LabMed

Overdose of Cocaine

At a Glance

Patients who overdose on cocaine can present with dilated pupils, tachycardia, hyperthermia, and hypertension. Cocaine induced cardiac arrhythmias and seizures can be seen in severe cases. Symptoms are exacerbated in patients who co-ingest alcohol with cocaine.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

A urine drug screen for the cocaine metabolite, benzoylecgonine, should be performed in any patient with suspected cocaine overdose. Urine drug screens provide rapid turnaround and are available in most laboratories. A positive result is consistent with recent ingestion of cocaine with some rare exceptions subsequently noted.

Most immunoassays target the cocaine metabolite, benzoylecgonine, which has a longer half-life and has low cross-reactivity for the parent compound. This allows cocaine ingestion to be detected for a longer period.

A blood alcohol test should also be ordered, as cocaine and alcohol are frequently co-ingested.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

Immunoassays for detecting benzoylecgonine in urine have good specificity, and 95% positive screening tests can be confirmed using a confirmatory technique, such as gas chromatography-mass spectrometry (GC/MS). However, clinical false-positive results may occur if the individual has undergone ear, nose, and throat (ENT) or ophthalmological surgery 1-2 days before testing when cocaine was used as an anesthetic. TAC (tetracaine, adrenaline, and cocaine), which is infrequently used in minor surgical procedures and on patients during skin suturing in the emergency department, may also cause positive result 1-2 days following procedure.

Drinking coca tea is common in people in South America, and this tea, after removing cocaine, can be imported to the United States. However, there are isolated reports of the presence of cocaine in coca tea (known as Mate de Coca or health Inca tea) sold in United States, and drinking such tea causes a patient to be positive on urine drug screen for cocaine metabolites.

There are no other over-the-counter (OTC) drugs or herbal supplements that interfere with testing for cocaine metabolite in urine.

Urine drug screens are qualitative, based on a cutoff value, typically 150 or 300 ng/mL for cocaine metabolite. Negative results do not exclude recent ingestion of cocaine. In addition, urine drug screens can be positive for 2-3 days after cocaine ingestion, and positive results may not indicate acute ingestion.

What Lab Results Are Absolutely Confirmatory?

Confirmatory techniques, such as GC/MS, should be utilized to confirm the presence of benzoylecgonine in urine and the recent ingestion of cocaine. Confirmation of cocaethylene, an active metabolite formed due to interaction of cocaine and ethyl alcohol, confirms abuse of both alcohol and cocaine.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Usually, benzoylecgonine, the cocaine metabolite, is present in the urine for 2-3 days after use. A follow-up urine drug screen several days after initial use can be used to see if the patient is abusing cocaine again.

Hair testing for cocaine can be used to evaluate if the person is cocaine free for 3-6 months.

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