Guidelines for Drugs of Abuse Testing vers 2012 - Brenneisen

Figure 21: Metabolism of Methaqualone
N
N
O
H C 3
N
N
O
H C 3
2-Hydroxy-methaqualone Methaqualone
6-Hydroxy-methaqualone
N
O
N
OH
CH 3
OH
2`-Hydroxy-methaqualone
16.12 Methylphenidate
Scene names: Ritas, Pep.
Glucuronides
N
N
O
H C 3
CH 3
CH 3
4`-Hydroxy-methaqualone
Glucuronides
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OH
HO
N CH 3
N
O
H C 3
N
O
H 3
N
C
CH 3
OH
3`-Hydroxy-methaqualone
Metabolism: Methylphenidate (Ritalin) is rapidly metabolized to the inactive ritalinic acid
(Fig. 22). Other metabolites are formed by hydroxylation, methylation,
oxydation and conjugation. Ethylphenidate can be detected after coconsumption
of ethanol. 80% of a methylphenidate dose is excreted within 24
h, 60-81% as ritalinic acid and 5-12% as 6-oxo-ritalinic acid [Baselt 2011].
Less than 1% is excreted unchanged; however, the percentage can be higher
at acidic urine pH.
T½: 1.4-4.2 h.
Detectability: At least 24 h (20 mg oral therapeutic dose [Solans 1994]).
Note: Methylphenidate cannot be detected by amphetamine and methylamphetamine
immunoassays [Taylor 2004]. Therefore, for the detection of use
a specific ELISA, GC/MS or HPLC-MS/MS is required [Solans 1994, Eichhorst
2004, Paterson 2012].