0071643192.pdf

PSYCHOBEHAVIORAL DISORDERS

794

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.