 0.00001, I ² = 59%) and pruritus after surgery (OR = 0.45; 95% CI: 0.30, 0.68; p = 0.0001, I ² = 0%). Besides, DEX attenuates inflammatory cytokine levels, such as IL-6 (MD = -5.73; 95% CI: -8.34, -3.12; p < 0.00001, I ² = 91%) and TNF-α (MD = -0.63; 95% CI: -0.76, -0.50; p < 0.00001, I ² = 89%). Finally, DEX increased the risk of bradycardia (OR = 1.66; 95% CI: 1.12, 2.45; p = 0.01, I ² = 15%), but the complication of hypotension did not differ between the two groups (OR = 1.30; 95% CI: 0.84, 2.04; p = 0.25, I ² = 0%). Conclusion: DEX is used for postoperative PCIA analgesia, which can significantly improve the analgesic effect, effectively control postoperative inflammatory response, reduce the dosage and adverse reactions of analgesics, and improve postoperative patient satisfaction. Of course, the impact of the immunosuppressive effect of DEX on the prognosis of patients needs further study. Systematic review registration: CRD42022340933, https://www.crd.york.ac.uk/prospero/.

The effect of preoperative oral carbohydrate on the time to colostrum and amount of vaginal bleeding after elective cesarean section

OBJECTIVE

To investigate the effect of oral carbohydrate at 2 h before elective cesarean section on postoperative recovery indicators such as the time to colostrum and vaginal bleeding.

METHODS

Women undergoing elective cesarean section under spinal-epidural anesthesia, aged 20-40 years, with a body mass index (BMI) of 19-30 kg/m² and an American Society of Anesthesiology (ASA) score of II were randomized to the oral carbohydrate group (the OC group), the oral placebo group (the OP group), or the control group (the C group). The OC group underwent oral carbohydrate preloading (300 mL/bottle), the OP group orally consumed 300 mL of distilled water, and the C group was forbidden from drinking or eating on the day of the operation. The time to colostrum, vaginal bleeding, time to exhaust, and complications were recorded.

RESULTS

A total of 38 participants in the OC group, 37 in the OP group, and 37 in the C group completed the study. Compared with the OP group and the C group, the OC group produced colostrum significantly earlier, had a lower amount of 24-h vaginal bleeding, and had a higher 24-h consumption of analgesics. Compared with OP and OC groups, the C group took longer to exhaust. No significant intergroup difference was observed for any other indicator.

CONCLUSION

Oral carbohydrates loading 2 h before elective cesarean section significantly reduces the time to produce colostrum and the amount of vaginal bleeding, which contributes to postoperative recovery.

Effect of dexmedetomidine on oxytocin-induced uterine contraction during optimal caesarean section anaesthesia

Numerous drugs are used during caesarean sections to provide regional and general anaesthesia. Dexmedetomidine has been used in some recent obstetric trials, but there are concerns about postpartum changes in uterine contractions. This study evaluated the effect of dexmedetomidine on oxytocin-induced uterine contractions in women undergoing caesarean section. Sixty women undergoing caesarean section in Lianyungang Second People's Hospital were randomly assigned to dexmedetomidine (group D, n = 30) or saline (group C, n = 30) groups. Equal volumes of saline or dexmedetomidine were administered intravenously (IV). During the intraoperative delivery of the foetus and placenta, oxytocin was administered to promote contractions. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were compared. The Ramsay scale was used to assess sedation, while the Tsai and Chu methods assessed shivering. Adverse intraoperative events were observed. All variables fluctuated significantly after anaesthesia onset in both groups but were most pronounced in group D. The VAS, Ramsay and shivering scores were significantly lower in group D compared to group C. During rapid IV infusion of oxytocin after foetal delivery, the incidence of nausea, vomiting, chest tightness and hypotension was significantly lower in group D than in group C.

