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Dental Therapeutics Exam 2 > Penicillins and Carbapenems > Flashcards

Penicillins and Carbapenems Flashcards

1
Q

Penicillins Mechanism of Action

A

Bind to Penicillin binding proteins (Transpeptidase), Defects in cell wall synthesis, Inhibit cross linking
Induce holing-like proteins in bacterial membrane - Cause lesions and collapse of membrane potential
Bacteriocidal

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2
Q

Chemistry of Penicillin

A

5 member ring attached to 4 member ring
Thiazolidine ring
Beta-Lactam ring

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3
Q

Penicillin G

A

Benzylpenicillin

Acid Labile - Destroyed in stomach acid - Administered IM or IV

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4
Q

Penicillin V

A

Phenoxymethylpenicillin

Better oral absorption (Less sensitive to food) - Gram positive organisms - Oral anaerobes or Spirochetes; q6h

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5
Q

Ampicillin

A

Amino group added on, Gram negative antibacterial spectrum, Reduce efficacy on Gram positive, Oral admin

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6
Q

Amoxicillin

A

Better oral absorption - More used in dentistry - Gram negative; q8h; No adjustment in compensated cirrhosis but avoid in decompensated; Used in patients with liver/kidney disease but adjust;

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7
Q

Natural Penicillins

A

Pen G
Pen VK
Procaine
Benzathine penicillin

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8
Q

Penicillin Spectrum

A

Narrow Spectrum
Gram+ve cocci and bacilli (Bacillus anthraces); Spirochetes - ANUG (Anaerobes and Spirochetes cause) - Treponema pallidum (syphilis); Oral anaerobes - Actinomyces (Actinomycosis - Lumpy tumors of jaw and tongue, Loss of wt. strength); Costridial infection - Gas gangrene (C. perfringens), Tetanus (C. tetani - eradicate vegetative forms of bacteria that persist, Use tetanus immune globulin); Anthrax - Pen G (Ciprofloxacin - Drug of choice); Streptococcal infections - Pen V or G - S. Pyogenes (Pharyngitis, otitis media, pneumonia, bacteremia, scarlet fever - chills, scarlet rash, sore throat, nephritis), Endocarditis (Enterococcal endocarditis - Pen G + Aminoglycoside); Penicillin G and Penicillin V (Natural) - Rat bite fever (Spirilum minor, Streptobacillus monliformis) - Pen G choice, Diptheria (Pen G for carrier state - antitoxin), Neisseria Meningitides (Meningitis - Pen G);

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9
Q

Aminopenicillins Spectrum

A

Amoxicillin or Ampicillin
Not penicillinase resistant;
Extended Spectrum (More Gram -);
Gram positive cocci and some Gram negative - ex. P.mirabilis, Salmonella, Shigella, E.Coli; Not active against Pseudomonas, Sensitive to Beta-lactamase, Combine with Beta-lactamase inhibitor clavulanic acid, sulbactam or tazobactam; Amoxicillin + Clavulanic Acid = Augmentin; Prevotella intermedia/nigrescens, F. nucleatum, other Prevotella species. P. gingival is found in periodontal pockets and all produce beta lactamase, treat with Amoxicillin + Clavulanic acid or Amoxicillin + Metronidazole; Prophylaxis prior to dental treatment; Spectrum includes more Gram neg organism, Efficacy got Gram pos degraded

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10
Q

Penicillinase-Resistant Penicillins

A

Methicillin (Injection), Nafcillin (Injection), Cloxacillin (Oral), Dicloxacillin (Best oral absorption), Oxacillin (Parenteral)
Flucloxacillin (Not in US)

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11
Q

Penicillinase-Resistant Penicillins Spectrum

A

Only used to treat infections caused by Beta-lactamase producing Staph Aureus (Bacteremia, Endocarditis, Pneumonia, Osteomyelitis)

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12
Q

MRSA Treatment

A

Vancomycin, Linezolid, Quinupristin-Dalfopristin

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13
Q

Anti-Pseudomonal Penicillin

A

Carboxypenicillins: Ticarcillin (and Carbenicillin) active against P. aeruginosa and Proteus
Ureidopenicillins: Piperacillin(-Tazobactam w/broadest spectrum of penicillins) (and Mezlocillin) extends spectrum of Ampicillin to include Pseudomonas, Enterobacteriaceae, Bacteroides
Sensitive to Beta-lactamase so use inhibitor
Mainly used for serious infections caused by Gram neg organisms [bacteremias, pneumonias, infections following burns, UTI resistant to Pen G, ampicillin - (P. aeruginosa, indole + proteus, enterobacter)]
Mezlocillin, Piperacillin, Ticarcillin - Inactivated by acid, Give IM or IV

