Interpretation of analytical results ,Doping

Dr. Juan Carlos López Corbalán, R.Ph (1981), Ph.D.(1990), MD (1999).

 Every patient is a world apart. One of the most difficult problems which is the clinical analyst is to interpret the results. Consider the following factors that can influence the results are: 
 A) Defects in the art. Are sufficiently explained in the previous topic. Unfortunately there is no universal technique. Depending on the substance that is intended to detect doping we have to choose carefully the technique employed. We have seen that the gas chromatography is very accurate but not useful for thermolabile substances and molecular weight greater than 1000.
B) Decomposition of the substance.
b.1) by oxidation. As happens to catecholamines. The containers are filled and tightly sealed to exclude atmospheric oxygen. Antioxidants can be added as metabisulfite or ascorbic acid, but these agents can reduce oxidized metabolites of some substances (and certainly gives a lot to suspect that the sample handling: no one would accept the results of a sample to which has added "something", although an antioxidant. The phenolic compounds (eg morphine) are readily oxidized to 4 degrees Celsius, and also sulfur-containing oxidized in alkaline media. 
 b.2) Hydrolysis: Local anesthetics or diacetyl morphine can be easily hydrolyzed during storage at room temperature or even at low temperatures. b.3) Light: The phenothiazines are photolabile. The general rule is that the samples must be isolated from the light, which is not really practical purposes. b.4) Temperature. Low temperatures favor the conservation of the sample. In the case of EPO, if the sample is kept at zero degrees, becomes corrupt and the results are NULL
  b.5) ​​Biological decomposition. This factor is very important in forensic expert evidence is often studied with long wait at the request of either party and come from bodies, not being the case that concerns us. It has traditionally been considered a glucose blood sample is converted to alcohol. This is actually for all practical purposes it is highly unlikely, since in reality the content of glucose in a blood sample without preservatives actually disappears in a few hours.
c) Pollution from the containers. Fundamentally type plasticizers are phthalates from plastic containers or containers plugs containing the samples. They can also be caused by impurities in the solvents used in extraction. They are also frequent phosphate esters from the tops of the containers. So it is desirable to know the possible interference of the material used in packaging and check on each batch  
d) Other problems. Individual differences in the pharmacokinetics of the product. ("Each person is a world"). They must study and compare the values ​​and the profiles of each person when there is reasonable doubt about a positive outcome. For example: Smoking is a popular route of administration for those who abuse controlled substances such as cocaine and heroin. Pyrolysis of these drugs leads to inhalation of not only drugs but also the products of combustion, due to its characteristics of rot. In the pyrolysis of smoked cocaine ("crack") is the methyl ester anhidroecgonina. Therefore, the identification of relatively high concentrations of this compound with cocaine in urine or other biological fluids or tissues indicates that the route of administration of cocaine in this case is the smoke. The techniques of RIA (radioimmunoassay assay) and EMIT are those used for cocaine, but may cross-react with structurally similar compounds registering false positives. The positive test for amphetamines and opiates is positive for the seeds of poppy seeds (which are not prohibited). Ma Huang extract (legal) tests positive for Ephedrine.
 There are medications that can cause problems. Methamphetamine can be produced as a racemic mixture of dextro and levo-optical isomers.

 We found that:
 Stereoisomers: they are mirror images. It is as if the two compounds are reflected in a mirror. They have what is called a single chiral center. Diastereomers, have more than one chiral center. This allows us to make a series of points: a) The d-methamphetamine is clearly forbidden, as a potent stimulant of the central nervous system, whereas l-methamphetamine (also called desoxiefedrina l) is an alpha-adrenergic stimulant that is in the NASAL SPRAY VICKS compound called, cross-reactivity Enzimuinmuno the test screening (EMIT). b) l-pseudoephedrine is a compound called "precursor drugs streets." Many drugs are obtained for clearing the nasal passages that are sold without prescription for treatment of colds. Using the "Nazi" (also called Leuckart Synthesis) with hydrogen iodide (HI), we obtain the d-methamphetamine.