Clinical Pharmacy Calculations MCQs

by Pharmaexam

Clinical pharmacy is a specialized area of pharmacy practice that focuses on the optimization of medication therapy to improve patient outcomes. It involves the direct involvement of pharmacists in patient care, working collaboratively with other healthcare professionals to ensure the safe, effective, and appropriate use of medications.

Here we design a quiz test containing 20 MCQs on clinical pharmacy calculations. It will help you to prepare for competitive exams or interviews.

Clinical Pharmacy Calculations MCQs

This free quiz test on clinical pharmacy calculations will help you to prepare for competitive exams or interviews.

1 / 20

A new cephalosporin antibiotic was given at a dose of 5 mg/kg by a single intravenous bolus injection to a 58-year-old man who weighed 75 kg. The antibiotic follows the pharmacokinetics of a one compartment model and has an elimination half-life of 2 hrs. Th e apparent volume of distribution is 0.28 L/kg, and the drug is 35% bound to plasma proteins.

What is the initial plasma drug concentration in this patient?

The equation for the initial plasma drug concentration:

2 / 20

Calculate the daily infusion volume of D10W to be administered to a neonate weighing 3 lb. 8 oz. on the basis of 60 mL/kg/day.

3 lb. 8 oz. = 3.5 lb. / 2.2 lb./kg = 1.59 kg or 1.6 kg

1.6 kg × 60 mL = 96 mL

3 / 20

If a patient is determined to have a serum cholesterol level of 200 mg/dL, what is the equivalent value expressed in terms of millimoles (mmol) per liter?

Molecular Weight (m.w. of cholesterol) = 387

1 mmol cholesterol = 387 mg

200 mg/dL = 2000 mg/L

387 (mg)/2000 (mg) = 1 (millimole)/X (millimoles)

X = 5.17 mmol/L

4 / 20

Determine the creatinine clearance rate for an 80-year-old male patient weighing 70 kg and having a serum creatinine of 2 mg/dL. [Use Cockcroft-Gault equations]

As per Cockcroft-Gault equation:

CrCl = [(140 - 80) × 70]/(72 × 2) (mg/dL)

= 60 × 70/144

= 4200/144

= 29.2 mL/min

5 / 20

The usual initial dose of chlorambucil is 150 ug/kg of body weight once a day. How many milligrams should be administered to a person weighing 154 lb?

We know,

150 ug = 0.15 mg & 1 kg = 2.2 lb;

Thus,

2.2 lb/154 lb = 0.15 mg/ X mg

X = 10.5 mg

6 / 20

The adult dose of a drug is 500 mg. What is the dose for a 2 year old child as per young rule?

Young rule = age in year/(age + 12) x adult dose

7 / 20

If a patient's mean pulmonary artery pressure is 14 mmHg, his left atrial pressure is 8 mmHg, and his cardiac output is 4.0 L/minute. What will be Pulmonary Vascular Resistance (PVR)?

PVR = {(Mean Pulmonary Artery Pressure – Left Atrial Pressure) ÷ Pulmonary Flow} × 80

8 / 20

With a normal tidal volume of 500 milliliters, a normal dead space of 150 milliliters, and a respiratory rate of 12 breaths per minute. What will be the alveolar ventilation rate?

Rate of alveolar ventilation can be calculated by following equation:

VA= Freq. × (VT - VD)

Where, VA is the volume of alveolar ventilation per minute, Freq. is the frequency of respiration per minute, VT is the tidal volume, and VD is the physiologic dead space volume.

9 / 20

A vancomycin solution containing 1000 mg of vancomycin hydrochloride diluted to 250 mL with D5W is to be infused at a constant rate with a continuous-drip intravenous infusion set that delivers 25 drops/mL. What flow rate (drops per minute) should be used to infuse all 250 mL of the
vancomycin hydrochloride solution in 2 hrs.?

10 / 20

If digoxin has a half-life of 35 hrs. how long will it take for a toxic plasma concentration of 8 ng/mL to decline to a therapeutic plasma concentration of 2 ng/mL?

For first-order elimination, it takes two half-lives for plasma drug concentration of 8 ng/mL to decline to 2 ng/ mL. Th e first half-life, the plasma drug concentration declines to 4 ng/mL, and the next half-life, the plasma drug concentration declines to 2 ng/mL.

11 / 20

A new cardiac glycoside is developed for oral and intravenous administration. The drug has an elimination half-life (t½) of 24 hrs. and an apparent volume of distribution (VD) of 3 L/kg. The effective drug concentration is 1.5 ng/mL. Toxic effects of the drug are observed at drug concentrations > 4 ng/mL. The drug is bound to plasma proteins at approximately 25%. The drug
is 75% bioavailable after an oral dose.

What is the loading dose (DL) for this patient?

When the maintenance dose is given at a dosage frequency equal to the half-life, then the loading dose is equal to twice the maintenance dose, in this case 540 μg, or 0.540 mg.

