PharmD Info

Nomograms are graphical tools used to calculate medication dosages based on various patient characteristics. Below are some commonly used nomograms in pharmacy practice:

Theophylline Nomogram:

The theophylline nomogram is used to calculate theophylline dosages based on a patient's serum theophylline concentration and weight. The nomogram is a graph that plots serum theophylline concentrations against weight, with different dosing zones indicated on the graph. The dose of theophylline is calculated based on the patient's weight and the serum theophylline concentration.

Dose (mg/kg) = desired serum concentration (mcg/mL) x lean body weight (kg) / 0.6

Example: A patient weighing 70 kg has a serum theophylline concentration of 10 mcg/mL. Based on the theophylline nomogram, the patient's theophylline dose should be 10 mg/kg. Therefore, the total dose of theophylline for this patient would be 700 mg.

Digoxin Nomogram:

The digoxin nomogram is used to calculate digoxin dosages based on a patient's serum digoxin concentration and weight. The nomogram is a graph that plots serum digoxin concentrations against weight, with different dosing zones indicated on the graph. The dose of digoxin is calculated based on the patient's weight and the serum digoxin concentration.

Dose (mg) = (desired serum concentration (ng/mL) x volume of distribution (L/kg) x lean body weight (kg)) / bioavailability

Example: A patient weighing 60 kg has a serum digoxin concentration of 2 ng/mL. Based on the digoxin nomogram, the patient's digoxin dose should be 0.125 mg. Therefore, the total dose of digoxin for this patient would be 7.5 mg.

Gentamicin Nomogram:

The gentamicin nomogram is used to calculate gentamicin dosages based on a patient's serum gentamicin concentration and weight. The nomogram is a graph that plots serum gentamicin concentrations against weight, with different dosing zones indicated on the graph. The dose of gentamicin is calculated based on the patient's weight and the serum gentamicin concentration.

Dose (mg/kg) = desired serum concentration (mcg/mL) x (0.2 x creatinine clearance (mL/min)) / (lean body weight (kg) x 0.9)

Example: A patient weighing 70 kg has a serum gentamicin concentration of 8 mcg/mL. Based on the gentamicin nomogram, the patient's gentamicin dose should be 3 mg/kg. Therefore, the total dose of gentamicin for this patient would be 210 mg.

Nomograms are useful tools for pharmacy students to calculate medication dosages in clinical scenarios. It is important for students to understand how to use and interpret nomograms to ensure safe and effective medication therapy for their patients.