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Pharmacology > Tetracyclines, Macrolides and Others > Flashcards

Tetracyclines, Macrolides and Others Flashcards

1
Q

Are crystalline amphoteric substances of low solubility

A

Free Tetracyclines

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2
Q

a glycylcycline and a semisynthetic derivative of minocycline, analog of tetracycline

A

Tigecycline

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3
Q
  • broad-spectrum bacteriostatic antibiotics that inhibit protein synthesis.
  • enter microorganisms in part by passive diffusion and in part by an energy-dependent process of active transport
A

Tetracyclines

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4
Q

Tetracyclines bind reversibly to the _____ subunit of the bacterial ribosome, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA- ribosome complex

A

30s

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5
Q

What are the three mechanisms of resistance to tetracycline analogs

A
  1. impaired influx or increased efflux by an active trans- port protein pump;
  2. ribosome protection due to production of proteins that interfere with tetracycline binding to the ribosome;
  3. enzymatic inactivation
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6
Q

what is the most important mechanism of resistance to tetracycline analogs?

A

production of an efflux pump and ribosomal protection

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7
Q

Tet(K) efflux pump of staphylococci confers resistance to ________ but not to doxycycline, minocycline, or tigecycline,

A

Tetracycline

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8
Q

Tet(M) ribosomal protection protein expressed by gram-positives produces resistance to tetracycline, doxycycline, and minocycline, but not to _________

A

Tigecycline

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9
Q

Absorption of tetracyclines:

approximately 30% for 1.______ 60–70% for 2.______; and 95–100% for 3.______

A
  1. chlortetracyline
  2. tetracycline, demeclocycline,methacycline,oxytetracycline
  3. doxycycline and minocycline
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10
Q

Absorption of tetracyclines occurs mainly in the ______ and is impaired by _____ (except doxy and minocycline)

A

upper intestine;food

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11
Q

teady-state peak serum concentrations of tigecycline are ______ at the standard dosage

A

0.6 mcg/mL

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12
Q

Minocycline is useful for eradication of the meningococcal carrier state. Why?

A

bec. it reaches very high concentrations in tears and saliva

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13
Q

Tetracyclines are excreted mainly in ???

A

bile and urine

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14
Q

______ in contrast to other tetracyclines, are eliminated by nonrenal mechanisms, do not accumulate signifi- cantly, and require no dosage adjustment in renal failure.

A

Doxycycline and tigecycline,

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15
Q

3 classifications of Tetracyclines

A
  1. short-acting (chlortetracycline,tetracyline and oxytetracycline)
  2. intermediate-acting (methacycline, demeclocycline)
  3. long-acting (doxycycline, tigecycline)
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16
Q

what is the half-life of tigecycline?

A

36 hours

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17
Q

the drug of choice in the treatment of infections caused by rickettsiae

A

tetracyclines

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18
Q

In cholera,_____ rapidly stop the shedding of vibrios,

A

tetracyclines

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19
Q

is indicated for plague,tularemia,and brucellosis.

A

tetracycline in combination with other antibiotics

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20
Q

can eradicate the meningococcal carrier state

A

Minocycline

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21
Q

inhibits the action of antidiuretic hormone in the renal tubule and has been used in the treatment of inappropri- ate secretion of antidiuretic hormone or similar peptides by cer- tain tumors

A

Demeclocycline

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22
Q

the first glycylcycline to reach clinical practice,

A

Tigecycline

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23
Q

formulated for intravenous administration only,

A

Tigecycline

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24
Q

chief adverse effect of tigecycline is ????

A

nausea

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25
Q

is Food and Drug Administration (FDA)-approved for treatment of skin and skin-structure infection, intra-abdominal infections, and community-acquired pneumoniq

A

Tigecycline

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26
Q

the oral tetracycline of choice because it can be given twice daily, and its absorption is not significantly affected by food

A

Doxycycline

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27
Q

are the most common reasons for discontinuing tetracycline medication

A

Nausea, vomiting, diarrhea

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28
Q

Hepatic necrosis has been reported with daily doses of tetracyclines of ____or more intravenously.

A

4g

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29
Q

Tetracyclines given along with______may produce nitrogen retention.

