This paper reports the integration of pharmacokinetic models of mammilla, chain, physiology, intravenous injection, intravenous infusion and extravascular administration into a single mathematical model. We have given a general mathematical treatment of this model and a common expression of drug concentration-time relationship. The model fits in any single or multiple dosing linear pharmacokinetic process involving in physiology, nonphysiology, and any compartmental administration and excretion.