# INBDE practice questions: FK8 — Pharmacology

Ten original INBDE practice questions on FK8 — Pharmacology, each answered on this page with a rationale and a source.

Last updated: 2026-08-10.

## Question 1

A 29-year-old woman has an acutely tender lower first molar with a red, swollen buccal vestibule. Two buccal infiltrations of 2% lidocaine with 1:100,000 epinephrine have failed to produce pulpal anesthesia, and she remains exquisitely sensitive to the explorer. What should the dentist do next?

- A. Deposit two further cartridges directly into the swollen vestibule at a faster rate
- B. Switch to a 4% ester anesthetic, which is unaffected by changes in tissue pH
- C. Conclude that she is allergic to lidocaine and defer treatment pending testing
- D. Give a regional block at a site away from the acutely inflamed tissue

**Answer D:** Give a regional block at a site away from the acutely inflamed tissue

Local anesthetics block voltage-gated sodium channels from inside the nerve, and only the uncharged base crosses the nerve membrane; pKa relative to tissue pH governs how much exists in that form. In infected, acidic tissue more drug is trapped as the charged species, less crosses, and the block fails — the commonest clinical failure. The remedy is a regional block away from the inflamed field rather than more solution into it. A does precisely what the mechanism predicts will fail, while adding dose and injection-rate risk. B misattributes the failure to drug class: esters and amides differ in metabolism and allergy, not in their dependence on tissue pH. C converts a predictable pH failure into an allergy; true amide allergy is rare, and it presents as a reaction, not a failed block.

**Common trap:** Answering a failed block with more solution into the inflamed site.

Source: Malamed, Handbook of Local Anesthesia

## Question 2

A healthy 22 kg seven-year-old needs restorations in two quadrants at one visit. The dentist will use 2% lidocaine with 1:100,000 epinephrine from cartridges labelled 1.7 mL, applying the conservative dental maximum of 4.4 mg/kg. What is the largest number of cartridges that stays within the limit?

- A. Two cartridges, since a third would exceed his 96.8 mg weight-based limit
- B. Three cartridges, since the 300 mg absolute adult ceiling has not been reached
- C. Four cartridges, since 1.7 mL of a 2% solution contains about 17 mg lidocaine
- D. Five cartridges, since 4.4 mg/kg governs only plain solutions without added epinephrine

**Answer A:** Two cartridges, since a third would exceed his 96.8 mg weight-based limit

A percentage is grams per 100 mL, so 2% lidocaine is 20 mg/mL and the cartridge volume printed on the carton converts that into milligrams: 1.7 mL delivers 34 mg. The conservative dental maximum of 4.4 mg/kg gives 96.8 mg for a 22 kg child, so two cartridges supply 68 mg while a third would reach 102 mg and breach the limit; sequence the appointment to the dose rather than the dose to the appointment. B applies an adult ceiling to a child, which is the commonest route to a paediatric overdose. C halves the conversion — per cent times ten is mg/mL, so 2% is 20 mg/mL. D invents an exemption: the conservative limit includes lidocaine with epinephrine, and the vasoconstrictor is counted separately against its own cap.

**Common trap:** Applying the adult milligram ceiling to a child instead of the weight-based limit.

Source: [AAPD local-anesthesia best practice](https://www.aapd.org/globalassets/media/policies_guidelines/bp_localanesthesia25.pdf)

## Question 3

A 40-year-old man reports a documented allergy to procaine, confirmed after a dermatological procedure some years ago. He has had no dental injection since then and is otherwise healthy. He now needs a lower molar restored. Which choice best reflects local-anesthetic allergy pharmacology?

- A. No local anesthetic may be used; the restoration must proceed without anesthesia
- B. A topical benzocaine gel is safe, because topical agents do not provoke allergy
- C. An amide such as lidocaine is appropriate; ester allergy reflects PABA metabolites
- D. Articaine is safest here, being the amide furthest removed from ester chemistry

**Answer C:** An amide such as lidocaine is appropriate; ester allergy reflects PABA metabolites

The class split predicts both metabolism and allergy. Esters — procaine, benzocaine and tetracaine — are hydrolysed by plasma esterases to PABA, the classic cause of true local-anesthetic allergy, while most amides such as lidocaine, mepivacaine, prilocaine and bupivacaine are metabolised mainly in the liver and true allergy to them is rare. A withholds an entire pharmacological class on the strength of a single-class reaction. B misses that benzocaine is itself an ester, and topical exposure is still exposure; benzocaine also carries a methemoglobinemia risk and may not be used orally in children under 2 years. D inverts the chemistry it invokes: articaine is the exception among the amides, carrying an ester side chain hydrolysed predominantly by plasma esterases.

