Pharmacology
Each Rx in the OSCE is worth 4 marks, broken into Drug · Disp · Sig · Repeats. One missing instruction costs a quarter of the question. The fastest way to bank these marks is to memorize the dozen blocks below verbatim.
4×
Marks per Rx
01
Antibiotic Decision Ladder
The "AMC-D" ladder. Climb only as needed.
A
Amoxicillin500 mg PO TID × 7 days
First line for almost everything dental: cellulitis, abscess, pericoronitis.
M
Metronidazole250–500 mg PO TID × 7 days
Adjunct to amoxicillin for severe periodontal infections (necrotizing). Anaerobic coverage.
A
Azithromycin500 mg loading, then 250 mg PO daily × 4 days
PCN allergy + many drug interactions to avoid. Macrolide of choice.
C
Clindamycin300 mg PO QID × 7 days
PCN allergy + severe infection. Broad anaerobic. C. difficile risk.
D
Doxycycline100 mg PO BID day 1, then daily × 7 days
Aggressive periodontitis (host modulation at low dose). Avoid in < 8 yo & pregnancy.
M
Memory Hook · "AMC-D"
Amoxicillin → Metronidazole → Azithromycin → Clindamycin → Doxycycline. Climb the ladder only when you need to.
02
Antibiotic Prescriptions
Memorize verbatim. The Disp number always equals the total tablets needed for the full course.
Amoxicillin 500 mg
First-line — abscess, cellulitis, pericoronitis
- Drug
- Amoxicillin 500 mg capsules
- Disp
- 21 capsules
- Sig
- 1 cap PO TID × 7 days
- Repeats
- 0
Metronidazole 250 mg
Adjunct in severe perio / necrotizing
- Drug
- Metronidazole 250 mg tablets
- Disp
- 21 tablets
- Sig
- 1 tab PO TID × 7 days
- Repeats
- 0
Azithromycin 250 mg
PCN allergy · drug-interaction concerns
- Drug
- Azithromycin 250 mg tablets
- Disp
- 6 tablets
- Sig
- 2 tabs day 1, then 1 tab daily × 4 days
- Repeats
- 0
Clindamycin 300 mg
PCN allergy + severe infection
- Drug
- Clindamycin 300 mg capsules
- Disp
- 28 capsules
- Sig
- 1 cap PO QID × 7 days
- Repeats
- 0
!
Trap · "Avoid Erythromycin / Clarithromycin"
Patients on β-blockers, Ca-channel blockers, digoxin, theophylline, statins, warfarin → many interactions. Default to azithromycin.
03
Analgesic Decision Tree
Patient type drives the answer. Three populations, three different first lines.
Pick by patient — adult · child · pregnant
04
Analgesic Prescriptions
Adults Adult
Acetaminophen 500 mg
Mild-moderate pain · all populations
- Drug
- Acetaminophen 500 mg tablets
- Disp
- 20 tablets
- Sig
- 1-2 tabs PO q4-6h PRN; max 4 g/day
- Repeats
- 0
Ibuprofen 400 mg
Mild-moderate pain · adult
- Drug
- Ibuprofen 400 mg tablets
- Disp
- 20 tablets
- Sig
- 1 tab PO q6h PRN with food
- Repeats
- 0
Tylenol-3 (Acet 300 / Cod 30)
Moderate pain · adult · short course
- Drug
- Acetaminophen 300 mg / Codeine 30 mg / Caffeine 15 mg
- Disp
- 20 tablets
- Sig
- 1-2 tabs PO q4-6h PRN
- Repeats
- 0
Percocet (Acet 325 / Oxy 5)
Moderate-severe pain · adult
- Drug
- Acetaminophen 325 mg / Oxycodone 5 mg
- Disp
- 20 tablets
- Sig
- 1 tab PO q4-6h PRN
- Repeats
- 0
Tramadol 50 mg
Moderate pain · NSAID alternative
- Drug
- Tramadol 50 mg tablets
- Disp
- 20 tablets
- Sig
- 1 tab PO q4-6h PRN; max 400 mg/day
- Repeats
- 0
Children & pregnancy Child Pregnant
Children's Acetaminophen 160 mg/5 mL
Pediatric · weight-based
- Drug
- Children's Acetaminophen 160 mg / 5 mL
- Disp
- 120 mL
- Sig
- 10-15 mg/kg PO q4-6h PRN; max 5 doses/day
- Repeats
- 0
Children's Ibuprofen 100 mg/5 mL
Pediatric · ≥ 6 months
- Drug
- Children's Ibuprofen 100 mg / 5 mL
- Disp
- 120 mL
- Sig
- 5-10 mg/kg PO q6-8h PRN with food
- Repeats
- 0
!
