158 Etorphine
the late 1980s when Rocket Racer won the Perth Cup by eight lengths and
continued running. The horse would not stop despite the jockey’s efforts; after
nearly another lap around the track, the horse collapsed and died. Reportedly
some human track competitors have used the same drug, accelerated their
pace as a race progressed, and had difficulty stopping after crossing the finish
line.
Drawbacks.In animal experiments dihydroetorphine interferes with the im-
mune system, interference that may make infections more likely. Etorphine
can send blood pressure up or down, reduce body temperature, and impair
heartbeat and breathing. Impaired breathing is also an unwanted effect ob-
served with dihydroetorphine, along with constipation, nausea, vomiting, diz-
ziness, and drowsiness.
Although etorphine is a standard veterinary medicine, knowledgeable users
treat it with great respect and keep an antidote on hand because accidental
injection can be fatal. The drug may be absorbed though the skin, and supplies
of etorphine are generally dyed red so users can readily tell if they have
touched it (such as a smear across a shirt or hand). Swift administration of an
antidote can prevent death.
The quantity needed to kill a person is so minute that its presence in a body
can be difficult or even impossible to detect. Harmless chemicals added to a
dose can make etorphine even harder to discover through laboratory tests.
The drug has also attracted military attention as a possible chemical warfare
agent.
Abuse factors.When humans in an experiment received etorphine they ex-
perienced euphoria and described the drug as feeling like morphine. Research-
ers who administered etorphine in that experiment concluded that the drug
is likely to be abused. Misuse has been noted in China. Other investigators
reached the same conclusion about dihydroetorphine from the way rats re-
sponded to it. The U.S. Drug Enforcement Administration has ruled that dihy-
droetorphine’s abuse potential is similar toheroin’s. The government of Hong
Kong has noted dihydroetorphine’s lower price and less stringent control
make it appealing to heroin addicts. Lawsuits against the tobacco industry
unearthed documentation indicating one company considered the possibility
that competitors might lace cigarettes with etorphine to add an addictive need
that could not be satisfied by other brands, thereby coercing consumer loyalty
to a particular product.
A mice study found no dependence at all after dihydroetorphine had been
administered for six days, but rat and mice research demonstrates that dihy-
droetorphine eventually produces enough dependence to cause withdrawal
symptoms. Investigators have noted that rats act as if dihydroetorphine is a
satisfactory substitute for heroin. Etorphine can prevent withdrawal symp-
toms in morphine addicts, an action demonstrating cross-tolerance between
the two drugs, but an etorphine dose holds off withdrawal symptoms for a
shorter time than morphine would. In rhesus monkey experiments etorphine
and dihydroetorphine are both cross-tolerant with morphine. In those same
experiments, when dihydroetorphine dosage was suddenly stopped, few
withdrawal signs appeared. Withdrawal symptom research on mice indicates
that dihydroetorphine may do more than substitute for morphine: A dihy-