Antibiotic Use In Dentistry

Kevin Nakagaki, D.D.S.

Director, Hospital Dental Clinic University of Minnesota

Writing Prescriptions

Rx: Drug Name (can be generic) Unit Dose (ex: Pen V K 500 mg, Elixer, Sol’n) Disp: # of pills, milliliters (ml) Sig: Directions for use. q24h (daily), q12h, q8h, q6h, q4h, prn pain, till gone Refills__ Signature DEA #

General Rules

  Write Legibly!!

Remember your audience (Generally non-docs) this will improve compliance.

   Preferable to order specific hourly dosage time (q12h vs. bid, q8h vs. tid, etc.) Sig: Specify # of pills to take each dose Prescribe an endpoint. (prn pain, till gone)

Barry Brainfart Dental Clinic 666 Bite Me Ln Crossbyte Falls, MN Ph: 555-YOU-HURT Pt. Name: Address: DOB:

 Rx: Date:  Disp:  Sig: Refill____ Barry Brainfart, DDS DEA:______________________

Antibiotic Strategies

   Cardinal Rules: 1) Use the right drug. 2) Use the right dose. 3) Use the correct dosing schedule. 4) Correct duration.

Hard and Fast —Especially early. Why?

Use a loading dose to rapidly achieve therapeutic blood levels.

 Avoid combinations of bacteriostatic and bacteriocidal drugs.

Considerations

    Gram Positive?

Gram Negative?

Mixed Infection?

Anaerobes?

Discussion: Antibiotic Choice

    Narrow Spectrum?

Extended/Broad Spectrum?

Designer Antibiotics?

Anaerobes? Consider if the infection is present > 3days or if no improvement.

Narrow Spectrum Antibiotics

     Specific for the pathogen.

Fewer disturbances of non-pathogenic bacteria.

Fewer side effects.

Rapid response for sensitive organisms.

Ex: Pen VK, Pen G, Erythromycin

Broad Spectrum Antibiotics

 Affects both Gram + and Gram – bacteria, better for mixed infections.

 May give up some effectiveness for Gram + to gain effectiveness for Gram -.  Examples: Amoxicillin, Ampicillin

Common Pathogens

Necrotic pulp and apical abscesses Obligate anaerobic bacteria Gram negative rods Prevotella & porphyomonas spp.

Fusobacterium spp.

Campylobacter rectus Gram positive rods Eubacterium spp.

Actinomycetes spp.

Gram positive cocci Peptostreptococcus spp.

Facultative anaerobic bacteria Gram positive cocci Strep and Entercoccus spp.

Common Pathogens

 Periodontal Diseases Gingivitis Fuso, strep, & actinomycetes Adult peritonitis Bacteroides, porphyomonas, peptostreptococcus & prevotella Acute necrotizing ulcerative gingivitis Spirochetes, prevotella, fuso Localized juvenile periodontitis Actinobacillus

Common Pathogens

 Fungal Infections Candida spp.

Mucorales spp.

Let’s Talk About Resistance

 Three main types – Chromosome mediated  Spontaneous mutations  Non-major form of drug resistance  Rarely lead to complete resistance – Plasmid mediated (conjugation)  VERY important from clinical standpoint  Mostly gram negs  Mediate resistance to multiple drugs  High transfer rate from cell to cell – Transposon (transduction and transformation)  Phage mediated  Clinically important for Gram +

Antibiotic Choices

ß-Lactams

 Natural penicillins – Pen VK and Pen G    MOA: Inhibit cell wall synthesis Dose: 250-500 mg qid x 7-10 days Contraindications: – Allergies – Poor renal fxn    Adverse events: GI upset Drug interactions: oral contraceptives Pregnancy category B

ß-Lactams

 Natural penicillins – Pen VK and Pen G  Bactericidal  Allergic reaction: rare (4 per 100,000)  Spectrum: – Strep, staph, enterococcus, neiseria, treponema, listeria  Resistance: – Mostly staph (>80%)

ß-Lactams

 Amino-penicillins – Amoxicillin, ampicillin    MOA: Inhibit cell wall synthesis Dose: 250-500 mg q 8 h x 7-10 days Contraindications: – Allergies – Poor renal fxn    Adverse events: GI upset Drug interactions: oral contraceptives Amoxicillin and clavulanic acid (Augmentin)

ß-Lactams

 Amino-penicillins – Amoxicillin, ampicillin  Bactericidal  “ampicillin” rash (4-10%)  Spectrum: – Strep, staph, enterococcus, neiseria, treponema, listeria, E. coli, proteus, H. Flu, shigella, salmonella  Resistance: – Entero, citro, serratia, proteus vulagris, provedincia, morganella, pseudomonas aeriginosa, acinetobacter

Cephalosporins

 Cephalexin (Keflex) – MOA: Inhibit cell wall synthesis – Dose: 250-1000mg q 6 h x 7-10 days – Contraindications:   Allergies Poor renal fxn – Adverse events: mild GI – Drug interactions: probenecid – Pregnancy category B

Cephalosporins

 Cephalexin (Keflex) – Bactericidal – Spectrum:  Gram + – Resistance:  Methicillin resistant gram + – Low cross sensitivity with PCN

Lincosamides

 Clindamycin (Cleocin) – MOA: binds to the 50S ribosomal subunit and inhibits protein synthesis – Dose: 100-450mg q 6 h x 7-10 days – Precautions:  Poor hepatic fxn – Adverse events: GI upset,

pseudomembraneous colitis

– Drug interactions: neuromuscular blocking agents – Pregnancy category B

Lincosamides

 Clindamycin – Bactericidal or static depending on concentration – Spectrum:  Gram +, anaerobes, parasites – Resistance  Enteroccocus *Clostridium diff. pseudomembranous colitis!!

