Pharm: L25: Penicillins Flashcards
*Know the MOA, (What she covers in lecture is what we need to know). *MOA for all of them. Route of Administration, Adverse Effects, (Broad spectrum, etc) *If she says something more than a couple of times, then KNOW IT!
Inhibitors of Cell Wall Synthesis
- What structure gives the bacterial cell wall rigidity and resistance to osmotic lysis in G+ and G- bacteria?
a. What are the major proteins involved in the synthesis of this cell wall structure?
b. What targets these major proteins?
c. What is this structure made of?
- PEPTIDOGLYCAN
a. Penicillin Binding Proteins (PBPs)
b. B-Lactam Antibiotics
c. Backbone of NAD and NAM (sugars that alternate); They have a chain of 4 AAs that extend down the backbones and a PEPTIDE Bride forms b/w them (cross-links the Peptide Chains)
Cell Wall/Peptidoglycan
- Major difference b/w Bacterial and Mammalian cells is the presence in bacteria of what?
- The Cell Wall protects bacterial cells from what?
- In G+, Peptidoglycan is what?
- What about G- ?
- Rigid Cell Wall External to the cell membrane
- Osmotic Rupture
- it’s the ONLY layered structure External to the Cell Membrane and is THICK (20-80 nm)
- There’s an outer membrane external to a thin Peptidoglycan Layer (1 nm)
Peptidoglycan formation
- Inhibition of any stage of the SYNTHESIS, Export, or assembly of the Peptidoglycan lead to what?
- How is Peptidoglycan formed?
- Where do B-LACTAMS act?
- Inhibition of Bacterial Cell Growth, and usually in CELL DEATH!
- Add Subunits (sugar w/5 AAs) that are made in the Cytoplasm. Transport thru cytoplasmic membrane to the cell surface, and Cross-linking occurs that cleaves the Terminal Stem-peptide AA.
- On the Peptidoglycan cell wall!
Peptidoglycan Synthesis
- Transglycosylation
a. Formed by what Proteins? - Transpeptidation
a. Formed by what proteins? - Where does B-Lactams affect this process?
- Joining NAM-NAG
a. PBPs - Cross Links Pentapeptides
a. PBPs - They Bind to the PBPs
- What do Glycopeptides do?
a. What is the name of one of them? - What do B-Lactam Antibiotics do?
a. Name the B-Lactam classes (4)
b. What inactivates them?
- Steric Inhibition of adding subunits to the Peptidoglycan Backbone
a. VANCOMYCIN - Prevent Cross-Linking (TRANSPEPTIDATION)
a. Penicillins, Cephalosporins, Carbapenems, and Monobactams
b. Penicillinases and B-Lactamases (Hydrolyze B-Lactam ring thus inactivating the antibiotic)
Lysis and Autolysins (*Know this stuff…she talked about this quite a bit)
- What is the MOST IMPORTANT thing to know about killing bacterium with B-Lactams? (what state do they have to be in)
- Which antibiotics that inhibit bacterial cell-wall synthesis are Bactericidal?
- What is the main cause of Lysis of the Bacterium?
a. How does this happen? - What PREVENTS the action of Cell Wall Synthesis Inhibitors?
a. What drug?
- Have to be in a STATE of GROWTH (if they are STATIC, then they will not work!!)
- Basically ALL OF THEM (cuz they lead to Osmotic Lysis)
- Lose cell-wall integrity due to their own Remodeling Enzymes (AUTOLYSINS): They cleave the Peptidoglycan bonds during normal cell growth.
a. When the antibiotics inhibit cell wall growth, AUTOLYSIS still occurs, leading to cell wall weakness and eventual lysis. - Protein Synthesis Inhibitors
a. Chloramphenicol
What is difficult to treat?
- Pseudomonas Aeruginosa!
* Learn these by Groups…
* Bactericidal
Inhibitors of Cell Wall Synthesis
- Agents that Affect the Cell wall? (2)
- B-Lactam Antibiotics and Other Antibiotics (Bacitracin, Vancomycin, and Daptomycin)
Inhibitors of Cell Wall Synthesis
- B-Lactam Antibiotics do what?
