Pediatric emergency medicine trisk 3142 3142
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Current Evidence. PCP was developed in the 1950s as a general anesthetic. It
rapidly fell into disuse because of disturbing emergence syndromes in
postoperative patients, but subsequently gained popularity as a drug of abuse,
with popularity peaking in the 1970s. Ketamine is a PCP analog with
approximately one-tenth the potency and a shorter duration of action that is used
for several therapeutic indications, but also may be a drug of abuse. Ketamine is
discussed in detail in Chapter 129 Procedural Sedation . Another drug with
related structure, but milder effects, is dextromethorphan, which is popular with
adolescents because of its ready availability as a legal, OTC cough suppressant.
PCP is easily synthesized and is often sold on the streets misrepresented as LSD,
mescaline, or marijuana. It is well absorbed across all mucous membranes and is
most popularly used by inhalation (often mixed into cigarettes or marijuana
joints), but it can be ingested, injected, or insufflated.
Chemically, PCP is an arylcyclohexylamine. More recently, novel PCP analogs
(including methoxetamine and 3- and 4-methoxyphencyclidine) have been
identified as emerging drugs of abuse. This group of drugs has a range of CNS
actions that range from hallucinations with smaller doses, to stimulation with
moderate doses (occasionally associated with seizures), to profound CNS
depression with respiratory arrest with large doses.
There is great variability in the metabolism of PCP. In general, 0.1 mcg/mL is
considered a toxic serum level. One cigarette may contain 1 to 100 mg. A dose of
5 to 10 mg may produce stupor and coma; with doses exceeding 10 mg,
respiratory depression and convulsions occur. A fatal dose is in the range of 1
mg/kg. Because PCP has a long elimination half-life (18 hours), clinical
symptoms may last for more than 12 hours; also, patients may have recurrent
symptoms when the drug undergoes enterohepatic recirculation.
