PTCB sample questions, with worked answers

A: Nitroglycerin and sildenafil. Nitrates and PDE5 inhibitors both cause vasodilation, and together they can produce profound hypotension. The other pairs are not contraindicated for this reason.

The trap: Picking nitroglycerin and metoprolol because both are heart drugs. The dangerous pair is a nitrate with a PDE5 inhibitor such as sildenafil.

B: cephalosporin antibiotic. Cephalexin is a cephalosporin antibiotic, used for bacterial infections.

D: Proscar. Finasteride 5 mg is sold under the brand name Proscar. It is a 5-alpha reductase inhibitor used for enlarged prostate (BPH).

A: Carvedilol. Carvedilol (Coreg) is a beta-blocker, with alpha-blocking activity too. Losartan is an angiotensin II receptor blocker, amlodipine a calcium channel blocker and hydrochlorothiazide a thiazide diuretic.

1. Beta-blockers share the -lol stem: metoprolol, atenolol, propranolol, carvedilol.
2. Carvedilol ends in -dilol, still a -lol.
3. The other three belong to the -sartan, -dipine and thiazide groups.

The trap: Looking only for "-olol". Carvedilol and labetalol end differently but are still beta-blockers.

B: Levothyroxine. Synthroid is levothyroxine (T4), thyroid hormone replacement for hypothyroidism. Liothyronine is T3 (Cytomel), methimazole treats an overactive thyroid, and levetiracetam (Keppra) is an anticonvulsant.

1. Synthroid is a thyroid hormone, dosed in micrograms.
2. Of the thyroid drugs, levothyroxine is T4 and the usual replacement.
3. Levetiracetam only looks similar: it is a seizure medicine.

The trap: Picking levetiracetam because it starts with "lev". Look-alike names are exactly what this domain tests.

B: Fluconazole 150 mg tablet. Fluconazole inhibits the liver enzyme (CYP2C9) that clears warfarin, so warfarin levels and the INR can rise and bleeding risk goes up. A single small dose of acetaminophen, loratadine and famotidine are not known for this effect.

1. The question asks which drug raises the INR, so look for an enzyme inhibitor.
2. Azole antifungals such as fluconazole are classic warfarin interactions.
3. The pharmacist decides; the technician flags it.

The trap: Choosing acetaminophen. Regular high doses can affect the INR, but a single dose is a far smaller concern than fluconazole.

B: Unopened insulin glargine vials. Unopened insulin is stored in the refrigerator at 36°F to 46°F (2°C to 8°C) and never frozen. The capsules, tablets and inhaler are kept at controlled room temperature.

1. Sort the order: which items are biologics or labeled "refrigerate"?
2. Insulin is labeled for refrigeration until opened.
3. Put it away first so it stays in range.

The trap: Thinking all insulin stays cold. An opened pen or vial can be kept at room temperature for the days its label allows, but unopened stock is refrigerated.

D: 72 hours. When the pharmacy cannot supply the full C-II quantity, the balance must be supplied within 72 hours. The 30-day window applies only when the patient or prescriber asks for a partial fill.

The trap: Choosing 30 days. That window is for a partial fill the patient or prescriber asks for; when the pharmacy is short, it is 72 hours.

D: September 24, 2026. Schedule III and IV prescriptions may be refilled up to 5 times within 6 months of the date written, whichever comes first. Six months after March 24, 2026 is September 24, 2026; any refills left after that expire.

B: July 15, 2026. Alprazolam is Schedule IV. Schedule III and IV prescriptions may be refilled up to 5 times and not after 6 months from the date written: January 15 plus 6 months is July 15, 2026.

1. Schedule: alprazolam is C-IV.
2. Rule: up to 5 refills within 6 months of the date written.
3. January 15, 2026 + 6 months = July 15, 2026.

The trap: Using one year, the rule many states use for non-controlled prescriptions. Controlled III to V is 6 months.

C: AL3528417. Add the 1st, 3rd and 5th digits: 3 + 2 + 4 = 9. Add the 2nd, 4th and 6th and double: (5 + 8 + 1) × 2 = 28. 9 + 28 = 37, so the check digit is 7. The second letter must be L for Lopez, so AL3528417.

1. Odd places: 3 + 2 + 4 = 9.
2. Even places doubled: (5 + 8 + 1) × 2 = 28.
3. Total 37: the last digit, 7, must be the check digit. Second letter L for Lopez.

The trap: Checking only the arithmetic. AM3528417 passes the check digit but has M, not L, as the second letter.

B: 9:00 a.m. Thursday. Hydrocodone combinations are Schedule II. When the pharmacy is short, the balance must be supplied within 72 hours; otherwise the pharmacist notifies the prescriber and no more may be dispensed on that prescription. Monday 9:00 a.m. plus 72 hours is Thursday 9:00 a.m.

1. Schedule II, and the pharmacy is short: the 72-hour rule applies.
2. Monday 9:00 a.m. + 72 hours = Thursday 9:00 a.m.
3. The 30-day window is only for partial fills the patient or prescriber asks for.

The trap: Using 30 days. That window, from CARA 2016, applies when the patient or prescriber requests the partial fill.

B: 3 g. Retail sales are limited to 3.6 g of base a day and 9 g in 30 days. 9 g minus the 6 g already bought leaves 3 g, which is under the 3.6 g daily cap, so 3 g is the most.

1. 30-day limit: 9 g. Already bought: 6 g. Room left: 3 g.
2. Daily limit: 3.6 g. 3 g is under it.
3. The smaller limit wins: 3 g.

The trap: Selling the full daily 3.6 g. Both limits apply, and the 30-day limit is the one that binds here.

