GPhC Pharmaceutical Sciences & Calculations 2

Question 1

A patient weighing 70 kg requires a drug at 5 mg/kg/day in two divided doses. What is each dose?

Accepted Answer

175 mg

Answer

Total daily dose = 70 × 5 = 350 mg. Divided into 2 doses: 350 ÷ 2 = 175 mg per dose.

Question 2

An infusion of 500 mg in 250 mL is running at 50 mL/hour. What is the rate in mg/hour?

Accepted Answer

100 mg/hour

Answer

Concentration = 500/250 = 2 mg/mL. Rate = 2 mg/mL × 50 mL/hour = 100 mg/hour.

Question 3

Which excipient acts as a preservative in multi-dose eye drops?

Accepted Answer

Benzalkonium chloride

Answer

Benzalkonium chloride (BAC) is the most commonly used preservative in multi-dose ophthalmic preparations. It prevents microbial contamination.

Question 4

What is the purpose of an enteric coating on a tablet?

Accepted Answer

To prevent dissolution in gastric acid

Answer

Enteric coatings resist gastric acid and dissolve in the higher pH of the small intestine, protecting acid-labile drugs or preventing gastric irritation.

Question 5

A solution has a pH of 3. What does this indicate?

Accepted Answer

Acidic solution

Answer

pH below 7 indicates an acidic solution. pH 7 is neutral; above 7 is alkaline. pH 3 is strongly acidic.

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GPhC Pharmaceutical Sciences & Calculations 2