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Pharm > Tetracyclines ,Glyclines, Sulfonamides, Chloramphenicol and urinary tract agents > Flashcards

Tetracyclines ,Glyclines, Sulfonamides, Chloramphenicol and urinary tract agents Flashcards

1
Q

MOA: tetracylines (tetracycline, doxycycline and minocycline) and glycylcyclines (tigecycline)

A

They reversibly bind the 30S ribosomal subunit to inhibit the binding of aminoacyl transfer-RNA to the
acceptor (A) site on the mRNA-ribosomal complex. This prevents addition of amino acid residues on
elongating peptide chain.

Bacteriostatic; Bactericidal against very susceptible organisms

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2
Q

MOR: tetracylines

A
  • Acquisition of genes on mobile elements via efflux pumps, ribosomal protection proteins, and enzymes that deactivate drugs
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3
Q

Is there cross-resistance between tetracyclines?

A

Cross-resistance observed between tetracyclines, except

for minocycline

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4
Q

Which drug is not affected by the mechanisms of resistance?

A

• Tigecycline resistant to these mechanisms

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5
Q

Spectrum: tetracyclines

A

G+ aerobes (MSSA, PSSP is mostly susc.)
G- aerobes
Anaerobes

Rickettsia
Chlamydia
Mycoplasma
Spirochetes
Strep
Legionella
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6
Q

Spectrum: tigecycline

A

G+ aerobes (incl. MRSA)
G- aerobes (incl, VRE)
Anaerobes

Not proteus or pseudomonas

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7
Q

Treating bacteremias with tigecycline?

A

No

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8
Q

Treating UTIs with tigecycline?

A

No

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9
Q

Absorption of tetracyclines and glycylcyclines overall

A

 Absorbed best on an empty stomach

 Absorption impaired by di- and trivalent cations

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10
Q

Bioavailiability of tetracycline

A

60-80%

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11
Q

Bioavailiability of doxycyline and minocycline

A

90-100%

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12
Q

Affect of food on absorption of tetracyclines and glycylcyclines

A

Absorbed best on an empty stomach

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13
Q

What slows down tetracycline and glycylcycline absorption

A

Divalent and trivalent cations

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14
Q

Distribution: tetracyclines and glycylcyclines

A

Widely distributed with good penetration into synovial fluid,
prostate, seminal fluid

Minimal CSF penetration

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15
Q

Elimination: tetracyclines

A

Tetracycline - excreted unchanged in the

urine

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16
Q

Is dosage adjusted in renal failure?

A

Yes

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17
Q

Half lives of tetracycline and demeclocycline

A

Tetracycline half-life = 6 to 12 hours; demeclocycline half-life = 16 hours

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18
Q

Elimination of doxycycline, minocycline and tigecycline

A

Doxycycline and minocycline (metab) and tigecycline (biliary)

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19
Q

Do doxycycline, minocycline and tigecycline require dose adjustment in renal failure?

A

No

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20
Q

Do doxycycline, minocycline and tigecycline require dose adjustment in renal failure?

A

Doxy and mino do not

Tigecycline DOES

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21
Q

Are tetracyclines and tigecyclines removed during hemodialysis?

A

Minimally

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22
Q

Half-lives of doxy, mine and tige and dosing (general)

A

Half-lives are long, but they are all dosed every 12 hours!

