A nomogram for prediction of absorption rate coefficient

Background Previous studies have suggested that nomogram can simplize complicated calculations of several varibles. A simple nomogram was constructed to estimate absorption rate coefficient (k a) by using the peak time (t peak ) and the elimination rate coefficient (k e) of drugs administered orally Methods The nomogram was based on the plasma concentration-time (C-T) curve equation and the function relation between t peak , k a and k e A mathematical analysis was presented for the construction of single chart nomogram To check the degree of accuracy of the developed nomogram, we used it to analyze retrospective profiles of 46 drugs and compared the k a values obtained graphically and those calculated by numerically solving the descriptive equation In addition, we measured the carbocisteine concentration of 18 healthy volunteers by HPLC with fluorescence detection To analyze performance error, the measured carbocisteine concentrations were compared with predicted concentrations by the k a obtained from the nomograms along with the other pharmacokinetic parameters Results The estimated of k a values from nomograms were in very close proximity with the numerical values The performance error was as follows: median performance error (MDPE) and median absolute performance error (MDAPE) were 1 32% and 18 15%, respectively Conclusions The developed nomogram is accurate and reliable The size of performance error meets the demand of clinical pharmacokinetics Therefore, the nomograms can offer another convenient and easy method for rational individualized dosage regimens