Antibiotic Use In Dentistry Dr. Soukaina Ryalat

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 #

Most antibiotics have 2 names, the trade or brand name, created by the drug company that manufactures the drug, and a generic name, based on the antibiotic's chemical structure or chemical class. Trade names such as Keflex and Zithromax are capitalized. Generics such as cephalexin and azithromycin are not capitalized.

Antibiotics have 2 names : Generic name ; based on chemical constituents of the drug & it is not capitalized . Trade name ; created by the drug company & it is capitalized. Examples : generic name: cefalexin ( 1st generation cephalosporin) Trade name: Sporidex produced by Ranbaxy company & Keflex by Lilly company.

Antibiotic Strategies Cardinal Rules: 1) Use the right drug. 2) Use the right dose. 3) Use the correct dosing schedule. 4) Correct duration. Use a loading dose to rapidly achieve therapeutic blood levels. Avoid combinations of bacteriostatic and bacteriocidal drugs.

Most odontogenic infections are caused by mixed organisms . Rules for prescribing antibiotics: Use the write drug Use the write dose Use the correct dose schedule & correct duration. Most odontogenic infections are caused by mixed organisms . When we prescribe antibiotic we have to reach MIC ( Minimum Inhibitory Concentration: is the smallest concentration of an antimicrobial needed to stop bacterial growth ). Most of the drugs take their action within 2-3 days but we give an extra 2 days to make sure that the patient has taken the drug the right way & the desired effect has been achieved ( patient compliance).

Considerations Gram Positive? Gram Negative? Mixed Infection? Anaerobes?

Broad Spectrum Antibiotics Affects both Gram + and Gram – bacteria, better for mixed infections. 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.

Facultative anaerobic bacteria Gram positive cocci Peptostreptococcus spp. Facultative anaerobic bacteria Strep and Entercoccus spp.

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

Antibiotic 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 V and Pen G MOA (mechanism of action): 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 V 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: Resistance: Gram + Resistance: Methicillin resistant gram + Low cross sensitivity with PCN

Cephalosporins, 1st generation Cefadroxil DURICEF Cefazolin ANCEFKEFZOL Cephalexin KEFLEX Mainly skin and soft-tissue infections Gastrointestinal upset and diarrhea NauseaAllergic reactions

Cephalosporins, 2nd generation CefaclorCefoxitin MEFOXIN Cefprozil CEFZIL Cefuroxime CEFTINZINACEF Loracarbef Some respiratory infections and, for cefoxitin MEFOXIN , abdominal infectionss Gastrointestinal upset and diarrheaNauseaAllergic reactions

Cephalosporins, 3rd generation Cefixime SUPRAX Cefdinir OMNICEF Cefditoren SPECTRACEF CefoperazoneCefotaxime CLAFORAN Cefpodoxime VANTIN

Ceftazidime FORTAZTAZICEF Ceftibuten CEDAX Ceftizoxime CEFIZOX Ceftriaxone ROCEPHIN

3d generation Given by mouth: Broad coverage of many bacteria for people with mild-to-moderate infections, including skin and soft-tissue infections. Given by injection: Serious infections (such as meningitis or infections acquired in a hospital)

Cephalosporins, 4th generation Cefepime MAXIPIME Serious infections (including Pseudomonas infections), particularly in people with a weakened immune system and infections due to susceptible bacteria resistant to other antibiotics

Cephalosporins, 5th generation Ceftobiprole Complicated skin infections, including foot infections in people with diabetes, due to susceptible bacteria, such as Escherichia coli, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus (MRSA)

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 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: Resistance: 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: GI upset. Drug interactions: warfarin, Li+ Pregnancy category D

Nitroimidazoles Metronidazole Bactericidal Spectrum: Resistance: 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: Resistance: 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 Regulations

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.

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

Prophylaxis antibiotic recommendations 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. Documentation.

Pharmaceutical pregnancy categories : Category A : Adequate & well controlled studies on both humans & animals have failed to demonstrate risk to the fetus. Category B : Animal reproduction studies have failed to demonstrate a risk to the fetus & there are no adequate & well controlled studies in pregnant women. Category C : Animal reproduction studies have shown an adverse effect on the fetus & there are no adequate & well controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risk.

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?

Cost of Therapy $ (~10 Days) Generic if Available Drug Name Cost of Therapy $ (~10 Days) Generic if Available Pen VK 6.81 Amoxicillin 8.41 Ampicillin 12.45 Cephalexin 15.65 Clindamycin 38.45 Azithromycin 41.52 Clarithromycin 74.45 Augmentin 76.82 Doxycycline 5.15 Metronidazole 9.65 Ciprofloxacin 76.65 Nystatin 9.86 Clotrimazole 97.05 Ketoconazole 30.69 Fluconazole 116.25