ABP ABP Pharmacology and Antimicrobials 2 — Questions and Answers
Question 1: A patient on long-term phenytoin therapy presents with generalized gingival enlargement. What is the primary pharmacological mechanism causing this condition?
- Increased histamine release from mast cells
- Fibroblast proliferation and decreased collagen degradation (Correct answer)
- Increased prostaglandin E2 production
- Immune-mediated gingival infiltration by lymphocytes
Correct answer: Fibroblast proliferation and decreased collagen degradation
Phenytoin-induced gingival enlargement results from fibroblast overstimulation and reduced collagenase activity, leading to excessive collagen accumulation.
Question 2: Which calcium channel blocker is most frequently associated with drug-influenced gingival enlargement?
- Diltiazem
- Verapamil
- Nifedipine (Correct answer)
- Amlodipine
Correct answer: Nifedipine
Nifedipine has the highest reported prevalence of drug-influenced gingival enlargement among calcium channel blockers, affecting up to 20% of users.
Question 3: In patients taking warfarin, what INR range is generally considered acceptable for routine periodontal surgical procedures?
- INR < 1.5
- INR 1.5–2.0
- INR 2.0–3.0 with local hemostatic measures (Correct answer)
- INR > 3.5 requires hospitalization only
Correct answer: INR 2.0–3.0 with local hemostatic measures
Current evidence supports performing routine periodontal surgery in anticoagulated patients with INR up to 3.0 using local hemostatic measures without altering anticoagulation.
Question 4: Which bisphosphonate route of administration carries the highest risk of medication-related osteonecrosis of the jaw (MRONJ) in periodontal patients?
- Weekly oral alendronate
- Daily oral risedronate
- Intravenous zoledronic acid (Correct answer)
- Transdermal estrogen with oral alendronate
Correct answer: Intravenous zoledronic acid
Intravenous bisphosphonates such as zoledronic acid used in oncology have dramatically higher MRONJ risk than oral bisphosphonates due to greater bioavailability and potency.
Question 5: Metronidazole is contraindicated with which commonly prescribed cardiovascular medication due to risk of a disulfiram-like reaction and potentiation of anticoagulation?
- Atorvastatin
- Warfarin (Correct answer)
- Lisinopril
- Metoprolol
Correct answer: Warfarin
Metronidazole inhibits CYP2C9, increasing warfarin plasma levels and risk of bleeding, and can also cause a disulfiram-like reaction if alcohol is consumed.
Question 6: What is the recommended duration of systemic metronidazole (500 mg) plus amoxicillin (500 mg) adjunctive therapy for generalized aggressive periodontitis according to most clinical protocols?
- 3 days
- 5 days
- 7–8 days (Correct answer)
- 14 days
Correct answer: 7–8 days
The most studied and commonly recommended protocol is 500 mg of each antibiotic three times daily for 7–8 days, coinciding with or immediately after full-mouth debridement.
ABP ABP Pharmacology and Antimicrobials 2
A patient on long-term phenytoin therapy presents with generalized gingival enlargement.
What is the primary pharmacological mechanism causing this condition?