**Common trap:** Treating a topical agent as exempt from the class that caused the allergy.

Source: [FDA oral benzocaine safety action](https://www.fda.gov/media/113345/download)

## Question 4

A 70-year-old man with stable, medically managed ischaemic heart disease needs two lower molars restored at one visit. The dentist plans 2% lidocaine with 1:100,000 epinephrine in cartridges labelled 1.7 mL. How much vasoconstrictor may reasonably be planned for the appointment?

- A. About 0.2 mg, the figure cited for a healthy adult appointment
- B. About 0.04 mg, roughly two cartridges, with aspiration and slow injection
- C. None at all; epinephrine is contraindicated in any patient with heart disease
- D. Any amount, provided the lidocaine total stays below 300 mg for the appointment

**Answer B:** About 0.04 mg, roughly two cartridges, with aspiration and slow injection

Concentration is written as a ratio: 1:100,000 is 0.01 mg/mL, so a 1.7 mL cartridge carries 0.017 mg of epinephrine. The commonly cited ceiling is about 0.2 mg per appointment for a healthy adult and about 0.04 mg — roughly two cartridges — for a patient with significant but stable cardiovascular disease, which two 1.7 mL cartridges meet at 0.034 mg. A applies the healthy-adult figure to a cardiac patient. C is the over-correction the literature warns against: withholding vasoconstrictor produces shallow anesthesia, pain, and a surge of the patient's own epinephrine that cannot be dosed or stopped. D counts only the anesthetic, when the vasoconstrictor is a separate drug in the same cartridge with its own limit. Whether elective care suits him at all is decided first.

**Common trap:** Counting the milligrams of anesthetic and forgetting the vasoconstrictor's separate cap.

Source: Malamed, Handbook of Local Anesthesia

## Question 5

A healthy 27-year-old woman has an impacted third molar removed surgically. She takes no medicines and has no ulcer, renal or asthma history, and she is not pregnant. Before she leaves she asks what to take for the pain tonight. What should the dentist recommend first?

- A. Ibuprofen 400 mg with acetaminophen 500–1000 mg, at the lowest effective dose
- B. An opioid–acetaminophen combination, since a surgical extraction is a painful procedure
- C. Codeine alone, holding the ibuprofen back for breakthrough pain over the weekend
- D. A routine delayed opioid prescription, to be filled if the ibuprofen proves inadequate

**Answer A:** Ibuprofen 400 mg with acetaminophen 500–1000 mg, at the lowest effective dose

The ADA's 2024 acute dental pain guideline places NSAID alone, or NSAID plus acetaminophen, first-line for most adults, keeping opioids for the uncommon case where non-opioids fail or are contraindicated; ibuprofen 400 mg with acetaminophen 500–1000 mg matches or beats typical opioid combinations with fewer harms, and NSAIDs act on exactly the prostaglandin mechanism that generates inflammatory dental pain. B selects on the invasiveness of the procedure rather than the evidence. C makes an opioid the base analgesic and discards the drug whose mechanism fits the pain. D is the "just-in-case" delayed prescription the guideline's good-practice statements advise against. Count every acetaminophen source, including combination products, and keep the total within the adult ceiling.

**Common trap:** Letting the invasiveness of the procedure, not the evidence, pick the analgesic.

Source: [ADA 2024 Clinical Practice Guideline — Acute Dental Pain Management (adolescents, adults and older adults)](https://www.ada.org/-/media/project/ada-organization/ada/ada-org/files/resources/research/2024-pain-guidelines/14205c_chairside_guide_adult_extraction_final.pdf)

## Question 6

A 31-year-old woman at 24 weeks' gestation has irreversible pulpitis in a lower molar and is in severe pain. She is otherwise healthy, and her obstetrician has given no specific analgesic instruction. What is the appropriate pain plan while definitive dental treatment is arranged?

