Pharmaceutical Calculations

7

Creatinine Clearance Calculation:

1. CrCl for males= (98-0.8×(Patientss age in years- 20))÷ Serum creatinine (mg/dL)

2. CrCl for females= 0.9 × CrCl for males

Volume of Distribution Calculation

Volume of Distribution (Vd)=

  ^{Total amount of drug in body (D)}⁄_{Drug Blood Plasma Concentration (Cp)}

So, Vd = D/Cp

Loading Dose (D_L) Calculation

Loading dose = desired peak concentration (mg/L) × Volume of distribution (L)

Loading dose (DL)=

Volume of distribution × Plasma drug concentration

Salt form of the drug × Fraction of drug bioavilability

D_L = (Vd× C_av)/(S×F)

Dose ratio = Loading dose/ Maintenance dose

Dose ratio= D_L/D_o

Dose rate (mg/hr) = ^{Total dose (mg)}/_{dosing interval (hr)}

Maintenance Dose Calculation

Maintenance dose (mg/hr)= desired peak concentration (mg/L) × drug  Clearance (L/hr)

Loading dose Calculation

Loading dose = desired peak concentration (mg/L) × Volume of distribution (L)

Capsule filling Calculation

1. Capsule fill weight = Tapped density of powder × Capsule volume( ml)

2. Additional diluent required= (Volume unocupied× 0.8)g

Friability Calculation

Percentage friability= [(W1-W2)/W1]×100

Loss on Drying (LOD) Calculation

LOD = Weight of water in a sample/ Total weight of wet sample

%LOD= [W1-W2)/W1]×100

 [ W1⇨ weight of wet sample, W2⇨ Weight of dry sample]

Moisture Content Calculation

Moisture content = Weight of water in a sample/ Weight of dry sample

%MC = [(W1-W2)/W2]×100  

[ W1⇨ weigth of wet sample, W2⇨ Weight of dry sample]

Potency Calculation

Required Potency=  ^{Standard Potency} × 100%
 _{.    ...       .  ....... .......................  Potency} 

  

Conversion faction of a molecule =

molecular weight of the compound/ molecular weight of the mole

Potency