One compartment-open-model

one compartment model

1. Acquaintance Name of the group : Conviction Group No : Male - 01 Members of the group : Rana Ahmed – ( PHA -14001) Mahfujul Hasan – ( PHA -14002) Faisal Amin – ( PHA -14014) Md Shydhur Rahman – ( PHA -14015) Nasim Ahmed – ( PHA -14013) 1

2. One Compartment Model Drugs

3. One Compartment Open Model The body is considered as a single, kinetically homogeneous unit. This model applies only to those drugs that distributes rapidly throughout the body. Drugs move dynamically in an out of this compartment. Elimination is first order ( monoexponential ) process with first order rate constant. Rate of input (absorption) > rate of output (elimination). 3

4. Types Depending on rate of input, several one compartment open models are : One compartment open model, i.v. bolus administration. One compartment open model , continuous i.v. infusion . One compartment open model, e.v. administration, zero order absorption. One compartment open model, e.v. administration, first order absorption . 4

5. Intravenous Bolus Administration 5

6. Intravenous Infusion   Rapid i.v. injection is unsuitable when the drug has potential to precipitate toxicity or when maintenance of a stable concentration or amount of drug in the body is desired. In such a situation, the drug (for example, several antibiotics, theophylline, procainamide, etc.) is administered at a constant rate (zero-order) by i.v. infusion. 6

7. Intravenous Infusion 7

8. Extravascular Administration When a drug is administered by extra vascular route (e.g. oral, im ., rectal, etc.), absorption is a prerequisite for its therapeutic activity. The rate of absorption may be described mathematically as a zero-order or first-order process. A large number of plasma concentration- time profiles can be described by a one- compartment model with first-order absorption and elimination. However, under certain conditions, the absorption of some drugs may be better described by assuming zero-order (constant rate) kinetics. 8

9. Extravascular Administration Distinction between zero-order and first-order absorption processes. Figure a is regular plot, and Figure b a semi log plot of amount of drug remaining to be absorbed (ARA) versus time t.   Time 9

10. Extravascular Administration 10 Figure : The absorption and elimination phase of the plasma concentration – time profile obtained after extravascular administration of a single dose of a drug. dXa

11. Thank You 11