A 40-year-old man comes into the hospital complaining of fever, cough, chills, a

Question

A 40-year-old man comes into the hospital complaining of fever, cough, chills, and malaise. Subsequently, he is diagnosed with pneumonia. You decide to treat him with Antibiotic X. Initially you dose him with 5882 mg. In this patient, Antibiotic X has a volume distribution of (Vd) 10 L. The volume distribution is the volume of blood and plasma in which the drug distributes. The clearance rate (C.) of the drug is 0.1 L/min. The clearance rate is the volumetric rate of elimination of the drug in the volume of distribution. Antibiotic X has a bioavailability of 85% (ie, 15% of the drug is not available to be used by the body). (a) To prepare an injection, you dilute the initial drug dose of 5882 mg in 5 mL of water What is the drug concentration in m/L? The molecular weight of Antibiotic X is 372 g/m. (b) What is the effective concentration in mg/L of this drug in the body after dosing? (c) At what rate is the antibiotic eliminated from the body in mg/min? (d) Typically, after the initial dose, a multiple-day course of Antibiotic X is given to treat pneumonia. How do you think that the clearance rate of the drug would be affected if the patient was alcoholic? Hint: what organ(s) degrade drugs and other toxins?

Explanation / Answer

Patient will be treated with antibiotic X.

Initially, dose him 5882 mg.

X has volume distribution of 10L.

The clearance rate is 0.1L/min

X has bioavailability of 85%.

a) So, molecular weight is 372g/mol. That means, 372 g of molecule in present in 1lt which gives 1 mol.

Here, one needs to add 5882mg of drug in 5ml.

If 5ml contains 5882mg of drug, then 1lt contains 1176400 mg drug.

Now 372g is present in 1mol. So, 1176400mg will be 3.16 mol.

So, the drug concentration is 3.16mol/L

b)Now, initially you prepared drug of 5882 mg in 5 ml.

As the volume distribution is 10L, 5882 mg drug will be distributed in 10L. But 85% is available for the body.

So, actually, 5000mg drug will remain available in 10L.

So, now the concentration is 500mg/L.

c)The clearance rate of the drug is 0.1L/min

As, the concentration is 500mg/L, 0.1L contains 50mg drug.

So, 50mg drug will be eliminated from the body in one minute.

d)Now, kidney is the most important organ involved in the elimination of drugs. Alcohol damages kidney. So, in thit case, drug clearance decreases.

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