0071643192.pdf

TOXICOLOGY

DRUGS OF ABUSE

Cocaine

Natural alkaloid derived from the coca shrub; occasionally still used medici-
nally as an ester-type topical anesthetic and local vasoconstrictor

Timing and duration of symptoms vary with preparation (see Table 6.18).

Cocaine alkaloid (“crack, free base”) is heat stable and is usually smoked.
Cocaine hydrochloride cannot be smoked, but is water soluble and may be
snorted or injected.

MECHANISM/TOXICITY

Cocaine has multiple mechanisms of action:

■ Blocks presynaptic reuptake of biogenic amine neurotransmitters (ie,
norepinepherine, serotonin, dopamine) →sympathomimetic effects.
■ Na++channel blockade →local anesthesia and IA/IC cardiac antidysryth-
mic effects.

SYMPTOMS/EXAM

■ Sympathomimetic toxidrome
■ CNS: Agitations, hallucinations
■ Tachycardia, hypertension
■ Hyperthermia with diaphoretic (not dry) skin
■ Mydriasis
■ Muscular rigidity
■ Wide complex tachycardia: From Na+channel blockade.

DIFFERENTIAL

■ May be confused with anticholinergic toxidrome (dry skin = anticholiner-
gic, wet skin = sympathomimetic)
■ Serotonin syndrome
■ Encephalomeningitis
■ Thyroid storm
■ Ethanol/sedative hypnotic withdrawal

DIAGNOSIS

■ Usually clear from history and examination
■ Urine screens for metabolite benzoylecgonine
■ Clears in 72 hours
■ ECG: Establish rhythm and screen for ischemic changes
■ CT of abdomen and pelvis: May be indicated if body packer or stuffer

TABLE 6.18. Timing of Symptoms Following Cocaine Use

ROUTE ONSET(SECONDS)PEAK(MINUTES)DURATION(MINUTES)

Inhalation 3—5 1—3 5—15

IV 10—60 3—5 20—60

Oral/intranasal 60—300 15—30 60—90

Sympathomimetic

toxidrome:

Agitation

Hyperthermia

Tachycardia

Hypertension

Mydriasis

Diaphoresis