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Pharmacology I > Module 3 > Flashcards

Module 3 Flashcards

Antimicrobials

1
Q

Beta-lactam antibiotics MOA

A

Interfere with cell wall synthesis by binding to penicillin-binding proteins (PBP), transpeptidase enzymes that catalyze peptidoglycan cross-linking. This compromises the overall cell wall integrity leading to osmotic lysis making beta-lactams bactericidal.

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2
Q

Penicillin structure

A

consists of a thiazolidine ring, a side chain, and a beta-lactam ring which is essential for antibiotic activity

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3
Q

Natural penicillins

A

penicillin G and penicillin V

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4
Q

Semisynthetic penicillins (aminopenicillins/extended-spectrum penicillins)

A

ampicillin and amoxicillin

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5
Q

Antistaphylococcal penicillins

A

developed to resist hydrolysis by staphylococcal beta-lactamases and include methicillin, nafcillin, oxacillin, and dicloxacillin

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6
Q

Ureidopenicillin/Antipseudomonal penicillin

A

piperacillin

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7
Q

beta-lactamase inhibitors

A

enhance the ability of beta-lactams to fight bacteria by inhibiting an enzyme produced by the bacteria which deactivates beta-lactams like penicillin, include sulbactam, clavulanate, and tazobactam (do not work against all beta-lactamases)

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8
Q

beta-lactam and beta-lactamase inhibitor combos available

A

ampicillin/sulbactam (Unasyn - IV), amoxicillin/clavulonate (Augmentin - PO), and piperacillin/tazobactam (Zosyn - IV)

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9
Q

penicillin G,V antibacterial spectrum

A

gram-positive streptococcus pneumoniae, group A strep, group B strep, group C,G strep, and Viridans streptococci (seen with IVDU) and gram-negative cocci including Neisseria meningitidis. Anaerobes including peptostreptococcus, prevatella spp., fusobacterium spp., clostridium spp., spirochetes including treponema pallidum and borrelia burgdorferi, and other organisms including Pasteurella multocida (cat bites). No staph coverage.

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10
Q

Penicillin administration

A

penicillin G has poor oral bioavailability, requires frequent IV dosing due to short half-life (0.5 hours), and requires dose and interval adjustment for renal insufficiency. Penicillin G IM formulations are available (procaine and benzathine penicillin). Penicillin V has better oral bioavailability.

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11
Q

Antistaphylococcal penicillins antibacterial spectrum

A

active against gram-positive cocci covered by pen G as well as S. aureus and S. epidermidis, no gram-negative coverage

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12
Q

Antistaphylococcal penicillin administration

A

short half-lives, nafcillin and oxacillin require frequent IV/IM dosing whereas dicloxacillin is administered PO, no dose adjustment is required for renal and hepatic impairment for dicloxacillin and oxacillin but caution should be taken with nafcillin in patients with concomitant renal and hepatic impairment

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13
Q

Semisynthetic penicillins (ampicillin and amoxicillin) antibacterial spectrum

A

similar gram-positive activity to pen G but slightly less active against group A strep, group B strep, and S. pneumoniae. Ampicillin is more active against Listeria monocytogenes (cause of meningitis in immunocompromised patients, newborns, and elderly) and 2X more active against enterococci than penicillin. Has some activity against gram-negative H. influenzae and E. coli (40% ampicillin resistance due to beta-lactamases). Not useful for S. aureus infections.

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14
Q

Ampicillin administration

A

requires frequent IV dosing (q 4-6 hours) due to short half-life and dose adjustment with renal insufficiency, has fair oral bioavailability

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15
Q

Amoxicillin administration

A

has better oral availability than ampicillin but can be administered by IV (1-2 g q 6 hours), most active of the penicillins against penicillin-resistant S. pneumoniae

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16
Q

How does combining beta-lactamase inhibitors with ampicillin and amoxicillin increase their spectrum of activity? (Unasyn and Augmentin)

A

Increases activity against gram-positive methicillin-sensitive S. aureus (MSSA), gram-negative H. influenzae producing beta-lactamase, E. coli, K. pneumoniae, and K. oxytoca, and Anaerobic Bacteroides fragilis.

