What are macrolides?
Contain many-member lactone rings to which are attached one or more deoxy sugars
What is the mechanism of erythromycin?
Inhibits protein synthesis by binding to 50S ribosomal subunits of sensitive microorganisms
What is erythromycin most effective against?
Gram positive cocci (staph and strep), and gram positive bacilli and some gram negative
What happens when erythromycin passes through the first pass?
Cholestatic hepatitis - causes smooth muscle contraction as it goes through the bile duct, causing bile to back up into the liver
As erythromycin goes through the GI tract, it kills bacteria and causes what?
What drug is no longer effective against oral organisms due to resistance, and are no longer often used in dentistry?
What are the 3 reasons why we don't use erythromycin in dentistry, and is considered a red flag?
- Oral bugs are resistant to drugs
- GI side effects
- Dangerous drug interactions (causing seizures, other serious effects)
Describe clarithromycin (Biaxin)?
- Bactericidal at doses used for SBE prophylaxis (dentistry)
What is the drug of choice for upper respiratory tract infections, and used for STDs?
Azithromycin (Zithromax - "Z-Pack")
What is the half-life of azithromycin?
What type of drug is clindamycin?
What is the mechanism of action of Clindamycin?
Antibacterial - interferes with bacterial protein synthesis - inhibits peptide bond formation
What is an indication for clindamycin?
Orofacial infections and periodontal infections caused by anaerobic bacteria
What is the drug of choice for orofacial infections in penicillin allergic patients, and is also used for endodontic infections?
What is the important preparation of clindamycin?
clindamycin HCl (Cleosin) **Know this
Is clindamycin broad or narrow spectrum?
What are some adverse effects of clindamycin?
- Gastrointestinal - diarrhea, nausea, vomitting, etc
- Super infection
- Clostridium difficile --> pseudomembranous colitis
What cuases Colitis caused by C-diff?
Why don't you want to take an anti-diarrheal agent when they have pseudomembranous colitis?
The C-diff exotoxin will continue to irritate colon, may cause ulceration/perforation allowing bacteria into peritoneum
The greatest number of antibiotic-associated cases of C diff diarrhea are from what?
What is the mechanism of action for tetracycline?
Acts on gram negative bacteria - binds to 30S ribosome = inhibits bacterial protein synthesis
What is tetracyclines impaired by?
Milk products, aluminum, sodium bicarbonate, divalent cations, iron
- Mechanism is chelation and increased gastric pH
What drug is stoed in gingical crevicular fluid, dentin and enamel of unerupted teeth (teratogenic effect)?
What are some adverse effects of tetracyclines?
- Renal toxicity
- FDA Pregnancy category = D
What are some common preparations of tetracycline?
What is the most used tetracycline used in dentistry and what is its mechanism of action?
doxycycline - inhibits collegenase, the enzyme that breaks down connective tissue and bone
What is a subantimicrobial dose that only inhibits collagenase but doesn't kill bacteria?
doxycycline hyclate (Periostat)
Atridox - subgingivally
What is the most potent tetracycline, and causes staining of teeth in adults?
What is locally-applied minocycline called?
Tetracyclines are contraindicated with what?
What are you supposed to do with tetracyclines and iron/dairy/antacids?
Wait a min of 2 hours
What are oral contraceptives drug interactions with antibiotics?
Hormones activated by gut flora - possibility to get pregnant
What are the drug interactions with antibiotics and oral anticoagulants (warfarin)?
- Antimicrobials kill bacteria making vitamin K
- No competitor for warfarin
- Excessive anticoagulation = very thin blood!
What is vancomycin (Vancocin) mechanism of action?
Inhibits bacterial cell wall synthesis, different than penicillins