RDA Dental Pharmacology and Pain Management — Questions and Answers
Question 1: A patient reports taking warfarin (Coumadin). Which concern is most relevant to the dental team before any invasive procedure?
- The patient may experience increased sensitivity to local anesthetics
- The patient has an elevated risk of prolonged bleeding due to anticoagulation (Correct answer)
- The patient may have a reduced response to antibiotics
- The patient is at higher risk for a hypertensive crisis in the chair
Correct answer: The patient has an elevated risk of prolonged bleeding due to anticoagulation
Warfarin is an anticoagulant that inhibits vitamin K-dependent clotting factors, increasing bleeding time. Before invasive procedures, the dental team must know the patient's INR (International Normalized Ratio). Stopping warfarin without medical consultation can expose patients to dangerous thrombotic events, so the prescribing physician must be consulted.
Question 2: Epinephrine is added to local anesthetic cartridges primarily to:
- Reduce the risk of allergic reaction to the anesthetic
- Lower the patient's blood pressure during the procedure
- Cause vasoconstriction, which prolongs anesthetic duration and reduces systemic absorption (Correct answer)
- Prevent post-operative infection at the injection site
Correct answer: Cause vasoconstriction, which prolongs anesthetic duration and reduces systemic absorption
Epinephrine is a vasoconstrictor that constricts local blood vessels, keeping the anesthetic in the injection site longer and slowing its absorption into the bloodstream. This prolongs the duration of anesthesia, deepens the block, and reduces the risk of systemic toxicity from rapid absorption.
Question 3: Amoxicillin is the first-line antibiotic for dental infection prophylaxis in eligible patients with cardiac conditions. For a patient who is allergic to penicillin, which antibiotic is the standard alternative?
- Metronidazole (Flagyl)
- Clindamycin (Correct answer)
- Ciprofloxacin
- Tetracycline
Correct answer: Clindamycin
Per American Heart Association guidelines, clindamycin is the recommended alternative for infective endocarditis prophylaxis in patients unable to take penicillin/amoxicillin due to allergy. Metronidazole targets anaerobes and protozoa but is not the AHA-recommended prophylaxis alternative. Ciprofloxacin and tetracycline are not indicated for this purpose.
Question 4: A patient who takes an SSRI antidepressant asks if they can take ibuprofen for post-operative pain. The dental assistant should advise them to:
- Take ibuprofen freely—SSRIs have no interaction with NSAIDs
- Consult the prescribing physician, as SSRIs combined with NSAIDs increase the risk of gastrointestinal bleeding (Correct answer)
- Avoid all pain medications because SSRIs cause extreme sensitivity to analgesics
- Use ibuprofen only at double the normal dose to overcome the interaction
Correct answer: Consult the prescribing physician, as SSRIs combined with NSAIDs increase the risk of gastrointestinal bleeding
SSRIs inhibit platelet serotonin uptake, impairing platelet aggregation. When combined with NSAIDs like ibuprofen (which also inhibit platelet function and damage the gastric mucosa), the risk of GI bleeding increases significantly. Patients should be directed to consult their prescribing physician before combining these medications.
Question 5: Which category of drugs can cause gingival hyperplasia (overgrowth of gum tissue) as a side effect, requiring close attention during periodontal assessment?
- Calcium channel blockers (e.g., nifedipine) (Correct answer)
- Beta-blockers (e.g., metoprolol)
- ACE inhibitors (e.g., lisinopril)
- Diuretics (e.g., furosemide)
Correct answer: Calcium channel blockers (e.g., nifedipine)
Calcium channel blockers—particularly nifedipine (used for hypertension and angina)—are well-known to cause drug-induced gingival hyperplasia in some patients. Other drugs with this side effect include phenytoin (seizure medication) and cyclosporine (immunosuppressant). The dental team must document all current medications at every appointment.
Question 6: The maximum recommended dose of lidocaine (2% with 1:100,000 epinephrine) for a healthy adult is approximately 4.4 mg/kg, not to exceed 300 mg. If a cartridge contains 36 mg of lidocaine, what is the maximum number of cartridges that can be administered to a 70 kg healthy adult?
- 2 cartridges
- 4 cartridges
- 8 cartridges (Correct answer)
- 10 cartridges
Correct answer: 8 cartridges
Maximum dose = 4.4 mg/kg × 70 kg = 308 mg; capped at 300 mg per package insert. Dividing 300 mg by 36 mg/cartridge = 8.3, rounded down to 8 cartridges. The dental assistant must know this calculation to help recognize when the number of requested cartridges approaches a toxic threshold.
RDA Dental Pharmacology and Pain Management
A patient reports taking warfarin (Coumadin).
Which concern is most relevant to the dental team before any invasive procedure?