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17
Q

Piperacillin-Tazobactam (Zosyn) antibacterial spectrum

A

has similar gram-positive activity to ampicillin and excellent streptococcal coverage as well as expanded gram-negative activity against Pseudomonas aeruginosa (associated with diabetic would infections), Serratia marcescens, and Enterobacter spp. Excellent anaerobic activity against B. fragilis. Useful for nosocomial pneumonia, intra-abdominal infections, and complicated wound infections. No MRSA coverage.

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18
Q

Piperacillin-Tazobactam (Zosyn) administration

A

Requires frequent IV dosing (no oral) due to short half-life (1 hour) and is usually 4.5 g IV q 6 hours for Pseudomonas but q 8 hours for non-Pseudomonas. Requires dose and interval adjustment for renal insufficiency.

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19
Q

narrow-spectrum, beta-lactamase susceptible drugs (natural penicillins) general antibacterial activity

A

active against strep, enterococci, anaerobes (except B. fragilis), and spirochetes (most staph aureus resistant)

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20
Q

Why is methicillin not used clinically anymore in the United States?

A

it has the potential to cause acute interstitial nephritis

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21
Q

very narrow-spectrum, beta-lactamase resistant drugs (Antistaphylococcal penicillins) general antibacterial activity

A

active against S. aureus (MSSA), S. epidermidis, and strep

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22
Q

wider spectrum, beta-lactamase susceptible drugs (semisynthetic penicillins) general antibacterial activity

A

active against strep, enterococci, Listeria monocytogenes, beta-lactamase negative E. coli, Haemophilus influenzae, and Moraxella catarrhalis (staph aureus is resistant)

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23
Q

broad-spectrum, anti-gram-negative, beta-lactamase susceptible drugs (antipseudomonal) antibacterial activity

A

retains the activity of ampicillin and is also active against Pseudomonas aeruginosa (staph aureus is resistant)

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24
Q

What is the main structural difference between penicillins and cephalosporins?

A

Cephalosporins contain R1 and R2 side chain substitutions which alter their antibacterial spectrum and pharmacokinetics making them resistant to hydrolysis by many penicillinases (beta-lactamases)

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25
Q

What are the main similarities between penicillins and cephalosporins?

A

Both penicillins and cephalosporins contain beta-lactam rings which inhibit cell wall synthesis and are bactericidal

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26
Q

How does the antimicrobial activity of cephalosporins change as the generation increases?

A

Lower-generation cephalosporins have more activity against gram-positive organisms (staph and strep) and higher-generation cephalosporins have more activity against gram-negative and less activity against gram-positive organisms (more broad spectrum)

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27
Q

1st generation cephalosporins

A

cefazolin and cephalexin

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28
Q

2nd generation cephalosporin

A

cefoxitin, cefuroxime, cefotean, cefaclor, and cefprozil

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29
Q

3rd generation cephalosporins

A

ceftriaxone and ceftazidime

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30
Q

4th generation cephalosporin

A

cefepime

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31
Q

5th generation cephalosporin

A

ceftaroline

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32
Q

1st generation cephalosporins antibacterial spectrum

A

active against strep, S. aureus (MSSA), Proteus mirabilis, sensitive E. coli, and Klebsiella spp. (PEcK)

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33
Q

2nd generation cefuroxime antibacterial spectrum

A

improved gram-negative activity including beta-lactamase-positive H. influenzae and Neisseria spp. (HEN PEcKS) and slightly reduced gram-positive activity (crosses blood-brain barrier)

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34
Q

3rd generation ceftriaxone antibacterial spectrum

A

has the longest half-life of all the cephalosporins and retains the gram-positive activity of 1st generation cephalosporins but has improved gram-negative activity (used to treat community-acquired pneumonia and is the drug of choice for CNS infections - crosses blood-brain barrier), is also active against Neisseria gonorrhoeae.

