Poisoning and Overdose
Answers
217.The answer is c. (Rosen, pp 2187-2190.) The patient drank
insecticide,which is primarily composed of organophosphate compounds
(eg, Malathion). These compounds inhibit acetylcholinesterase,the enzyme
responsible for the breakdown of acetylcholine. The patient is having a “cholin-
ergic crisis.” Overstimulation of muscarinic and nicotinic receptors leads to his
symptoms, commonly remembered by the mnemonics SLUDGE(salivation,
lacrimation,urination,defecation, gastrointestinal [GI] upset, emesis) or
DUMBBELS(defecation,urination,miosis,bronchospasm, bronchorrhea,
emesis,lacrimation,salivation). The treatment for organophosphate toxicity is
atropineandpralidoxime (2-PAM).Atropine is an anticholinergic, therefore
it competitively inhibits the excess acetylcholine. Pralidoxime works to regen-
erate acetylcholinesterase, therefore also limiting the amount of acetylcholine
available in neuronal synapses.
(a)Naloxone is used to reverse opiate (eg, heroin) overdoses. (b)NAC is
used in acetaminophen overdoses. (d)Flumazenil reverses benzodiazepines
(eg, diazepam). (e)Physostigmine is a reversible cholinesterase inhibitor. Its
effect is to increase acetylcholine in the pre- and postsynaptic junctions. This
will worsen the patient’s condition by exacerbating the cholinergic syndrome.
218.The answer is a.(Rosen, pp 2214-2215.)GHBis a natural neurotrans-
mitter that induces sleep. GHB has been sold as a muscle builder (release of
growth hormone), a diet aid, and a sleep aid. Patients with GHB overdose
generally have a decreased level of consciousness. In contrast to other seda-
tive/hypnotic overdoses, the level of consciousness tends to fluctuate quickly
between agitation and depression. A distinctive feature of GHB intoxication
isrespiratory depression with apnea, interrupted by periods of agitation
and combativeness,especially following attempts at intubation.
(b)Diazepam, a benzodiazepine, also depresses mental and respira-
tory function but typically patients remain sedate. (c)Cocaine is a stimu-
lant that increases HR, BP, and usually causes the pupils to dilate. (d)PCP
intoxication may cause bizarre behavior, lethargy, agitation, confusion, or
violence. Unlike GHB, this drug acts more as a stimulant than a depressant.
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