Logistic Regression Model: The Effect of Endogenous Magnesium Level on the Concentration of Magnesium Drugs in a Bioequivalence Study

The comparative bioavailability and bioequivalence of drugs containing magnesium citrate were studied. Logistic regression models were constructed to assess the effect of the background magnesium content on the magnesium concentration after use of the drugs. The following pharmacokinetic parameters were evaluated: the maximum concentration of magnesium in whole blood of volunteers (C-max), the time to reach the maximum concentration of magnesium in whole blood of volunteers (t(max)), and the area under the plasma-concentration(time pharmacokinetic curve (AUC((0-t))). Arecalculation taking into account the endogenous magnesium level was used for a correct calculation of the pharmacokinetic parameters. The studied drugs were found to be bioequivalent with calculated 90% confidence intervals falling within the acceptable range of 80 - 125%. Logistic regression models were constructed where the concentrations after taking the studied drugs were chosen as the dependent variables; the background magnesium contents, the influential factor. The correlation between the background value and C(max )in volunteers that took the studied and reference drugs was noticeable and positive (on the Chaddock scale) at 0.650 and 0.667, respectively, and statistically significant (p < 0.006 and p < 0.005). The resulting model took into account 42.3% and 44.4%, respectively, of the factors determining changes in the C-max level. It was concluded that construction of a logistic regression model of the relationship between the background magnesium concentration and the concentration after taking the studied drugs could be considered one possible predictor that can be used to assess the bioavailability of drugs containing magnesium salts.