MeperidineShiveringAnalgesics, OpioidAdjuvants, AnesthesiaAnalgesia, ObstetricalBiotransformationPromethazineHydroxyzineChromatography, High Pressure LiquidDihydroergotamineMetabolomicsMetabolomeAlfentanilGas Chromatography-Mass SpectrometryAnalgesia, EpiduralChloral HydrateConscious SedationPreanesthetic MedicationFentanylMagnetic Resonance SpectroscopyCesarean SectionAnalgesia, Patient-ControlledMorphineMass SpectrometryButorphanolDextropropoxypheneMicrosomes, LiverAnalgesics, Non-NarcoticKetorolac TromethamineSufentanilChromatography, LiquidHydroxylationAnesthesia, SpinalKetorolacSerotonin SyndromeAnesthetics, LocalNarcoticsSkin TemperatureTolmetinCytochrome P-450 Enzyme SystemDose-Response Relationship, DrugAnesthesia, DentalPain MeasurementGlucuronidesTandem Mass SpectrometryAnesthesia, EpiduralDiazepam