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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
is Food and Drug Administration (FDA)-approved for treatment of skin and skin-structure infection, intra-abdominal infections, and community-acquired pneumoniq
Tigecycline
26
the oral tetracycline of choice because it can be given twice daily, and its absorption is not significantly affected by food
Doxycycline
27
are the most common reasons for discontinuing tetracycline medication
Nausea, vomiting, diarrhea
28
Hepatic necrosis has been reported with daily doses of tetracyclines of ____or more intravenously.
4g
29
Tetracyclines given along with______may produce nitrogen retention.
diuretics
30
Intravenous injection of tetracyclines can lead to????
venous thrombosis
31
Systemically administered tetracycline, especially demeclocycline, can induce ???
sensitivity to sunlight or ultraviolet light, particularly in fair-skinned persons.
32
a group of closely related compounds characterized by a macrocyclic lactone ring to which deoxy sugars are attached.
Macrolides
33
prototype drugs of Macrolides
erythromycin
34
consists of two sugar moieties attached to a 14-atom lactone ring, was obtained in 1952 from Streptomyces erythreus.
Erythromycin
35
are semisynthetic derivatives of erythromycin
Clarithromycin and Azithromycin
36
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.
Erythromycin
37
Erythromycin: | Inhibition of protein synthesis occurs via binding to the______ ribosomal RNA.
50s
38
how is peptide chain elongation prohibited?
blocking of polypeptide exit tunnel
39
is active against susceptible strains of gram-positive organisms, especially pneumococci, streptococci, staphylococci, and corynebacteria
Erythromycin
40
What are the 3 mechanisms of resistance against erythromycin?
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
What are the 2 most important mechanisms of resistance in gram positive organisms?
Efflux and methylase production
42
Erythromycin base is destroyed by stomach acid and must be administered with enteric coating. True or False?
True
43
What is the best-absorbed oral preparation of erythromycon?
lauryl salt of the propionyl ester of erythromycin (erythromycin estolate)
44
Erythromycin serum half-life is approximately_____ normally and ____in patients with anuria.
1.5 hrs;5 hrs
45
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
Erythromycin
46
has been recommended as prophylaxis against endocarditis during dental procedures in individuals with valvular heart disease,
Erythromycin
47
Oral erythromycin base (1 g) is sometimes combined with ________ for preoperative preparation of the colon.
oral neomycin or kanamycin
48
most common reason for discontinuing erythromycin and substituting another antibiotic.
Gastrointesinal Intolerance
49
Erythromycin increases serum concentrations of oral digoxin by increasing its bioavailability. True or False?
True
50
is derived from erythromycin by addition of a methyl group and has improved acid stability and oral absorption compared with erythromycin.
Clarithromycin
51
is more active against Mycobacterium avium complex
Clarithromycin
52
Clarithromycin is metabolized in ???
Liver
53
The major metabolite of Clarithromycin is?
14-hydroxyclarithromycin,
54
a 15-atom lactone macrolide ring compound, is derived from erythromycin by addition of a methylated nitrogen into the lactone ring.
Azithromycin
55
is highly active against Chlamydia sp.
Azithromycin
56
Azithromycin tissue half-life of?????
2-4 days
57
Azithromycin should be administered when?
should be administered 1 hour before or 2 hours after meals
58
semisynthetic 14-membered-ring macrolides, differing from erythromycin by substitution of a 3-keto group for the neutral sugar l-cladinose.
Ketolides
59
Telithromycin is metabolized in the____ and eliminated by a combination of ______.
liver: biliary and urinary excretion
60
It is a reversible inhibitor of the CYP3A4 enzyme system and may slightly prolong the QTc interval
telithromycin
61
now indicated only for treatment of community-acquired bacterial pneumonia.
Telithromycin
62
can result in hepatitis and liver failure.
Telithromycin
63
is a chlorine-substituted derivative of lincomycin,
Clindamycin
64
like erythromycin, inhibits protein synthesis by inter- fering with the formation of initiation complexes and with amino- acyl translocation reactions.
Clindamycin
65
3 mechanisms of Resistance to clindamycin,
1. mutation of the ribosomal receptor site; 2. modification of the receptor by a constitutively expressed methylase 3. enzymatic inactivation of clindamycin.
66
Clindamycin is metabolized by ______, and both active drug and active metabolites are excreted in_____
liver; bile and urine
67
indicated for the treatment of skin and soft-tissue infections caused by streptococci and staphylococci.
Clindamycin
68
Clindamycin is now recommended rather than erythromycin for prophylaxis of endocarditis in patients with valvular heart disease. true or false?
True
69
is an effective alternative to trimethoprim-sulfamethoxazole for moderate to moderately severe Pneumocystis jiroveci pneumonia in AIDS patients
Clindamycin plus primaquine
70
combination with ????? for AIDS-related toxoplasmosis of the brain.
pyrimethamine
71
Administration of clindamycin is a risk factor for diarrhea and colitis due to ???
Clostridium difficile
72
is a combination of two streptogramins— quinupristin, a streptogramin B, and dalfopristin, a streptogramin A—in a 30:70 ratio.
Quinupristin-dalfopristin
73
Resistance is due to modification of the quinupristin binding site (MLS-B type resistance), enzymatic activation of dalfopristin, or efflux. True or false?
False. enzymatic inactivation of dalfopristin dapat
74
half-life of quinupristin?
half-life of 0.85hr
75
half-life of dalfopristin?
0.7 hours
76
significantly inhibit CYP3A4, which metabolizes warfarin, diazepam, astemizole, terfenadine, cisapride, nonnucleo- side reverse transcriptase inhibitors, and cyclosporine,
Quinupristin and dalfopristin
77
is a potent inhibitor of microbial protein synthesis
Chloramphenicol
78
bacteriostatic broad-spectrum antibiotic that is active against both aerobic and anaerobic gram-positive and gram- negative organisms
Chloramphenicol
79
clinically significant resistance to chloramphenicol is due to
production of chloramphenicol acetyltransferase,
80
is a prodrug that is hydrolyzed in the intestine to yield free chloramphenicol.
Chloramphenicol palmitate
81
hydrolyzes to yield free chloramphenicol,
chloramphenicol succinate
82
an alternative to a β-lactam antibiotic for treatment of bacterial meningitis occurring in patients who have major hypersensitivity reactions to penicillin.
Chloramphenicol
83
is used topically in the treatment of eye infections
Chloramphenicol
84
What is the adverse effect of chloramphenicol on newborn babies
gray baby syndrome
85
is a member of the oxazolidinones, a new class of synthetic antimicrobials.
Linezolid
86
Linezolid inhibits protein synthesis by preventing formation of the ribosome complex that initiates protein synthesis. True or false?
True
87
What is the binding site of Linezolid?
binding site, located on 23S ribosomal RNA of the 50S subunit
88
Resistance to linezolid is caused by?
mutation of the linezolid binding site on 23S ribosomal RNA.
89
Linezolid is metabolized by ????,
oxidative metabolism
90
approved for vancomycin-resistant E faecium infections; nosocomial pneumonia; community-acquired pneumonia
Linezolid
91
The principal toxicity of linezolid is ????
hematologic
92
is the most common manifestation of linezolid intoxication
Thrombocytopenia

Pharmacology (12 decks)

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