Antibiotics (Pens) Flashcards
What are the major antibiotic categories (there are more)
- Beta-lactams: penicillins, cephalosporins, carbapenems, monobactams
- Macrolides and clindamycin
- Tetracyclines/ glycylcyclines
- Glycopeptides
- Aminoglycosides
- fluoroquinolones
- Sulfonamides and trimethoprim
- Metronidazole
- Linezolid
What are the types of beta lactams:
- Penicillins , cephalosporins, carbapenems, monobactams
What is the structure of penicillins
- All penicillins share the same basic structure (6-aminopenicillanic acid: thiazolidine ring attached to a beta-lactam ring)
Are penicillins bacteriostatic or bactericidal
- Bactericidal
MOA of penicillins
- Bind to penicillin binding protein (PBP) which results in inhibition of peptidoglycan synthesis and activation of autolytic enzymes in cell wall
How does resistance to penicillins develop
- Production of beta-lactamases
- Lack of PBPs or altered PBPs
- Efflux of drug out of cell
- Failure to synthesize peptidoglycans such as mycoplasmas or metabolically inactive bacteria
What are the pharmacokinetics of penicillins
- Oral bioavailability (F) varies
- Wide tissue distribution including CNS
- Most are excreted by the kidneys
- Short half life meaning frequent dosing
- Concentration independent drug
Are penicillins concentration independent or dependent drugs
- Independent
What are concentration independent or dependent drugs
a) Concentration dependent drug: higher the concentration the greater effect
- Would want to give as much drug without giving toxicity
b) Independent: once you reach a specific threshold there is no greater effect
- Want to maintain that threshold concentration
- this means that ideally you would administer continuous intravenous drip however this is very inconvenient
Are penicillins safe in pregnancy, breast feeding
- Safe in pregnancy
- Distributed to breast milk but not a contra indication
Drug interaction between penicillins and oral contraceptives
- Potential drug interaction
- With penicillins you get destruction of estrogen and this can reduce the efficacy of the oral contraceptives
What penicillin can be taken with food
- Amoxicillin
What adverse effects with penicillins (considered the safest antibiotics)
- Allergic reactions (most common drug allergy)
- Anaphylactic shock
- Serum sickness (fever, joint pain, and rash)
- Skin rashes
- Fever nephritis (inflammation of the nephron) , eosinophilia (higher levels of eosinophils)
- Seizures, encephalopathy delirium (brain disorder)
- Electrolyte imbalances
- Neutropenia (to few neutrophils), thrombocytopenia (platelet count in your blood is too low)
- Diarrhea, gi upset
Types of natural penicillin
- Penicillin G
- Penicillin V (oral formulation)
What makes penicillin V different then penicillin G
- Penicillin V is oral
- More acid stable but still needs to be taken on an empty stomach
- Penicillin G is acid labile (not used orally)
What destroys natural penicillins
- Beta-lactamases
What is penicillin G available as
- Aqueous Pen G, procaine Pen G, and benzathine Pen G
- Procaine/ benzathine IM only: toxic IV
- The salts have different durations of activity
What are natural penicillins spectrum of activity
- Highly active against gram positive bacteria and spirochetes
- Often DOC for streptococci, pneumococci, meningococci, spirochetes, clostridia, anaerobic, gp robs and actinomyces
- Enterococci
Isoxazole penicillins
- Methicillin, cloxacillin, nafcillin, flucloxacillin, dicloxacillin
What is an MRSA
- Methicillin resistant staph aurous
What is the canadian drug used for MSSA
- Cloxacillin is the Canadian drug used for MSSA
How do the isoxazole penicillins react with beta-lactamases
- Relatively resistant
What were isoxazole penicillins designed for
- Staph aureus
What are isoxazole penicillins uses
- Staphylococcal infections
- Not MRSA
Aminopenicillins (spectrum and what destroys them)
- Destroyed by beta lactamases
Active against both gp and gn organisms
What are the types of aminopenicillins
a) Ampicillin
- Used IV
- More acid stable than natural penicillins but poor bioavailability
b) Amoxicillin
- Used orally
- Better absorption then ampicillin
- Available combined with clavulanic acid
Uses of aminopenicillins
- Streptococci, enterococci, Neisseria sp, non-beta-lactamase producing H. influenzae, E. Coli, P. mirabilis, salmonella..
What is clavulanic acid
- Beta-lactamase inhibitor
What is H. influenzae
- A bacteria and not the same as influenza virus
What do beta lactamases do
- Open the beta lactam ring of penicillins and cephalosporins meaning they are no longer active
What are ESBLs
- Extended spectrum beta lactamases found in E.coli and klebsiella pneumoniae
What is NDM-like
- New Delhi metallo-beta-lactase
- Found in acinetobacter baumannii
- Destroys even more beta lactam rings then ESBLs
What is the drug within ureidopenicillins
- Piperacillin
What are the uses of ureidopenicillins
- Increased activity against gn rods
Active against pseudomonas aeruginosa
What formulations are ureidopenicillins found
- Parenteral only (IV and IM)
- Available combined with beta lactamase inhibitor tazobactam
What is tazobactam
Beta lactamase inhibitor
What is the similar structure between cephalosporins
- 7-aminocephalosporonic acid
