Page 14 - Journal of Special Operations Medicine - Summer 2015

of complicated rescue and medical care. Among those placebo in 13 Naval crew members. In a larger study
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who have tried palliative medication, only 21.3% of re- of 55 healthy Naval crew members, cinnarizine similarly
sponders to our survey experienced relief. Clearly, mo- reduced VOR gain in SHA testing, with no changes to
tion sickness is a common problem in this community phase lead. Similar to other antimotion sickness medi-
17
of Operators. cations, cinnarizine given in combination with dimenhy-
drinate had no clinically significant effect on vestibular
To help aircrew members overcome this ailment, the evoked myogenic potentials. 16
USAF has adapted a stepwise program—the Airsickness
Management Program—involving habituation, desensi- In a placebo-controlled, double-blind study, varying
tization from exposure to Coriolis stimulation, and tem- doses of cinnarizine in healthy volunteers revealed some
porary treatment with medications to help rehabilitate impairment of performance and increased sleepiness.
18
members who are affected by airsickness during train- The authors of that study recommended against its
ing. However, failure of this program ultimately leads use in aircrew involved in tasks requiring continuous
11
to elimination from aircrew training and, potentially, attention. 18
the USAF. Given the severity of symptoms and the im-
pact on safety during flight, the USAF only rarely grants A 2012 study investigated the efficacy and side effects
aeromedical waivers for a history of airsickness, and not of cinnarizine and transdermal scopolamine in Israeli
for ongoing issues with the condition. Naval Forces in a study with a crossover design. Par-
ticipants had a known history of seasickness and par-
Until January 2014, medication use for motion sickness ticipated on two different voyages in which they were
was prohibited for USAF flyers outside of the rehabilita- given either 1.5mg transdermal scopolamine or 25mg
tion program during aircrew training, due to potential cinnarizine. The results revealed that scopolamine was
side effects affecting job duties. Rare exceptions have significantly more effective than cinnarizine, and cin-
been reserved for Operators (PJs, combat controllers, narizine had a significantly higher rate of drowsiness
and CROs) performing maritime operations, and the (34%). The authors cited previous studies that reported
exception only applies to the use of ondansetron. Scopo- rates of drowsiness with cinnarizine between 8% and
lamine and promethazine remain exclusive to the mo- 77% (study doses were not provided). Another study
19
tion sickness program in training to allow for instructor comparing these two medications in Naval crew found
supervision while at risk for medication side effects. that while scopolamine was found to be more effective,
13
However, are the symptoms of the condition less debili- it also had more adverse effects. In that study, how-
20
tating than the side effects of the medications to prevent ever, the scopolamine was in tablet form. 20
our military members from taking certain medications?
Inconsistency with plasma concentration of scopola-
mine has been suggested to contribute to the varied
Literature Review on findings of efficacy in studies. One previous study in-
21
Motion Sickness Medications
vestigated plasma concentrations of scopolamine in 61
In this case report, the PJs were offered cinnarizine by Navy Sailors wearing a 1.5mg patch. A statistically
21
the captain. It provided rapid relief with no untoward significant improvement in efficacy occurred in patients
effects. Here, we discuss studies that have reported ef- whose plasma concentration was more than 160pg/mL.
fectiveness of motion sickness medications and identi- Although it would be expected for side effects to be
fied side effects of these medications. higher in those whose concentrations were higher, no
such findings occurred during this study. 21
Cinnarizine is a noncompetitive antagonist of H1-
histamine receptors with calcium channel blocking ac- As mentioned, the military is concerned with medica-
tivity. It may increase blood flow and viscosity with tions’ therapeutic effects and potentially negative effects
14
anti vasoconstrictive activity, and improve perfusion of on cognitive performance. Gordon et al. evaluated 60
22
the vestibular nuclei. 15,16 The drug may act as a labyrinth Naval crew members’ performance on several cogni-
sedative, due to its calcium channel blocking activity tive tests to study possible cognitive effects of dimen-
within the inner ear, inhibiting the influx of calcium ions hydrinate (100mg), cinnarizine (50mg), and transdermal
from the endolymph to the vestibular sensory cells. Re- scopolamine (1.5mg). Only dimenhydrinate showed
14
duced vestibular sensitivity has been suspected to be re- statistically significant worsened performance on some
lated to lower susceptibility to motion sickness, whether tests. Side effect profiles were also evaluated and the
22
naturally in individuals or pharmacologically induced. only statistically significant side effect found compared
Cinnarizine has been shown to reduce the vestibulo- to its placebo was with scopolamine (dry mouth).
oc ular reflex (VOR) gain in rotary-chair sinusoidal Drowsiness, although present for each drug, was not
harmonic acceleration (SHA) testing in comparison to statistically significant in any of the medications. 22

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