Transdermal delivery of anti-emetics such as Ondansetron and Promethazine have several benefits. For
instance, first pass metabolism and stomach degradation can be avoided and more consistent plasma levels
can be maintained. In addition, topical administration can be an alternative to deliver medication when oral
intake is limited due to nausea and vomiting. This could be of particular interest for pediatric patients who may
have difficulties in frequency of administration, adverse taste, possibility of incomplete intake, difficulty in
swallowing a pill, and fear of needles. There may also be a preference of interest for those patients frequently
vomiting before a pill form has absorbed, such as morning sickness in pregnancy.
The topical formulation of the drug has been found very competitive to both rectal suppositories and oral
dosage forms in that variable blood levels, first-pass metabolism, unpredictable peaks in blood levels, and
variable bioavailability may be minimized. Topical administration of these products has been reported to
provide antiemetic relief to patients in need of treatment, while minimizing side effects and adverse reactions
known to occur with many other formulations and routes of administration.
These products are thought to work by coordinating with the vomiting center in the lateral medullary reticular
formation in the pons. Chemicals in the cerebrospinal fluid and blood can have a direct stimulating effect at
the vomiting center mediated through dopaminergic, cholinergic and histaminic neurochemical receptor sites.
These pathways are antagonized by Odansetron, in which it blocks these neurochemical receptor sites by providing medication levels for treating or preventing the condition of emesis.