0071643192.pdf

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PSYCHOBEHAVIORAL DISORDERS


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Since the development of newer antidepressants, MAOIs are reserved for atypi-
cal or refractory depression. There are five MAOIs approved in the United
States: selegiline (antiparkinsonian), phenelzine and trancyclopromine (anti-
depressants), fluazolidane (antibiotic), and procarbazine (antineoplastic).

Serotonin Syndrome

Can be caused by any drug (or combination of drugs) that increase central
serotonin transmission by stimulation of the 5-HT1Aand 5-HT 2 postsynaptic
receptors; most cases occur at therapeutic levels of drugs (see Table 16.10)

SYMPTOMS/EXAM
Typically rapid onset of muscle rigidity (lower extremities >upper extremities),
hyperthermia, diaphoresis, confusion/disorientation, agitation, myoclonus,
tremor, ataxia, hypertension, tachycardia, tachypnea, anxiety, coma

DIFFERENTIAL
Same as for MAOI toxicity

DIAGNOSIS
Diagnosis is clinical. Serotonin syndrome is easily missed or misdiagnosed.
Rule out other causes.

TREATMENT
■ Stop offending drug.
■ Supportive care/ABCs
■ Activated charcoal/gastric lavage if overdose
■ Up to 25% will need intubation and ventilatory support.
■ Benzodiazepines for muscle rigidity
■ IV fluids for rhabdomyolysis
■ Cyproheptadine (an antiserotonergic agent) for severe cases

Neuroleptic Malignant Syndrome (NMS)

Onset occurs about 2 weeks after initiation of typical and atypical anti-
psychotic drugs, although this reaction has also been seen in patients on a stable
drug regimen.

RISK FACTORS
Rapid drug loading, high dosage, increase in dosage, use of high potency
antipsychotic (droperidol, haloperidol, loxapine), parenteral form, dehydra-
tion, previous episodes of NMS

TABLE 16.9. MAOI Toxicity (Continued)

TOXICITY ONSET SYMPTOMS/EXAM DIFFERENTIAL TREATMENT

(need at least a 2-wk “washout”
period after stopping MAOIs).
Indirect acting symphatomimetics
(ephedrine, guanethedine,
pseudoephedrine) can also cause
a tyramine-like reaction.
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