The success of drug therapy is highly dependent on the choice of the drug, the drug product, and the design of the dosage regimen. The choice of the drug is generally made by the physician after careful patient diagnosis and physical assessment. The choice of the drug product (eg, immediate release vs modified release) and dosage regimen is based on the patient’s individual characteristics and known pharmacokinetics.

6. Success
• Drug
of
• Drug product
Therapy
• Dosage Regimen

9. Estimation of
initial dosage of
drug
Evaluation of the
patient
Adjustment of
the dosage
regimen

12. Fixed model
Adaptive model

17. Empirical
clinical data
Personal
experience
Clinical
observation

31. In-
patient
out-
patient

32. Time( in hr)
Plasmaconc.(µg/ml)
MEC
MTC
Therapeutic
range
Plot showing conversion from IV infusion to oral dosing
CSS
IV infusion
Oral
dose

36. Dosing interval in hr
PlasmaDrugConc.
MEC
MTC
Loading dose
D0 D0 Do Do D0
Maintenance Doses D0

40. Sub-therapeutic Level
Toxic Level
Therapeutic Range
Plasmadrugconcentration
Time

41. Drugs Therapeutic range
Digoxin 1-2 ng/mL
Gentamycin 5-10 µg/mL
Pheytoin 10-20 µg/mL
Theophyline 10-20 µg/mL
Amikacin 20-30 µg/mL

51. 51
Selection of Drug
Dosage Regimen Design
Evaluation of Patient’s Response
To Determine need for measuring serum
drug conc.

52. Assay for drug concentration
Pharmacokinetic evaluation
Dosage Adjustment
Monitoring serum drug concentration
Special Recommendations

60. Once dailydosing

65. Multiple daily dosing

67. FACTORS: DRUG
ADMINISTRATION OR BLOOD
DRAWING

68. FACTORS: PHARMACOKINETICS

70. FACTORS: LABORATORY