Background
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Postpartum pain is linked to with postpartum depression, breastfeeding difficulties, and chronic pain.1
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Intrathecal morphine (ITM), the gold standard for post-cesarean analgesia, is not always feasible.
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Intravenous (IV) methadone as an alternative:
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Long-lasting systemic opioid
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Anti-N-methyl-d-aspartate (NMDA) receptor antagonism
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Serotonin and norepinephrine reuptake inhibition
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A retrospective study showed that IV methadone lowers pain scores and opioid requirements for cesareansunder general anesthesia.2

Hypothesis
In patients undergoing scheduled cesarean delivery, there would be a decrease in opioid requirement at 0-48 hours in patients receiving 0.2 mg/kg (maximum 20 mg) intravenous methadone compared to patients that received150 mcg intrathecal morphine.

Study Design and Methods
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Single-center prospective, randomized, double-blinded pilot
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30 patients undergoing scheduled cesarean delivery
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Exclusion criteria:
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Chronic pain
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Chronic opioid use
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Substance use disorder
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BMI > 50.0 kg/m²

Primary outcome: Total opioid consumption at 24-48 hours after delivery in the groups.
Secondary outcomes: NRS pain scores, obstetric quality of recovery (ObsQoR10), and side effects were assessed at12, 24, 36, 48hours in person and at one-week postpartum via textmessage.

Results
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No significant difference in maternal demographic or obstetric factors
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Patients in the methadone group required more opioids across all time points (Figure 1)
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No significant difference in pain scores (Figure 2), ObsQoR10, or global health state scores
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No significant difference inintra-operative andpost-operative respiratory depression at all time points
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Patients in IV methadone group did report a significantly lower rate of pruritus across all timepoints (p<0.05, Figure 3)

Conclusion & Discussion
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Patients who received ITM requiredless opioids in the first 48 hours aftercesarean delivery compared to those who received IV methadone.
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Although IV methadonedid not appear to provide superior analgesia compared to ITM, it enabled comparable post-cesarean recovery with an acceptable side-effect profile.
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In patients who do not receive ITM, consider using IV methadone for post-cesarean analgesia.