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Improvements in the quantitative analysis of drugs in biological tissues, such as plasma, and the increasing sophistication of computers and software along with access to the Internet have greatly accelerated the development of pharmacokinetics. Computer software programs now allow for the rapid solution of complicated pharmacokinetic equations and rapid modeling of pharmacokinetic processes. Computers simplify tedious calculations and allow more time for the development of new approaches to data analysis and pharmacokinetic modeling. In addition, computer software is used for the development of experimental study designs, statistical data treatment, data manipulation, graphical representation of data, pharmacokinetic model simulation, and projection or prediction of drug action. Furthermore, computers are used frequently for written reports, documentation, and archiving.
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A variety of computers are now available. Personal computers (PCs) may be used independently or linked together into local networks (LANs) that share many application software packages. Each type of computer has an operating system (OS), which is a collection of programs that allocates resources and enables algorithms (well-defined rules or processes for solving a problem in a finite number of steps) to be processed. Windows, Mac OS, and more recently, LINUX, are examples of commonly used operating systems. Most PC users have access to the Internet via a modem or through wireless that allows PCs to access remote information at various sites on the Internet that provide a variety of free or commercial pharmacokinetic (PK) programs.
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A computer package or software is a program of instructions written in a computer language. This software is needed to run the computer. The computer operating system must support the computer language of the software. In the past, computer users needed to be competent in computer programming and usually had knowledge of at least one computer language such as Pascal, C, or Basic. As a result of the availability of various commercial and noncommercial pharmacokinetic applications and spreadsheets, such as Excel, very little computer programming is required for many applications in pharmacokinetics. Some examples are given below.
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Pharmacokinetic software consists of computer programs designed for computation and easy solution of pharmacokinetic problems. Not all computer programs satisfy the user's full requirements, but many provide the following.
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Fitting drug concentration–time data to a series of pharmacokinetic models, and choosing the one that best describes the data statistically: Typically, a least-squares program is employed, in which the sum of squared differences between observed data points and theoretic prediction is minimized. Usually, a mathematical procedure is used iteratively (repetitively) to achieve a minimum in the sum of squares (convergence). Some data may allow easier convergence with one procedure rather than another. The mathematical method employed should be reviewed before use.
Fitting data into a pharmacokinetic or pharmacodynamic model defined by the user: This method is by far the most useful, because any list of prepared models is often limited. The flexibility of user-defined models allows continuous refinement of the model as new experimental ...