A phase 4 trial depicted that compared with transversus abdominis plane block with bupivacaine hydrochloride alone, the correctly placed transversus abdominis plane block using long-acting liposomal bupivacaine plus bupivacaine hydrochloride as part of a multimodal analgesia protocol incorporating intrathecal morphine led to a decline in the opioid intake and enhanced analgesia in females undergoing cesarean delivery under spinal anesthesia.

A phase 4, randomized, prospective, multicenter, double-blind trial was carried to assess the efficacy and safety of transversus abdominis plane block with liposomal bupivacaine plus bupivacaine hydrochloride versus bupivacaine hydrochloride alone after cesarean delivery.

The study cohort included females with term pregnancies undergoing cesarean delivery under spinal anesthesia. Overall, 186 participants were randomized to (i) Group A (n=96): Transversus abdominis plane block with liposomal bupivacaine (266 mg) plus bupivacaine hydrochloride (50 mg), or (ii) Group B (n=90): Bupivacaine hydrochloride 50 mg alone.

The efficacy was determined in a protocol-compliant analysis set. The total postsurgical opioid consumption (oral morphine equivalent dosing) through 72 hours was the major outcome. Utilizing the visual analog scale, the pain intensity was estimated. Recording of adverse events after therapy was done through day 14.

The total opioid consumption through 72 hours was lowered with liposomal bupivacaine plus bupivacaine hydrochloride in comparison with bupivacaine hydrochloride alone with a least-squares mean (LSM) treatment difference of −16.5 mg. The area under the curve of pain intensity scores through 72 hours supported noninferiority of liposomal bupivacaine plus bupivacaine hydrochloride versus bupivacaine hydrochloride alone (LSM therapy difference, −30.6), with a predefined noninferiority margin of 36, as shown below:

In an assessment of all treated subjects, including those not fulfilling criteria for inclusion in the protocol-compliant analysis, no difference was noted in the postsurgical opioid intake between the groups. Both the groups displayed comparable safety profile.

In the liposomal bupivacaine plus bupivacaine hydrochloride cohort, about 63.6% of participants witnessed an adverse event after therapy compared to 56.2% in the bupivacaine hydrochloride-alone cohort. Serious adverse events after therapy were found to be rare (approximately 3% in both arms).
Thus, there is an opioid-lowering benefit of adding liposomal bupivacaine to bupivacaine transversus abdominis plane blocks in females undergoing cesarean delivery.