Rate of input:, where τ is the dosing intervalīy solving for C p, you get the following:Īs a further simplification, we know that there is a relationship between dose, clearance, and bioavailability shown by the following equation:īy rearranging terms we can get the following: This parameter can be calculated based on the steady state definition where the rate of input is equal to the rate of elimination.
The first is the average plasma concentration at steady state, or C ss. These parameters are not necessarily more important however, they are useful because of the unique situation when drug input rate and elimination rate are equivalent. There are several special PK parameters associated with steady state kinetics. PK parameters associated with steady state And the replenishment of eggs represent taking new doses of medication. Using the eggs represents the variety of clearance mechanisms that eliminate drug molecules from circulation. The eggs represent individual drug molecules in the body. If this process repeats itself over many days, it would appear that the eggs never change … there are always 12 eggs in the carton even though you use them for various meals and recipes. In this hypothetical scenario, the eggs are at steady state because the rate of elimination is equal to the rate of input.
So when you wake up the next morning, the carton is full of eggs. Someone in your house notices the empty spots in the carton of eggs and purchases 2 more eggs and places them in the carton. And imagine that when you use 2 eggs to make an omelette for breakfast. Another way to think of this is imagine a carton of eggs in your kitchen.