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Pharmacology > Antimycobaterial Drugs > Flashcards

Antimycobaterial Drugs Flashcards

1
Q

Traditional first-line agents for treatment of tuberculosis

A

Isoniazid (INH)
Rifampin
Pyrazinamide
Ethambutol

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2
Q

The most active drugs in treating TB

A

Isoinazid and rifampin

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3
Q

Combination of this drug for 9 months will cure 95-98% of cases of tuberculosis

A

Isoniazid-rifampin

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4
Q

In practice, therapy is usually initaited with a??? Until susceptibility of the clinical isolate has determined.

A

Four-drug regimen of isoniazid, rifampin, pyraziamide and ethambutol

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5
Q

Most active drug for the treatment of tuberculosis caused by susceptible strains

A

Isoniazid

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6
Q

Isoniazid inhibits most ___ bacteria and less effective against??

A

Tubercle bacilli
Nontuberculous mycobacteria

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7
Q

What does isoniazid inhibits?

A

Inhibits mycolic acids , which are essential components of mycobacterial cell wall

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8
Q

What is a mycolic acid?

A

An esential component of mycobacterial cell wall

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9
Q

____ a prodrug that is activated by KatG, the mycobacterial catalase-peroxidase

A

Isoniazid

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10
Q

Activated form of isoniazid forms a covalent complex with an?

A

Acyl carrier protein (AcpM) and KasA, a beta-ketoacyl carries protein synthetase WHICH BLOCKS MYCOLIC ACID SYNTHESIS.

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11
Q

Resistance to isoniazid is associated with mutations resulting in?

A
  • Overexpression of inhA, which encodes an NADH0-dependent acyl carrier protein reductase
  • Mutation or deletion of the katG egne
  • promoter mutation resulting in overexpression of aphC, gene involved in protection from oxidative stress
  • mutation in kasA
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12
Q

___ or more active agents should ALWAYS be used to treat active tuberculosis to prevent ___ during therapy

A

At least two
Emergence of resistance

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13
Q

In taking isoniazid, should you take with meal or without meal?

A

Without meal (optimally on an empty stomach)

Because peak concentration with decrease up to 50% when taken with a fatty meal

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14
Q

Typical adult dose and children dose of isoniazid in

A

300mg
5mg/kg

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15
Q

Metabolism of isoniazid

A

Acetylation by liver N-acetyltransferase

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16
Q

Average HL of isoniazid

A

Less than 1hr and 3hrs

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17
Q

Isoniazid metabolites and a small amounts of unchanged drug are excreted in?

A

Urine

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18
Q

Isoniazid dose in children

A

5mg/kg/d

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19
Q

Is recommended for those with conditions predisposing to neuropathy, an adverse effect of isoniazid

A

Pyridoxine

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20
Q

Isoniazid as a single agent is also indicated for treatment of?

A

Latent tuberculosis

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21
Q

Duration of taking isoniazid in treating TB

A

9 months

Dosage 300 mg/d or 900mg twice weekly

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22
Q

The most common major toxic effect of isoniazid

A

Isoniazid-induced hepatitis

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23
Q

Adverse effects of isoniazid

A

Hepatoxicity, peripheral neuropathy

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24
Q

What drug should you give in patients taking isoniazid to prevent peripheral neuropathy

(PN = adverse effect of isoniazid)

A

Pyridoxine

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25
Q

A semisynthetic derivative of rifamcyin, an antibiotic produced by amycolatopsis rifamycinica, formerly named streptomyces mediterranei

A

Rifampin

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26
Q

Rifampin is active against what organism?

A

GRAM + ORGANISMS

Some gram - org, like neisseria and haemophilus

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27
Q

This drug has no cross resistance, but there is a cross-resistance to its other derivatives

A

Rifampin

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28
Q

Derivatives of rifampin

A

Rifabutin and rifapentine

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29
Q

Binds to the B subunit of bacterial DNA-dependent RNA polymerase and thereby inhibits RNA synthesis

A

Rifampin

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30
Q

MOA of rifampin

A

Binds to the b subunit of bacterial DNA-dependent RNA polymerase and thereby inhibits RNA synthesis.

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31
Q

What causes resistance to rifampin

A

Mutations in rpoB gene for the B subunit of RBA polymerase

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32
Q

Excretion of rifampin

A

Liver into bile

The bulk is excreted as a deacylated metabolite in feces and small amount excreted in the urine.

