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9780521704632c18 CUFX213A/Peck 9780521618168 December 28, 2007 13:51
18 Antiemetics and related drugshydroxylation and subsequent glucuronide conjugation to inactive metabolites. Its
half-life is 3 hours. The dose should be reduced in hepatic impairment.
While ondansetron clearly has a place in the treatment of nausea and vomiting
it has not universally been shown to be superior to low-dose droperidol or a phe-
nothiazine. This together with its higher cost suggests it should be used only when
conventional therapy is expected to or has failed.Miscellaneous
Steroids
The role of dexamethasone as an antiemetic has traditionally been confined to
chemotherapy induced nausea and vomiting. However more recently it has been
used at a dose of 2.5–10 mg to prevent post-operative nausea and vomiting. Its mode
of action in this area is uncertain.Acupuncture
Several studies have demonstrated the effectiveness of acupuncture in the preven-
tion of PONV. The acupuncture point lies between the tendons of flexor carpi radialis
and palmaris longus about 4 cm from the distal wrist skin crease. It should be per-
formed on the awake patient and is free from side effects.Canabinoids
Nabilone acts at the VC and has been used as an antiemetic following chemotherapy.Benzodiazepines
Lorazepam is used as an antiemetic during chemotherapy. It has amnesic and seda-
tive properties. Its mode of action as an antiemetic is uncertain but it may modify
central connections to the VC and prevent the anticipatory nausea that is seen with
repeated doses of chemotherapy.