Effect of Dexmedetomidine on Cardiac Output among Parturient with Severe Preeclampsia after Cesarean Section

This study was to investigate the hemodynamic effect of dexmedetomidine among parturient with severe preeclampsia after cesarean section. Parturient with severe preeclampsia were randomly allocated to receive dexmedetomidine (0.2-0.7 μg/kg/h) or equivalent volumes of 0.9% saline as control after cesarean section, respectively. A total of 36 parturient with severe preeclampsia were enrolled, including 18 in the dexmedetomidine (DEX) group and 18 in the saline group. Compared with the saline group, among those in the DEX group, CO was reduced by 1.30 L/min (95% CI: -2.36 to 0.25; $P=0.019$ ). Additionally, HR (-13.79 bpm, 95% CI: -22.02 to -5.58; $P=0.002$ ), SBP (-16.11 mmHg, 95% CI: -30.56 to -1.66; $P=0.030$ ), DBP (-10.48 mmHg, 95% CI: -18.27 to -2.69; $P=0.002$ ), and MAP (-12.36 mmHg, 95% CI: -22.05 to -2.66; $P=0.014$ ) were reduced in the DEX group compared with the saline group. In contrast, there were no changes observed in SV and ICON between groups. In conclusion, dexmedetomidine reduces cardiac output by inhibiting the acceleration of heart rate without sacrificing myocardial contractility and stroke volume.

Recent Advances in the Clinical Value and Potential of Dexmedetomidine

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has sedative, anxiolytic, analgesic, sympatholytic, and opioid-sparing properties and induces a unique sedative response which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Recent studies indicate several emerging clinical applications via different routes. We review recent data on dexmedetomidine studies, particularly exploring the varying routes of administration, experimental implications, clinical effects, and comparative advantages over other drugs. A search was conducted on the PubMed and Web of Science libraries for recent studies using different combinations of the words “dexmedetomidine”, “route of administration”, and pharmacological effect. The current routes, pharmacological effects, and application categories of dexmedetomidine are presented. It functions by stimulating pre- and post-synaptic α2-adrenoreceptors within the central nervous system, leading to hyperpolarization of noradrenergic neurons, induction of an inhibitory feedback loop, and reduction of norepinephrine secretion, causing a sympatholytic effect, in addition to its anti-inflammation, sleep induction, bowel recovery, and sore throat reduction effects. Compared with similar α2-adrenoceptor agonists, dexmedetomidine has both pharmacodynamics advantage of a significantly greater α2:α1-adrenoceptor affinity ratio and a pharmacokinetic advantage of having a significantly shorter elimination half-life. In its clinical application, dexmedetomidine has been reported to present a significant number of benefits including safe sedation for various surgical interventions, improvement of intraoperative and postoperative analgesia, sedation for compromised airways without respiratory depression, nephroprotection and stability of hypotensive hemodynamics, reduction of postoperative nausea and vomiting and postoperative shivering incidence, and decrease of intraoperative blood loss. Although the clinical application of dexmedetomidine is promising, it is still limited and further research is required to enhance understanding of its pharmacological properties, patient selection, dosage, and adverse effects.

Effects of anesthetic agents on contractions of the pregnant rat myometrium in vivo and in vitro

BACKGROUND

Several anesthetic agents are used in cesarean sections for both regional and general anesthesia purposes. However, there are no data comparing the in vivo effects of propofol, sevoflurane, and dexmedetomidine on the contraction of the myometrium in pregnant rats. The aim of this study was to investigate the effect of these anesthetic agents on myometrial contraction and elucidate the underlying mechanisms.

METHODS

Contraction force and frequency changes in response to propofol, dexmedetomidine, or sevoflurane were evaluated in vivo and in vitro. To test the effect of arachidonic acid on myometrial contraction enhanced by dexmedetomidine, changes in myometrial contraction with dexmedetomidine after administration of indomethacin were evaluated. The amount of phosphorylated myosin phosphatase target subunit 1 (MYPT1) in the membrane fraction was expressed as a percentage of the total fraction by Western blot analysis.

RESULTS

This study demonstrated that dexmedetomidine enhances oxytocin-induced contraction in the myometrium of pregnant rats, whereas propofol and sevoflurane attenuate these contractions. The dexmedetomidine-induced enhancement of myometrial contraction force was abolished by the administration of indomethacin. Propofol did not affect oxytocin-induced MYPT1 phosphorylation, whereas sevoflurane attenuated oxytocin-induced MYPT1 phosphorylation.