Macrolides

 Azithromycin (Zithromax), clarithromycin (Biaxin) – MOA: bind to the 23S rRNA in the 50S subunit ribosome – Dose: 250-500 mg/day x 5-10 days – Precautions :  Poor hepatic fxn – Adverse effects: GI – Drug interactions: Cytochrome P-450 (Remember Seldane?) – Pregnancy category B

Macrolides

 Azithromycin, clarithromycin – Bactericidal – Spectrum:  Gram +, gram -, anaerobes – Resistance:  B. fragilis, and strep pneumo

Tetracyclines

 Doxycycline (Vibramycin) – MOA: inhibit protein synthesis by preventing aminoacyl transfer RNA from entering the acceptor sites on the ribosome – Dose: 100mg qd-bid x 7-14 days – Contraindications:   Food pregnancy – Adverse events: GI – Drug interactions: anti-epileptics – Pregnancy category D

Tetracyclines

 Doxycycline – Bacteriostatic – Spectrum:  Broad, Gram +, -, anaerobes, aerobes, and spirochetes – Resistance:  Widespread, cross resistance – PHOTO SENSITIVITY!!!

Nitroimidazoles

 Metronidazole (Flagyl) – MOA: reduced intermediate interacts and breaks the bacterial or parasitic DNA – Dose: 250-1000 mg q 6-8 h x 7-10 days – Precautions : poor hepatic fxn – Adverse events: HA, N/V/D – Drug interactions: EtOH, warfarin, Li+ – Pregnancy category D

Nitroimidazoles

 Metronidazole – Bactericidal – Spectrum:  Gram - anaerobes – Resistance:  Rare, H. Pylori?

– Unpleasant metallic taste

Fluoroquinolones

 Ciprofloxacin (Cipro) – MOA: Inhibition of DNA gyrase, and Topo II – Dose: 250-500 mg qd x 7-10 days – Contraindications: <18 yrs old, pregnancy – Adverse events: spontaneous tendon rupture – Drug interactions: probenacid, warfarin – Pregnancy category C

Fluoroquinolones

 Ciprofloxacin – Bactericidal – Spectrum:  Very broad except B. frag – Resistance:  MRSA, MRSE

Antifungals

 Nystatin – MOA: inhibit cell wall synthesis – Dose: 5 ml swish and swallow q 4 h x 10-14 d – GI upset – Drug interactions: minor – Pregnancy category C

Antifungals

 Clotrimazole (Mycelex), ketoconazole (Nizoral), fluconazole (Diflucan) – MOA: inhibit cell wall synthesis – Dose: 200-800 mg qd x up to 12 months – GI upset – Drug interactions: major p-450 enzyme inhibitor, interactions with many drugs – Pregnancy category C

ADA/AAOS Advisory Statement July 1997

AAOS Statement

Antibiotic prophylaxis is NOT recommended for dental patients with plates, pins, or screws, nor is it routinely recommended for MOST dental patients with TOTAL JOINT REPLACEMENTS.

AAOS recommendations

 Prophylaxis recommended – Total joint replacement within the last two years AND:  Compromised immune system

OR

 Type 1 DM

OR

 Previous prosthetic joint infections

OR

 Malnourishment

OR

 Hemophilia

AAOS recommendations

 Prophylaxis antibiotic recommendations – Same as AHA

OR

– No specific regimen recommended – Keflex is often the first drug of choice

Legal Considerations

    The dentist may not be aware of the patient’s medical condition.

 Physician may not be aware of the advisory statements or of the dental procedure to be performed.

Vicarious Liability: “The devil made me do it” “I forgot to take my antibiotic.” Documentation.

Legal Considerations

    I forgot my antibiotics!

Animal studies have shown antibiotics are effective up to 2 hours after the procedure.

 Differentiate between prophylaxis vs. treatment of an early infection.

Take into consideration patient’s risk factors.

Legal twists.

In Summary….

Principles of Antibiotic Therapy

 Therapeutic effectiveness – Clinical indications  Pharmcodynamics, pharmacokinetics – Age and extent of infection

Patient factors

  Age, allergies, compliance, pregnancy risk Patient function – Renal, hepatic, immunosuppresion, route applicability  Cost – Brand name, length of course, alternatives?

Pen VK

Drug Name

Amoxicillin Ampicillin Cephalexin Clindamycin Azithromycin Clarithromycin Augmentin Doxycycline Metronidazole Ciprofloxacin Nystatin Clotrimazole Ketoconazole Fluconazole

Cost

Cost of Therapy $ (~10 Days) Generic if Available

6.81

8.41

12.45

15.65

38.45

41.52

74.45

76.82

5.15

9.65

76.65

9.86

97.05

30.69

116.25

Dental Infection Acute—Rapid growth < 3 days Pen VK 500mg q6h or Amox 500mg q8h or Cephalosporin Allergic to PCN Chronic > 3 days Think Anaerobes Add Metronidazole 250-500mg To PCN, Amox, or Ceph Clindamycin 300mg q8h Clindamycin 300mg q8h or Cephalosporin (check allergic Rxn) or Azith or Clarithromycin