#### Steady state concentration equation

## What is the steady state concentration?

Steady-state concentration (C_{ss}) occurs when the amount of a drug being absorbed is the same amount that’s being cleared from the body when the drug is given continuously or repeatedly. Steady-state concentration is the time during which the concentration of the drug in the body stays consistent.

## How long does it take a drug to reach steady state?

Everyone knows how long it takes to reach a steady state if a drug is given at a regular interval: four to five half-lives.

## How is VD calculated?

Volume of Distribution, Clearance, and KEFormula | Volume of Distribution = Total Dose / Concentration.VD = 2,000 / 600 = 3.33 L.Formula | VD = CL / KE.(2,000 / 600) = 0.05/ KE = 0.015 hr (-)Formula | Half Life = 0.693 / KE.Half Life = 0.693 / 0.015 = 46.2 hours.

## What is a steady state equation?

A steady state for a differential equation is a solution where the value of y does not change over time. For example, consider an economy with capital and depriciation.

## What is steady state concept?

In chemistry, a steady state is a situation in which all state variables are constant in spite of ongoing processes that strive to change them. The steady state concept is different from chemical equilibrium.

## What is minimum effective concentration?

Minimum Effective Concentration (MEC) – the lower level of a drug in the body that will still be effective.

## What is an example of steady state?

One of the simplest examples of such a system is the case of a bathtub with the tap open but without the bottom plug: after a certain time the water flows in and out at the same rate, so the water level (the state variable being Volume) stabilizes and the system is at steady state.

## How do you calculate steady state plasma concentration?

The half-life can be calculated with the following formula:t 1/2 = 0,693•Vd/CL. where Vd is the volume of distribution at the steady-state, and CL is the clearance. Vd = Q/[P] Vd = D/C0. CL = drug elimination rate/[P] LD = SSC•Vd/B. MD = SSC•CL•DI/B. K0 = CL•SSC. AR = 1 dose/FD.

## How many half lives does it take to get to steady state?

We call this “steady state.” It takes somewhere between 5 and 6 half-lives for a medication to reach steady state. Thus, medications with short half-lives reach steady state relatively quickly, while those with long half-lives take a long time to reach steady state.

## What does 5 half lives mean?

Generally it is considered that it takes 5.5 half-lifes for a drug to be removed from the body, in that it is considered to no longer have a clinical effect. So for Ambien it would take approximately 11 hours (2 hours X 5.5) to be eliminated from your body.

## How do you calculate a drug’s half life?

In brief :Half-life (t½) is the time required to reduce the concentration of a drug by half.The formula for half-life is (t½ = 0.693 × Vd /CL)Volume of distribution (Vd) and clearance (CL) are required to calculate this variable.

## How do you calculate the steady state of a drug?

The time to reach steady state is defined by the elimination half-life of the drug. After 1 half-life, you will have reached 50% of steady state. After 2 half-lives, you will have reached 75% of steady state, and after 3 half-lives you will have reached 87.5% of steady state.