Test Questions on Therapeutics ID Bergman

Flashcard maker : Pat Coker
Penicillins: Mechanisms of Resistance

  • Beta Lactamase Producing
  • Alteration of PBPs (MRSA)
  • Modification of outer cell membrane (Most G-)

Penicillin G Route of Administration
Penicillin VK Route of Administration
Benzathine Penicillin G Route of Administration
Long Acting IM
Procaine Penicillin G Route of Administration
Short Acting IM
Oxacillin Route of Administration
Nafcillin Route of Administration
Dicloxacillin Route of Administration
Ampicillin Route of Administration
Amoxicillin Route of Administration
Ticarcillin Route of Administration
Piperacillin Route of Administration
Why is Ticarcillin not used much in the hospital?
It is formulated with Na+ and is harmful to sick patients — don’t want to overload someone that has CHF with Na+
Amoxicillin/Clavulanic Acid Route of Administration
Ampicillin/Sulbactam Route of Administration
Ticarcillin/Clavulanic Acid Route of Administration
Piperacillin/Tazobactam Route of Administration
Which antibiotics out of the penicillin classes do not need to be renally dosed?

  1. Nafcillin (primarily hepatic)
  2. Oxacillin (renal and hepatic)

Adverse Reactions of Penicillins

  • Allergic Rxns

Anaphylaxis (can’t rechallenge with another beta lactam)

Urticaria (hives)

Drug Fever

  • GI (N/V/D – occurs with PO classes)
  • Hematologic
  • Neurologic (seizures)

Cephalosporins: Mechanism of Resistance

  1. Beta Lactamases
  2. Alteration of PBPs
  3. Outer cell membranes changes

Cefazolin Route of Administration
Cephalexin Route of Administration
Cefuroxime Route of Administration
Cefoxitin Route of Administration
Cefotetan Route of Administration
Ceftriaxone Route of Administration
Cefotaxime Route of Administration
Ceftazidime Route of Administration
Cefepime Route of Administration
Route of Elimination for Cephalosporins




Ceftriaxone (biliary)


Adverse Reactions of Cephalosporins

  • Allergic Rxns



Drug Fever

  • Hematologic
  • Neurologic
  • Disulfiram-Like Reactions (MTT side chain only)

Cefotetan, cefamandole, cefmetazole, cefoperazone, moxalactam

Flushing, Vomiting – with concomitant alcohol consumption

Increased INR

Carbapenems: Mechanism of Resistance

  • Decreased penetration (G- bacilli)
  • Altered PBPs
  • Production of broad spectrum Beta Lactamases

Carbapenems are excreted by which route?
Imipenem Route of Administration
Meropenem Route of Administration
Ertapenem Route of Administration
Doripenem Route of Administration
Which Carbapenem is administered with Cilastatin?


  • It is susceptible to dehydropeptidase 1 of the renal brush border
  • Cilastatin is a DHP 1 inhibitor

Adverse Reactions of Carbapenems

  • Diarrhea

high risk of C. difficile

  • Allergic reactions

Anaphylaxis, urticaria, drug fever

Cross reaction with penicillins is higher than cephalosporins

  • Seizures (Imipenem > all other beta lactams, due to accumulation of cilastatin)

Aztreonam Route of Administration
Aztreonam: Mechanism of Resistance
Extended Spectrum Beta Lactamases
Adverse Reactions of Aztreonam

Weakly Immunogenic (due to one ring)


People with PCN allergy can use aztreonam

Aminoglycosides: MOA

  • Binds irreversibly to 30S bacterial ribosomal subunit –> interference of genetic code and inhibition of protein synthesis
  • Bactericidal

Aminoglycosides: Mechanism of Resistance

  • Ribosomal mutation –> drug cannot bind to 30S subunit
  • Reduce transport into cell
  • Plasmid-mediated aminoglycoside-modifying enzymes

Aminoglycosides route(s) of elimination



Good for G- UTIs

Advantages of Once Daily Dosing of Aminoglycosides

  • Improves peak to MIC ratio and maximizes concentration dependent bactericidal activity
  • Takes advantage of post-antibiotic effect
  • Gives kidneys time to recover so possibly less nephrotoxicity
  • Less potential for resistance
  • Lower cost of supplies at nursing time

Aminoglycosides can be used in synergy to fight what types of infections?