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33
Q

What cytochrome P450 isoforms does rifampin strongly induces

A

CYP1A2
CYP2C9
CYP2C19
CYP2D6
CYP3A4

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34
Q

Oral dose of rifampin

A

600mg in adult
10 mg/kg/d in children

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35
Q

Alternative drug for patients with latent TB that has isoniazid resistant strain

A

Rifampin. 600mg daily for 4 months as a single drug.

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36
Q

____ must be administered with isoniazid or other antituberculous drug to patients with active TB to prevent emergence of drug-resistant mycobacteria.

A

Rifampin

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37
Q

Oral dose of 600mg twice aday for 2 days can eliminate meningococcal carriage

A

Rifampin

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38
Q

Treatment of serious staphylococcal infections

A

Rifampin

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39
Q

20mg/kg once daily for 4 days, used as prophylaxis in contacts of children with haemophilus influenzae type b disease

A

Rifampin

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40
Q

Adverse effects of rifampin

A

Harmless orange color to urine, sweat and tears.

Rashes, thrombocytopenia and nephritis.

Flu-like syndrome with intermittent dosing.

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41
Q

Similar to rifampin but less cytochrome p450 induction and fewer drug interactions

A

Rifabutin. PO

42
Q

Long acting analog of rifampin that may be given once weekly in select cases during the continuation phase of TB treatment or for treatment of latent TB

A

Rifapentine. PO

43
Q

MOA of ethambutol

A

Inhibits mycobacterial arabinosyl transferase, which are involved in the polymerization reaction of arabinoglycan, an essential component of the mycobacterial cell wall

44
Q

EmbCAB operon encodes?

A

Arabinosyl transferases

45
Q

Essential component of the mycobacterial cell wall.

A

Arabinoglycan

46
Q

Involved in the polymerization reaction of arabinoglycan

A

Arabinosyl transferases

47
Q

Ethambutol is well absorbed from the?

48
Q

Excretion of ethambutol

A

20% in feces
50% in urine

49
Q

Resistance to ethambutol if due to?

A

Overexpressio of embgene products or within the embB structural gene

50
Q

Resistance to ethambuol emerges rapidly when?

A

The drug is given alone. Therefore, ethambutol is always given in combination with other antiTB drug

51
Q

Ethambutol is also used in combination with other agents for the treatment of nonTB mycobacterial infections such as

A

Mycobacterium avium complex (MAC) or M. Kansasii

52
Q

Most common adverse effect of ethambutol

A

Retrobulbar neuritis - loss of visual acuity and red-green color blindness

53
Q

Ethambutol is relatively contraindicated to?

A

Children who aretoo young to permit VAC test and red-green color discrimination

54
Q

A relative of nicotinamide, and it is used only for the treatment of TB

A

Pyrazinamide

55
Q

What pH level is pyrazinamide inactive and active

A

Inactive = neutral pH
Active = 5.5 - inhibits tubercle bacilli

56
Q

This drug is taken up by macrophages and exerts its activity against mycobacteria residing within the acidic environment of lysosomes

A

Pyrazinamide

57
Q

Active form of pyrazinamide

A

Pyrazinoic acid

58
Q

most tubercle bacilli are inhibited by

A

streptomycin

59
Q

route of administration of streptomycin sulfate

60
Q

most common adverse effect of streptomycin

A

vertigo and hearing loss

61
Q

is related to isoniazid and similarly blocks the synthesis of mycolic acids

A

ethionamide

62
Q

route of administration of ethionamide

63
Q

ethionamide is metabolized by the?

64
Q

most tubercle bacilli are inhibited in vitro by

A

ethionamide

65
Q

a peptide protein synthesis inhibitor antibiotic obtain from streptomyces capreolus

A

capreomycin

66
Q

route of administration of capreomycin

67
Q

____ (15 mg/kg/d) is an important injectable agent for treatment of drug-resistant tuberculosis.

A

Capreomycin

68
Q

___ penetrates into macrophages and is active against both extracellular and intracellular organism

69
Q

____ is observed in 10-20% of patients given isoniazid with greater than 5mg/kg/d but it is infrequently seen with the standard 300-mg adult dose

A

Peripheral neuropathy

70
Q

Oral dosage of rifampin 600mg twice daily for 2 days can eliminate?

