Dosing regimens

Question 1

Dosing regimens are designed to deliver the correct…

Answer 1

Dose of drug
Route of administration
Interval between doses

Question 2

What factors need to be considered for antibiotics

Answer 2

Drug
- Pharmacodynamics/Pharmacokinetics
- Toxicity
Organism
- Susceptibility to antibiotic class
- Resistant subpopulations
Patient
- Pre-existing disease
- Sensitivity to side effects

Question 3

Maximal concentration (Cmax)

Answer 3

The peak plasma concentration reached

Question 4

Area under curve (AUC)

Answer 4

The total dose of drug over the MIC

Question 5

Time greater than MIC (T>MIC)

Answer 5

The duration for which plasma concentration is greater than MIC

Question 6

Post-antibiotic effect (PAE)

Answer 6

The “trough” period where concentration is below MIC (but may still be having pharmacological effects)

Question 7

The higher the concentration of drug…

Answer 7

the more rapid/effective the microbicidal effect

Question 8

The longer the duration of the drug…

Answer 8

the more rapid/effective the microbicidal effect

Question 9

Why does aminoglycosides require therapeutic drug monitoring

Answer 9

Measure serum levels
Monitor for therapeutic effect
Monitor for side effects

• narrow therapeutic window
• aminoglycosides are ototoxic + nephrotoxic @ high conc
• clearance of aminoglycosides is renal

Question 10

Why does dosing regimen need to be adjusted

Answer 10

Impairment of

• Renal function
• Hepatic function
• Plasma protein levels
• Organ and tissue perfusion

Impact on:

• Volume of distribution
• Clearance
• Absorption (bioavailability)