Page 30 - Journal of Special Operations Medicine - Summer 2015

but a 3.3% rate in the promethazine group. A small, treatment group received ondansetron, 4mg IV, and
4
early comparison of ondansetron and promethazine in the placebo group received IV saline. In the ondanse-
the treatment of hyperemesis gravidarum showed equiv- tron group, the frequency of PONV was significantly
alence in the relief of nausea, weight gain, days of hos- decreased from 52% to 22%. 43
pitalization, and total number of doses of medication. 38
Unlike promethazine, for which there is good evi-
Two separate systematic reviews published in 1999 dence to demonstrate antagonism to opioid analgesia,
compared ondansetron with metoclopromide or droper- as described, ondansetron appears to have a neutral
29
idol in the treatment of PONV. 34,35 Cox demonstrated or synergistic effect. Jellish et al. compared patient-
35
44
that compared to metoclopramide, 10mg, ondansetron, controlled analgesia administration of morphine, mor-
4mg, had higher patient satisfaction and better treat- phine plus ondansetron, and placebo for pain control in
ment of nausea. The findings of Domino et al. were patients immediately recovering from skull surgery and
34
confirmatory, showing that ondansetron (1mg, 4mg, found the morphine-plus-ondansetron combination had
and 8mg) demonstrated essentially equivalent therapeu- the lowest pain scores, shortest postanesthesia discharge
tic effects to droperidol (0.625mg, 1mg, and 1.25mg) time, lowest rescue dose, and highest patient satisfac-
with no increase in the incidence of adverse effects. A tion, although, paradoxically, they reported equivalent
34
2014 head-to-head comparison of ondansetron, meto- incidence and severity of nausea and vomiting.
clopramide, and placebo for acute, undifferentiated nau-
sea in the ED showed equivalence in patient satisfaction, Like promethazine, ondansetron is available in oral
effects, and side effects in all three arms. Of note, this form, as well; however, ondansetron is available as
36
study compared ondansetron, 4mg, to metoclopramide, an orally disintegrating tablet (ODT) that is absorbed
20mg, which is double the normal recommended dose through the buccal and sublingual mucosa and does
of metoclopramide. not require swallowing or gastrointestinal absorption.
7
Ondansetron ODT has been shown to be just as effec-
Compared to other 5-HT antagonists (i.e., granisetron, tive as IV ondansetron in the management of chemo-
3
tropisetron, and dolasetron), ondansetron was as effec- therapy-related nausea and PONV 46,47 and better than
45
tive for prophylaxis of PONV, but granisetron, when IV saline in the management of undifferentiated nausea
studied by Tang and Malone, was more effective than in the prehospital setting. Although oral ondansetron
40
48
ondansetron in the treatment of postoperative nausea. reaches peak serum levels at 2.3 hours, compared to 5
Metaxari et al. found ondansetron equal to granise- minutes after IV administration, it has essentially the
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49
tron in control of PONV in thyroid surgery, but only for same bioavailability, and there do not appear to be
49
6 hours compared to granisetron’s 12 hours. Ondanse- any clinically significant differences in time of onset and
tron, however, is far more commonly used, especially in time to therapeutic effect. 3,46,48
the ED setting, than granisetron, and there are much
2
more data and experience for its safe and effective use in A prospective study of 2,071 patients (2,005 adults,
that environment. 66 children) who received either ondansetron, 4mg (in
adults) given either IV, IM, or ODT, in a nonrandom-
Ondansetron has been shown to be effective in pro- ized, uncontrolled, observational protocol, found effec-
phylaxis of PONV. Chen et al. studied patients who tive control of nausea in all three groups. ODT and IM
42
3
received ondansetron IV 30 minutes before the end of ondansetron were statistically equivalent and IV was
shoulder arthroscopy and found it reduced the incidence better than both IM (−0.8 on a 10-point visual analog
of PONV. Additionally, the patients using ondansetron scale [VAS]; p = .03) and ODT (−1.1; p < .001); how-
had “lower pain intensity and lower analgesic injection ever, all three showed a statistically significant change in
needs than the control group.” In a series of 100 pa- VAS for nausea. 3
42
tients undergoing mandibular osteotomy, Talesh et al.
39
compared the effectiveness of ondansetron and meto- In a randomized, double-blind, placebo-controlled com-
clopramide for the prevention of PONV and found parison of IV and ODT ondansetron, Grover et al.
46
ondansetron provided a significant improvement in ef- found no difference between ondansetron, 4mg IV, and
fect: an 11% incidence of vomiting with ondansetron ondansetron, 8mg ODT. An argument can be made that
compared with 28% in the metoclopramide group. In a this was not an equivalent treatment, since the bioavail-
randomized, double-blind, placebo-controlled study of ability of ODT ondansetron appears to be 90%, but
50
65 women undergoing total abdominal hysterectomy, both 4mg and 8mg doses of ondansetron have been
Tzeng et al. compared ondansetron versus saline shown to be effective in oral and parenteral forms.
43
placebo for the prophylactic treatment of PONV. All
patients received epidural morphine, 3mg, for post- Additionally, ondansetron ODT does not appear to have
operative pain relief. Before morphine injection, the the same arrhythmogenic side effects as the IV form,

20 Journal of Special Operations Medicine Volume 15, Edition 2/Summer 2015