Analysis of blood for mefenamic acid in male human after oral administration

The concentrations of mefenamic acid in the plasma of 8 healthy male volunteers were determined by UV analysis following oral administration of 500 mg tablets. The mefenamic acid molecule was found to absorb rapidly and the concentration was detectable even after 30 minutes of the drug intake by the volunteers. The plasma concentration versus time data was used for the determination of absorption and disposition kinetics parameters of the drug by one after oral administration of mefenamic acid the mean plus-minus SEM values for the absorption kinetic parameters were for time to peak concentration (T-max) 2.163 plus- minus 0.024 hours (range 1.491 to 3.59 hours), C-max 5.20 plus-minus 0.039 mg/L (range 3.541 to 6.56 mg/L), absorption half life 0.411 plus minus 0.006 hours (range 0.2507 to 0.7230 hours) and the absorption rate constant (Ka) 1.892 plus-minus 0.023 I/h (range 0.962 to 2.765 I/h). The disposition kinetics parameters revealed mean plus-minus SEM values for AUC 115.42 plus- minus 1.754 h.mg/L and ranged between 63.97 to 216.9 h.mg/L, volume o f distribution 90.02 plus-minus 0.830 L, ranged between 67.32 to 127.0 L, elimination half-life 13.96 plus minus 0.213 hours and ranged between 9.289 to 20.24 hours and the mean residence time (MRT) 20.80 plus-minus 0.307 hours and ranged between 14.09 to 37.93 hours. Remarkable variations were noted when the present findings were compared with the respective values cited in the literature. Inadequate studies on the pharmacokinetics of mefenamic acid made it difficult to conclude that the genetically influences are the only basis of these variations. The other variation factors may include differences in study design, subject selection, drug dose, dosage forms, route of administration, analytical methods and species difference. The use of various pharmacokinetics computational techniques and pharmacokinetics software may also be the variation determinant.