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RavLect11: PCNs
Penicillins
| Term | Definition |
|---|---|
| Action of Penicillins | Bactericidal Beta-lactam: requires peptidoglycan and PBP to work Cell wall active: must bind PBP to interrupt cellular structure & inhibit cell wall synthesis Synergistic with aminoglycosides, additive w/ quinolones |
| Mechanims of penicillin resistance | Beta-lactamase/Penicillinase Altered cell wall penetration PBP’s PBP affinity alteration |
| Penicillinase (enzyme alteration) | Resistance from PCNs |
| PBP affinity alteration (mutation of proteins and binding affinity) B-lactamase inhibitors will NOT work | PBP2x for strep pneumonia PBP2a for staph aureus |
| Natural Penicillins | Pen G Pen G potassium or sodium Pen VK Pen G Benzathine Pen G Procaine Combination of Benz and Procaine |
| Activity of Natural PCNs | Neisseria (resistance building) - Pen G good for N. meningitidis Strept pneumo (not good for PBP2x); Pen G benzathine for S. pharyngitis & syphilis Also commonly used for dental infection prophylaxis |
| Excretion of PCNs | Rapid excretion in urine (blocked with Probenecid. This raises PCN levels) But no dose adjustment needed in renal dysfunction. Warning: extra high PCN dose in pt with renal dysfxn could lead to seizures! |
| Tissue penetration of PCNs | PCNs penetrate most tissues except the prostate, the eye and the CSF unless inflammation exists |
| Are PCNs concentration or time dependent? | Beta-lactams are concentration INdepedent (TIME above MIC is more important than concentration level). Thus, doubling the dose is not as effective as a long-acting or continuous infusion. |
| Pen G | Usually in IV form, but available in IM Contain Na+ and K+, so problematic in ptx with HF & renal dysfxn. |
| Pen V | Oral form. QID b/c very short half life! Take on empty stomach since acid deteriorates beta-lactam ring. |
| Pen G Benzathine IM weekly Pen G Procaine | for Strep pharyngitis and Syphilis |
| Penicillinase Resistant PCNs (additional acyl side chain prevents B-lactamase ring destruction by penicillinases) | Methi-, Naf-, Oxa-, Cloxa-, Dicloxa- cillins (mainly use Naficillin IV & Dicloxacillin PO) |
| Penicillinase Resistant PCN spectrum of action | for Staphylococcal (MSSA, MSSE) skin, bone infection (only used after sensitivity has been proven. Not used empirically) NOT active if methicillin resistant (MR-) NOT active against Enterococcus, Listeria |
| Ampicillin dose adjustment? | adjust Ampicillin for renal dysfunction |
| Penicillinase Resistant PCN dose adjustment? | No renal or hepatic adjustment needed (but Naf requires hepatic monitoring since it elevates AST and causes hepatotoxicity) |
| Naficillin | 1) Staph sensitive 2) IV form 3) thrombophlebitis 4) monitor liver function |
| Methicillin | only used for testing for MRSA or MRSE since it is renally toxic |
| Aminopenicillins | Ampicillin (IV) take on empty stomach Amoxicillin (PO) take with or w/o food. Amoxil is TID b/c short half life |
| Most common causes of CAP, RT (resp tract) infections, otitis media, meningitis | Strept pneumoniae H. influenza. |
| Aminopenicillin spectrum of action | Enterococcus especially! usually combined: [Amp + Gent] Strept pneumoniae (resistance building) H. influenza. Listeria Monocytogenes E. Coli Klebsiella |
| Carboxypenicillin | Ticarcillin |
| Ticarcillin SoA | No G+ activity More active against G- organisms (Enterobacteriaceae, Pseudomonas aeruginosa -but not as effective as Piperacillin) Not v. effective against Klebsiella |
| Ticarcillin ADRs | Renal dysfunction accumulation Na+ overload platelet dysfunction (binds ADP like Plavix so it has antiplatelet properties) MUST monitor platelets! hypokalemia |
| Ureidopenicillins | Piperacillin |
| Piperacillin SoA | Amp SoA + #1 ABx for Pseudomonas (think "P"). If a drug can Tx Pseudomonas, it can Tx all G- (except ESBL & NDM1)! SPACE organisms (G-): Serratia Pseudomonas Acinetobacter Citrobacter Enterobactericeae family |
| Unasyn | Ampicillin + Sulbactam |
| Augmentin | Amoxicillin + Clavulanic acid |
| Timentin | Ticarcillin + Clavulanic acid |
| Zosyn | Piperacillin + Tazobactam |
| β-lactamase inhibitors | Bactams & clavulanic acid (additives to the baseline drugs of "godzilla-cillins") |
| Godzilla-cillins SoA | B-lactamase producing- E.coli B-lactamase producing- B. fragilis (anaerobe) & whatever the baseline drugs cover NOT effective for ESBL producers |
| Clavulanic acid ADRs | diarrhea & liver dysfxn so DON'T give too much by doubling dose of Godzilla-cillins! |
| Augmentin (Amox + Clav. acid) ADRs | Diarrhea Yeast infection |
| Why use unasyn over ampicillin for intra-abdominal infection? | E. coli and b. frag (anaerobe) produce beta lactamase. FYI: Enterococcus does NOT produce B-lactamase. |
| Penicillin ADRs | ALLERGIC RXNS! hemolytic anemia (rare) drug-related fever Diarrhea Neutropenia from prolonged use Electrolyte disturbances Seizures at high doses Inactivated when mixed with AGs Timentin has platelet dysfxn |
| Pediatric dose of Amoxicillin | 80-100mg/kg/day |
Created by:
cheeoh
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