G+ Infections



Which aminoglycoside has the best Pseudomonas aeruginosa activity?
Adverse Reactions of Aminoglycosides

Aminoglycosides are Mean O’l Guys!

  • Nephrotoxicity
  • Ototoxicity (vestibular and auditory)
  • Neuromuscular Blockade (if infused too quickly)

Sulfamethoxazole: MOA

  • Structural analoge of p-aminobenzoic acid (PABA), the building block used by bacteria to make dihydrofolic acid
  • Dihydrofolic acid is used to make folic acid, which is used for nucleotide synthesis
  • Sulfamethoxazole competitively inhibits bacterial dihydropteroate synthetase, an enzyme critical for folic acid biosynthesis

Trimethoprim: MOA

  • Competitively inhibits dihydrofolate reductase, inhibiting conversion of dihydrofolic acid to tetrahydrofolic acid, the metabolically active cofactor for synthesis of purines, thymies, and DNA

TMP-Sulfamethoxazole is the DOC for what infections?
TMP-Sulfamethoxazole is the only PO drug for:
Staphylcoccus aureus (including MRSA) infections
Gentamicin Route of Administration
Tobramycin Route of Administration
Amikacin Route of Administration
Streptomycin Route of Administration
TMP-Sulfamethoxazole are eliminated by what routes?



Good for UTIs

Adverse Reactions of TMP-Sulfamethoxazole

  • Hypersensitivity reactions
  • Crystallization in the Kidneys – counsel patients to take with water
  • Hematologic – bone marrow suppression at high doses

Tetracyclines: MOA

  • Binds reversibly to 30S bacterial ribosomal subunit
  • Blocks attachment of tRNA to an acceptor site on the mRNA ribosomal complex

Doxycycline Route of Administration
Indications of Tetracyclines

  • Respiratory Infections
  • Genital Infections
  • Skin Infections

Adverse Reactions of Tetracyclines

  • Photosensitivity
  • Discoloration of Developing TeethCI ; 8 yo, pregnant, nursing mothers
  • Esophageal Ulceration

Tigecycline: MOA

  • A glycylcycline antibiotic
  • Similar MOA as tetracyclines (inhibits 30S ribosomal subunit)
  • 5X binding affinity — overcomes resistance mechanisms (ribosomal and efflux pumps)

Tigecycline: Spectrum of Activity

  • Staph. aureus (inclusing MRSA)
  • Enterococcus (including VRE, excluding Proteus mirabilis)
  • Strep. pneumoniae (including PRSP)
  • Enterics (including ESBLs)
  • Non-Enterics (excluding P. aeruginosa)
  • Respiratory G-
  • Anaerobes
  • Atypicals


Adverse Effects of Tigecycline
Tigecycline Route of Administration
When should you decrease maintenance dose of Tigecycline?
Patients with liver failure
Macrolides: MOA
Reversibly inhibits 50S ribosomal subunit
Adverse Effects of Macrolides
Erythromycin Drug Interactions
Hepatic Cytochrome P450 – inhibits CYP 3A4
Clarithromycin Drug Interactions
Hepatic Cytochrome P450 – inhibits CYP 3A4
Major Problem with Telithromycin
Hepatic Failure
Quinolones: MOA
Inhibits bacterial Topoisomerase II and IV
Quinolones: Mechanism of Resistance

  • Point mutations
  • Decrease outer membrane permeability

Ciprofloxacin Route of Administration
Levofloxacin Route of Administration
Moxifloxacin Route of Administration

Which of the following are used for systemic AND urinary tract infections?

  1. Moxifloxacin
  2. Levofloxacin
  3. Ciprofloxacin
  4. Gemifloxacin

Ciprofloxacin and Levofloxacin are used for bacteremia and UTIs


Moxifloxacin is NOT used for UTIs

Gemifloxacin is used for respiratory tract infections ONLY

Adverse Effects of Quinolones

  • CNS effects (dizziness)
  • Arthropathy
  • Tendonitis/Tendon Rupture (Black Box Warning for kids – inhibits cartilage development)
  • QT Interval Prolongation

What is a critical counseling point for a patient that is on a quinolone and is taking an iron supplement?