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35
Q

3rd generation ceftazidime antibacterial spectrum

A

loses gram-positive activity but is active against gram-negative rods including Pseudomonas (used to treat nosocomial infections)

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36
Q

4th generation cefepime antibacterial spectrum

A

has excellent gram-negative and gram-positive activity against Pseudomonas (nosocomial infections)

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37
Q

5th generation ceftaroline antibacterial spectrum

A

effective against MRSA but has no Pseudomonas coverage (approved for CAP and acute bacterial skin infections) - only used for MRSA if there is an allergy to vancomycin (under lock and key)

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38
Q

Aztreonam (IV/IM) MOA

A

a monobactam beta-lactam antibiotic that binds to PBP3 preventing peptidoglycan cross-linking (has no cross-allergenicity with beta-lactams and used when allergy to penicillin)

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39
Q

Aztreonam antibacterial spectrum

A

has broad gram-negative activity including Pseudomonas aeruginosa but no gram-positive or anaerobic activity (used as an alternative to aminoglycosides and 3rd generation cephalosporins)

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40
Q

Vancomycin MOA

A

bactericidal non-beta-lactam antibiotic that inhibits cell wall synthesis by binding the D-Ala-D-Ala terminal of the forming peptidoglycan preventing cross-linking

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41
Q

Vancomycin antibacterial spectrum

A

narrow-spectrum activity against drug-resistant gram-positive infections (drug of choice for MRSA) and C. difficile (given PO because bacteria is in the colon), no gram-negative activity. VRE and VRSA resistant due to substitution of D-Lactate for terminal D-Alanine

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42
Q

Vancomycin administration

A

administered through IV unless for treating C. diff (oral) and dose adjustment required in renal impairment

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43
Q

Vancomycin adverse effects

A

infusion-related flushing (or red man syndrome) and dose-dependent ototoxicity and nephrotoxicity especially in the setting of other toxic drugs

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44
Q

Daptomycin MOA

A

bactericidal lipopeptide that disrupts the bacterial cell membrane

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45
Q

Daptomycin antibacterial spectrum

A

narrow-spectrum activity against gram-positive bacteria only (useful for treating infections due to resistant gram-positive cocci including MRSA and vancomycin-resistant enterococci - VRE)

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46
Q

Daptomycin administration

A

administered through IV only and dose interval adjustment required for renal impairment

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47
Q

Daptomycin toxicity

A

myositis (myopathy, muscle pain)

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48
Q

Carbapenems

A

synthetic beta-lactam antibiotics which only differ slightly in structure from the penicillins that are highly resistant to beta-lactamases (Imipenem, Meropenem, and Ertapenem)

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49
Q

Carbapenems antibacterial spectrum

A

broad-spectrum antibacterial activity against gram-positive cocci (MSSA, MSSE, and S. Pneumoniae, not MRSA or E. faecium), gram-negative rods and resistant gram-negative rods (Pseudomonas aeruginosa and Enterobacter spp.), and anaerobes

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50
Q

Carbapenem administration

A

administered through IV and penetrate well into body tissues and fluids including CSF when meninges are inflamed.

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51
Q

Imipenem administration

A

inactivated by renal dehydropeptidase (DHP) so is administered with cilastatin which inhibits DHPs

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52
Q

Adverse effects of Imipenem

A

Can cause encephalopathy and seizures, other carbapenems less likely to do so

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53
Q

extended spectrum beta-lactamases (ESBLs)

A

found mainly in E.coli and Klebsiella spp. but also occasionally found in different species of the Enterobacteriaceae, Pseudomonas, H. influenzae, and Neisseria gonorrheae (increasing use of 3rd generation cephalosporins has contributed to their rise)

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54
Q

Fosfomycin MOA

A

bactericidal through the inhibition of first step of bacterial cell wall synthesis and the enzyme pyruvyl transferase (given when patient has multiple allergies)

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55
Q

Fosfomycin antibacterial spectrum

A

activity against some MDR organisms including ESBL-producing E. coli but mainly used in treatment of UTIs particularly those caused by E. coli and Enterococcus faecalis

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56
Q

Fosfomycin administration

A

oral as a one-time 3 g dose, requires no dose adjustment for renal impairment

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57
Q

Fosfomycin most common adverse effects

A

diarrhea and vaginitis

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58
Q

Aminoglycoside MOA

A

Bactericidal protein synthesis inhibitor that targets the 30S subunit of bacterial ribosomes

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59
Q

Aminoglycoside antibacterial spectrum

A

synergistic with cell wall inhibitors (beta-lactams and vancomycin) with broad spectrum activity against many gram-negative rods including Pseudomonas. Most frequently used clinically for empiric therapy of serious infections caused by aerobic gram-negative bacilli, not effective against anaerobes.

