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Pharmacology > Sulfonamides, Trimethoprim, Quinolones > Flashcards

Sulfonamides, Trimethoprim, Quinolones Flashcards

1
Q

As structural analogs of PABA, sulfonamides

inhibit ______ and folate production.

A

dihydropteroate synthase

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2
Q

Microorganisms stimulated by sulfonamides in their growth.

A

Rickettsiae

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3
Q

Activity of sulfonamides is poor against?

A

Anaerobes

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4
Q

intrinsically resistant to

sulfonamide antibiotics

A

Pseudomonas aeruginosa

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5
Q

Relationship between sulfonamides and trimethoprim or pyrimethamine

A

synergism

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6
Q

Forms of sulfonamide resistance

A

Mutations that
(1) cause overproduction of PABA
(2) cause production of a folic
acid-synthesizing enzyme that has low affinity for sulfonamides
(3) impair permeability to the sulfonamide

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7
Q

Sulfonamides are absorbed in the CSF and CNS. True or false?

A

True

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8
Q

Therapeutic concentrations of sulfonamides are

in the range of ?

A

40–100 mcg/mL of blood

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9
Q

Long acting sulfonamide

A

Sulfadoxine (7 - 9 days)

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10
Q

Intermediate acting sulfonamides

A

Sulfadiazine
Sulfamethoxazole
Sulfapyridine

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11
Q

Trimethoprim half-Life

A

Intermediate (11 hours)

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12
Q

Pyrimethamine half-Life

A

Long (4–6 days)

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13
Q

drug of choice for infections such as Pneumocystis
jiroveci (formerly P carinii ) pneumonia, toxoplasmosis, nocardiosis,
and occasionally other bacterial infections

A

trimethoprim-sulfamethoxazole (bactrim)

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14
Q

sulfonamides used almost exclusively to treat urinary tract infections

A

Sulfisoxazole and sulfamethoxazole

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15
Q

first-line

therapy for treatment of acute toxoplasmosis

A

Sulfadiazine-pyrimethamine

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16
Q

should also be administered

to minimize bone marrow suppression when taking Sulfadiazine-pyrimethamine

A

Folinic acid, 10 mg orally each day

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17
Q

a second-line agent in the treatment of

malaria

A

pyrimethamine with sulfadoxine (Fansidar)

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18
Q

widely used in ulcerative

colitis, enteritis, and other inflammatory bowel disease

A

Sulfasalazine (salicylazosulfapyridine)

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19
Q

effective
in the treatment of bacterial conjunctivitis and as adjunctive
therapy for trachoma

A

Sodium sulfacetamide ophthalmic solution or ointment

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20
Q

used topically but can be absorbed from burn sites

A

mafenide acetate

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21
Q

AE of mafenide acetate

A

The drug and
its primary metabolite inhibit carbonic anhydrase and can cause
metabolic acidosis

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22
Q

much less toxic topical sulfonamide and is preferred

to mafenide for prevention of infection of burn wounds

A

Silver

sulfadiazine

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23
Q

particularly serious and

potentially fatal AE when taking sulfonamides

A

SJS

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24
Q

The 7 most common adverse effects when taking sulfonamides

A

fever, skin
rashes, exfoliative dermatitis, photosensitivity, urticaria, nausea,
vomiting, diarrhea

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25
Q

Other unwanted effects when taking sulfonamides include?

A

stomatitis, conjunctivitis, arthritis, hematopoietic disturbances, hepatitis, and, rarely, polyarteritis nodosa and psych

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26
Q

when given in large doses, particularly

if fluid intake is poor, can cause crystalluria

A

Sulfadiazine

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27
Q

Crystalluria is treated

by administration?

A

sodium bicarbonate to alkalinize the urine

and fluids to increase urine flow

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28
Q

Other renal AE of sulfonamides

A

nephrosis

allergic nephritis

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29
Q

Sulfonamides can cause hemolytic or aplastic anemia, granulocytopenia,
thrombocytopenia, or leukemoid reactions. Sulfonamides
may provoke hemolytic reactions in patients with?

A

glucose-6-

phosphate dehydrogenase deficiency

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30
Q

Trimethoprim, a trimethoxybenzylpyrimidine, selectively inhibits
bacterial _______ which converts dihydrofolic
acid to tetrahydrofolic acid

A

dihydrofolic acid reductase

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31
Q

Pyrimethamine, another benzylpyrimidine,
selectively inhibits dihydrofolic acid reductase of _____
compared with that of mammalian cells.