- A. Ibuprofen 600 mg three times daily, since NSAIDs are safest in the second trimester
- B. Naproxen at the lowest effective dose, because it is pregnancy category B
- C. No analgesic at all until after delivery, when drug exposure no longer matters
- D. Acetaminophen for pain, avoiding NSAIDs from about 20 weeks unless specifically advised

**Answer D:** Acetaminophen for pain, avoiding NSAIDs from about 20 weeks unless specifically advised

Definitive dental treatment is the real analgesic here, and the drug question is settled by FDA pregnancy advice: avoid NSAIDs from about 20 weeks onward unless specifically advised, use the lowest effective dose for the shortest time if they are necessary between 20 and 30 weeks, and avoid them after 30 weeks. At 24 weeks with no obstetric instruction, acetaminophen is the reasonable choice. A treats the second trimester as a safe window that the advice does not grant. B quotes a letter category that no longer exists: the Pregnancy and Lactation Labeling Rule removed A/B/C/D/X in 2015 in favour of narrative sections. C leaves severe pain and untreated pulpitis in place, which is neither analgesia nor safety.

**Common trap:** Trusting a remembered pregnancy letter category instead of current labeling.

Source: [FDA NSAID pregnancy safety communication](https://www.fda.gov/drugs/drug-safety-and-availability/fda-recommends-avoiding-use-nsaids-pregnancy-20-weeks-or-later-because-they-can-result-low-amniotic)

## Question 7

A dental student preparing a prescription for a pregnant patient asks the supervising dentist to confirm the drug's "pregnancy category" from the package insert. She has read the insert twice and can find no letter anywhere in it. What should the supervisor explain?

- A. The letter was omitted in error and should be sought from the manufacturer
- B. Only prescription products still carry letters; over-the-counter labels have now dropped them
- C. The letter categories were removed in 2015 and replaced by narrative sections
- D. The letters were retained but moved to the outer carton, not the insert

**Answer C:** The letter categories were removed in 2015 and replaced by narrative sections

The FDA's Pregnancy and Lactation Labeling Rule, effective June 30, 2015, removed the A/B/C/D/X pregnancy letter categories and replaced them with narrative Pregnancy, Lactation, and Females and Males of Reproductive Potential subsections that must be read rather than looked up. A treats a deliberate regulatory change as a printing omission and sends the student to a manufacturer for something no longer produced. B invents a split between prescription and over-the-counter labeling that the rule does not create. D relocates the letters rather than retiring them. Quoting a remembered category is a recognised trap precisely because the single letter compressed away the nuance the narrative sections now set out, which is the information a prescribing decision in pregnancy actually needs.

**Common trap:** Hunting for a letter category that has not appeared on labeling for a decade.

Source: [FDA Pregnancy and Lactation Labeling Rule (PLLR)](https://www.fda.gov/drugs/labeling-information-drug-products/questions-and-answers-pregnancy-and-lactation-labeling-rule)

## Question 8

A healthy 35-year-old man has severe pain from a necrotic lower molar with a localised buccal swelling. He is afebrile, with no trismus, no lymphadenopathy and no spreading cellulitis. He asks for antibiotics to settle it down before the root canal. What is the appropriate management?

- A. Amoxicillin for seven days now, with the pulpectomy arranged once the course finishes
- B. Definitive dental treatment with analgesia now; antibiotics follow a systemic indication
- C. Amoxicillin with metronidazole today, since a localised swelling is already an abscess
- D. Analgesia alone for a week, deferring both antibiotics and treatment until it settles

**Answer B:** Definitive dental treatment with analgesia now; antibiotics follow a systemic indication

For an immunocompetent adult with pulpal or periapical pain and localised swelling, the treatment is definitive dental treatment — pulpectomy, extraction or drainage — plus analgesia; systemic antibiotics are decided by systemic involvement or another clinical indication, not by pain and swelling alone. This patient has no fever, trismus, lymphadenopathy or spreading cellulitis. A is the "antibiotics to calm it down before the root canal" prescription the guideline was written to eliminate, and it postpones the only step that removes the source. C compounds the same error with a second drug, treating the word abscess as its own indication when antibiotics do not drain. D withholds the definitive treatment too, leaving an untreated source and uncontrolled pain.

