Estimation of infant dose and exposure to pethidine and norpethidine via breast milk following patient-controlled epidural pethidine for analgesia post caesarean delivery

Determination of pethidine of abuse and relevant metabolite norpethidine in urine by ultra-performance liquid chromatography-tandem mass spectrometry

Pethidine is an opiate agonist used orally and parenterally. Pethidine-containing drugs abuse is frequently encountered on health workers and patients. The analysis methods used to determine the abuse of pethidine are important for forensic toxicology. Pethidine is metabolized to norpethidine by the liver. Therefore, the determination of pethidine and norpethidine in urine is one of the methods to determine the abuse of pethidine. In this study, we have developed a precise, simple and rapid ultra-performance liquid chromatography-tandem mass spectrometer method for the determination of pethidine and norpethidine simultaneously. The developed method was validated in terms of selectivity and linearity which was in the range of 9-1800 ng/mL for both pethidine and norpethidine. The intra-assay and inter-assay accuracy and precision were found within acceptable limits of the EMA guideline. Lower limits of quantitation were 9 ng/mL for both pethidine and norpethidine. The developed method was successfully applied for the determination of both analytes in the real samples.

[Which medications are safe while breastfeeding? : A synopsis for the anesthetist, obstetrician and pediatrician]

Pharmacokinetic data on drug administration during lactation are often inconsistent or missing. For legal reasons medicinal drug product information generally advises to interrupt breastfeeding for 24 h after medication intake. However this is not standard of care in clinical practice as the mother should be instructed to initiate breastfeeding as soon as possible after giving birth. At the same time the medication exposure over the breast milk for the newborn should be minimized. Aim of this article is to summarize pharmacokinetic data and to give important clinical information on medications frequently administered during the lactation period. As a general rule a mother can start breastfeeding following anesthesia as soon as she is able to get her baby latched on her breast.

Changes in milk composition associated with pethidine-PCEA usage after Caesarean section

The effect of pethidine as patient-controlled epidural analgesia (PCEA) on specific biochemical components in breast milk in relation to the timing of secretory activation is not well investigated. The aim of this study was to compare biochemical timing of secretory activation between women who had a vaginal (V) or Caesarean birth with pethidine-PCEA (CBP). Several milk samples were collected daily from 36 mothers (17 V, 19 CBP) for the first 265 h post-partum. Protein and lactose concentrations and Na+ and K+ ion levels were measured. Samples were assigned to three time periods: 0-72, >72-165 and >165-265 h post-partum for statistical analyses. Data were analyzed using linear mixed effect models. In the first 72 h post-partum, the mean difference in lactose concentration was 5 gL-1 higher in group V (P < 0.05). From >72-165 h post-partum, protein and Na+ concentrations were lower in group V (P = 0.05, P = 0.02), and K+ levels were higher in group V (P < 0.001). From >165-265 h post-partum, there were no significant differences between the groups. Biochemically, secretory activation had occurred by 72 h post-partum in both groups. There were greater variations in measured biochemical components observed within group CBP initially. However, by 165 h post-partum, there were no differences in the biochemical components between the groups. This suggests that effects of pethidine-PCEA are diminished by 72 h post-partum and undetected by 165 h.

Safety of the breast-feeding infant after maternal anesthesia

There has been an increase in breast-feeding supported by the recommendations of the American Academy of Pediatrics and the World Health Organization. An anesthesiologist may be presented with a well-motivated breast-feeding mother who wishes to breast-feed her infant in the perioperative period. Administration of anesthesia entails acute administration of drugs with potential for sedation and respiratory effects on the nursing infant. The short-term use of these drugs minimizes the possibility of these effects. The aim should be to minimize the use of narcotics and benzodiazepines, use shorter acting agents, use regional anesthesia where possible and avoid agents with active metabolites. Frequent clinical assessments of the nursing infant are important. Available literature does suggest that although the currently available anesthetic and analgesic drugs are transferred in the breast milk, the amounts transferred are almost always clinically insignificant and pose little or no risk to the nursing infant.

Simultaneous determination of pethidine and norpethidine in mouse plasma by liquid chromatography-electrospray ionization source-mass spectrometry

This study aims to develop an analytical method for the simultaneous determination of pethidine and norpethidine in mouse plasma using the liquid chromatography-electrospray ionization source-tandem mass spectrometry (LC-ESI-MS-MS) method. After being alkalified, the plasma specimens were extracted by liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a C18 column (150 × 2.1 mm internal diameter, 5 μm) using a mobile phase consisting of acetonitrile/water (5 mM ammonium acetate in water, pH 6.2, 40:60, v/v) during a total run time of 4.0 min. The mass spectrometer was operated under the positive ionization mode. The multiple reaction monitoring with the transitions of m/z 248.1 → 174.2, 234.2 → 160.0 and 389.2 → 201.1 was used to quantify pethidine, norpethidine and cetirizine (internal standard), respectively. Linear calibration curves were obtained over concentration ranges of 8.24-8,440.00 ng/mL for pethidine, and 6.15-6,300.00 ng/mL for norpethidine. The intra- and interday precisions and accuracies were <15% (relative standard deviations, RSDs), and the accuracies were within the interval of 94-103% for both. The lower limits of quantification in mouse plasma were 8.24 ng/mL for pethidine and 6.15 ng/mL for norpethidine. Subsequently, the validated method was successfully applied to a pharmacokinetics study of pethidine and its metabolite, norpethidine, in mice.

A comparison of early sucking dynamics during breastfeeding after cesarean section and vaginal birth

BACKGROUND

The impact of cesarean section (CS) birth and pethidine for post-CS epidural analgesia on early breastfeeding behavior is unclear. This study aimed to measure infant sucking and breastfeeding behavior in infants of mothers who delivered by CS (CS group) and used pethidine patient-controlled epidural analgesia (PCEA) after CS with that of infants who were delivered by vaginal birth (V group), during secretory activation and again after the establishment of lactation.

SUBJECTS AND METHODS

Sucking dynamics and milk intake of breastfeeding infants were assessed on approximately 3 and 20 (follow-up) days postpartum (CS group, n=19; V group, n=15). Nipple diameters, tongue movement, and nipple position during sucking were measured from ultrasound scans of the intra-oral cavity during breastfeeding. Time of the first breastfeed and day of breast fullness were recorded, and infant neurobehavior was assessed.

RESULTS

CS infants displayed more anterior tongue movement on Day 3 than at follow-up compared with the V group, which showed a similar amount of movement at each assessment (p for interaction<0.001). Compared with the V group, the CS group showed faster suck rates, especially on Day 3 (p<0.001), later times to first breastfeed (p=0.01) and breast fullness (p=0.03), and lower neurobehavioral scores (p=0.047). Breastfeeding duration and milk intake were similar between groups.

CONCLUSIONS

Although the observed effect of CS birth followed by pethidine PCEA after CS during the period of secretory activation was small, our results indicate that successful initiation of lactation may require additional breastfeeding support and monitoring at Day 3 postpartum for mothers who undergo CS.