Effect Of Some Drugs On Common Clinical Biochemistry Tests

Many therapeutic drugs could influence the results of laboratory tests. These effects mainly come from in vitro analytical interference (in vitro effect) and biological effect (in vivo effect). A drug and / or its metabolites might interfere single or multi-processes in quantitative analysis for another chemical. Kroll defined an interference as: an effect of a chemical existed in the sample could change the correct value of a result. In particular for an analyte, it appeared as the influence on the concentration or activity. Clinically, neither has doctor nor laboratory scientist paid enough attention to the problem of drugs affecting the test results. In explaining the test results, particularly for some abnormal results, this influence factor was ignored. So our research is to dig into the problem and raise doctor and laboratory scientist attention on it. Our works mainly include the follow two parts.1. The in vitro interference research of adrenaline and dopamine on some common clinical biochemical test items.It was revealed that adrenaline had a strong positive interference on FMN assay, a positive interference on LD assay, but a negative interference on Cr, UA, TG, TCH, HDL-C and DBIL tests. The relative formula between the interference rate of adrenaline on FMN, Cr, UA, TG, TCH, LD, DBIL, HDL-C tests and the serum concentration of adrenaline was y = 1223.3x + 41.296, y = -15.918 ln(x) - 101.71, y = 140.21x2 - 205.22x -0.1519, y = -137.17x - 3.6884, y = -12.746x2 - 31.864x - 0.043, y = 16.84x2 + 2.2482x + 2.0596, y = -51.369x2 - 49.965x - 0.3533, y = -84.81x + 3.0979, respectively.Dopamine showed a strong positive interference on FMN assay, a positive interference on LD assay, but a negative interference on Cr, UA, TG, TCH, HDL-C, DBIL assays. The relative formula between the interference rate of dopamine on FMN, Cr, UA, TG, TCH, HDL-C, LD, DBIL tests and the serum concentration of dopamine was y = 546.37x 0.6017, y = -11.541 ln(x) - 86.828, y = 80.484x2 - 145.78x -2.2874, y = 154.87x2 - 243.22x + 4.1927, y = -36.136x + 1.8976, y = 52.253x2 - 107.05x - 0.2915, y = 1.9947 ln(x) + 5.7905 and y = -103.98x - 1.9346, respectively. Both adrenaline and dopamine are chemicals with reducibility, and could interfere above tests based on oxidation-reduction reaction. 2. The preliminary research of rifampicin interference in vitro and in vivo on common clinical biochemistry analysis and the interfering mechanisms.Rifampicin is a usual clinical anti-tuberculosis drug. It had positive analytical interferences on FMN, DBIL, TBIL assays and negative on Cr, UA assays in vitro. There is a linear correlation between the interference intensity and the concentration of rifampicin added in serum. The relative formula between the interference rate of rifampicin on FMN, Cr, UA, DBIL, TBIL and the concentration of rifampicin was y = 0.6177x - 1.6134, y = -1.4513x + 0.4677, y = -0.428x + 0.3782, y = 3.6029x -0.3292 and y = 1.7404x + 0.6418, respectively. Rifampicin had also biological effect (in vivo effect) on clinical biochemistry tests. Research on the effect of rifampicin orally administrated(q.d×3) in 16 volunteers on routine biochemistry tests indicated that, during the oral dosage, at the trough concentration in blood, rifampicin had an effect on FMN, DBIL assays, at the peak concentration, it could influence FMN, DBIL, TBIL, Cr and Ca assays. So rifampicin could increase the levels of FMN, DBIL, TBIL in serum and decrease the Cr in vivo.Preliminary investigation on the mechanism of rifampicin interference indicated that rifampicin had an absorption at the bilirubin testing wavelength (450 nm), which increased the absorbance at start point, otherwise in the process of reaction, rifampicin with reducibility could react with vanadate, and it caused a decrease of the absorbanceproduced by rifampicin at 450 nm. The bilirubin assay itself is a negative phase reaction, and rifampicin resulted in a positive interference to bilirubin assay. The probable interference me...