Hospital and Clinical Pharmacy Exam Help & Online Tutoring

First, the name. Students and examiners write it as hospital and clinical pharmacy, in that order, and that is the phrase worth remembering when you search your own syllabus and past papers.

The subject joins two things that sound similar and are assessed differently:

• Hospital pharmacy is the department. Organisation, staffing, drug store and inventory, purchase, formulary, sterile preparation, distribution to wards.
• Clinical pharmacy is the work done at the patient's side. Medication history, ward rounds, drug information, monitoring, counselling, adverse reaction reporting.

Almost every question falls into one of three types, and they reward different things:

1. Define, or write short notes. A definition, one line on why it exists, one example. Short.
2. Compare, classify, or give reasons. The marks are in the reason, not the list. A table of four systems with no sentence explaining the trade-off scores poorly.
3. Numerical. A dose, a clearance, a rate, a strength. These are the questions most often left blank, and they are the easiest marks on the paper once the formula is known.

This page spends most of its length on the third type, because that is the one no set of downloadable notes actually works through.

A note on the figures below: they are teaching examples for coursework. Real prescribing and monitoring follow your hospital's own protocols and current national guidance.

The sentence that earns the mark: clinical pharmacy is not a different department, it is a different *function*, and in most hospitals the same pharmacists do both. A candidate who writes that they are two separate departments has misunderstood the subject.

For the department side in depth, including formulary and committee work, inventory analysis and infusion calculations, see hospital pharmacy help. For the patient side, including structured case notes, medication review and interpreting monitoring results, see clinical pharmacy help.

This is the most commonly set calculation in the subject, and the one most often answered with the wrong rule.

The case. The adult dose of a drug is 500 mg. The patient is a child of 6 years, 20 kg, 115 cm tall.

Method 1 — Young's rule (age based)

child dose = adult dose × age ÷ (age + 12)

= 500 × 6 ÷ 18 = 166.67 mg, so about 167 mg

Method 2 — Clark's rule (weight based)

child dose = adult dose × weight in kg ÷ 70

= 500 × 20 ÷ 70 = 142.86 mg, so about 143 mg

Method 3 — body surface area

First the surface area, by the Mosteller formula:

BSA = √(height in cm × weight in kg ÷ 3600) = √(115 × 20 ÷ 3600) = √0.6389 = 0.80 m²

Then the dose, against an adult surface area of 1.73 m²:

child dose = 500 × 0.80 ÷ 1.73 = 231.01 mg, so about 231 mg

Now look at what just happened. The three methods gave 167 mg, 143 mg and 231 mg for the same child. The highest is 61.5% above the lowest. These are not small differences, and the examiner knows it.

That is exactly why the question is set. The surface area method is preferred for most drugs because surface area tracks metabolic rate and organ function far better than age or weight alone. Age-based rules in particular assume an average-sized child, so they fail badly on a child who is small or large for their age. Say that in the answer and the marks follow; produce one number from one rule with no comment and they do not.

Many drugs are cleared by the kidney, so the dose depends on renal function. The serum creatinine on its own does not tell you renal function, and that is the whole point of the question.

The case. A man of 68 years weighs 70 kg. Serum creatinine is 1.4 mg/dL.

Cockcroft–Gault, male

CrCl = (140 − age) × weight ÷ (72 × serum creatinine)

= (140 − 68) × 70 ÷ (72 × 1.4)

= 72 × 70 ÷ 100.8 = 5,040 ÷ 100.8 = 50 mL/min

The same patient, if female. Multiply by 0.85:

50 × 0.85 = 42.5 mL/min

Now the point of the question. Take a man of 25, same 70 kg, same creatinine of 1.4:

= (140 − 25) × 70 ÷ 100.8 = 115 × 70 ÷ 100.8 = 8,050 ÷ 100.8 = 79.86 mL/min

Identical laboratory result. 50 mL/min against 79.86 mL/min — a clearance nearly 60% higher in the younger patient, from age alone. The older patient has substantially reduced renal function that the creatinine value conceals, because less muscle mass produces less creatinine in the first place.

That is the examinable conclusion: a normal-looking serum creatinine in an elderly or thin patient can hide significantly reduced clearance, which is why dose adjustment is based on calculated clearance rather than on the raw creatinine.

A loading dose fills the volume of distribution quickly, so the patient reaches a therapeutic concentration without waiting several half-lives. The maintenance dose then replaces what is cleared.

The case. A 70 kg patient. The drug has a volume of distribution of 0.5 L/kg and a target plasma concentration of 15 mg/L.

Volume of distribution

Vd = 0.5 L/kg × 70 kg = 35 L

Loading dose, as active drug

LD = Vd × target concentration = 35 × 15 = 525 mg

Now the part that is actually being tested. Suppose the preparation is a salt of the drug, and only 80% of its weight is the active drug, so the salt factor S is 0.8. The general form is:

LD = (Vd × target concentration) ÷ (S × F)

where F is bioavailability. Taking F as 1 for an intravenous dose:

LD = 525 ÷ 0.8 = 656.25 mg

So 656.25 mg of the salt delivers 525 mg of active drug. Dividing by 0.8 rather than multiplying is the step candidates get backwards: you need *more* of the salt, not less, because part of its weight is not the drug. If your answer came out smaller than 525 mg, the division went the wrong way.

Two further marks are usually available. The loading dose depends on the volume of distribution, not on clearance. The maintenance dose depends on clearance, not on the volume of distribution. Writing both sentences shows you understand why they are separate calculations.

A common question is simply *which drugs require monitoring*. Listing names scores a little; giving the criteria scores properly. A drug is a candidate when:

• its therapeutic index is narrow, so the toxic concentration sits close to the effective one;
• plasma concentration varies widely between patients on the same dose;
• the effect cannot be read off easily at the bedside, unlike blood pressure or blood glucose;
• there is an established relationship between concentration and effect;
• a reliable assay exists and the result arrives in time to act on.

That last criterion rules out a great many drugs, and saying so distinguishes a strong answer.

Timing is half the answer. A level taken before distribution is complete is meaningless, and digoxin is the standard example, since the sample must be drawn well after the dose rather than soon after it. For most drugs the sample is a trough, taken immediately before the next dose, and a level reported without the time it was taken relative to dosing cannot be interpreted at all.

Quote the reference range your own syllabus or laboratory gives. Ranges differ between assays, laboratories and local protocols, and an examiner marks against the range you were taught. Interpreting results against a case is covered on the clinical pharmacy page.