  • CI when taking both at same moment in time
  • Separate Quinolone and Iron supplement
  • Iron supplement 1 hr before Quinolone or 2 hours after Quinolone
  • Some say 4 before or 4 after

Clindamycin: MOA

Lincosamide Antibiotic


Inhibits bacterial protein synthesis by binding to 50S ribosomal subunit

Route of Elimination for Clindamycin

Hepatically Metabolized


No dosage adjustment for renal impairment

T/F: Clindamycin requires dosage adjustment in patients that are renally retarded



Only patients that are hepatically retarded need dosage adjustments, b/c it is hepatically metabolized

Adverse Effects of Tigecycline

  • Diarrhea
  • GI upset

Metronidazole: MOA

  • Enters cell by passive diffusion and is activated by reductive processes
  • This produces short-lived metabolites that damage bacterial DNA and subsequently causes cell death

Metronidazole Route of Elimination

  • Hepatically metabolized
  • No dosage adjustment unless severe kidney failure

Metronidazole Route of Administration
Adverse Effects of Metronidazole

  • CNS effects
  • GI upset
  • Metallic taste
  • Disulfiram-Like Reaction (possible but not likely – don’t use with alcohol)

Chloramphenicol: MOA

  • Binds reversibly to 50S bacterial ribosomal subunit
  • Inhibits protein synthesis

Chloramphenicol Route of Elimination
Primarily metabolized in liver
Adverse Effects of Chloramphenicol

  • Aplastic anemia (irreversible)
  • Bone marrow suppression (reversible)
  • Gray Baby Syndrome (primarily neonates)

Vancomycin Route of Administration
Vancomycin Route of Elimination
Adverse Effects of Vancomycin

  • Nephrotoxicity – not as bad as aminoglycosides
  • Drug Fever
  • Infusion-Related Side Effects

“Red Man” Syndrome



Quinupristin/Dalfopristin: MOA
Dalfprostin has been shown to inhibit the early phase of protein synthesis while Quinupristin inhibits the late phase of protein synthesis
Quinupristin/Dalfopristin Route of Elimination

  • Metabolized to several active major metabolites
  • Fecal excretion constitutes the main elimination route for both parent drugs and their metabolites

Quinupristin/Dalfopristin Spectrum of Activity

  • Enterococcus faecium (VRE), not E. faecalis
  • Staph. aureus
  • Strep. pyogenes

Adverse Effects of Quinupristin/Dalfopristin

  • Inflammation at infusion site
  • Arthralgia/myalgia

Linezolid: MOA

Oxazolidine Antibiotic


Binds to 23S rRNA of the 50S subunit –> prevents formation of a functional 70S initiation complex


-static against Staph.

-cidal against Strep.

Linezolid Route of Elimination

  • Renal clearnace is low and suggests net tubular reabsorption
  • Mainly Non-Renal

Linezolid Spectrum of Activity



Strep. pneumoniae

Adverse Effects of Linezolid
Linezolid Drug Interactions
MAOI – may lead serotonin syndrome
Daptomycin: MOA

Cyclic Lipopeptide Antibiotic

  • Inserts lipophilic tail into cytoplasmic membrane –> forms a channel that causes depolarization
  • Efflux of K+ and perhaps other ions inhibits macromolecular synthesis and leads to cell death
  • Kills bacteria but leaves cell wall intact which may potentially lead to toxins being suddenly released into the system

Daptomycin Spectrum of Activity

Aerobic G+



Adverse Effects of Daptomycin



Not a selective agent and can target cell membranes of skeletal muscles

Daptomycin Route of Administration
Telavancin Route of Administration
Telavancin: MOA


  • Combines mechanisms of both vancomycin (glycopeptide) and daptomycin (cyclic lipopeptide)
  • Works on cell wall and cell membrane
  • Bactericidal


Adverse Effects of Telavancin


Black Box Warning: Birth Defects

Telavancin Route of Elimination
Chloramphenicol Route of Administration
Azithromycin Route of Administration
Quinupristin/Dalfopristin Route of Administration
Linezolid Route of Administration

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