Lecture 11 - beta lactams

Why are penicillin’s good for UTIs?

95% of each dose is unchanged in urine

What is an example of a narrow spectrum penicillin?

Penicillin G

What are two examples of aminopenicillins?

1. Ampicillin

2. Amoxicillin

What is an example of a penicillinase-resistant/antistaphylococcal penicillin?

Nafcillin

What is an example of an extended spectrum penicillin/antipseudomonal penicillins?

Piperacillin

What are three b-lactamase inhibitors?

1. Clavulanic acid

2. Sulbactam

3. Tazobactam

What is an example of carbapenem?

Imipenem

What is an example of monobactem?

Aztreonam

How do penicillin’s work?

Contain b-lactam that bind to transpeptidase (PBP) and inhibit peptidoglycan synthesis

What are the general penicillin characteristics? What are they effective against?

-Bactericidal

-Time dependent

-More potent against gram (+)

What are some penicillin’s degraded?

GI amidase, b-lactamases, stomach acid, alkalinity (milk/urine)

How are anti-staphylococcal penicillin’s resistant? What is an example?

-Transpeptidase mutations

-Ex. Methicillin

How do b-lactams become resistant to antibiotics?

-Inactivation of antibiotic by b-lactamase (cleave b-lactam ring)

-plasmid mediated

What is the most common adverse reaction with penicillin?

Mild GI upset

What occurs with penicillin’s in herbivores (ex. guinea pigs)?

Severe colitis/dysbiosis

What type of allergy is associated with penicillin? What causes the reaction? What is the potential cross reactivity risk?

-Type I

-b-lactam rings cause anaphylaxis

-Cross reactivity risk between penicillins and cephalosporins

What are common drug combinations with penicillins? Why?

-Clavulanic acid, sulbactam, tazobactam

-b-lactamase inhibitors

How is imipenem toxic? How can this be avoided?

-Extensively metabolized by renal tubules

-Combined with cilastatin

How is cephalosporin similar to penicillin?

Structure, mechanism of action, and some toxicities

How is cephalosporin different from penicillin?

Broader spectrum of activity

Compared to penicillins, cephalosporins are….

-Less sensitive to GI amidases, bacterial b-lactamases and alkalinity

-Resistant to acidity

What an example of 1st generation cephalosporin?

Cefazolin

What are four examples of cephalosporin?

1. Ceftiofur

2. Ceftazidime

3. Cefovecin

4. Ceftriaxone

What are the adverse reactions seen with cephalosporin?

-Nephrotoxicity but depends on cephalosporin

-Allergies (less common)

-Potential cross reactivity

What is convenia? How long does it last?

-3rd generation cephalosporin used in dogs and cats

-Mainly for skin infections

-Long half live (1 injection for 14 days)