Chronotherapeutics of intrathecal fentanyl added to bupivacaine for labour analgesia

ABSTRACT

Chronotherapeutics is the optimization of pharmacotherapies, taking into consideration rhythm-dependence in the kinetics and dynamics of medications plus predictable-in-time variability in the manifestations and severity of human disease. The aim of the present work was to determine whether the efficacy and side-effects of intrathecally administered mixture of a small dose of fentanyl and bupivacaine, to relieve labour pain, is influenced by the hour of administration. One hundred parturients requesting neuroaxial labour analgesia were assigned to one of four equal groups based on the time period when the intrathecal mixture was administered. Group E= evening, group N= night, group M= morning and group AN= afternoon. Maternal demographic and obstetric data, and the characteristics of the intrathecal blocks were recorded Demographic data, gestational age and cervical dilatation were similar in the four groups. The incidence of oxytocin use was lower in E and N groups than M and AN groups. The base-line visual analog pain score [VAPS] was higher in E and N groups than in M and AN groups. The onset of analgesia was delayed in E and N groups than M and AN groups [8.6 [3.4], 8.2 [3.1] Vs 6.5 [2.5], 6.6 [2.6], mm respectively]. There were no significant cant differences between groups as regard the upper sensory level, the number of parturients with detectable motor block or side effects. The duration of analgesia was shorter in groups E and N than in groups M and AN [75 [22] and 71 [19] Vs 108 [33] and 102 [31] mm respectively]. Maternal and midwife satisfaction scores were lower in groups E and N than in groups M and AN but no significant difference at 30 mm and at reinjection. Fentanyl and bupivacaine exhibit a temporal pattern of kinetics and dynamics when administered intrathecally for labour analgesia and this should be considered in future comparative studies and in analysis of previous studies and clinically to administer the suitable dose over the 24 hours of the day