Metadona frente a fentanilo como adyuvante en anestesia subaracnoidea con bupivacaína. Estudio doble ciego, controlado con placebo, comparativo, aleatorizado

The addition of methadone to bupivacaine significantly prolonged the postoperative analgesic effect of spinal anesthesia and shortened sensory-motor block duration, enhancing patient comfort after surgery.