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Research Assistant Professor Department of Medicine University of Pittsburgh Medical Center 3504 Fifth Avenue, Suite 200 Pittsburgh, Pennsylvania 15213-2582 fax 412/383-4898 shethh{at}dom.pitt.edu
Drug Information Pharmacist University of Pittsburgh Drug Information Center Instructor School of Pharmacy University of Pittsburgh Pittsburgh
Director Drug Use and Disease State Management Program University of Pittsburgh Medical Center Assistant Professor Department of Pharmacy & Therapeutics School of Pharmacy University of Pittsburgh
Vice Chair of Quality Improvement and Patient Safety Department of Medicine Assistant Professor of Medicine and Psychiatry School of Medicine University of Pittsburgh
Published Online, June 14, 2005. www.theannals.com, DOI 10.1345/aph.1E361b
The strategy for combining antiemetic medications with differing chemoreceptor sites of action may have better effectiveness in preventing PONV considering the multifactorial etiology and existence of multiple emetic neuroreceptors. This agrees with the findings of Habib et al.1 that promethazine was a more effective rescue drug compared with ondansetron for PONV after failure of prophylaxis with ondansetron. The risk of PONV is related to 4 primary patient-related risk factors: (1) female gender, (2) nonsmoking status, (3) postoperative opioid use, and (4) history of PONV/motion sickness.2 Recent consensus guidelines denote these patient-related factors, plus anesthetic- and surgery-related factors, as necessary for evaluation of PONV risk and recommend prophylaxis for all high-risk patients.3
Efficacy of the preventive antiemetic is related to the perioperative
administration time, with the goal being near the end of
surgery.4
Promethazine is recommended for PONV rescue in doses of 12.5–25 mg given
intravenously, but its use is limited in outpatient settings due to its
sedating effects. There have been reports of ineffective prevention of PONV
related to promethazine monotherapy in doses of 
12.5
mg.5,6
Thus, the effectiveness of low-dose promethazine for PONV requires further
study.
Serotonin antagonists alone may not be as effective as older antiemetics in treatment of PONV.7 However, their safety profile, especially their lack of sedating properties, as well as the limited availability and safety concerns with older antiemetics, has prompted practitioners to use serotonin antagonists preferentially in populations, such as elderly patients, who may be sensitive to oversedation and hemodynamic changes. One study found antihistaminic agents, such as promethazine and hydroxyzine, to be the most frequent inappropriately prescribed drug class in elderly Georgia nursing home residents.8 Although the promethazine dosing range is not described in that report, the current recommendations cite doses of 12.5–25 mg for adults.9
Our report mainly describes adverse promethazine outcomes in medically
compromised patients on general patient care units. Such patients are not as
closely monitored as are those in the postoperative setting, which was the
setting for the study by Habib et al. It is our understanding that most
institutions continue to use promethazine doses of 12.5 mg in nonmonitored
settings for patients with complex comorbidities. We caution against the use
of promethazine in elderly patients and in those receiving opioids and/or
central nervous system depressants in nonmonitored settings. Until data are
available demonstrating the safety and efficacy of doses <12.5 mg in such
populations, our adverse event experience prompts us to recommend serotonin
receptor antagonists as the safer antiemetic choice in these patients.
References
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