Bioanalysis is the method used to determine the concentration of drugs, their metabolites and / or endogenous substances in the biological matrices such as blood plasma, serum, cerebrospinal fluid, urine and saliva. Bioanalytical methods are widely used to quantitative drugs and their metabolites in the physiological matrices and the methods could be applied to studies in areas of human clinical pharmacology and non-human pharmacology toxicology. Bioanalytical method employed for the quantitative determination of drugs and their metabolites in biological fluids plays a significant role in the evaluation and interpretation of bioequivalence, pharmacokinetics and toxic kinetic studies. It helps in carrying studies like pharmacodynamics, toxicology, pharmacokinetics, bioequivalence, therapeutic drug monitoring (TDM) and clinical studies. Initial stages these studies are done only to find out over dosage conditions and in toxicological studies. When concentration of drug in biological matrix is known, then pharmacokinetic parameters are calculated from that. Bioanalytical studies are important in drug discovery and development. So these studies are performed carefully.

The most common samples obtained for biopharmaceutical analysis are blood, urine, and feces, especially if the drug or metabolite is poorly absorbed or extensively excreted in the bile. Other media that can be utilized includes saliva, breath and tissue. The choice of sampling media is determined largely by the nature of used in the study. For example, drug levels in a clinical pharmacokinetic study demand the use of blood, urine, and saliva. A bioavailability study may require drug level data in blood and or urine whereas a drug identification or drug abuse problem may be solved with only one type of biological sample.

Detection of drug or its metabolite in biological media is usually complicated by the matrix. Because of this, various types of cleanup procedures involved i.e. solvent extraction and chromatography are employed to effectively separate drug components form endogenous biological materials. The sensitivity and selectivity of the assay method was limited by the efficiency of the cleanup methodology. If the blood is allowed to clot and is then centrifuged, about 30 to 50% of the original volume is collected as serum (upper level). Plasma generally is preferred because of its greater yield from blood. Blood, serum or plasma samples can be utilized for bioanalytical studies and may require protein denaturation steps before further processes. If plasma or serum is used for the analytical procedure, the fresh whole blood should be centrifuged immediately at 5000 rpm for approximately 5 to 10 min, and the supernatant should be transferred by means of a suitable device, such as pasture pipette, to a clean container of appropriate size of storage. Urine is the easiest one to obtain from the patient and also permits collection of large and frequently more concentrated samples. The lack of protein in a healthy individual’s urine obviates the need for denaturation steps, because urine samples are readily obtained and often provide the greatest source of metabolites, they are frequently analyzed in drug metabolism studies.

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 Amelia Johnson
 Managing Editor
Single Cell Biology.