CONCLUSIONS

Inhibition of myofilament calcium sensitivity may underlie the inhibition of myometrial contraction induced by sevoflurane. Arachidonic acid may play an important role in the enhancement of myometrial contraction induced by dexmedetomidine by increasing myofilament calcium sensitivity. Dexmedetomidine may be used as a sedative agent to promote uterine muscle contraction and suppress bleeding after fetal delivery.

Retrospective Comparison of the Safety and Effectiveness of Dexmedetomidine Versus Standard of Care Before and During Cesarean Delivery in a Maternity Unit in Zhengzhou, China

Background

The objective of the present study was to test the hypothesis that intravenous dexmedetomidine is safe and effective when administered to women before and during cesarean section.

Material/Methods

The analysis included 392 women who received spinal anesthesia and no analgesia prior to undergoing elective cesarean delivery. Of them, 115 women received dexmedetomidine before anesthesia and during delivery (DX cohort), 109 received normal saline before anesthesia and during delivery and dexmedetomidine after delivery (SC cohort), and 168 received normal saline only before anesthesia and during delivery (CN cohort). Data about the women’s consumption of sufentanil and ondansetron during hospitalization, onset of lactation, and hospital stays were retrospectively collected and analyzed.

Results

Most of the women in the study were primiparous (362/392). The women in the DX cohort received less sufentanil during their hospital stays than those in either of the other 2 cohorts (SC comparison: 151.45±11.15 μg vs. 175.12±25.15 μg, P<0.0001, q=8.776; CN comparison: 151.45±11.15 μg vs. 185.42±37.45 μg, P<0.0001, q=13.911). Also, the women in the DX cohort received less ondansetron before discharge and had shorter times to first lactation and hospital stays than those in the SC and CN cohorts.

Conclusions

Administering dexmedetomidine before spinal anesthesia appears to be safe and effective for women undergoing elective cesarean delivery.

Effects of Dexmedetomidine on the Pharmacokinetics of Dezocine, Midazolam and Its Metabolite 1-Hydroxymidazolam in Beagles by UPLC-MS/MS

Objective

We developed and validated a sensitive and reliable UPLC-MS/MS method for simultaneous determination of dezocine (DEZ), midazolam (MDZ) and its metabolite 1-hydroxymidazolam (1-OH-MDZ) in beagle plasma and investigated the effect of dexmedetomidine (DEX) on the pharmacokinetics of DEZ, MDZ and 1-OH-MDZ in beagles.

Materials and Methods

Diazepam was used as the internal standard (IS); the three analytes and IS were extracted by acetonitrile precipitation and separated on an Acquity UPLC BEH C18 column using acetonitrile-0.1% formic acid as mobile phase in gradient mode. In positive ion mode, the three analytes and IS were monitored by multiple reaction monitoring (MRM). Six beagles were designed as a double cycle self-control experiment with 0.15 mg/kg in the first cycle (Group A). After a 1-week washout period, the same six beagles were slowly injected intravenously with 2 µg/kg DEX in the second cycle (Group B), with continuous injection for 7 days. On the seventh day, 0.5 hr after intravenous injection of 2 µg/kg DEX, the six beagles were intramuscularly given with DEZ 0.33 mg/kg and MDZ 0.15 mg/kg.

Results

Under the conditions of this experiment, this method exhibited a good linearity for each analyte. The accuracy and precision were all within the acceptable limits in the bioanalytical method, and the results of recovery, matrix effect and stability have also met the requirements.

Conclusion

The developed UPLC-MS/MS method for simultaneous determination of DEZ, MDZ and 1-OH-MDZ in beagles plasma was accurate, reproducible, specific, and suitable. DEX could inhibit the metabolism of DEZ and MDZ and increase the exposure of DEZ and MDZ in beagles. Therefore, the change of therapeutic effect and the occurrence of adverse reactions caused by drug–drug interaction should be paid attention to when the drugs were used in combination.