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14
Q

Procaine and Benzathine Admin

A

IM Slow Release forms

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15
Q

Penicillin Distribution

A

Most 20-50% Plasma bound, Some beta lactamase resistant genes 90-95% bound; Cross placenta are distributed into breast milk as weak acids; Well distributed, Do not enter CSF unless inflamed meninges

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16
Q

Penicillin Metabolism and Excretion

A

Primarily eliminated by renal route, Rapidly excreted by kidney through filtration and tubular secretion, Pen V 50% metabolized by liver
Biliary excretion - Particularly nafcillin, oxacillin - Piperacillin partly biliary
Renal compromised - Total daily dose reduction or interval reduction or use Clindamycin or Azithromycin (Min urinary excretion)
Take Penicillin 1hr before/2hr after meal
Antibiotics - Prolong Warfarin (EXCEPT Dicloxacillin)

17
Q

Probenacid

A

Inhibits tubular secretion, Used to elevate penicillin blood levels

18
Q

Penicillin Adverse Effects

A

Allergic Rxns - Hypersensitivity; Skin rashes of various types (High with Ampicillin), Public health problem
Acute Anaphylactic rxns - Rare, But fatal; Treat w/Epi, Skin test with Penicilloyl Polylysine helpful but not always conclusive (May need diphenhydramine &/ glucocorticoid anti-inflammatories)
Superinfection by Resistant organisms - ex. Pseudomembranous colitis (C. difficile), More likely with extended spectrum agents
Electrolyte disorder - Rapid IV infusion of Potassium Salt of Penicillin G produces hyperkalemia leading to arrhythmias and cardiac arrest
Very high doses lower seizure threshold

19
Q

Metabolite of Penicillin

A

D-Benzylpenicillenic acid

20
Q

Mechanism of Resistance to Penicillin

A

Change in Penicillin Binding Protein - Important in gram-positive cocci ex. S. aureus resistance to methicillin and pneumococcus
Increased production of Beta-Lactamase enzymes - Main mechanism of resistance
Development of tolerance by loss of autolysis mechanism (Agents become bacteriostatic)

21
Q

Penicillin Uses in Dentistry

A

Treat post extraction infections, post surgical infections, pericoronitis, dentoalveolar abscesses, osteomyelitis, cellulites, ulcerative gingivitis, periodontitis, prophylaxis

22
Q

Amoxicillin + Metronidazole

A

Treat Aggregatibacter (Actinobacillus) Actinomycetemcomitans associated periodontitis and aggressive/and or advanced forms of chronic periodontitis

23
Q

Oral Regimens for Dental Procedure

A

Amoxicillin
Adult: 2g
Children: 5mg/kg

24
Q

Unable to Take Oral Meds Regimens for Dental Procedure

A 
Ampicillin
Adults: 2g IM or IV
Children: 50mg/kg IM or IV
Cefazolin or Ceftriaxone
Adults: 1g IM or IV
Children: 50mg/kg IM or IV
25
Q

Allergic to Penicillin/Ampicillin Oral Regimens for Dental Procedure

A 
Cephalexin
Adults: 2g
Children: 50mg/kg
Clindamycin
Adults: 600mg
Children: 20mg/kg
Azithromycin or Clarithromycin
Adults: 500mg
Children: 15mg/kg
26
Q

Allergic to Penicillins/Ampicillins and Unable to Take Oral Regimens for Dental Procedure

A 
Cefazolin or Ceftriaxone 
Adults: 1g IM or IV
Children: 50mg/kg IM or IV
Clindamycin
Adults: 500mg IM or IV
Children: 20mg/kg IM or IV
27
Q

Carbapenems Chemistry

A

Imipenem/Cilastatin
Meropenem
Contains C instead of S in 5member ring

28
Q

Carbapenems Spectrum of Action

A

Broad Spectrum
Active VS Gram - and Gram + organisms
NOT Active VS MRSA (Altered PBP), VRE, Choice for Enterobacter infections, Useful for treatment of pulmonary, intra-abdominal and soft tissue infections caused by mix of bacteria

29
Q

Carbapenems Mechanism of Action

A

Bind to PBPs 1 and 2 rather than PBP 3 to which Aminopenicillins bind, Small size allows easy penetration of Gram - envelope through Porins

30
Q

Carbapenems Pharmacokinetics

A

Not absorbed from GI tract so IV or IM, Hydrolyzed rapidly by dehydropeptidase 1 present in brush border of proximal renal tubule; Must be administered with Cilastatin - a competitive inhibitor of dehydropeptidase 1 - Cilastatin prevents destruction of Imipenem ring; Meropenem is resistant to degradation by dehydropeptidase 1

31
Q

Carbapenems Adverse Effects

A

Imipenem at high doses causes seizures, less with Meropenem; GI complaints of N, V, D, skin rash and rare neutropenia

32
Q

Carbapenems Resistance

A

Alteration of porins so drug can’t access periplasmic space

Dental Therapeutics Exam 2 (8 decks)

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