A

protozoa

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32
Q

Sulfonamides are bacteriostatic or bacteriocidal?

A

Bacteriostatic when used solely

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33
Q

Resistance to trimethoprim can result from?

A

reduced cell permeability

overproduction of dihydrofolate reductase

production of
an altered reductase with reduced drug binding

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34
Q

Resistant enzymes against trimethoprim may be coded within _____ that exhibit a broad host range, accounting
for rapid and widespread dissemination of trimethoprim resistance?

A

transposons on

conjugative plasmids

35
Q

Trimethoprimsulfamethoxazole

can also be given intravenously. True or False?

A

True

36
Q

trimethoprim is more lipid-soluble than sulfamethoxazole,

it has a larger volume of distribution than the latter drug. True or false?

A

True

37
Q

Ratio of trimethoprim-sulfamethoxazole in formulation

A

1T:5S

38
Q

Ratio of trimethoprim-sulfamethoxazole in peak plasma concentrations

A

1T:20S

39
Q

The
dose of trimethoprim-sulfamethoxazole should be reduced by half for patients with creatinine clearances
of?

A

15–30 mL/min

40
Q

concentrates in prostatic fluid and
in vaginal fluid, therefore, it
has more antibacterial activity in prostatic and vaginal fluids than
many other antimicrobial drugs.

A

Trimethoprim (a weak base)

41
Q

Trimethoprim can be given alone in what dosage in acute

urinary tract infections?

A

100 mg twice daily

42
Q

A combination of trimethoprim-sulfamethoxazole is effective

treatment for a wide variety of infections including?

A 
P. jiroveci
pneumonia shigellosis
systemic salmonella infections
urinary
tract infections prostatitis
some nontuberculous mycobacterial
infections
most Staphylococcus aureus
strains, both methicillin-susceptible and methicillin-resistant,  respiratory tract pathogens such as pneumococcus,
Haemophilus sp, Moraxella catarrhalis, and K pneumoniae (
Mycoplasma pneumoniae ).
43
Q

Respiratory tract pathogen that is resistant to trimethoprim-sulfamethoxazole

A

Mycoplasma pneumoniae

44
Q

One double strength tablet of trimethoprim-sulfamethoxazole contains?

A

each tablet contains trimethoprim

160 mg plus sulfamethoxazole 800 mg

45
Q

DS tablet of trimethoprim-sulfamethoxazole given every 12 hours is effective for?

A

treatment for urinary tract infections and prostatitis

treatment for infections caused by susceptible
strains of shigella and salmonella

46
Q

It is the agent of choice for moderately severe

to severe pneumocystis pneumonia

A

80 mg trimethoprim plus
400 mg sulfamethoxazole per 5 mL diluted in 125 mL of 5%
dextrose in water IV for 60 - 90 minutes

47
Q

used for treatment of

leishmaniasis and toxoplasmosis

A

oral Pyrimethamine and sulfadiazine

48
Q

Patients highly at risk for AE of trimethoprim-sulfamethoxazole

A

Patients

with AIDS and pneumocystis pneumonia

49
Q

The important quinolones are?

A

synthetic fluorinated analogs of

nalidixic acid

50
Q

Quinolones are classified as?

A

DNA gyrase inhibitors

51
Q

Quinolones block bacterial DNA synthesis by inhibiting?

A 
bacterial
topoisomerase II (DNA gyrase) and topoisomerase IV
52
Q

Inhibition of

DNA gyrase prevents?

A

prevents the relaxation of positively supercoiled DNA

that is required for normal transcription and replication

53
Q

Inhibition

of topoisomerase IV interferes with?

A

separation of replicated chromosomal

DNA into the respective daughter cells during cell division

54
Q

Earlier quinolones such as nalidixic acid did not achieve systemic
antibacterial levels and were useful only in the treatment of?

A

lower

urinary tract infections

55
Q

the least
active of the fluoroquinolones against both gram-negative and
gram-positive organisms, with minimum inhibitory concentrations
(MICs) fourfold to eightfold higher than those of ciprofloxacin

A

Norfloxacin

56
Q

comprise a second group of quinolones possessing
excellent gram-negative activity and moderate to good activity
against gram-positive bacteria

A

Ciprofloxacin, enoxacin, lomefloxacin, levofloxacin, ofloxacin, and
pefloxacin

57
Q

MICs of second group of quinolones for gram-negative cocci and bacilli, including Enterobacter sp, P aeruginosa , Neisseria meningitidis, H aemophilus sp, and Campylobacter jejuni?

