Background and Goal of Study: The aim of the present study was to evaluate the optimum dose of ropivacaine by comparing three different dosing regimens of plain ropivacaine 1% (naropin 10 mg/ml, Astra Zeneca) administered intrathecally to subarachnoid space and demonstrated the effects of anesthesia in pregnant women scheduled for cesarean section and effects in newborn.
Materials and methods: Sixty ASA grade I-II patients scheduled to undergo elective cesarean sections under spinal anesthesia were included in the study. The patients were randomly assigned into three groups, 
Group 1 received 15 mg ropivacaine 1%, 
Group 2 received 20 mg ropivacaine 1%, and 
Group 3 received 25 mg ropivacaine 1%. 
Sensorial block and motor block times and time to reach maximal sensorial block, and motor block time, time to two-segment regression of sensory block. The rates of complications; hypotension, bradycardia, allergic reactions, shivering, nausea and vomiting, time to first analgesic requirement and VAS scores, the umbilical blood gas analysis, and apgar scores of newborn were recorded. One-way analysis of variance (One-way ANOVA) was used to compare variables between the groups, intragroup comparison of the variables was performed by the paired samples t-test, and chi-square test was used to analyze the complications.
Results and discussion: In our study intraoperative hemodynamic variables were not significantly different between the three groups, and sensorial block and motor block times and time to reach maximal sensorial block, and motor block time were similar between the three groups. The time to two-segment regression of sensory block was longer in Group 3 compared to other groups, and the difference was statistically significant (p < 0.05). Hypotension and ephedrine requirement was significantly higher in Group 3 compared to the other two groups (p < 0.05). The time to first analgesic requirement and VAS scores were similar, and there was no significant difference between the groups (p >0.05). The results of umbilical blood gas analysis and Apgar scores were similar between the three groups, and fetal acidosis was not observed (pH < 7.20) (p >0.05).
Conclusion: We hypothese that although ropivacaine administration produced rapid induction of anesthesia and satisfactory anesthesia level, ropivacaine 15mg and 20 mg dosing regimen is suggested for safe intrathecal administration.

Intrathecal ropivacaine in cesarean delivery: comparison of three different dosing regimens