Question

10. The amount of medication that is in the blood (and available to reach cells and treat the underlying condition) is often different than the dose that was given. The fraction of a dose of medication that is in the blood stream and has not been chemically modified (metabolized) by the body is referred to as its bioavailability. When a medication is administered intravenously, its bioavailability is considered to be 100% at the time of administration and this decreases with time as it is metabolized and/or excreted. When a medication is administered orally, its bioavailability is much- less due to incomplete absorption and being metabolized on passing through the liver. The graphs below show the concentration of azithromycin in the blood in subjects who were administered 500 mg of the medication orally or intravenously. Oral Dosage IV Dosage 4000 3500 Azithromycin (Hg/L) Azithromycin (Hg/L) 0 10 40 50 0 10 40 50 20 30 Time (Hours) 20 30 Time (Hours) From the graphs, determine for the healthy patients: a. When were the peak concentrations achieved for IV and for oral administration of the medication? b. What were the peak concentrations achieved for IV and for oral administration of the medication? c. What were the concentrations after 12 hours for IV and for oral administration of the medication?

Answer 1

Assuming no information other than the graph is available, the answers should be:
a) IV dosage: peak concentration is achieved at the time of administration of the medication.

Oral dosage: peak concentration is achieved approximately 3-4 hours after administration of the medication.

b) IV dosage: peak concentration achieved is 3500 $\mu$ g/L.

Oral dosage: peak concentration achieved is approximately 275 $\mu$ g/L.

c) Concentrations of medication after 12 hours for:

IV dosage: approximately 100 $\mu$ g/L.

Oral dosage: approximately 75 $\mu$ ​​​​​​​g/L.

Hope this helps.