STANDARD TREATMENT — Pharmacologic options for prevention of motion sickness are limited. Over-the-counter first-generation antihistamines such as dimenhydrinate (Dramamine, and others) and meclizine (Bonine, and others) are effective, but they cause sedation.4 A transdermal formulation of the anticholinergic drug scopolamine (Transderm Scop, and generics) placed behind the ear can prevent symptoms of motion sickness; it can cause sedation, dry mouth and other anticholinergic adverse effects, and hyperthermia.5,6 Promethazine has been used when over-the-counter antihistamines and scopolamine are ineffective, but data on its effectiveness are limited and it causes sedation.

MECHANISM OF ACTION — The binding of substance P to NK-1 receptors plays a role in the transmission of stress and pain signals, contraction of smooth muscles, and emesis. Tradipitant selectively inhibits substance P/NK-1 receptors in the central nervous system, GI tract, and other peripheral tissues.

CLINICAL STUDIES — FDA approval of tradipitant was based on the results of two double-blind trials (Motion Syros and Motion Serifos) in a total of 681 adults with a history of motion sickness who were randomized to receive a single dose of tradipitant 85 mg, tradipitant 170 mg, or placebo 60 minutes before taking a 2- to 5-hour boat trip. In both trials, participants who took tradipitant were significantly less likely than those who took placebo to experience vomiting during the trip, the primary endpoint (see Table 2).7,8

ADVERSE EFFECTS — The most common adverse effects (incidence ≥5% and more often than with placebo) of tradipitant in the pivotal trials were somnolence, headache, and fatigue.

DRUG INTERACTIONS — Tradipitant is a substrate of CYP3A4; concurrent use of strong CYP3A4 inhibitors can increase tradipitant serum concentrations.9

PREGNANCY AND LACTATION — No adequate data are available on tradipitant use in pregnant or lactating women. No adverse developmental effects were observed in animal studies. Tradipitant is present in animal milk; breastfed infants should be monitored for somnolence.

DOSAGE, ADMINISTRATION, AND COST — The recommended dosage of tradipitant is 85 mg or 170 mg taken once about one hour before an event expected to cause motion-induced vomiting; only one dose per 24-hour period is recommended. The drug should be taken on an empty stomach (one hour before or two hours after a meal). The wholesale acquisition cost for one 85-mg capsule of Nereus is $255.10

CONCLUSION — Tradipitant (Nereus) is effective in preventing motion-induced vomiting. How it compares to transdermal scopolamine (Transderm Scop, and generics) or to inexpensive over-the-counter antihistamines such as dimenhydrinate (Dramamine, and others) and meclizine (Bonine, and others) remains to be determined.

View the Comparison Chart: Drugs for Motion Sickness

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