B: Wrong strength. The drug is correct but the strength dispensed differs from what was prescribed, which is a wrong-strength (abnormal dose) error. Dosage form refers to the product type, such as tablet or liquid.

The trap: Calling it a dosage form error. The drug and the tablet form are right; only the strength is wrong.

A: Have the patient stop and bring the bottle in for pharmacist review. Clonidine and clonazepam (Klonopin) are a classic look-alike/sound-alike pair, and this may be a dispensing error. The pharmacist must verify the contents, notify the prescriber, and document and report the error. The two drugs are not interchangeable, and continuing a benzodiazepine unintentionally is unsafe.

The trap: Treating it as a side effect to wait out. A new symptom after a refill, with a look-alike name on the label, is a possible dispensing error for the pharmacist.

A: right ear, left ear or each ear. "AD, AS, AU" can be misread as OD, OS, OU (right eye, left eye, each eye). ISMP recommends writing "right ear, left ear or each ear" instead.

A: "U" can be read as a 0, so 6 units becomes 60. ISMP lists "U" for units as error-prone because a handwritten U can look like a 0 or a 4, turning 6U into 60 or 64. The safe way is to write "units" in full: "6 units".

1. Ask how the abbreviation could be misread.
2. A U next to a number looks like a zero.
3. So the dose can be read ten times too high; write "units".

The trap: Thinking the issue is the unit itself. Insulin is dosed in units; the problem is the abbreviation.

A: Scanning the stock bottle bar code against the prescription. Scanning the stock bottle matches its NDC to the drug on the prescription, so a look-alike name pulled by mistake is flagged at once. Counting, expiration checks and patient identifiers do not compare the drug itself.

1. The error is the wrong drug, a look-alike name.
2. Only one step compares the drug in hand with the drug ordered: the bar code scan.
3. The pharmacist's final check is a second barrier, not the first.

The trap: Choosing the date-of-birth check. It confirms the right patient, not the right drug.

C: Oral methotrexate for non-cancer use. Oral methotrexate taken weekly for conditions such as rheumatoid arthritis is a high-alert medication: taking it daily instead of weekly has caused deaths. Pharmacies add safeguards such as clear weekly labeling and counseling.

1. High-alert means a mistake causes serious harm, not that mistakes are common.
2. Weekly methotrexate taken daily is a known fatal error.
3. The other three are low-risk at usual doses.

The trap: Picking a drug because it is common. High-alert is about the harm an error causes.

B: 2.25 g. A w/v percent is grams per 100 mL. 0.9% is 0.9 g in 100 mL, so 250 mL holds 0.9 × 250 ÷ 100 = 2.25 g.

D: Take 2 tablets by mouth three times daily as needed for pain. 2 tab = 2 tablets; po = by mouth; tid = three times daily; prn pain = as needed for pain.

B: 6 days. 10 mL twice daily is 20 mL a day. 120 ÷ 20 = 6 days.

D: 200 mg. A w/v percent is grams per 100 mL. 1% is 1 g in 100 mL, so 20 mL holds 1 × 20 ÷ 100 = 0.2 g = 200 mg.

A: 30. Add each step: 4 × 3 = 12, 3 × 3 = 9, 2 × 3 = 6 and 1 × 3 = 3. 12 + 9 + 6 + 3 = 30 tablets, for a 12-day supply.

1. 4 × 3 = 12
2. 3 × 3 = 9; 2 × 3 = 6; 1 × 3 = 3
3. 12 + 9 + 6 + 3 = 30 tablets

The trap: Answering 12, the number of days. The question asks for tablets.

A: 5 mL. 44 lb ÷ 2.2 = 20 kg. 40 mg × 20 kg = 800 mg a day, given as two doses of 400 mg. At 400 mg per 5 mL, each dose is 5 mL.

1. 44 lb ÷ 2.2 = 20 kg
2. 40 mg/kg/day × 20 kg = 800 mg/day; ÷ 2 doses = 400 mg
3. 400 mg ÷ 400 mg × 5 mL = 5 mL

The trap: Using pounds as kilograms: 40 × 44 = 1,760 mg a day gives 11 mL a dose, more than double the right amount.

A: 125 mL/hr. Rate equals volume divided by time: 1,000 mL ÷ 8 hours = 125 mL per hour.

1. Volume: 1,000 mL. Time: 8 hours.
2. 1,000 ÷ 8 = 125
3. 125 mL/hr

The trap: Dividing by minutes when the question asks for hours.

A: 42. 4 hours is 240 minutes. 500 mL ÷ 240 min = 2.08 mL per minute, and 2.08 × 20 drops = 41.7, or about 42 drops per minute.

1. 4 hours × 60 = 240 minutes
2. 500 mL ÷ 240 = 2.083 mL/min
3. 2.083 × 20 = 41.7, about 42 gtt/min

The trap: Answering 125, the rate in mL per hour, instead of converting to drops per minute.

A: 12.5 g. A 5% weight-in-volume solution has 5 g per 100 mL. 250 mL ÷ 100 × 5 g = 12.5 g.

1. 5% w/v = 5 g in every 100 mL.
2. 250 mL is 2.5 × 100 mL.
3. 2.5 × 5 g = 12.5 g

The trap: Answering 5 g, the amount in 100 mL, not in 250 mL.

A: 12345-0678-90. Billing uses a 5-4-2 format. A 5-3-2 NDC needs a leading zero in the middle (product) segment: 12345-0678-90.

1. Target format: 5-4-2.
2. The labeler (5) and package (2) segments already fit.
3. The product segment has 3 digits, so add a zero in front: 0678.

The trap: Adding the zero to the wrong segment. The zero goes in front of whichever segment is short.