Antibiotic review

Antibiotics Review
Compiled from Dr. Naegerʼs lectures on 10/16/2007, 10/23/2007 & 10/30/2007.
Meant to be a high-level outline of topics covered; obviously not exhaustive.
Sulfonamides
1. sulfacetamide
• Available in 10%, 15% and 30%; 10% & 15% not very effective; 30% used as a placebo (stings on insertion) therapy in certain patients.
2. trimethoprim
• polytrim--Trimethoprim + Polymyxin-B--#1 prescribed therapy for children w/eye
Penicillin Drugs
Natural Penicillins
1. Penicillin-G: IM
2. Penicillin-V: PO Best against strep
Anti-Staph Penicillins
1. Methicillin: First anti-staph penicillin;
2. Dicloxacillin: 500 mg QID
Penicillins With Gram (-) Spectra
1. Ampicillin: First good gram (-) spectrum penicillin. Widely used by pediatricians.
2. Amoxicillin: Broken down by beta lactamases.
• Dosage: Children weight dependant• Dosage: Adults 250 mg TID (common dose); 500 mg TID & 875 MG BID are also 3. Augmentin: Combination of Amoxicillin + Clavulanic Acid (CA); CA “augments”
amoxicillin such that it is resistant to beta-lactamases.
• Dosage: Strength is given by the amount of Amoxicillin: all forms have 125mg CA.
• Dosage: 875 mg BID or 500 mg TID• Irritating to GI tract; diarrhea is likely. Take after meal to help prevent GI upset.
• Orbital pseudo tumor: Responds well to augmentin.
Cephalosporins
• Cephalosporins have 6-member alpha ring (vs. penicillinʼs 5-member ring)
• Currently, all cephalosporins are said to be be resistant to beta-lactamase.
• Controversy over whether penicillin allergy is contraindication for cephalosporins.
• Dicloxacillin has essentially the same spectrum of activity as cephalosporins.
1. First Generation:
1. cephazolin (500 mg QID IM): can be fortified into eye drop (not at all common)
for patients with bacterial conjunctivitis with severe gram (+) penicillinase resistant organism 2. cephalexin (500 mg QID PO): comparable to dicloxacillin; very inexpensive;
1. cefoxitin: (boards)activity against anaerobes
2. cefuroxime: least expensive; therapeutically equivalent to rest of 2nd
1. ceftriaxome (Rocephin®): IM; children w/recurring ear infections; mixed with
1. ceftazidime: PO; 90%+ effective against pseudomonas;
1. cefepime (Maxipime®): most expensive
Cephalosporin indications:
• Gram (+): cephalexin (Keflex®) 500 mg QID
• Gram (-): cefuroxime (Ceftin®) 500 mg BID
Penicillins and cephalosporins both have the same mechanism, but differ in half-life and spectrum of activity.
Aminoglycosides
Used by O.D.ʼs in topical agents
VERY toxic: reversibly renal toxic; irreversibly ototoxic (destroys hair cells of inner ear)
Myoneural blocking effect
1. streptomycin: not on market any more
2. neomycin: NOT used systemically; in eye drops; NO activity against pseudomonas
3. gentamicin
4. tobramycin
5. Tobradex®: combination of tobramycin & dexamethazone (steroid)
6. Zylet®: combination of tobramycin & loteprednol
Tetracyclines
1. chlortetracycline (Aueromycin®): “Gold mold”; ophthalmic ung.; donʼt see much
2. doxycycline (Vibramycin®): “most likely to encounter”
• longer acting (BID use)
• drug of choice for prophylaxis of anthrax
• used to treat peridontal disease (all tetracyclines are heavily secreted in saliva)
• meibomian gland dysfunction (MGD) treatment
• contraindications: children under 12; pregnant women
3. minocycline (Minocin®); discolored teeth, tongue, gingiva, buccal cavities; believed that prolonged use would permanently discolor teeth.