Trap · NSAID-NO list
Anticoagulants · bleeding disorders · severe asthma · heart failure · peptic ulcer/GERD/Crohn's · kidney disease · kidney transplant · prior MI · lithium use · 3rd-trimester pregnancy. Default to acetaminophen.
05
Antibiotic Prophylaxis
Single dose 30-60 min before procedure. Indications are narrow.
Indications
| Cardiac | Joint |
|---|---|
|
|
Regimen — single dose 30-60 min pre-procedure
Amoxicillin 2 g
Standard prophylaxis
- Drug
- Amoxicillin 500 mg capsules
- Disp
- 4 capsules
- Sig
- Take all 4 caps (2 g) 30-60 min before appointment
- Repeats
- 0
Cephalexin 2 g
Non-anaphylactic PCN allergy
- Drug
- Cephalexin 500 mg capsules
- Disp
- 4 capsules
- Sig
- Take all 4 caps (2 g) 30-60 min before appointment
- Repeats
- 0
Azithromycin 500 mg
Anaphylactic PCN allergy
- Drug
- Azithromycin 250 mg tablets
- Disp
- 2 tablets
- Sig
- Take both tabs (500 mg) 30-60 min before appointment
- Repeats
- 0
Clindamycin 600 mg
Anaphylactic PCN allergy (alternative)
- Drug
- Clindamycin 300 mg capsules
- Disp
- 2 capsules
- Sig
- Take both caps (600 mg) 30-60 min before appointment
- Repeats
- 0
06
Drug-Disease Interactions
The drugs the OSCE expects you to avoid per condition.
| Condition / Drug | Avoid | Reason |
|---|---|---|
| Warfarin | Aspirin · NSAIDs · Erythromycin · Metronidazole | ↑ INR / bleeding |
| β-blockers | Erythromycin · Clarithromycin · NSAIDs (chronic) | ↑ β-blocker level / ↓ effect |
| Calcium-channel blockers | Erythromycin · Clarithromycin | ↑ CCB level → hypotension |
| Digoxin | Erythromycin · Clarithromycin · Acetaminophen | ↑ digoxin toxicity |
| Theophylline | Erythromycin · Clarithromycin · Ciprofloxacin | ↑ theophylline toxicity |
| Statins | Erythromycin · Clarithromycin | Rhabdomyolysis risk |
| SSRIs / Tramadol | Tramadol with SSRI | Serotonin syndrome |
| Methotrexate | NSAIDs · Aspirin | ↑ MTX toxicity |
| Lithium | NSAIDs · Tetracyclines · Metronidazole | ↑ lithium toxicity |
| MAOIs | Epinephrine (limit) · Meperidine · Tramadol | Hypertensive crisis · serotonin syndrome |
| Sulfonylureas (diabetes) | Aspirin · NSAIDs | Hypoglycemia |
| Viagra / Cialis | Nitroglycerin | Severe hypotension |
| Cocaine (recent use) | Epinephrine | Hypertensive crisis · MI |
✓
Key · The "epi limit" rule
Cardiac patients · uncontrolled hypertension · recent MI · MAOI users · cocaine users → 0.04 mg total epinephrine (≈ 2 cartridges of 1:100,000). Otherwise the limit is 0.2 mg (~10 cartridges).