Pentazocine is a synthetically-prepared
prototypical mixed agonist-antagonist narcotic (opioid
analgesic) drug of the benzomorphan class of opioids used to
treat mild to moderately severe pain. Pentazocine is sold under
several brand names, such as Fortal, Talwin NX (with the mu-antagonist
naloxone, will cause withdrawal in opioid dependent persons),
Talwin, Talwin PX (without naloxone), Fortwin (Lactate
injectable form) and Talacen (with acetaminophen). This compound
may exist as one of two enantiomers, named (+)-pentazocine and
(-)-pentazocine. (-)-pentazocine is a kappa-opioid receptor
agonist, while (+)-pentazocine is not, instead displaying a
ten-fold greater affinity for the sigma receptor. Talwin PX is
the main pentazocine pharmaceutical in Canada, where laws and
regulations prohibit the addition of naloxone to the formulation
for non-therapeutic purposes. Related drugs include phenazocine,
dezocine, cyclazocine, salvinorin A (distantly) and several
chemicals used in research on the central nervous system, and
the Greek equivalent of the first letter of the name of the drug
ketocyclazocine is the source of the name of the kappa opioid
receptor type, as is the case with morphine and mu receptors and
dynorphin and delta opioid receptors.
Development and government approval
Pentazocine was developed by the Sterling Drug Company,
Sterling-Winthrop Research Institute, of Rensselaer, New York.
It was approved by the Food and Drug Administration in June 1967
after being favorably reviewed following testing on 12,000
patients in the United States. The analgesic compound was first
made at Sterling in 1958. U.S. testing was conducted between
1961 - 1967. By mid 1967 Pentazocine was already being sold in
Mexico, England, and Argentina, under different trade names.
Adverse effects
Side effects are similar to those of morphine, but pentazocine
may be more likely to cause hallucinations and other
psychotomimetic effects; cardiovascular effects make it
unsuitable for use in myocardial infarction. Unlike morphine,
its respiratory depressant action is subject to a "ceiling"
effect. 38 milligrams of pentazocine has the same pain relieving
capacity as 10 milligrams of morphine.[1] It can be used as an
analgesic for dental extractions except in heroin-dependent
patients.
Tissue Damage at Injection Sites
Severe necrosis and sepsis of the skin, subcutaneous tissues,
and underlying muscle have occurred (sometime requiring
amputation of limb) at the injection sites of addicts who have
received multiple doses of pentazocine lactate (Sosegon, Fortwin).
Constant rotation of injection sites is essential. In addition,
animal studies have demonstrated that Pentazocine is tolerated
less well subcutaneously than intramuscularly.
Recreational use
In the 1970s, recreational drug users discovered that combining
pentazocine with tripelennamine (a first-generation
ethylenediamine antihistamine most commonly dispensed under the
brand names Pelamine and Pyribenzamine and used both clinically
and on the street to potentiate opioids and mitigate some of the
side effects like itching, especially of codeine and morphine)
produced a euphoric sensation much like that brought on by
heroin. Users who were already addicted to the latter often used
this combination when heroin was unavailable. Since
tripelennamine tablets are typically blue in color and
brand-name Pentazocine is known as Talwin(hence "T's"), the
pentazocine/tripelennamine combination acquired the slang name
Ts and blues. After health-care professionals and
drug-enforcement officials became aware of this scenario, the
narcotic-antagonist naloxone was added to preparations
containing pentazocine, and the reported incidence of its abuse
has declined precipitously since. It is commonly asserted that
the use of pentazocine with tripelennamine originated amongst
dentists, doctors, and nurses in the Middle Western United
States. A more recent recreational route is pentazocine combined
with methylphenidate (Ritalin) via the oral route, insufflation
or mixed intravenously.
