Long-term use of intrathecal droperidol as an excellent antiemetic in nonmalignant pain--a retrospective study.

UNLABELLED Over the past five years our pain practice encountered eight patients (5 female, 3 male) with chronic non-malignant pain syndromes, in whom any meaningful pain reduction via opioid analgesics (either by oral or systemic and/or intraspinal route) had resulted in profound nausea and/or vomiting despite generous use of available and/or affordable anti-emetics. After obtaining proper consents, small, incremental doses of intrathecal droperidol were added to these patients having implanted intrathecal narcotic drug delivery system. Significant reduction of nausea and vomiting without any side effects from droperidol was obtained while adequate pain reduction is achieved. PROCEDURE All patients had implanted programmable Medtronic Synchromed pumps with intrathecal access catheters. The intrathecal catheter tip placement varied depending on the pain pathology of the patient. Six of eight patients were started and remained on morphine sulfate intrathecally for their opioids. Two patients with contraindications to morphine had fentanyl and hydramorphone as their intrathecal opioid respectively. The intrathecal dose of droperidol was started low (22.7 +/- 18.6 micrograms/day). All patients were on simple continuous pump dosing during the study. RESULTS All patients achieved statistically significant antiemesis (77 +/- 10% P < 0.001) as well as statistically significant pain relief (84 +/- 7% P < 0.005) early on (within two pump refills). As the intrathecal dose/day of droperidol was increased to 124.7 +/- 114.8 micrograms/day as well as their intrathecal pain medication use, the degree of significance of antiemesis improved to 86 +/- 9% (P < .001) which was a statistically significant improvement of P < or = 0.05 level from the starting dose of droperidol in each patient. For the six patients on morphine the antiemesis improved to 88 +/- 10% (P < or = .003), also statistically significantly different at P < or = 0.05 level from the starting antiemesis level. During this period the intrathecal morphine dose was doubled from 4.76 +/- 2.43 mg/day to 9.5 +/- 6.5 mg/day (P < or = .001). Patients had no adverse effects from the use of droperidol at these doses (no sedation, changes in mental status, no signs or symptoms of arachnoiditis, no new sensory or motor disturbance, or any other indications of nerve toxicity detected.). Serial neurological studies involving MRI and CT, with contrast, EMG every 6-12 month showed no intrathecal catheter tip irritation sequelae in our patients either. CONCLUSIONS We find droperidol in microgram doses of 5-300/day intrathecally a safe antiemetic to use along with opioid analgesics. We did not use droperidol intrathecally alone as its use systemically without an opioid companion base is fraught with concern in anesthesia literature ("calm looking on the outside-agitated on the inside"). We would suggest a minimal starting dose of 20-30 micrograms/day of droperidol, adjust most probably upwards by 25-50% on subsequent pump refills until the desired effect is established. The scientific literature is rich with references to the brainstem chemoreceptor trigger zone, the floor of the fourth ventricle, and other nausea center locations (area postrema, the circumventricular organ, etc.). We would like to suggest that droperidol's direct actions on these centers are involved with antiemesis at these small doses.