Clinical pharmacokinetics and therapeutic drug monitoring

1. NOMOGRAMS AND
TABULATIONS IN
DESIGNING DOSAGE
REGIMEN
DESIGN OF DOSAGE REGIMEN

2. NOMOGRAMS TABULATIONS
DESIGNING OF
DOSAGE REGIMEN

3. DOSE
DOSAGE
DOSAGE
REGIMEN

4. Approaches to design dosage regimen
1. Emperical dosage regimen : The physician makes the decision based on
empirical linical data. This method however is not very accurate.
2. Individual dosage regimen : It is the most accurate approach and based on the
pharmacokinetics of drug in the individual patient. The approach is
suitable for hospitalized patient, but is quite expensive.
3. Dosage regimen based on population average : Dosage regimen is calculated
based on average pharmacokinetic parameters from clinical studies
published in the drug literature.
This method is based upon one of the methods :
i. Fixed : Here population average pharmacokinetic parameters are used directly to
calculate dose calculation.
ii. Adaptive : It is based on both population average pharmacokinetic parameters of the
drug as well as patients variables such as weight, age, sex, BSA and known patients
pathophysiologica; conditions such as renal disease.

5. NOMOGRAMS
Greek, nomos – law, gramme - line
A graphical calculating device, a two dimensional diagram designed to allow the
approximate graphical computation of a mathematical functions

6. An infant is 45cm tall and
weighs 2.5 kg. what is the
infants BSA?
𝐵𝑆𝐴 = 𝐻𝑡 𝑐𝑚 𝑋 𝑊𝑡 (𝑘𝑔)
3600
45𝑋 2.5
3600
= 112.5
3600
=
=
0.03125
0.17
=
𝑚2

7. APPLICATIONS OF NOMOGRAMS IN
PHARMACOKINETIC STUDIES
 Population based nomograms have been recommended for initial dosing of
most drugs currently subjected to therapeutic drug monitoring, including
aminoglycosides, digoxin and theophylline [narrow therapeutic index].
 In order to keep dosage regimen calculation simple, complicated equations
are often solved.
 The result displayed diagrammatically on special scaled axes to produce a
simple dose recommendation based on patient information.
 Some nomograms make use of certain physiologic parameters, such as serum
creatinine concentration, to help modify the dosage regimen according to
renal function.
 For many marketed drugs, the manufacturer provides tabulated general
guidelines for use in establishing a dosage regimen for patients, including
loading dose and maintenance dose.

8. APPLICATIONS OF NOMOGRAMS IN
PHARMACOKINETIC STUDIES
 Nomogram is a predictive tools.
 They provide individual predictions based on the characteristics of one single
patient.
 The prediction are derived from hundreds or even thousands of patients who
presented with the same condition.
 Individual predictions represent one of the advantages of the nomograms,
relative to risk groupings of patient populations who share similar disease
characteristics.

9. Meena is a 50 year old female who has been diagnosed with pneumonia secondary to psudomona
aeruginosa. The provider would like to add tobramycin to Meena’s current regimen.
Actual body weight=70 kg
Height= 67’’
Ideal body weight= 61.6kg
SCr= 0.9 mg/dl
Pseudomonas MIC for tabromycin = 1mcg/ml
Step 1
• Determine which body weight to
choose.
• Actual body weight is not 1.2X’s
greater than actual body weight
• So use actual body weight of 70kg.
Step 2
• Calculate dose
• Dose of tobramycin = (7mg/kg) (70kg)
= 490mg
Step 3
• Draw tobramycin level 6-14 hours after dose
given.
• Level drawn after 10hrs and comes back at
6mcg/ml.
Step 4
• Utlilize Hartford Nomogram to determine
dosing interval

11. Meena is a 50 year old female who has been diagnosed with pneumonia secondary to psudomona
aeruginosa. The provider would like to add tobramycin to Meena’s current regimen.
Actual body weight=70 kg
Height= 67’’
Ideal body weight= 61.6kg
SCr= 0.9 mg/dl
Pseudomonas MIC for tabromycin = 1mcg/ml
Siersback- Nelson
Nomogram

12. NOMOGRAMS
ADVANTAGES
 Very low cost [paper and ink]
 Very easy to use, especially for
inexperienced practitioners.
 No power required.
 Very complex equations are easily
solved.
 Very fast to use.
DISADVANTAGES
 Tend to wear out.
 May be difficult to create.
 Limited accuracy.
 Highly specialized to few
equations.

13. TABULATIONS
 For many marketed drugs, the manufacturer provides tabulated general
guidelines for use in establishing a dosage regimen for patients, including
loading dose and maintenance dose.

15. Siersback- Nelson
Nomogram

16. THANK YOU