A Randomized controlled trial of intramuscular pentazocine compared to intravenous paracetamol for pain relief in labor at Aminu Kano Teaching Hospital, Kano

Abstract

Background: Labor is generally considered to be a very painful experience. Epidural analgesia which is the gold standard for labor pain relief is not widely available, affordable, or feasible, especially in our environment. Parenteral opioid analgesics,  which are more commonly used, can cause nausea and vomiting in the patient and respiratory depression in the neonate;   hence, they cannot be used in all stages of labor. There is thus the need for an alternative analgesic with similar or superior analgesic effect to opioids but without their fetomaternal side effects.

Objectives: The objective of this study was to compare the efficacy of intramuscular (IM) pentazocine and intravenous (IV) paracetamol infusion in relieving labor pain at Aminu Kano Teaching Hospital, Kano.

Study Design: It was a randomized controlled study.

Methodology: One hundred women with singleton uncomplicated pregnancies and spontaneous labor at term were randomly assigned to the study group or control group. Women in the study group received an IV infusion of 1000 mg of paracetamol while women in the control group received a single dose of 30 mg of pentazocine intramuscularly. Labor pain perception was assessed using visual analog scale (VAS) scores at presentation and after delivery while maternal satisfaction  assessed using Likert scale, and maternal and fetal complications were recorded after delivery. Statistical analysis was done using computer software SPSS Version 20.0. Chi‑square, Fisher’s exact test, t‑test, and Mann–Whitney U‑tests were used to  compare means and proportions as appropriate for statistically significant differences, setting the level of significance (P value) at <0.05.

Results: There were no statistically significant differences between the two groups in their sociodemographic characteristics, obstetric characteristics, and labor  characteristics. There was also no statistically significant difference in the VAS pain  scores between the two groups before administration of the analgesics (P = 0.968) and after administration of the analgesics (P = 0.225). The maternal satisfaction with pain relief among the patients in the two groups was also found to be similar (P = 0.341). Nausea (P = 0.002), vomiting (P = 0.012), and  drowsiness (P < 0.001) were significantly higher in the pentazocine group when compared with the paracetamol group. None of the patients in the two groups  developed dyspnea during labor, skin rashes, or persistently low systolic blood pressure of <90 mmHg, and none had persistent fetal heart rate abnormalities during labor or appearance, pulse, grimace, activity, and respiration (APGAR) scrores <7 at the 1st or 5th min after delivery.   However, the mean APGAR score of the neonates at 1 min was significantly higher in the paracetamol group (P = 0.033), while there was no difference in the mean APGAR scores of the neonates in the two groups at 5 min after delivery (P = 0.152).

Conclusion: The analgesic efficacy of IV paracetamol was similar to that of IM pentazocine in labor, with similar levels of  maternal satisfaction with pain relief, but IV paracetamol was associated with significantly lower rates of adverse effects.

Key words: Labor; pain relief; paracetamol; pentazocine.