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60
Q

Aminoglycoside administration

A

administered daily through IV/IM (except for Neomycin [oral] which is too toxic for IV) with limited tissue penetration and no CNS penetration, dose adjustment required for renal impairment

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61
Q

Aminoglycoside adverse effects

A

can have toxic effects on the kidney and both the auditory and vestibular components of the 8th cranial nerve (ototoxicity). Toxicity causes irreversible damage to the cochlear and vestibular cells depending on the length of exposure and loop diuretics. Longer courses of therapy can also cause reversible nephrotoxicity potentiated by other renal-toxic agents.

62
Q

Aminoglycosides contraindication

A

patients with Myasthenia gravis due to risk of paralysis

63
Q

Streptomycin clinical use

A

Second-line treatment for Tuberculosis but more toxic than newer agents

64
Q

Gentamycin clinical use

A

used similar to Tobramycin for serious gram-negative infections including treatment of Pseudomonas (especially in CF), Enterobacter, Proteus, and undefined sepsis and endocarditis

65
Q

Amikacin clinical uses

A

resistant to bacterial enzymes that inactive aminoglycosides like gentamycin and used only as last resort (under lock and key)

66
Q

Neomycin clinical use

A

used as topical ointments or orally in surgical prophylaxis for bowel surgery

67
Q

Tetracycline MOA

A

Bacteriostatic protein synthesis inhibitor that targets the 30S subunit of bacterial ribosomes

68
Q

Tetracycline antibacterial spectrum

A

active against many gram-positive, and gram-negative bacteria, and atypicals, alternate choice for MRSA and VRE treatment

69
Q

Tetracycline clinical use

A

tetracycline and doxycycline are most widely used to treat Chlamydia, Rickettsia, Mycoplasma (esp. M. pneumonia) infection, Tick-borne diseases, Gonococcal infections, pelvic inflammatory disease, anthrax, malaria, and tularemia. Can be used at lower doses to treat acne and rosacea.

70
Q

Tetracycline administration

A

administered orally with food to minimize GI distress (absorption decreased by dairy food and antacids) and distributed to most body fluids including CSF but not at a high enough level to treat CNS infection. Doxycycline is the only tetracycline that can be given to patients with renal impairment

71
Q

Tetracycline adverse effects

A

causes gastric discomfort if taken without food, photosensitivity, inhibition of bone growth in kids, discoloration of teeth of fetus and children brown, superinfections (yeast infections and C. diff), and vestibular side effects (dizziness, nausea, and vomiting)

72
Q

Tetracycline contraindications

A

pregnancy and children under 8 years old

73
Q

Tigecycline MOA

A

Bacteriostatic protein synthesis inhibitor that targets the 30S subunit of bacterial ribosomes, binding better than tetracycline and doxycycline. It is derived from minocycline and was specifically designed to overcome resistance to tetracycline/doxycycline which is mediated by efflux pumps and ribosomal protection.

74
Q

Tigecycline clinical use

A

used to treat complicated infections by MRSA and VRE, complicated intra-abdominal infections, CAP, Enterobacteria, Mycobacteria, and all other tetracycline targets (under lock and key)

75
Q

Tigecycline adverse effects

A

same as tetracyclines - N/V/D, photosensitivity, and chelation

76
Q

Chloramphenicol MOA

A

Bacteriostatic protein synthesis inhibitor which binds to the 50S subunit of bacterial ribosomes and blocks aminoacyl from binding to the acceptor site, inhibiting peptidyl transferase reaction and translation.

77
Q

Chloramphenicol antibacterial spectrum

A

widely distributed in tissues and crosses blood-brain barrier where it is active against many gram-positive and gram-negative bacterial including anaerobes, bactericidal against H. influenzae, S. pneumoniae, and N. meningitidis, VRE, and Rocky Mountain Spotted Fever

78
Q

Chloramphenicol clinical use

A

use in the United States is limited by severe adverse reactions but it is used widely outside the country for treatment of bacterial meningitis

79
Q

Chloramphenicol adverse effects

A

causes Gray baby syndrome in infants due to incomplete hepatic development characterized by cyanosis and cardiovascular collapse, bone marrow suppression, anemia, and pancytopenia (may be fatal), drug-drug interactions may increase levels of warfarin and phenytoin

80
Q

Macrolides MOA

A

Bacteriostatic protein synthesis inhibitor which irreversibly binds to the 50S subunit in bacterial ribosomes and inhibit translocation steps in protein synthesis. Include erythromycin, clarithromycin, and azithromycin.