- Inhibit Cell Wall Synthesis, thus they are BACTERICIDAL!!
Penicillins, Cephalosporins, Carbapenems, and Monobactams
- What are the 4 B-Lactam Groups?
a. Why are they called B-Lactams? - What 4 are Not B-Lactams?
- Penicillins, Cephalosporins, Monobactams, and Carbapenems
a. They all have a B-Lactam Ring - Vancomycin, Phosphomycin, Bacitracin, and Cycloserine
Penicillins
- Natural Penicillins (4)
- Penicillinase Resistant (3): NOM
- Extended Spectrum (AA)
- Antispeudomonal (PTC)
- PENICILLIN G; Pen V, Procain Pen G, Benzathine Pen
- NAFCILLIN, Oxacillin, and Methicillin
- AMPICILLIN, Amoxicillin
- PIPERACILLIN, Ticarcillin, Carbenicillin
Penicillins: Chemistry
- What is the main structural requirement for their activity?
- Antibacterial Activity of Penicillin RESIDES in what?
a. What happens if this is destroyed?
b. What destroys it?
- Its nucleus
- in the INTACT B-LACTAM RING
a. Loss of ANTIBACTERIAL ACTION
b. B-LACATAMASE (PENICILLINASE)
Natural Penicillins
- What are they again? (Name the 4)
- What is the BIG thing to remember about this group (Have the HIGHEST what?)
a. Not so good for what bacteria?
b. What is the trend to remember? - INACTIVATED BY what?
- ANTIPSEUDOMONAL Activity?
- How does the body get rid of them?
a. What can be TAKEN with them to help decrease elimination rates? - CNS penestration?
- Pen G, Pen V, Benzathine Pen, and Procaine Pen G
- HIGHEST antibacterial activity against G+ BACTERIA!! (even G+ Anaerobic Bacteria)
a. not so good for SOME G- Bacteria
b. As you go down the list of PENICILLINS that she listed, know that Natural Penicillins Have the HIGHEST G + activity, and lowest G- activity, and G+ activity decreases as G- activity Increases moving to the next groups. - PENICILLINASE (B-LACTAMASE)
- NONE!
- Active Transport in the Kidney
a. Probenicid - POOR
Mechanism of Action of Penicillins
- Type of Antibiotics?
- What stage of Cell Wall Synthesis do they INHIBIT?
- When are they ONLY BACTERICIDAL?
- BACTERICIDAL
- FINAL STAGE (Cross-linking: Transpeptidation). Bind to PBPs. (PBPs catalyze the RxN that removes the Terminal Alanine to form a crosslink w/the nearby peptide)
- ONLY when bacteria are ACTIVELY GROWING and Synthesizing CELL WALLS
Natural Penicillins: Route of Administration
- Pen G?
- Pen V
- Benzathine Pen
- Pro Pen G
- (IV, IM)
- Orally useful (tends to be Acid resistant)
- IM
- IM
* Works well agains Streptococcus Pneumoniae (but resistance to Pen G has occurred and is increasing); Good against SYPHILIS.
- Penicillinase-Resistant Penicillins
- What are they? (NOM)
- Activity?
- BIG THING ABOUT THIS GROUP?
- Some of them are what?
- DOC for what?
a. % that is resistant to this drug? - How is it removed?
- How do you treat?
a. What if the drugs don’t work? - Which drug is used for TESTING ONLY!
- NAFCILLIN, Oxacillin, Methicillin
- LOWER ACTIVITY against Certain G + and some G- Coverage
- RESISTANT to PENICILLINASE!
- Acid Stable and Highly Protein bound!
- Penicillinase Producing S. Aureus (MSSA)
a. More than 20% of S. Aureus (MRSA) - HEPATIC Metabolism and RENAL Excretion
- Use NAFCILLIN for a short period of time (IM/IV) then switch to Oxacillin (Oral).
a. Treat with MAGGOTS! They’ll eat the dead tissue - Methicillin
MRSA: Mechanism of Resistance *REMEMBER this INFO!!
