Expected Drug Levels in Hair of Proven Drug Users

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The trapping of drugs in hair has been shown to be dose dependent (55,56). Many variables, however, impact the use of hair results to indicate amount of drug use. These include biochemical individuality, effective washing, and cosmetic treatments. Severe cosmetic treatments can reduce the amount of some drugs in hair, whereas normal shampooing serves to decontaminate, although only partially in many cases.

Analyses of the hair from drug users who have tested positive in urinaly-sis provide a reference range of drug concentrations to be expected of such hair. Large studies of this nature have been performed by this laboratory for cocaine (19), opiates (21), methamphetamine (20), and marijuana (21). PCP was also studied, but with few users identified (21). These studies also included negative control groups wherein hair samples from 60-80 nondrug-using subjects were collected and tested negative by both screening and confirmation analyses. In these studies, the cut-off levels (concentrations of the parent drugs in hair above which samples are considered positive) were 5 ng/10 mg hair for cocaine and methamphetamine, 2 ng/10 mg hair for morphine, 3 ng/10 mg hair for PCP, and 1 pg/10 mg hair for carboxy-THC, the metabolite found in hair as a result of marijuana use. All results of the studies were obtained by LC-MS-MS, GC-MS, or GC-MS-MS after application of our laboratory's wash procedures (31).

8.1.1. Cocaine and Metabolites in Hair of Cocaine Users

In the case of cocaine, 70 urine cocaine-positive subjects had hair drug levels ranging from 6.5 to 2270 ng/10 mg hair, with 6 samples in the range of 5-20 ng/10 mg hair, 25 in the range of 21-200 ng/10 mg hair, and 39 greater than 200 ng/10 mg hair (19). Three metabolites were analyzed in these samples: BE, CE, and norcocaine. CE is a definitive metabolite in that it can form only by the simultaneous ingestion of cocaine and ethanol. For this reason, CE is not present in all cocaine-user hair samples. BE, listed here as a percentage of cocaine, was found to range from 1.5 to 51%, with 3 samples less than 5%,

Fig. 3. (facingpage) Liquid chromatography-tandem mass spectrometry positive ion chemical ionization calibrations for the determination of cocaethylene and norcocaine at the cut-off of 0.5 ng/10 mg hair by isotope dilution.


Fig. 4. Gas chromatography-tandem mass spectrometry negative ion chemical ionization calibration for the determination of carboxy-tetrahydrocannabinol in hair using the dual derivative and isotope dilution methodology. Precursor to product ion transitions, retention time, and both quantitations are shown.

Fig. 4. Gas chromatography-tandem mass spectrometry negative ion chemical ionization calibration for the determination of carboxy-tetrahydrocannabinol in hair using the dual derivative and isotope dilution methodology. Precursor to product ion transitions, retention time, and both quantitations are shown.

22 samples between 5 and 10%, and 45 samples greater than 10%. Positive identification of BE in a test specimen in workplace testing is required to qualify the sample as cocaine positive. However, there is still uncertainty as to what levels of this metabolite are expected to be present in all cocaine users. Of those samples containing less than 5% BE relative to cocaine, one subject with 831 ng cocaine/10 mg hair and two positive urine tests showed a 1.5% BE content. Another subject with 80 ng cocaine/10 mg hair, a positive urine test, and 4.5 ng

CE/10 mg hair gave a 4.25% BE content. A third subject with 6.6 ng cocaine/ 10 mg hair and one positive urine test had a 4.5% BE content. The 25 subjects with BE between 5 and 10% were all proven cocaine users, some with two positive urine tests and many with CE as well. These results indicate that cocaine users at all levels of use can vary in the amounts of BE detected in the hair, and that a requirement for a minimum ratio of BE to cocaine can lead to an erroneous false-negative result on a confirmed, admitted cocaine user. In light of the above, the requirement that a positive sample contain BE in the amount of 5% of the cocaine value is a conservative policy in interpreting results.

Concentrations of CE greater than 0.5 ng/10 mg hair were present in about half of the samples with cocaine >5 ng/10 mg hair. The CE levels ranged from 0 to 127.9 ng, with 17 samples (24%) containing none, 17 (24%) containing less than 0.5 ng, 20 samples (28.6%) from 0.5 to 10 ng, and 16 samples (22.9%) greater than 10 ng, all in 10 mg of hair.

Norcocaine ranged from 0 to 55.6 ng/10 mg hair. Of 70 samples, 6 (8.6%) were less than 0.5 ng, 34 (49.3%) ranged from 0.5 to 10 ng, and 30 (43.5%) were greater than 10 ng, again all in 10 mg of hair.

8.1.2. Methamphetamine in Hair of Drug Users

Forty subjects provided hair samples in the study of methamphetamine users (20). Hair samples had methamphetamine levels from 7.1 to 344 ng/ 10 mg hair, with 6 samples (15.4%) less than 20 ng/10 mg hair, 17 (43.6%) between 20 and 100 ng/10 mg hair, and 16 (41%) greater than 100 ng/10 mg hair. The levels of the metabolite amphetamine in these hair samples ranged from 0.1 to 44.6 ng/10 mg hair, with very low levels (<0.5 ng) in 4 samples with methamphetamine values from 7.1 to 78.9 ng/10 mg of hair.

8.1.3. Opiates in Hair of Heroin Users

Hair analysis offers distinct advantages relative to urinalysis in detecting heroin use, as it is not subject to positive results due to poppy-seed ingestion and it reliably shows the presence of the metabolite 6-monoacetylmorphine (6-MAM). In hair analysis for opiates, 6-MAM in a washed hair sample is a reliable indicator of heroin use. In a study of 68 subjects with urine morphine results above 2000 ng/mL by GC-MS, 37 were positive and 31 were negative for 6-MAM, whereas all the hair samples of these subjects contained 6-MAM, with the levels ranging from 0.8 to 527.2 ng/10 mg hair (21). The morphine levels in these samples ranged from 3.1 to 558.8 ng/10 mg hair.

8.1.4. Carboxy-THC and PCP in Hair

PCP levels in hair range from the cut-off of 3 to as high as 150 ng/10 mg hair (21). In head hair of 65 subjects shown positive in urine tests for marijuana use, carboxy-THC, the metabolite of cannabis, ranged from 0.3 to 76.3 pg/ 10 mg hair (21).

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