81
Q

Erythromycin antibacterial spectrum

A

active against gram-positive bacteria but resistance is increasing

82
Q

Clarithromycin antibacterial spectrum

A

active against gram-positive bacteria and has better activity than erythromycin against H. influenzae, Chlamydia, Legionella, and Moraxella, also used for the treatment of Helicobacter pylori

83
Q

Azithromycin antibacterial spectrum

A

active against atypical respiratory infections including Mycoplasma pneumoniae and Legionella infection, Mycobacterium avium complex (associated with AIDS), strep pharyngitis in penicillin allergic patients and is drug of choice for chlamydial STI

84
Q

Erythromycin administration

A

administered as enteric-coated tablets with good bioavailability, not given IV which is associated with a high incidence of thrombophlebitis (no CNS penetration)

85
Q

Azithromycin administration

A

administered orally without food and is stable in stomach acid without enteric-coating (food decreases absorption), also available in IV formulation, has the longest half-life of all the macrolides - relatively short abx. course required (no CNS penetration)

86
Q

Clarithromycin administration

A

administered orally or through IV and dose adjustment is required for renal impairment because it is eliminated by the kidneys (other macrolides are excreted in the bile), no CNS penetration

87
Q

Macrolides adverse effects

A

well tolerated with the most common adverse effect being GI upset (least common with azithromycin), jaundice resulting from cholestatic hepatitis may develop with erythromycin (avoid in patients with hepatic dysfunction)

88
Q

Macrolides drug-drug interactions

A

interfere with CYP3A4 and inhibit hepatic metabolism of several drugs including atorvastatin, simvastatin, carbamazepine, warfarin, theophylline, etc.

89
Q

Clindamycin MOA

A

A lincosamide which inhibits peptidyl transfer by binding to the 50S ribosomal subunit and is bacteriostatic.

90
Q

Clindamycin antibacterial spectrum

A

has narrow spectrum activity against gram-positive cocci including MRSA and anaerobes including B. fragilis

91
Q

Clindamycin administration

A

administered orally or IV as well as topical

92
Q

Clindamycin clinical use

A

used to treat anaerobic bacterial infections as well as MRSA-associated skin and dental infections (penetrates abscesses)

93
Q

Clindamycin adverse effects

A

diarrhea, nausea, vomiting, penicillin-like rash, and is a major cause of C. diff. pseudomembranous colitis

94
Q

Linezolid MOA

A

Protein synthesis inhibitor that binds to the 50S ribosomal subunit of bacteria and prevents initiation of protein synthesis. Mostly bacteriostatic but can be bactericidal to streptococci and C. perfringens.

95
Q

Linezolid antibacterial spectrum

A

has very narrow spectrum activity against resistant gram-positive cocci such as MRSA and VRE

96
Q

Linezolid administration

A

administered orally or through IV, no renal dose adjustment required

97
Q

Linezolid adverse effects

A

causes dose-dependent thrombocytopenia, potentiation of serotonin syndrome when used in combination with many anti-depressants

98
Q

Streptogramins MOA

A

bactericidal protein synthesis inhibitor that consists of two components (quinupristin/dalfopristin) that bind to a separate site on the 50S ribosomal subunit and synergistically interrupt protein synthesis.

99
Q

Streptogramins antibacterial spectrum

A

has relatively narrow spectrum activity against gram-positive aerobic bacteria and is only used for treatment of MRSA and VRE

100
Q

Streptogramins administration

A

administered through IV and undergoes hepatic metabolism and excretion in the feces

101
Q

Streptogramins adverse effects

A

arthralgia and myalgia

102
Q

Why is a single higher daily dose of aminoglycosides better than multiple lower doses given at timed intervals throughout the day?

