Fentanyl 165breathing hazard those opioid-naive patients often do not receive fentanyl.
Nonetheless, it is sometimes used for childbirth, surgery, and dentistry and
for persons suffering from lower back ache and pain in bones and joints.
Physicians even give fentanyl to infants.
The drug can promote sleepiness and slow a person’s pulse rate, alertness,
and physical motions. Such effects interfere with ability to operate automo-
biles or machinery. Other unwanted actions include itching, constipation,
urine retention, nausea and vomiting, increased blood pressure, and fainting
upon standing up. Cases of muscle rigidity have been reported. Laboratory
tests suggest fentanyl might worsen a body chemistry disease called por-
phyria.
Fentanyl can provoke seizures in persons prone to such affliction. A drastic
treatment for seizures is surgical removal of a brain lobe where seizures orig-
inate, and instrument readings during the operation guide surgeons on how
much of the brain to remove. Fentanyl is a standard surgical anesthetic, and
one study found that the drug can temporarily create seizures in healthy por-
tions of the brain, thereby misleading surgeons about how much they should
remove.
Like many other drugs, fentanyl has stronger effects on older persons, and
dosage should be adjusted accordingly.
Abuse factors.Tolerance and dependence can occur, with typical opioid
withdrawal symptoms. Just three days of medical dosing can produce enough
dependence to cause uncomfortable withdrawal upon sudden stoppage of the
drug, an exceptionally short time compared to most opioids. Animal experi-
ments indicate thatbuprenorphinecan alleviate fentanyl withdrawal.
Drug interactions.Normally people should avoid fentanyl if they have
taken monamine oxidase inhibitors (MAOIs—found in some antidepressants
and other medicine) in the past two weeks, as MAOIs can greatly increase
opioid actions. For the same reason, using fentanyl with other depressants
(includingalcohol) can be risky.Midazolamhydrochloride and fentanyl ap-
pear to boost each other’s actions. The HIV/AIDS medicine ritonavir makes
a fentanyl dose last longer.
Cancer.Whether fentanyl causes cancer is unknown, although laboratory
tests with one version of the drug yielded no indication of cancer-causing
potential.
Pregnancy.Rats receiving fentanyl have lower fertility rates and bring fewer
pregnancies to term, compared to rats not receiving the drug, and those effects
occurred at smaller doses than humans typically receive. When fentanyl citrate
has been given to pregnant rats, birth defects in their offspring have not been
attributed to the drug. Whether fentanyl causes congenital malformations in
humans is unknown. An infant can be born with dependence if the mother
has been using fentanyl. The drug passes into a nursing mother’s milk but
not in amounts deemed harmful to an infant.
Additional information.Alfentanil (Schedule II, CAS Registry No. 71195-
58-9) is a derivative of fentanyl used for pain control and anesthesia. Effects
last only a few minutes. Depending on dosage form, pain relief is 1 to 10 times
stronger than morphine. When given to a pregnant woman alfentanil appar-
ently passes into the fetus. The drug can produce muscle rigidity in infants.