Presentation on theme: "1 CHAPTER 4 INTRAVENOUS INFUSION. 2 ONE COMPARTMENT MODEL WITH IV INFUSION This can be obtained by high degree of precision by infusing drugs i.v. via."— Presentation transcript:
1 CHAPTER 4 INTRAVENOUS INFUSION
2 ONE COMPARTMENT MODEL WITH IV INFUSION This can be obtained by high degree of precision by infusing drugs i.v. via a drip or pump in hospitals
3 PK of Drug Given by IV Infusion Zero-order Input (infusion rate, R) First-order Output (elimination)
5 Stopping the Infusion Stopping the infusion before reaching steady state Infusion stops
6 Stopping the Infusion Equations
7 Steady State Concentration IV Infusion until reaching C ss
8 Steady State Concentration (C ss ) Theoretical SS is only reached after an infinite infusion time Rate of elimination = k el C p
9 Steady State Concentration (C ss ) Rate of Infusion = Rate of Elimination The infusion rate (R) is fixed while the rate of elimination steadily increases The time to reach SS is directly proportional to the half-life After one half-life, the C p is 50% of the C SS, after 2 half-lives, C p is 75% of the C ss …….
10 Steady State Concentration (C ss ) In clinical practice, the SS is considered to be reached after five half-lives
11 Increasing the Infusion Rate If a drug is given at a more rapid infusion rate, a higher SS drug concentration is obtained but the time to reach SS is the same.
12 Loading Dose plus IV Infusion D L with IV infusion at the same time Loading dose IV infusion D L + IV infusion
13 Loading Dose plus IV Infusion D L is used to reach SS rapidly
14 Reaching SS Immediately Let, D L = C ss V d But, C ss V d = R / k el Therefore, if a D L = R / k el is given SS will be reached immediately but
15 Reaching SS Immediately IV D L equal to R /k el is given, followed by IV infusion at a rate R