A

a single higher dose per day is less toxic because the concentration is above the toxicity threshold for a shorter amount of time than if three lower doses were administered at timed intervals throughout the day

103
Q

Fluoroquinolones MOA

A

bind to topoisomerase IV and DNA gyrase enzymes which inhibits DNA replication, bactericidal

104
Q

Fluroquinolones administration

A

administered orally or through IV (bioavailability equivalent), ciprofloxacin is dosed twice daily whereas levofloxacin and moxifloxacin are dosed once daily. Ciprofloxacin and levofloxacin require dose adjustment for renal impairment due to renal elimination.

105
Q

1st generation fluoroquinolone

A

norfloxacin

106
Q

2nd generation fluoroquinolone

A

ciprofloxacin

107
Q

3rd generation fluoroquinolone

A

levofloxacin

108
Q

4th generation fluoroquinolone

A

moxifloxacin

109
Q

Ciprofloxacin antibacterial spectrum

A

has broad spectrum activity against gram-negative bacteria including Pseudomonas aeruginosa, staphylococci (MSSA), and atypical bacterial including chlamydia, mycoplasma, and legionella

110
Q

Levofloxacin antibacterial spectrum

A

has slightly less gram-negative activity than ciprofloxacin but has better activity against strep pneumoniae and atypicals, active against Pseudomonas aeruginosa

111
Q

Moxifloxacin antibacterial spectrum

A

same activity as 2nd and 3rd generation fluoroquinolones as well as activity against anaerobes (has poor activity against Pseudomonas aeruginosa)

112
Q

Fluoroquinolones adverse effects

A

causes mild GI effects such as nausea, vomiting, and diarrhea as well as headache, dizziness, and insomnia. May cause confusion in the elderly. Causes phototoxicity, neuromuscular blockade, and increased risk of tendinopathy and rupture. Can also cause QT prolongation in patients who are predisposed to arrhythmias or on other medications that may prolong QT interval.

113
Q

Fluoroquinolones contraindications

A

in patients with Myasthenia gravis, in pregnancy, and in children (due to articular cartilage erosion)

114
Q

Fluoroquinolones drug-drug interactions

A

may raise serum concentration of warfarin and cyclosporine

115
Q

Ciprofloxacin clinical uses

A

pyelonephritis, UTIs, abdominal infections, prostatitis, traveler’s diarrhea, bone/joint infections, diabetic infections, skin infections, bite wounds, anthrax, Pseudomonas infections in CF, poor coverage against pneumococci, no MRSA coverage

116
Q

Levofloxacin clinical uses

A

same as cipro but has better activity against Strep pneumo, often used for respiratory infections

117
Q

Moxifloxacin clinical uses

A

same as cipro but has better activity against strep pneumo and anaerobes, often used for respiratory infections, no Pseudomonas coverage

118
Q

Nitrofurantoin MOA

A

involves the bacterial conversion of drug to highly reactive intermediates that react nonspecifically with many targets (ribosomal targets, synthetic machinery of proteins, RNA, DNA, and metabolic enzymes, bactericidal

119
Q

Nitrofurantoin antibacterial spectrum

A

bactericidal against many gram-positive and gram-negative bacteria

120
Q

Nitrofurantoin clinical use

A

used for empiric treatment of uncomplicated cystitis (UTI), concentrates in urine but does not have good tissue distribution

121
Q

Nitrofurantoin adverse effects

A

anorexia, nausea, and vomiting as well as neuropathies and hemolytic anemia in patients with glucose-6-phosphate-dehydrogenase deficiency, also associated with interstitial pulmonary fibrosis

122
Q

Nitrofurantoin contraindications

A

patients with renal impairment

123
Q

Metronidazole MOA

A

activated by a single reduction step by the bacteria which forms radicals and reacts with nucleic acids, damaging DNA and leads to cell death

124
Q

Metronidazole antibacterial spectrum

A

bactericidal under anaerobic conditions against Bacteroides difficile (formerly Clostridium), Helicobacter pylori (part of a multi-drug regimen)

125
Q

Metronidazole clinical uses

A

used to treat a wide variety of anaerobic infections including trichomoniasis, SSSIs, bone and joint infections, endocarditis, gynecologic infections, intra-abdominal infections, lower respiratory tract infections, systemic anaerobic infections, and traveler’s diarrhea

126
Q

Metronidazole adverse effects

A

most common is GI upset but can also cause a Disulfiram-like reaction with ethanol (flushing, tachycardia, and hypotension)

127
Q

What is the first-line treatment for non-severe (C. difficile infection) CDI?