A

Meningococcal carriage

71
Q

Rifampin, 20 mg/kg (maximum 600 mg) once daily for 4 days, is used as prophylaxis in contacts of children with?

A

Haemophilus influenzae type b disease

72
Q

a synthetic, water-soluble, heat-stable compound, dispensed as the dihydrochloride salt.

A

Ethambutol

73
Q

Resistance to ethambutol emerges rapidly when the drug is used alone or with combination?

74
Q

Pyrazinoic acid disrupts mycobacterial cell membrane metabolism and transport functions

A

Pyrazinamide

75
Q

Parent compound of PZA is metabolized by the ___ but metabolites are ___ cleared

A

Liver
Renally

76
Q

An important front-line drug used in conjunction with isoniazid and rifampin in short course regimen as a “sterilizing agent” active against residual intracellular organisms that may case relapse

A

Pyrazinamide

77
Q

Major adverse effect:

Hepatoxicity, photosensitivity and hyperuricemia

78
Q

Penetrates into cells poorly and is active mainly against extracellular tubercle bacilli

A

Streptomycin

79
Q

a structural analog of d-alanine—inhibits cell wall synthesis,

A

Cycloserine

80
Q

Most serious toxic effects of cycloserine

A

Peripheral neuropathy and CNS dysfunction, including depression and psychoses

81
Q

a folate synthesis antagonist that is active almost exclusively against M tuberculosis. It is structurally similar to p-amino-benzoic acid (PABA) and is thought to have a similar mechanism of action to the sulfonamides

A

Aminosalicylic acid PAS

82
Q

Very high concentrations of aminosalicylic acid are reached in the urine, which can result in

A

Crystalluria

83
Q

is indicated for treatment of tuberculosis suspected or known to be caused by streptomycin-resistant or multidrug- resistant strains. This drug must be used in combination with at least one and preferably two or three other drugs to which the isolate is susceptible for treatment of drug-resistant cases.

84
Q

had been used for treatment of tuberculosis caused by streptomycin-resistant strains, but it is no longer available in the USA

85
Q

are an important addition to the drugs avail- able for tuberculosis, especially for strains that are resistant to first- line agents.

A

Fluoroquinolones

86
Q

4 kinds of fluoroquinolones

A

Ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin

87
Q

The most active fluoroquinolones against M tuberculosis in vitro

A

Moxifloxacin

88
Q

A fluoroquinolones that tends to be slightly more active than ciprofloxacin

A

Levofloxacin

89
Q

has been used in combination with other second- and third-line drugs to treat patients with tuberculosis caused by multidrug-resistant strains.

90
Q

What drug has this adverse effect?

Bone marrow suppression, irreversible peripheral and optic neuropathy

91
Q

should be used only for multidrug-resistant strains that also are resistant to several other first- and second-line agents

92
Q

is often used in place of rifampin for treatment of tuberculosis in patients with HIV infection who are receiving antiretroviral therapy with a protease inhibitor

93
Q

A derivative of rifampin that can cause leukopenia, thrombocytopenia and optic neuritis

94
Q

used for treatment of tuberculosis caused by rifampin- susceptible strains during the continuation phase (first 2 months of therapy)

A

Rifapentine

95
Q

a diarylquinoline, is the first drug with a novel mech- anism of action against M tuberculosis to be approved since 1971.

A

Bedaquiline

96
Q

What does bedaquiline inhibits?

A

Inhibits ATP synthase in mycobacteria

97
Q

The most common adverse effect if this drug are nausea, arthralgia and headache. This has been associated with both hepatoxicity and cardiac toxicity

A

Bedaquiline

98
Q

Nontuberculous mycobacteria are formerly known as ???

A

Atypical mycobacteria

99
Q

The most widely used drug in treatment of leprosy

A

Dapsone (diaminodiphenylsulfone)

100
Q

may also be used to prevent and treat Pneumocystis jiroveci pneumonia in AIDS patients.

101
Q

Suflones can cause erthyhema nodosum leprosum, what drug can it suppress the adverse effect?

A

Thalidomide

102
Q

a phenazine dye used in the treatment of multi- bacillary leprosy, which is defined as having a positive smear from any site of infection

A

Clofazimine

Pharmacology (15 decks)

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