 

12 / 20

A new cardiac glycoside is developed for oral and intravenous administration. The drug has an elimination half-life (t½) of 24 hrs. and an apparent volume of distribution (VD) of 3 L/kg. The effective drug concentration is 1.5 ng/mL. Toxic effects of the drug are observed at drug concentrations > 4 ng/mL. The drug is bound to plasma proteins at approximately 25%. The drug
is 75% bioavailable after an oral dose.

What is the oral maintenance dose, if given once a day, for a 68-year-old man who weighs 65 kg and has congestive heart failure (CHF) and normal renal function?

13 / 20

A 35-year-old man who weighs 70 kg and has normal renal function needs an intravenous infusion of the antibiotic carbenicillin. The desired steady state plasma drug concentration is 15 mg/dL. The physician wants the antibiotic to be infused into the patient for 10 hrs. Carbenicillin has an elimination half-life (t½) of 1 hr. and an apparent volume distribution (VD) of 9L in this patient.

If the patient’s renal clearance for carbenicillin is 86 mL/min, what is the hepatic clearance for carbenicillin?

14 / 20

A 35-year-old man who weighs 70 kg and has normal renal function needs an intravenous infusion of the antibiotic carbenicillin. The desired steady state plasma drug concentration is 15 mg/dL. The physician wants the antibiotic to be infused into the patient for 10 hrs. Carbenicillin has an elimination half-life (t½) of 1 hr. and an apparent volume distribution (VD) of 9L in this patient.

What is the total body clearance rate for carbenicillin in this patient?

15 / 20

A 35-year-old man who weighs 70 kg and has normal renal function needs an intravenous infusion of the antibiotic carbenicillin. The desired steady state plasma drug concentration is 15 mg/dL. The physician wants the antibiotic to be infused into the patient for 10 hrs. Carbenicillin has an elimination half-life (t½) of 1 hr. and an apparent volume distribution (VD) of 9L in this patient.

What is the recommended loading dose?

16 / 20

A 35-year-old man who weighs 70 kg and has normal renal function needs an intravenous infusion of the antibiotic carbenicillin. The desired steady state plasma drug concentration is 15 mg/dL. The physician wants the antibiotic to be infused into the patient for 10 hrs. Carbenicillin has an elimination half-life (t½) of 1 hr. and an apparent volume distribution (VD) of 9L in this patient.

Assuming that no loading intravenous dose was given, how long after the initiation of the intravenous infusion would the plasma drug concentration reach 95% of the theoretic steady-state drug concentration?

The time it takes for an infused drug to reach the Css depends on the elimination half-life of the drug. The time required to reach 95% of the Css is equal to 4.3 times the half-life, whereas the time required to reach 99% of the Css is equal to 6.6 times the half-life. Because the half-life in the current case is 1 hr., the time to reach 95% of the Css is 4.3×1 hr. or 4.3 hrs.

17 / 20

A 35-year-old man who weighs 70 kg and has normal renal function needs an intravenous infusion of the antibiotic carbenicillin. The desired steady state plasma drug concentration is 15 mg/dL. The physician wants the antibiotic to be infused into the patient for 10 hrs. Carbenicillin has an elimination half-life (t½) of 1 hr. and an apparent volume distribution (VD) of 9L in this patient.

Assuming that no loading dose was given, what rate of intravenous infusion is recommended for this patient?

18 / 20

A new cephalosporin antibiotic was given at a dose of 5 mg/kg by a single intravenous bolus injection to a 58-year-old man who weighed 75 kg. The antibiotic follows the pharmacokinetics of a one compartment model and has an elimination half-life of 2 hrs. Th e apparent volume of distribution is 0.28 L/kg, and the drug is 35% bound to plasma proteins.

How long after the dose is exactly 75% of the drug eliminated from the patient’s body?

For any first-order elimination process, 50% of the initial amount of drug is eliminated at the end of the first half-life, and 50% of the remaining drug (i.e., 75% of the original amount) is eliminated at the end of the second half-life. Because the drug in the current case has an elimination half-life (t ½ ) of 2 hrs, 75% of the dose is eliminated in two half-lives or 4 hrs.

19 / 20

A new cephalosporin antibiotic was given at a dose of 5 mg/kg by a single intravenous bolus injection to a 58-year-old man who weighed 75 kg. The antibiotic follows the pharmacokinetics of a one compartment model and has an elimination half-life of 2 hrs. Th e apparent volume of distribution is 0.28 L/kg, and the drug is 35% bound to plasma proteins.

How much drug remains in the patient’s body (DB) 8 hrs. after the dose?

20 / 20

A new cephalosporin antibiotic was given at a dose of 5 mg/kg by a single intravenous bolus injection to a 58-year-old man who weighed 75 kg. The antibiotic follows the pharmacokinetics of a one compartment model and has an elimination half-life of 2 hrs. Th e apparent volume of distribution is 0.28 L/kg, and the drug is 35% bound to plasma proteins.

What is the predicted plasma drug concentration (Cp) at 8 hr. after the dose?

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