A

Oral vancomycin (bacteriostatic against C. difficile)

128
Q

What is the second-line treatment for non-severe CDI?

A

Oral fidaxomicin - a macrolide (bactericidal against C. difficile)

129
Q

What is the third-line treatment for non-severe CDI if allergy to vancomycin or fidaxomicin?

A

Oral metronidazole (bacteriostatic against C. difficile)

130
Q

Sulfonamides MOA

A

inhibit folate metabolism (synthetic analog of PABA)

131
Q

Trimethoprim MOA

A

inhibits the enzyme dihydrofolate reductase

132
Q

What is the advantage of combining sulfamethoxazole with trimethoprim (Bactrim- TMP/SMX)

A

sulfamethoxazole works synergistically with trimethoprim making the combination bactericidal whereas each drug alone is bacteriostatic and require host defenses to clear infection

133
Q

TMP/SMX antibacterial spectrum

A

(treatment for UTIs) active against H. influenzae, Legionella (in URIs but does not cover Strep pneumo), Salmonella (excellent biliary tree penetration), Pneumocystitis Jirovecii, Listeria monocytogenes (in combination with amoxicillin), and Toxoplasmosis

134
Q

TMP/SMX adverse effects

A

hypersensitivity reactions including rash and Stevens-Johnson Syndrome (rare), neonatal kernicterus (Sulfa), hyperkalemia, megaloblastic anemia, leukopenia, thrombocytopenia (TMP), and hemolytic anemia may occur in patients with glucose-6-phosphate-dehydrogenase deficiency (sulfa)

135
Q

TMP/SMX drug-drug interactions

A

warfarin, phenytoin, and methotrexate

136
Q

TMP/SMX contraindications

A

in newborns, pregnant women, and patients with renal disease

137
Q

TMP/SMX administration

A

typically administered orally but can also be given through IV for treatment of severe pneumonia caused by P. jirovecii

138
Q

Rifaximin MOA

A

inhibits RNA polymerase and is bacteriostatic, minimally effects CYP

139
Q

Rifampin MOA

A

inhibits RNA polymerase and is bactericidal, powerful inducer of many CYPs known

140
Q

Rifaximin clinical uses

A

treatment of traveler’s diarrhea, hepatic encephalopathy, IBS/SIBO

141
Q

Rifaximin adverse effects

A

peripheral edema, nausea, and rash

142
Q

Rifampin clinical uses

A

oral treatment of Mycobacterium tuberculosis (can not be used alone due to rapid resistance) and MRSA

143
Q

Rifampin adverse effects

A

hepatoxicity, GI upset, rash, orange-red tears, saliva, urine, and sweat, has a large capacity for drug-drug interactions due to the induction of multiple CYPs in liver

143
Q

Isoniazid MOA

A

inhibits the synthesis of mycolic acids which are essential components of mycobacterial cell walls

143
Q

Isoniazid antibacterial spectrum

A

bactericidal against actively growing tubercle bacilli and less effective against nontuberculous mycobacteria, penetrates into macrophages and is active against both intracellular and extracellular organisms

144
Q

Isoniazid administration

A

administered orally along with pyridoxine to prevent peripheral neuropathy, no dose adjustment required for renal impairment

145
Q

Isoniazid clinical uses

A

can be paired with rifampin to treat most strains of tuberculosis (however a four-drug combo is usually used for first two months of treatment - referred to as ‘intensive phase’)

146
Q

Isoniazid adverse effects

A

hepatotoxicity/hepatitis is most serious effect, rash, fever, and neuropathy

147
Q

Ethambutol MOA

A

inhibits mycobacterial arabinosyl transferases which are essential enzymes that function in the synthesis of the mycobacterial cell wall

148
Q

Ethambutol administration

A

always administered in combination with other anti-TB drugs to prevent resistance

149
Q

Ethambutol antibacterial adverse effects

A

optic neuritis which results in diminished visual acuity and loss of ability to discriminate between red and green, the risk of optic neuritis increases with higher doses and in patients with renal impairment

Pharmacology I (5 decks)

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