**Common trap:** Reading a localised swelling as an antibiotic indication in a systemically well adult.

Source: [ADA antibiotic guideline for urgent pulpal/periapical pain and swelling](https://www.ada.org/resources/research/science/evidence-based-dental-research/antibiotics-for-dental-pain-and-swelling)

## Question 9

A 58-year-old man with a history of angina develops chest tightness during an implant consultation. He is conscious and seated upright, he carries his own sublingual nitroglycerin, and the assistant has brought oxygen and the emergency kit. What must be established before the tablet is given?

- A. Whether he has eaten recently, since food alters sublingual absorption
- B. Whether he has taken aspirin today, which would bar the nitroglycerin
- C. Whether his systolic pressure exceeds 160, the threshold for nitrates
- D. Whether he has taken sildenafil, tadalafil, vardenafil or avanafil

**Answer D:** Whether he has taken sildenafil, tadalafil, vardenafil or avanafil

Nitroglycerin is contraindicated with the PDE-5 inhibitors sildenafil, tadalafil, vardenafil and avanafil, because the combination can cause severe hypotension, syncope or myocardial ischaemia; the question is asked before reaching for the bottle. The rest of the response is to stop, position, give oxygen, activate emergency services, then one tablet sublingually at the first sign of the attack, repeated every 5 minutes to no more than three tablets in 15 minutes. A is irrelevant to a sublingual route that bypasses the gut and its first-pass loss entirely. B inverts standard first aid: chewed aspirin belongs alongside oxygen and emergency activation in suspected myocardial infarction, not on a contraindication list. C invents a blood-pressure threshold that nitroglycerin labeling does not set for an anginal attack.

**Common trap:** Reaching for the emergency drug before asking the one question that bars it.

Source: [Nitroglycerin sublingual tablets FDA labeling](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=61759752-dd07-4bed-8079-b578e3930519)

## Question 10

A 63-year-old woman with a prosthetic heart valve needs an extraction. She also had a knee replaced last year, and her chart records anaphylaxis to amoxicillin. Her orthopaedic surgeon's office has sent a note asking for "the usual cover for the joint." What should she receive?

- A. Azithromycin or clarithromycin 500 mg, or doxycycline 100 mg, before the extraction
- B. Cephalexin 2 g before the extraction, as the standard penicillin-allergy alternative
- C. Clindamycin 600 mg before the extraction, since the valve and joint both qualify
- D. No prophylaxis at all, because a documented anaphylaxis removes every option

**Answer A:** Azithromycin or clarithromycin 500 mg, or doxycycline 100 mg, before the extraction

Prophylaxis requires a highest-risk cardiac condition and a procedure that manipulates gingival tissue or the periapical region or perforates oral mucosa; her prosthetic valve and the extraction satisfy both, while the prosthetic knee is generally not an indication. With anaphylaxis to amoxicillin the permitted alternatives are azithromycin or clarithromycin 500 mg, or doxycycline 100 mg. B fails the operational rule that survives the unsettled cross-reactivity debate: no cephalosporin after anaphylaxis, angiedema or urticaria to penicillin or ampicillin. C offers the agent the 2021 statement removed, and credits the joint for an indication it does not create. D abandons an indicated regimen when non-beta-lactam options exist.

**Common trap:** Letting the joint, or a remembered clindamycin alternative, drive the prophylaxis decision.

Source: [2021 AHA Scientific Statement + current AHA wallet card](https://www.heart.org/-/media/files/health-topics/infective-endocarditis/infective-endocarditis-wallet-card.pdf)

## Next step

[Take the free INBDE practice test](https://dentovio.com/inbde/free-practice-test)

Official reference: [JCNDE — Integrated National Board Dental Examination](https://jcnde.ada.org/inbde). Original exam-style questions written for study, never recalled exam content. Independent educational preparation, not clinical advice, and not affiliated with or endorsed by the Joint Commission on National Dental Examinations.