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DHA Pharmacology & Dosage Calculations Practice Questions
Pharmacology is one of the largest parts of every Gulf nursing exam. Expect high-alert drugs, antidotes, side effects to report and dosage calculations. Below are 5 free sample questions for the DHA Registered Nurse exam, each with the answer and a rationale.
What this topic covers
- Dosage and IV drip-rate calculations
- Anticoagulants and their antidotes
- Insulin and oral hypoglycaemics
- Digoxin, diuretics and potassium
- Opioids, naloxone and paracetamol toxicity
- Antibiotics, lithium and high-alert medicines
The full bank has 150 pharmacology & dosage calculations questions, part of 1,500 questions across 16 nursing topics.
Free DHA pharmacology & dosage calculations questions
1. Furosemide 40 mg IV is prescribed. The ampoule contains 10 mg/mL. How many millilitres should the nurse draw up?
- A. 0.4 mL
- B. 8 mL
- C. 4 mL
- D. 2 mL
Show answer and rationale
40 mg ÷ 10 mg/mL = 4 mL.
Reference: Standard dosage calculation – injectables
2. A patient starting rifampicin should be told to expect which harmless effect?
- A. Orange-red discoloration of urine, sweat and tears
- B. Green discoloration of stools
- C. Blue discoloration of the lips
- D. White patches on the fingernails
Show answer and rationale
Rifampicin commonly turns body fluids orange-red; this is harmless but can permanently stain soft contact lenses.
Reference: Standard nursing pharmacology – rifampicin
3. A patient is discharged with a transdermal fentanyl patch. Which statement by the patient shows a need for further teaching?
- A. "I will apply each new patch to a different area of skin."
- B. "I will remove the old patch before applying a new one."
- C. "I will fold used patches sticky side together before disposal."
- D. "I will use a heating pad over the patch when my pain is worse."
Show answer and rationale
Heat increases absorption of fentanyl from the patch and can cause overdose and respiratory depression. The other statements are correct practice.
Reference: Standard nursing pharmacology – transdermal opioids
4. A patient on day 5 of IV clindamycin develops frequent, foul-smelling watery diarrhoea. What should the nurse suspect?
- A. Clostridioides difficile infection
- B. Lactose intolerance
- C. An expected minor effect of the antibiotic
- D. An allergic reaction to the antibiotic
Show answer and rationale
Antibiotics, particularly clindamycin, disrupt normal gut flora and allow C. difficile overgrowth; the nurse should report it, place the patient on contact precautions and send a stool sample.
Reference: Standard nursing pharmacology – antibiotics; CDC C. difficile guidance
5. A child weighing 12 kg is prescribed a drug 250 mg orally every 8 hours. The safe dose range is 25–50 mg/kg/day. What should the nurse do?
- A. Give the dose because it is below the safe range
- B. Give half of the prescribed dose and document the change
- C. Give the dose because it is within the safe range
- D. Withhold the dose and clarify with the prescriber because it exceeds the safe range
Show answer and rationale
Safe range = 25–50 mg/kg/day × 12 kg = 300–600 mg/day. Prescribed = 250 mg × 3 doses = 750 mg/day, which exceeds the maximum, so the nurse must withhold and clarify. A nurse cannot change a dose independently.
Reference: Standard dosage calculation – paediatric safe dose range
Study tip
Practise calculations until they are automatic. Write the formula down and check the answer is sensible before you choose.
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