Compartment modeling ppt

Types,Qualities,Applications

1. COMPARTMENT MODELING BINU ANAND FIRST YEAR M.PHARM NAZARETH COLLEGE OF PHARMACY 1

2. 2 Drug movement within the body is a complex process. The major objective is therefore to develop a generalized and simple approach to describe, analyse and interpret the data obtained during in vivo drug disposition studies PHARMACOKINETIC MODELS

3. QUALITIES OF A PHARMACOKINETIC MODEL Validity : It should have practical applicability and should be valuable in describing events chosen accurately with high precision. Prediction ability : These models predict the qualitative and quantitative changes in the parameters that are rate constants and half lives of the drugs. Consistency of results : Reproducibility is an important quality of a mathematical model. 3

4. APPLICATIONS OF PHARMACOKINETIC MODELS Characterizing the behavior of drugs in patients. Calculating the optimum dosage regimens for individual patients. Evaluating the bioequivalence between different formulations of same drug. Determining the influence of altered physiology or disease state on drug ADME. Explaining the drug intractions . 4

5. The two major approaches in the quantitative study of various kinetic processes of drug disposition in body are 1. Model approach 2. Model independent approach

6. Types of pharmacokinetic models Compartment models ; are also called empirical models. Physiological models ; are realistic models. Distributed parameter models ; are also realistic models. 6

7. COMPARTMENT MODELS A compartment is a group of tissues with similar blood flow and drug affinity. A compartment is physiologic or anatomic region. Compartment is the traditional and most widely used approach to pharmacokinetic characterization of drug. These models simply interpolate the experimental data and allow on empirical formula to estimate drug concentration with time. 7

8. ASSUMPTIONS OF COMPARTMENTAL MODELS The body is represented as a series of compartment arranged in series or parallel to each other. The rate of drug movement between compartment is described by first order kinetics. Rate constants are used to represent rate of entry into and exit from compartment. A statistical analysis of plasma concentration time data is another method used to find out no.of compartments. 8

9. APPLICATIONS OF COMPARTMENT MODELING It is a simple and flexible approach and is widely used It gives a visual representation of various rate process involved in drug disposition. It is useful in predicting drug concentration time profile in both normal and pathological conditions . It is useful in relating plasma drug levels in therapeutic and toxic effects in body. Its simplicity allows for easy tabulation of volume of distribution, half life etc . 9

10. TYPES OF COMPARTMENT MODELS Based on whether the compartment is arranged in parallel or series. The compartmental models are classified into four types, they are; Mammillary model Catenary model Open model Closed model 10

11. 11 MAMMILLARY MODEL- The mammilary model is the most common compartment model used in pharmacokinetics. It consists of one or more peripheral compartments connected to the central compartment in a manner similar to connection of satellites to a planet . They are joined parallel to the central compartment. The central compartment comprises of plasma and highly perfused tissues such as lungs, liver, kidney etc. which rapidly equilibrate with drugs.

12. 12 The peripheral compartments or tissue compartments are those with low vascularity and poor perfusion. Distribution of drugs to those compartments is through blood. Movement of drug can be defined by first-order kinetics.

13. 13 CATENARY MODEL The compartments are joined to one another in a series like compartments of a train. It is rarely used because it is not observed that anatomicaly or physiologically various organs are directly linked to the blood compartment .

14. CONCLUSION 14 In pharmacokinetic studies, compartment models have been termed as “DETERMINISTIC”. The simplicity and flexibility of the compartment model is the principle reason for its wide application. Because of its simplicity they often serves as a “FIRST MODEL ” that requires refinement. In spite of such an advantage it generally regarded as somewhat empirical and lacking physiologic relevance .

15. REFERENCE Biopharmaceutics and pharmacokinetics, D.M. Brahmankar and Sunil.B.Jaiswal , 1 st edition. Applied biopharmaceutics andpharmacokinetics , Leon Shargel and Andrew.Y.U , 4 TH edition. Biopharmaceutics and pharmacokinetics, Venkateswarulu 15

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