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23
Q

Indications: tetra, doxy, mino, tige

A

Atypical pneumonia
STDs
Rickettsial infections, incl. rocky mountain fever

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24
Q

Specific indications: doxy

A
  1. Community-acquired pneumonia – due to PSSP, Mycoplasma spp, and Chlamydophila spp.
  2. Chlamydial infections including psittacosis, lymphogranuloma venereum,
    and nongonococcal urethritis
25
Specific indications: tige
Polymicrobial infections caused by susceptible bacteria (not caused by Proteus or Pseudomonas) in the following conditions: 1. Complicated skin and skin structure infections 2. Complicated intra-abdominal infections
26
Can pregnant women take tetracyclines and tigecyclines?
No. They cause permanent tooth discolorations of primary dentition. Children under 8 also shouldn't take them.
27
Adverse effects: tetracycline, minocycline, doxycycline
``` GI photosensitivity hepatotoxic Discolor teeth (pregs + kids) Fanconi syndrome (if outdated) ```
28
MOA: trimethoprim-sulfamethoxazole (sulfonamides) | Bactrim
Sulfamethoxazole: competitively inhibits dihydropteroate synthetase, preventing the incorporation of PABA into folic acid Trimethoprim: competitively inhibits the activity of dihydrofolate reductase to prevent the reduction of dihydrofolate to tetrahydrofolate Synergistically inhibit folate synthesis, stopping the production of DNA. Bactericidal
29
Resistance to Bactrim
Bacterial resistance is mediated by point mutations in dihydropteroate synthase and/or altered production or sensitivity of bacterial dihydrofolate reductase. Resistance has been reported in E. coli, Klebsiella spp., Proteus mirabilis, H. flu, Salmonella spp, and Staph
30
Spectrum: Bactrim
G+ aerobes: S. aureus (incl. some MRSA, esp. CA-MRSA), S. pyogenes, and Nocardia G- aerobes: most Enterobacteriaceae and Stenotrophomonas maltophilia. DOC - Pneumocystis carinii/ jiroveci TMP-SMX is NOT active against pseudomonas or anaerobes
31
Indications: Bactrim
UTIs Prostatitis DOC- Pneumocystis carinii/jiroveci pneumonia Skin and soft tissue infections due to CA-MRSA Stenotrophomonas maltophilia infections
32
Adverse Effects: Bactrim
GI, rash, bone marrow | supprxn, renal
33
Drug Ixns: Bactrim
Warfarin
34
MOA: chloramphenicol
Inhibits protein synthesis by reversibly binding to the larger 50S subunit Binding to the ribosome prevents attachment of the amino acid-containing end of the aminoacyl-tRNA to its binding region preventing peptide bond formation. This mechanism produces a static effect against most bacteria except H flu, Strep. pneumo and Neisseria meningitidis.
35
Spectrum: chloramphenicol
G+ anaerobes: strep, NOT staph or enteroc G- anaerobes: most, NOT pseudomonas ``` Anaerobes Spirochetes Rickettsiae Chlamydiae Mycoplasmas ```
36
Absorption: chloramphenicol
Encapsulated form - great bioavailability IV administration produces active chloramphenicol levels in serum that are 70% of those obtained after oral administration, because the drug is not completely hydrolyzed. The iv preparation is the soluble but inactive drug that is rapidly hydrolyzed within the body to become biologically active. Intramuscular injection produces levels similar to iv administration but may have delayed absorption from the injection site.
37
Distribution: chloramphenicol
Due to high degree of lipid solubility, low protein bindingand small molecular size, chorampheicol diffuses well into tissues and body fluids. CSF levels are 30-50% of the serum concentration, even w/o meningitis
38
Elimination: chloramphenicol
i. 90% liver, where it is conjugated with glucuronic acid forming monoglucoronide. Due to wide variation in the metabolism and excretion in children, dosage requirements vary by age with lower daily doses in newborns. ii. Monoglucoronide is excreted in the bile into the small intestine, hydrolyzed by bacterial enzymes to aglycone, reabsorbed and conjugated with glucuronic acid again. This enterohepatic circulation results in about 80-90% of the monoglucoronide being excreted by the kidney.
39
Toxicity: chloramphenicol
Narrow therapeutic window. Monitor newborns and premature infants, patients with hepatic disease and patients taking interacting drugs. Peak serum levels should be maintained between 15-25 g/mL and trough levels between 5-15 g/mL in patients with meningitis, 10-20 g/mL in patients with other infections. Toxicity occurs in those with levels 40 g/mL.
40
In renal insufficiency, adjust dose?
No
41
In hepatic insufficiency, adjust dose?
Yes - decrease dose
42
Indications: chloramphenicol
Not a first line treatment in the US Developing countries: Infant Meningitis w/ pcn allergy Rickettsia in kids and preg
43
Adverse effects: chloramphenicol
BM supprxn | Gray Baby
44
Drug ixns: chloramphenicol
A. Phenobarbital reduces serum concentrations of chloramphenicol by 30-40% with increased concentrations of Phenobarbital by 50%. B. Cyclosporine concentrations increased by chlorampnenicol increasing the risk for renal dysfunction, cholestasis, paresthesias. C. Decreased effectiveness of cyclophosphamide due to decreased metabolism to active cyclophosphamide. D. Rifampin/rifabutin decreases chloramphenicol levels E. Reduces tacrolimus blood concentrations.
45
MOA: Nitrofurantoin
May require enzymatic reduction within the bacterial cell wall. The reduced compounds are capable of binding to ribosomal proteins. Nitrofurantoin has also been shown to inhibit synthesis of inducible enzymes by blocking translation and also to inhibit bacterial respiration and pyruvate metabolism.
46
Spectrum: Nitrofurantoin
E. coli, Citrobacter sp, GBS, Staph | saprophyticus, Enterococcus (incl. many VRE strains)
47
Bioavailability: nitrofurantoin
40-50%. | Absorption occurs rapidly in the small intestine and is enhanced with food.
48
Distribution: nitrofurantoin
Urine concentrations are substantial Low to undetectable serum concentrations after standard oral doses. Does not go to prostate Short half-life
49
Elimination: nitrofurantoin
Mostly kidneys, involving | filtration, secretion, and reabsorption.
50
Increase or decrease nitrofurantoin in kidney failure
Increase in renal failure, because we want more drug at the urethra
51
Counterindications: nitrofurantoin
Renal insufficiency | Elderly
52
MOA methenamine
Becomes formaldehyde at an acidic pH and denature proteins and DNA Don't use with proteus
53
MOR methenamine
Alkaline urine makes it harder for drug to kill things
54
Counterindications : methenamine
avoid with gout and liver insufficiency
55
Spectrum: methenamine
Not really...it makes it harder for things to live
56
Absorption: methenamine
82-88% recovery in urine | Enteric-coated formulations reduce degradation but also take longer to absorb
57
Distribution: methenamine
Broad distribution in tissue, incl. breastmilk
58
Indication: methenamine
Prophylaxis in people with frequent UTIs Not effective in preventing UTIs in patients with chronic, indwelling urinary catheters
59
Adverse effects: methenamine
Gi, rash, prutitus, cystitis, neuropathy, anemia

Pharm (22 decks)

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