As the usage of the illegal drugs is increasing day-by-day, many researchers and physicians are finding different drug testing methods in order to detect and stop the usage of the drugs. Some of the different types of drug testing methods which are under usage are blood test, Hair test, Sweat test, Urine test and Saliva drug test.
Let us discuss how saliva can detect the presence of the drug in it. In general, the human saliva is also called as the Oral fluid. This saliva comes from the three major and several minor salivary glands. But, while strictly speaking the saliva and oral fluids are different. Oral fluid is the mixed saliva which comes from different glands and it also constitutes the small amount of quantities which are present in the mouth. But where as saliva is the fluid which comes from a specific salivary gland, which is free from other materials. But, we generally consider both as the same.
The different materials which are present in the oral fluid are the plasma electrolytes and other plasma constituents. The plasma electrolytes are potassium, chloride, sodium and bicarbonate. The different other plasma constituents are enzymes, immunoglobulins and DNA. In general an adult produces 1000ml of saliva. The rate of flow of the saliva while sleeping is 0.05ml/min where as the rate of flow while chewing gum it is 1ml/min to 3ml/min and of saliva is 0.5 ml/min.
By the researches made by the different scientists, physicians and doctors for detecting the presence of drug in saliva, they found that many drugs like ethanol, amphetamine, barbiturates, cocaine,heroin and cannabinoids etc., can be detected using the saliva. Some of the drugs will have excess concentrations in saliva than blood. Suppose for example, the oral fluid amphetamine concentrations are more in saliva than blood concentrations, after 48 hours of usage. Even the same will be the case with PCP.
Several factors which are affecting the saliva are the lipophilicity(ability of a compound to dissolve in fats) of the drug, degree of the protein binding , physical size etc.,
Apart from the parent drugs even the metabolites which are present in the drug will also affect the saliva because of lipid solubility nature. Then they pass through the capillary tube and acinar membranes of the oral fluid. Thus, saliva absorbs the drug in some cases and absorbs the metabolites in some cases.
