“TREATMENT OF NAUSEA AND VOMITING”
James Hallenbeck,
MD
What’s the
difference between Compazine (prochlorperazine) and Phenergan (promethazine)?
By understanding the pathophysiology of nausea and targeting antiemetics to
specific receptors, therapy can be optimized and side-effects minimized. An easy way to remember the causes of
vomiting is to use the VOMIT acronym. In the table below receptors involved in different types of
nausea are highlighted using this acronym. Blockade of these receptors allows rational, focused
therapy.
Type of nausea |
Receptors causing nausea |
Drug class useful |
Examples of DOC |
Vestibular |
Cholinergic,
Histaminic |
Anticholinergic, Antihistaminic |
Scopolamine
patch Promethazine |
Obstruction
of Bowel caused by constipation * |
Cholinergic,
Histaminic, ? 5HT3 |
Stimulate
myenteric plexus |
Senna products |
DysMotility of upper gut ** |
Cholinergic,
Histaminic, ? 5HT3 |
Prokinetics
stimulate 5HT4 receptors |
Metoclopramide Cisapride |
Infection,
Inflammation |
Cholinergic, Histaminic,
? 5HT3 |
Anticholinergic, Antihistaminic |
Promethazine |
Toxins
stimulating the CTZ in the brain such as Opioids*** |
Dopamine 2, 5HT3 |
Antidopaminergic, 5HT3 Antagonist |
Prochlorperazine, Haloperidol, Ondansetron |
* The most common cause of bowel obstruction is constipation. This is especially problematic in
patients on opioids. Treatment of
nausea related to mechanical bowel obstruction is controversial and stimulants,
such as senna may be inappropriate, especially if cramping is present.
** Dysmotility
of the upper gut is a common, under-appreciated cause of nausea, especially in
patients on opioids or anticholinergic drugs, both of which slow gut
motility. Patients typically
complain of early satiety in contrast to other patients, who have fasting
nausea. Metoclopramide is
contraindicated in Parkinson’s Disease and renal failure. Cisapride has numerous drug-drug
interactions, so beware! Both
prokinetic work poorly if anticholinergic drugs are co-administered. So don’t give promethazine for this
form of nausea!
*** Rising
serum levels of opioids stimulate the chemotactic trigger zone (CTZ), causing
nausea. Minimizing fluctuating
opioid levels, by using long-acting agents where possible, can limit this form
of nausea. Prochlorperazine is the
first-line suppository, haloperidol may be used orally or parenterally. Ondansetron, a 5HT3 antagonist is a
second-line agent that can be used where antidopaminergic drugs are
contraindicated, such as in Parkinson’s Disease.
Additional pearl:
There is no good evidence supporting the use of lorazepam as a sole agent for
nausea. Sedated patients may be
more prone to aspiration. Listed
below is a comparison of some commonly used antiemetics:
Scopolamine: a very potent, pure anticholinergic
agent.
Promethazine (Phenergan): antihistamine with potent anticholinergic
properties, very weak antidopaminergic agent. (So bad for opioid related
nausea.)
Prochlorperazine (Compazine): Potent
antidopaminergic, weak antihistamine, anticholinergic agent.
Haloperidol: Very potent anti-dopaminergic agent.
As you can see,
Phenergan and Compazine are very different drugs. Phenergan is useful for vertigo and gastroenteritis due to
infections and inflammation.
Compazine is preferred for opioid related nausea.
References:
·
Mannix KA. Palliation of nausea and vomiting. Oxford Text
Palliative Med. Second ed. 1998. Oxford. U. Press, NY.489-499.
·
Storey P, Knight
CF. UNIPAC Four: Management of Selected Nonpain Symptoms in the Terminally
Ill. 1996. American Academy of Hospice and
Palliative Medicine. Can order
via www.aahpm.org.
Edward E.
Rylander, M.D.
Diplomat American
Board of Family Practice.
Diplomat American
Board of Palliative Medicine.