A

diuretics

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30
Q

Intravenous injection of tetracyclines can lead to????

A

venous thrombosis

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31
Q

Systemically administered tetracycline, especially demeclocycline, can induce ???

A

sensitivity to sunlight or ultraviolet light, particularly in fair-skinned persons.

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32
Q

a group of closely related compounds characterized by a macrocyclic lactone ring to which deoxy sugars are attached.

A

Macrolides

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33
Q

prototype drugs of Macrolides

A

erythromycin

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34
Q

consists of two sugar moieties attached to a 14-atom lactone ring, was obtained in 1952 from Streptomyces erythreus.

A

Erythromycin

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35
Q

are semisynthetic derivatives of erythromycin

A

Clarithromycin and Azithromycin

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36
Q

general structure is shown with the macrolide ring and the sugars desosamine and cladinose.
It is poorly soluble in water (0.1%) but dissolves readily in organic solvents.
fairly stable at 4°C but lose activity rapidly at 20°C and at acid pH.

A

Erythromycin

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37
Q

Erythromycin:

Inhibition of protein synthesis occurs via binding to the______ ribosomal RNA.

A

50s

38
Q

how is peptide chain elongation prohibited?

A

blocking of polypeptide exit tunnel

39
Q

is active against susceptible strains of gram-positive organisms, especially pneumococci, streptococci, staphylococci, and corynebacteria

A

Erythromycin

40
Q

What are the 3 mechanisms of resistance against erythromycin?

A
  1. reduced permeability of the cell membrane or active efflux
  2. production (by Enterobacteriaceae) of esterases that hydrolyze macrolides
  3. modification of the ribosomal binding site (so-called ribosomal protection) by chromosomal mutation or by a macrolide-inducible or constitutive methylase.
41
Q

What are the 2 most important mechanisms of resistance in gram positive organisms?

A

Efflux and methylase production

42
Q

Erythromycin base is destroyed by stomach acid and must be administered with enteric coating. True or False?

A

True

43
Q

What is the best-absorbed oral preparation of erythromycon?

A

lauryl salt of the propionyl ester of erythromycin (erythromycin estolate)

44
Q

Erythromycin serum half-life is approximately_____ normally and ____in patients with anuria.

A

1.5 hrs;5 hrs

45
Q

a drug of choice in corynebacterial infections (diphtheria, corynebacterial sepsis, erythrasma); in respiratory,neonatal, ocular, or genital chlamydial infections; and in treatment of community-acquired pneumonia

A

Erythromycin

46
Q

has been recommended as prophylaxis against endocarditis during dental procedures in individuals with valvular heart disease,

A

Erythromycin

47
Q

Oral erythromycin base (1 g) is sometimes combined with ________ for preoperative preparation of the colon.

A

oral neomycin or kanamycin

48
Q

most common reason for discontinuing erythromycin and substituting another antibiotic.

A

Gastrointesinal Intolerance

49
Q

Erythromycin increases serum concentrations of oral digoxin by increasing its bioavailability.
True or False?

A

True

50
Q

is derived from erythromycin by addition of a methyl group and has improved acid stability and oral absorption compared with erythromycin.

A

Clarithromycin

51
Q

is more active against Mycobacterium avium complex

A

Clarithromycin

52
Q

Clarithromycin is metabolized in ???

A

Liver

53
Q

The major metabolite of Clarithromycin is?

A

14-hydroxyclarithromycin,

54
Q

a 15-atom lactone macrolide ring compound, is derived from erythromycin by addition of a methylated nitrogen into the lactone ring.

A

Azithromycin

55
Q

is highly active against Chlamydia sp.

A

Azithromycin

56
Q

Azithromycin tissue half-life of?????

A

2-4 days

57
Q

Azithromycin should be administered when?

A

should be administered 1 hour before or 2 hours after meals

58
Q

semisynthetic 14-membered-ring macrolides, differing from erythromycin by substitution of a 3-keto group for the neutral sugar l-cladinose.

A

Ketolides

59
Q

Telithromycin is metabolized in the____ and eliminated by a combination of ______.