Erythromycins
1. erythromycin (Ery-Tab®): 333 mg tablet taken TID for infection taken with food.
2. clarithromycin (Biaxin®): worst tasting suspension (“.spit it out, its an asshole!”
story.)• Taken BID for 10 days• inhibits P-450 3. azithromycin (Zithromax® “Z-Pak®”)
• typical dosage: ii pills (500 mg total) first day; i pill (250 mg) QD days 2-5 (6 pills • does not inhibit P-450 (only erythromycin safe for warfarin or other P-450
• also available as 1% topical ung. (can be used ophthalmically); safe for kids as • chlamydial conjunctivitis: treated with one-time dose (4 x 250 mg tablets).
Quinolones
1. First generation: nalidixic acid (NegGram®) taken BID x 7 days
2. Second generation: ciprofloxacin (Cipro®, Proquin®) *only quinolone w/action
against pseudomonas• cured pseudomonas infection in bone story.
• 0.3% eye drop 3. Third generation: levofloxacin (Levaquin®): taken QD x 10 days
4. Fourth generation:
• moxifloxacin (Vigamox®) 0.5%
• gatifloxacin (Zymar®) 0.3%
Miscellaneous
1. vancomycin: treatment of methicillin resistant staphylococcus aureus (MRSA)/
2. lincomycin/clindamycin: diarrhea (less with clindamycin). Leads to “Cleocin
colitis” Less diarrhea when taken with kaopectate.
3. metronidazole
• cidal drug• anaerobic infections• inhibits P-450• Side effects: metallic taste in mouth; disulfuran reaction--violently ill; < 1% have this reaction, however, everyone must be warned of possibility; rusty-red discoloration of urine (Story about his trip to Florida, “Bob” and the stewed prunes at Howard Johnsons, etc…) 4. chloramphenicol
• Effective against Rocky Mountain fever• causes agranulocytosis--red cell anemia: 1 in 40,000 to 1 in 200,000 irreversible Topical
1. bacitracin: ophthalmic ung.
2. polymyxin-B (of polytrim fame)
Ophthalmic (he mentioned these at the end of one of the lectures & never expanded
on them)
1. Pred-G
2. Ciprodex
Prescription Writing Review
Summarized from Dr. Naegerʼs 10/02/2007 lecture.
A prescription must be legal, appropriate & cost effective.
A prescription is a legal document.
In Missouri, the pharmacy is required to retain all prescriptions for 7 years.
A practitioner should exercise the same care for his prescription pad as he would for a stack of cash.
A prescription is required to have the following:
1. Patientʼs full name: no abbreviations
2. Address (required only for scheduled or controlled substances)
3. Date the Rx is written: NEVER POST/PRE-Date an Rx
4. Drug Name and dosage form
5. Number of doses: The number should be indicated as “#10 (ten)” to prevent
someone from writing an extra ʻ0ʼ to make the ʼ10ʼ a ʻ100.
6. Directions: Avoid “Take as Needed”, “as directed”, etc.
• “as directed” is allowable for cases such as “Z-Pak”, where package clearly indicates dosage schedule, or steroid tapering, where a separate written set of instructions (10/30, take 3; 10/31, take 2; 11/1, take 2, etc.) is provided 7. Refill Instructions
8. Signature (Left side allows for generic A-B rated substitution; Right side is
“Dispense as written”)--Should always sign on the left hand side 9. (Somewhere on the form), the name of the practitioner writing the prescription
should be legibly indicated (especially if legal signature is illegible).
10. DEA # is required for scheduled or controlled substances. YOUR DEA# SHOULD
*NOT* BE PRE-PRINTED ON THE FORM, NOR SHOULD IT APPEAR ON THE
FORM WHEN IT IS NOT REQUIRED!

Source: http://ryansfiles.selfip.net/OPTOM8260-FOSDMI/RKL_Notes/antibiotic%20review.pdf