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**Equation 14.6.5 Loading Dose**

Rewriting Equation 14.6.2 with Dose expressed more explicitly as the Maintenance Dose.

**Equation 14.6.6 Cp _{max}**

**Equation 14.6.7 Maintenance Dose**

or

**Equation 14.6.8 Maintenance Dose**

In the previous example Cp_{max} was 15.5 mg/liter

A suitable loading dose can be calculated as Cp_{max} • V = 15.5 x 10 = 155 mg as a bolus which would give Cp = 15.5 mg/liter. This loading dose could be followed by 100 mg every 6 hours to maintain the Cp_{max} and Cp_{min} values at 15.5 and 5.5 mg/liter, respectively.

What we need is the maintenance dose, the loading dose, and the dosing interval.

Dividing Equations 14.6.2 by Equation 14.6.3

**Equation 14.6.9 Cp _{max} and Cp_{min} provides 1/R**

therefore

taking the ln of both sides

Solving for Τ gives

A dosing interval of 8 hours would be more reasonable and keeps the concentration between the limits of MTC and MEC. Thus with τ' = 8 hr
and kel = 0.15 hr^{-1}

From Equation 14.6.6

**Equation 14.6.10 Maintenance Dose**

Maintenance dose = 35 x 25 x (1 - 0.301) = 612 mg

Again we can round the value to a more realistic value, a maintenance dose of 600 mg every 8 hours.

This regimen should be quite suitable as the maximum and minimum values are still within the limits suggested. All that remains is to calculate a suitable loading dose.

This loading dose could be round (down) to a more suitable 850 or 800 mg. Let's use 800 mg.

The dosing regimen is then a loading dose of 800 mg followed by a maintenance dose of 600 mg every 8 hours.
**To check this regimen**

__Concentrations from the loading dose__

NOTE the use of the loading dose in this equation and that the Cp_{max} is below the MTC.

__Concentrations from the maintenance dose__

and

Here we use the maintenance dose. Note, the Cp_{max} and Cp_{min} are below and above the MTC and MEC, respectively.

This answer can be expressed graphically.

**Figure 14.6.2 Plasma Concentration after Multiple IV Bolus Doses**

**Calculator 14.6.2 Calculate Cp _{min} and Cp_{max} after Multiple IV Bolus Doses**

Practice problems involving Cp

Other practice problems involving the calculation of Cp at three times during a uniform dosing interval with Linear or Semi-log graphical answers or calculation of Cp at three times during a non-uniform dosing interval with Linear or Semi-log graphical answers.

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