A

liver: biliary and urinary excretion

60
Q

It is a reversible inhibitor of the CYP3A4 enzyme system and may slightly prolong the QTc interval

A

telithromycin

61
Q

now indicated only for treatment of community-acquired bacterial pneumonia.

A

Telithromycin

62
Q

can result in hepatitis and liver failure.

A

Telithromycin

63
Q

is a chlorine-substituted derivative of lincomycin,

A

Clindamycin

64
Q

like erythromycin, inhibits protein synthesis by inter- fering with the formation of initiation complexes and with amino- acyl translocation reactions.

A

Clindamycin

65
Q

3 mechanisms of Resistance to clindamycin,

A
  1. mutation of the ribosomal receptor site;
  2. modification of the receptor by a constitutively expressed methylase
  3. enzymatic inactivation of clindamycin.
66
Q

Clindamycin is metabolized by ______, and both active drug and active metabolites are excreted in_____

A

liver; bile and urine

67
Q

indicated for the treatment of skin and soft-tissue infections caused by streptococci and staphylococci.

A

Clindamycin

68
Q

Clindamycin is now recommended rather than erythromycin for prophylaxis of endocarditis in patients with valvular heart disease. true or false?

A

True

69
Q

is an effective alternative to trimethoprim-sulfamethoxazole for moderate to moderately severe Pneumocystis jiroveci pneumonia in AIDS patients

A

Clindamycin plus primaquine

70
Q

combination with ????? for AIDS-related toxoplasmosis of the brain.

A

pyrimethamine

71
Q

Administration of clindamycin is a risk factor for diarrhea and colitis due to ???

A

Clostridium difficile

72
Q

is a combination of two streptogramins— quinupristin, a streptogramin B, and dalfopristin, a streptogramin A—in a 30:70 ratio.

A

Quinupristin-dalfopristin

73
Q

Resistance is due to modification of the quinupristin binding site (MLS-B type resistance), enzymatic activation of dalfopristin, or efflux. True or false?

A

False. enzymatic inactivation of dalfopristin dapat

74
Q

half-life of quinupristin?

A

half-life of 0.85hr

75
Q

half-life of dalfopristin?

A

0.7 hours

76
Q

significantly inhibit CYP3A4, which metabolizes warfarin, diazepam, astemizole, terfenadine, cisapride, nonnucleo- side reverse transcriptase inhibitors, and cyclosporine,

A

Quinupristin and dalfopristin

77
Q

is a potent inhibitor of microbial protein synthesis

A

Chloramphenicol

78
Q

bacteriostatic broad-spectrum antibiotic that is active against both aerobic and anaerobic gram-positive and gram- negative organisms

A

Chloramphenicol

79
Q

clinically significant resistance to chloramphenicol is due to

A

production of chloramphenicol acetyltransferase,

80
Q

is a prodrug that is hydrolyzed in the intestine to yield free chloramphenicol.

A

Chloramphenicol palmitate

81
Q

hydrolyzes to yield free chloramphenicol,

A

chloramphenicol succinate

82
Q

an alternative to a β-lactam antibiotic for treatment of bacterial meningitis occurring in patients who have major hypersensitivity reactions to penicillin.

A

Chloramphenicol

83
Q

is used topically in the treatment of eye infections

A

Chloramphenicol

84
Q

What is the adverse effect of chloramphenicol on newborn babies

A

gray baby syndrome

85
Q

is a member of the oxazolidinones, a new class of synthetic antimicrobials.

A

Linezolid

86
Q

Linezolid inhibits protein synthesis by preventing formation of the ribosome complex that initiates protein synthesis. True or false?

A

True

87
Q

What is the binding site of Linezolid?

A

binding site, located on 23S ribosomal RNA of the 50S subunit

88
Q

Resistance to linezolid is caused by?

A

mutation of the linezolid binding site on 23S ribosomal RNA.

89
Q

Linezolid is metabolized by ????,

A

oxidative metabolism

90
Q

approved for vancomycin-resistant E faecium infections; nosocomial pneumonia; community-acquired pneumonia

A

Linezolid

91
Q

The principal toxicity of linezolid is ????

A

hematologic

92
Q

is the most common manifestation of linezolid intoxication

A

Thrombocytopenia

Pharmacology (12 decks)

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