False-Positive LSD Drug Screening Induced by a Mucolytic Medication

¹ Institut für Klinische Chemie und Laboratoriumsmedizin, ,
² Institut für Gerichtsmedizin,
³ Klinik für Anästhesiologie, Klinikum der Johannes Gutenberg Universität, 55101 Mainz, Germany
^a Address correspondence to this author at: Institut für Klinische Chemie und Laboratoriumsmedizin, Langenbeckerstr. 1, 55101 Mainz, Germany; fax 0049-6131-17-6627.

To the Editor:

Since the early 1990s, the ingestion of lysergic acid diethylamide (LSD) as an inexpensive alternative to amphetamine derivatives has once again become widespread (1)(2). Consequently, screening of LSD has gained importance in clinical routine. The drug screening of a patient with a severe craniocerebral trauma showed a positive LSD screening by the homogeneous immunoassay CEDIA^® DAU LSD (Boehringer Mannheim). In spite of the 3-h half-life of LSD in plasma (3), the drug screening remained positive for several days. These samples were analyzed by means of fluorescence detection (FLD 1046A, Hewlett–Packard) after solid-phase extraction with HPLC technique (HP 1050, Hewlett–Packard) (4). The positive immunoassay results could not be confirmed. In the following study, we carried out a general screening of medications in urine using the HPLC technique (Remedi HS, Bio-Rad Laboratories). Ambroxol as well as Pirenzepin were detectable.

Because of other unexpected positive LSD results of patients of the same intensive care unit, we carried out a general LSD screening of 10 patients of this ward. All of these 10 samples tested positive by the CEDIA DAU LSD assay but could not be confirmed by the HPLC technique. All those patients had an Ambroxol medication and tested positive for Ambroxol in urine by the HPLC technique. Finally, we carried out a self-test. No LSD could be detected in a fasting urine sample of a volunteer who afterward took 5 mL of Mucosolvan^® juice (Dr. Karl Thomae) equivalent to 15 mg of Ambroxol-HCL. Another urine sample was analyzed as being positive 90 min after ingestion of Ambroxol. The addition of 50 µL of Mucosolvan juice to the LSD-negative fasting urine also led to a positive result. Mucosolvan juice diluted with two parts of distilled water resulted in a positive LSD test as well.

Ambroxol is a widespread and frequently used concomitant medication for infections of the upper respiratory tract. Predominantly, Ambroxol is used in an outpatient setting. In Germany, no less than ~40 pharmaceutical companies distribute Ambroxol. Ambroxol is widespread in most parts of Europe as well as in Japan, but it is not admitted, e.g., in the United States of America and the United Kingdom.

Therefore, LSD drug screening with the homogeneous immunoassay CEDIA DAU LSD yields a high incidence of false-positive results, especially in winter. In conclusion, Ambroxol administration should be excluded when a LSD screening in urine is performed by CEDIA DAU LSD. Moreover, positive results should be verified by a more specific method, such as GC/MS or HPLC techniques.

References

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