A

1–2 mcg/mL and often less

58
Q

Ciprofloxacin is the

most active agent of this group against gram-negative organisms, ____ in particular.

A

P aeruginosa

59
Q

the L-isomer of ofloxacin,
has superior activity against gram-positive organisms, including
Streptococcus pneumoniae

A

levofloxacin

60
Q

make up a third
group of fluoroquinolones with improved activity against grampositive
organisms, particularly S pneumoniae and some staphylococci

A

Gatifloxacin, gemifloxacin, and moxifloxacin

61
Q

During fluoroquinolone therapy, resistant organisms emerge in
about one of every ____, especially among staphylococci,
P aeruginosa , and Serratia marcescens

A

10^7 –10^9 organisms

62
Q

Resistance is due to one
or more point mutations in the quinolone binding region of the
target enzyme or to a change in the permeability of the organism. More recently
two types of plasmid-mediated resistance have been described. These are?

A

The
first type utilizes Qnr proteins, which protect DNA gyrase from the
fluoroquinolones. The second is a variant of an aminoglycoside
acetyltransferase capable of modifying ciprofloxacin

63
Q

Resistance to one
fluoroquinolone, particularly if it is of high level, generally confers
cross-resistance to all other members of this class. True or false?

A

True

64
Q

After oral administration, the fluoroquinolones are well absorbed
(bioavailability of?)

A

80 - 90%

65
Q

Oral absorption of quinolones is impaired by

A

divalent and trivalent cations, including those
in antacids

oral fluoroquinolones should be taken 2
hours before or 4 hours after any products containing these cations

66
Q

Dosage adjustment

for renal failure is not necessary for which quinolone?

A

moxifloxacin

67
Q

Nonrenally cleared fluoroquinolones are relatively contraindicated in patients with?

A

hepatic failure

68
Q

Quinolone not effective against UTIs?

A

Moxifloxacin

69
Q

Fluoroquinolones (except _____, which does not achieve adequate systemic concentrations)
have been used in infections of soft tissues, bones, and joints
and in intra-abdominal and respiratory tract infections, including
those caused by multidrug-resistant organisms such as Pseudomonas
and Enterobacter .

A

norfloxacin

70
Q

drug of choice for prophylaxis

and treatment of anthrax

A

Ciprofloxacin

71
Q

Quinolones effective in treating

chlamydial urethritis or cervicitis

A

Ciprofloxacin and levofloxacin

72
Q

occasionally used for treatment of tuberculosis and atypical mycobacterial infections

A

Ciprofloxacin, levofloxacin,

or moxifloxacin

73
Q

agents that may be suitable
for eradication of meningococci from carriers or for prophylaxis
of infection in neutropenic cancer patient

A

Ciprofloxacin, levofloxacin,

or moxifloxacin

74
Q

so-called respiratory fluoroquinolones effective and used
increasingly for treatment of upper and lower respiratory tract
infections

A

levofloxacin, gatifloxacin, gemifloxacin, and moxifloxacin

75
Q

With enhanced gram-positive activity and activity against

atypical pneumonia agents (chlamydiae, Mycoplasma , and Legionella

A

levofloxacin, gatifloxacin, gemifloxacin, and moxifloxacin

76
Q

Fluoroquinolones are generally well tolerated. The most common
effects are?

A

nausea, vomiting, and diarrhea

77
Q

Photosensitivity has been reported with which quinolones?

A

lomefloxacin and

pefloxacin

78
Q

ECG change that occurs with gatifloxacin, levofloxacin,

gemifloxacin, and moxifloxacin

A

QTc prolongation

79
Q

gatifloxacin, levofloxacin,

gemifloxacin, and moxifloxacin, should be avoided or used with caution in patients with which cardiac conditions?

A 
QT c interval prolongation
uncorrected hypokalemia
those receiving class IA (eg,
quinidine or procainamide) or class III antiarrhythmic agents
(sotalol, ibutilide, amiodarone)
patients receiving other
agents known to increase the QT c interval (eg, erythromycin, tricyclic
antidepressants)
80
Q

Quinolone associated with hyperglycemia
in diabetic patients and with hypoglycemia in patients
also receiving oral hypoglycemic agents

A

Gatifloxacin

81
Q

Fluoroquinolones may damage growing cartilage and cause an

arthropathy. Thus, these drugs are not routinely recommended for?

A

patients under 18 years of age.

82
Q

a rare complication

that has been reported in adults using quinolones

A

tendonitis

83
Q

Fluoroquinolones are considered safe for pregnancy. True or false?

A

False

Pharmacology (8 decks)

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