Antibiotics

Question 1

PCN Drug Interactions

Answer 1

1. Probenecid can increase levels
2. Beta lactams can increase warfarin levels (increase bleed risk) BUT **nafcillin/dicloxacillin can inhibit warfarin **
3. PCN increase MTX
4. PCN decrease mycophenolate

Question 2

PEN VK

Answer 2

Penicillin V Potassium
125-500 mg PO q6-12h
Empty stomach
1st line for strep, mild nonpurulent skin infxns
Gram +, enterocci/strep, anareobes
NO gram - or MSSA

Question 3

Bicillin LA
Bicillin CR

Answer 3

Pen G
IM 1.2-1.4 million units x 1
DOC for syphilis
NOT FOR IV USE

Question 4

Dynapen
Nafin/Nallpen/Unipen
Bactocill

Answer 4

• Antistaph - MSSA activity! No Enterococcus, anaerobes,gram-
• No renal adj
• Preferred for MSSA soft tissue, bone, joint, endocarditis & bloodstream infxns
• Dicloxacillin: PO 125-500 mg q6h
• Nafcillin: IV/IM 1-2gm q4-6h (VESICANT - central line preferred. Extravasion - use cold packs & hyaluronidase inj
• Oxacillin IV 250-2000mg q4-6h

Question 5

Moxatag/Amoxil
Augmentin
Unasyn
Principen

Answer 5

• Covers strep, enterococci, g+ anaerobes, HNEP
• beta-lactamase inhibitors - HNPEK + B.fragilis

Ampicillin rarely used PO, poor bioavailability
IV amp/Unasyn - NS only

Augmentin/Unasyn
* CI hx of cholestatic jaundic or hepatic dysfunction associated with previous use
* Severe renal dysfxn CrCl <30 mL/min - do not use ER forms of amox or Augmentin or 875 mg strength

Question 6

PCN ADE

Answer 6

• Seizures (accumulation in renal dysfxn)
• GI upset
• diarrhea
• rash (SJS/TEN), allergic rxns, anaphylaxis
• hemolytic anemic (Positive Direct coombs test)
• renal failure
• myelosuppression w/prolonged use
• incr LFTs

Question 7

Zosyn

Answer 7

piperacillin/tazobactam
Activity against Pseudomonas
IV 3.375 g q6h or 4.5 g q6-8h
Prolonged or extended infusions: 3.375g-4.5 g IV q8h (infuse over 4 hrs)

Contains 65 mg Na per 1 g piperacillin

Question 8

Cephalosporins

Answer 8

NO Enterococcus or atypicals

Question 9

1st gen cephs

Answer 9

1st gen: gram + (strep/staph), PEK
Cefazolin (Ancef): IV/IM 1-2 g q8h
* used for surg prophy
Cephalexin (Keflex): PO 250-500mg q6-12h
Cefadroxil (Duricef): PO 1-2 g Q12-24H

Question 10

2nd gen cephs

Answer 10

2nd gen: Cefuroxime - staph, HNPEK, resistant strep; cefotetan/cefoxitin- gram - anaerobes (B fragilis)
Cefuroxime (Ceftin): PO/IV/IM 250-1500mg q8-12h - separate from antacids
Cefotetan (Cefotan): IV/IM 1-2 gm q12h
* increase risk of bleeding & disulfiram-like rxn with ETOH
Cefaclor (Ceclor): PO 250-500 mg q8h
Cefoxitin (Mefoxin): IV/IM 1-2 gm q6-8h
Cefprozil (Cefzil): PO 250-500 mg q12-24h

Question 11

3rd gen cephs

Answer 11

f3rd gen: CTX, cefotaxime - strep, staph, gram + anaerobes, resistant HNPEK; ceftaz- Pseudomonas, NO gram+
Cefdinir (Omnicef): PO 300 mg 12h or 500 mg daily - separate from antacids
CTX (Rocephin): IV/IM 1-2g q12-24h
*CI: neonates (biliary sludging, kernicterus); use with Ca-containing iV products in neonates <28 days old
*no renal adj
*CNS penetration @ high doses (2 g q12) when meninges inflamed
Cefotaxime (Claforan): IV/IM 1-2g q4-12h
Cefditoren (Spectracef): PO 200-400mg q12h WF- separate from anatacids
Cefexime (Suprax): PO 400 mg divided q12-24h (available as chewable tab)
Cefpodoxime (Vantin): PO 100-400 mg q12 - separate from antacids
Ceftibuten (Cedax): PO 400 mg daily on empty stomach

Ceftazidime (Fortaz, Tazicef): IV/IM: 1-2gq8-12

Question 12

4th gen ceph

Answer 12

Cefepime (Maxipime)
IV/IM 1-2g q8-12h
4th gen: cefepime - gram -, Pseudomonas, gram + similar to CTX

Question 13

5th gen cephs

Answer 13

Ceftaroline (Teflaro)
IV 600mg q12
5th gen: ceftaroline - MRSA, gram + and -

Question 14

Ceph combos

Answer 14

ceftazidime/avabactam (Avycaz) - activity against some CRE
ceftolozane/tazobactam (Zerbaxa)
- added MDR Pseudomonas & gram neg rods