- Resistance is NOT Associated with what?
- What does MRSA produce?
- Can a B-Lactam be used to treat MRSA?
a. What can be used?
- with the production of B-Lactamase
- an ALTERNATE PBP that DECREASES the Affinity of B-Lactam Antibiotics to PBPs
- NO!
a. The only exception is CEFTAROLINE! (5th Gen Cephalosporin)
- Extended Spectrum Penicillins
- Coverage?
- ANTIPSEUDOMONAL ACTIVITY?
- Does resistance develop frequently?
- Susceptible to what?
- These drugs are resistant to what?
- How are they Excreted?
- DOC for what?
- What are the drugs and how are they taken?
- AMPICILLIN RASH: Is it a Hypersensitivity Reaction?
- LOWER G+ coverage and EXTENDED G- Coverage!
- NO!
- YES!
- B-LACTAMASE
- ACID resistant
- Urine
- LYSTERIA Infections
- AMPICILLIN and Amoxicillin (Oral)
- NO!!
- Antipseudomonal Penicillins
- What are they? (PTC)
- Spectrum (coverage)
- MAJOR USE against what 2 bacteria?
- Susceptible to what enzyme?
- How are they excreted?
- They are sensitive to what?
- USE IN COMBO with WHAT?
a. WHY?
- PIPERACILLIN, Ticarcillin, and Carbenicillin
- Bacteria covered by EXTENDED
- P. Aeruginosa (this is the ONLY PENICILLIN THATS ANTIPSEUDOMONAL!) and Acinetobacter
- to B-Lactamase (so comibine w/a Penicillinase Inhibitor)
- Renal (Kidney) Excretion
- Acid Sensitive
- with Aminoglycosides
a. to Prevent Resistance
B-Lactamase Inhibitors
- There are three of them
a. Adding them to certain Penicillins will do what?
b. However…?
- Sulbactam, Tazobactam, and Clavulanic Acid
a. They EXTEND the Spectrum of these Agents (so now include organisms resistant by virtue of B-Lactamase production)
b. Not all B-Lactamases are inhibited by these products and bacteria may develop resistance independent upon b-lactamase production (e.g. Altered PBP production and MRSA)
B-Lactamase Inhibitors: Combine with what Penicillins
- Clavulanic Acid
- Sulbactam
- Tazobactam
- Amoxicillin and Ticarcillin
- Ampicillin
- Piperacillin
* Not active against MRSA!
Bacterial Resistance: Penicillins
- Inactivation of penicillin by what?
- DECREASED PERMEABILITY of bacterial cell to Penicillins (what Gram bacteria?)
- ALTERATION of what?
- What enzymes NOT BECOMING ACTIVATED?
- LACK of WHAT?
- Bacterial B-Lactamase (Penicillinase)
- Gram -
- in PBPs which prevents penicillin from binding (MRSA)
- AUTOLYTIC ENZYMES.. Forms “Tolerant” Organisma (Listeria, and Staphylococci)
- LACK OF CELL WALL
TOXICITY
- Highest degree of toxicity?
- What 3 other things?
- ALLERGY (ALL FORMS) (Ampicillin Rash is NOT AN ALLERGY!) (Penicillins and Sulfonamides are the 2 most causes of ALLERGIES)
- Electrolyte imbalances, GI Effects (DWAI except for ERYTHROMYCIN has MAJOR GI EFFECTS); Superinfections
Pharmacokinetics
- What 5 things?
- Good tissue penetration
- Bad CNS Penetration
- Mostly excreted via RENAL
- Filtration and Tubular Excretion
- PROBENECID INHIBITS RENAL ELIMINATION!
Ampicillin Rash
- How long does it appear?
- High % of patients with what disease get this?
- RASH IS NOT ALLERGIC!. Does it preclude future use of penicilln?
- appears 3-14 days after start of therapy
- HIGH PERCENTAGE of INFECTIOUS Mononucleosis (EBV)
- NO!