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Tuberculosis Flashcards

1
Q

Among the 5 first line agents in the treatment of TB, which is not bacteriocidal?

A

Ethambutol (bacteriostatic)

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2
Q

This bactericidal drug is structurallysimilar to pyridoxine.

A

Isoniazid

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3
Q

At what concentrations does isoniazid able to eliminate bacilli tubercle?

A

.2mcg/ml or less

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4
Q

Isoniazid is an effective drug against Mycobacterium tuberculosis as it….. (MOA)

A

Inhibits mycolic acid synthesis

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5
Q

Isioniazid is a prodrug that is activated by?

A

KatG (mycobacterial catalase-peroxidase)

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6
Q

In its active form, isoniazid forms a covalent complex with __________ and __________

A

AcpM (acyl carrier protein)
And
KasA (b-ketoacylcarrier protein synthetase)

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7
Q 
Which among the following is TRUE regarding the development of isoniazid-resistant Mycobacterium?
A. Overexpression of inhA
B. Mutation or deletion of KatG gene
C. Mutation in KasA
D. Overexpression of ahpC
E. All of the above
A

E

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8
Q

This gene encodes NADH-dependent acyl carrier protein reductase. An overexpression of this gene causes resistance to isoniaZid

A

inhA

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9
Q

This is a putative virulence gene involved in protection of cell from oxidative stress. Overexpression of this gene causes resistance to isoniazid

A

ahpC

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10
Q

TRUE or FALSE: isoniazid is rapidly cleared by slow acetylators.

A

FALSE. RAPID ACETYLATORS

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11
Q 
Which of the following is NOT true regarding the Pharmacokinetics of isoniazId?
A. Excreted through liver into bile
B. Excreted in the urine
C. Readily absorbed from GIT
D. All of the above
A

A.

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12
Q

What is the adult dosage of Isoniazid?

A

300mg/day

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13
Q

What vitamin should be used in conjuction to isoniazid use for prevention of neuropathy?

A

Vit B (Pyridoxine)

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14
Q

Why is it that isoniazid may cause neuropathy?

A

Because isoniazid promotes its excretion

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15
Q

At 300mg oral dose of Isoniazid, peak plasma concentration of 3-5mcg/ml is achieved within how many hours?

A

1-2hrs

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16
Q

An alcoholic patient was diagnosed with TB. If isoniazid is to be given to the patient, what adverse effect should you watch out for?

A

Isoniazid induced hepatitis and peripheral neuropathy

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17
Q

This bactericidal drug is a semisynthetic derivative of Rifamycin

A

Rifampin

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18
Q

What is/are the most active drug/s against Myobacterium tuberculosis?

A

Isoniazid and Rifampin

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19
Q

At what concentrations does rifampin inhibit suscepitible organisms?

A

1mcg/ml or less

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20
Q

TRUE or FALSE: Rifampin is not cross resistant to any drug

A

False. Cross resistant to rifabutine and rifapentine (rifamycin derivatives)

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21
Q

What is the MOA of Rifampin?

A

Inhibits RNA synthesis

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22
Q

Rna synthesis of bacteria is inhibited by rifampin by binding to which subunit of bacterial dna-dependent RNA polymerase?

A

Beta-subunit

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23
Q

TRUE or FALSE: Rifampin is active only in gram positive bacteria.

A

False. Both gram neg and grom positive

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24
Q

Mutation in what gene is responsible for the development of rifampin resistance?

A

rpoB (gene for B-subunit of RNA polymerase)

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25
The following are true regarding the pharmacokinetics of Rifampin, EXCEPT: A. Excreted throught liver into bile B. Undergoes enterohepatic recirculation C. Bulk of its original form is excreted in the urine D. None of the above
C. (Bulk is excreted in the feces as deacetylated metabolites)
26
What is the adult dose for rifampin?
600mg/day (10mg/kg/d)
27
In patients with isoniazid-resistance in latent TB, how long is the rifampin medication?
4mos (@ 600mg/d)
28
What is the main complaint of patients taking rifampin?
Orange colored urine, sweat or tears (harmless)
29
Phenytoin is contraindicated in what bactericidal drug which reduces its metabolism?
Isoniazid
30
Rifampin is also considered as an active drug against other bacterial infections. In children with Haemophilus influenzae type b disease, what is the required dosage of Rifampin?
20mg/kg/d for 4days
31
``` Which among the adverse effects of Rifampin is not TRUE? A. Associated with tubular necrosis B. Cause light chain proteinuria C. Decrease elimination of cyclosporine D. Induce Cytochrome P450 isoforms ```
C. Increased dapat
32
TRUE or FALSE: ethambutol is a synthetic, lipid soluble, heat stable compound.
False. Water soluble
33
Mycobaacteria sp are inhibited by Ethambutol at what concentration?
1-5mcg/ml
34
What is the MOA of ethambutol?
Inhibits arabinosyl transferases
35
Resistance in ethambutol is caused by mutations and overexpression of what gene products?
Emb gene products
36
Most of the unchanged form of ethambutol is excreted in the...?
Urine (50%)
37
What is the ethambutol dosage for a patient with creatinine clearance of 9ml/min?
Half of normal dose (12.5mg/kg)
38
The concentrations of ethambutol in the blood peaks within 2-4hrs at what concentration?
2-5mcg/ml
39
The administration of ethambutol (25mg/kg/d) in children (especially
Loss of Visual Acuity And red-green color blindness
40
This bactericidal drug is a relative of nicotinamide and is slightly soluble in water.
PZA
41
TRUE or FALSE: PZA is inactive at neutral pH
TRUE
42
PZA is converted to pyrazinoic acid by what enzyme?
Pyrazinamidase
43
What is the MOA of PZA?
Disrupts mycobacterial cell membrane metabolism and transport function
44
Resistance to PZA occurs when there is a mutation in what gene? This gene encodes for pyrazinamidase
pncA
45
What is the half life of PZA?
8-11hrs
46
What is the normal adult dose of PZA?
40-50mg/kg 3x a week
47
All of the following are TRUE regarding PZA except: A. Well absorbed in the GIT B. Cross resistant with isoniazid C. Its parent compound is metabolized by the liver D. Its metabolites are renally cleared
B. No cross resistance with other mycobacterials
48
Give adverse reactions of PZA (5)
``` Hepatotoxicity Nausea Vomiting Drug fever Hyperuricemia (gout) ```
49
Most tubercle bacilli are inhibited by streptomycin at what concentration?
1-10mcg/ml
50
Streptomycin resistance is caused by alteration of theribosomal binding site due to point mutations in what 2 genes?
rpsL gene and rrs gene
51
This gene encodes for the s12 ribosomal protein gene
rpsL gene
52
``` Which among the following is TRUE about streptomycin A. Crosses the BBB B. ototixic C nephrotoxic D. All ofthe above ```
D
53
Give three main reasons why second line agents are given as an alternative to the first line drugs
1. Resistance to first line agents 2. Failure of clinical response to conventional therapy 3. Serious treatment-limiting adverse drug reaction
54
This second line agent is chemically related to isoniazid
Ethionamide
55
``` Which among the following is TRUE about ethionamide A. Blocks mycolic acid synthesis B. Metabolized by the liver C. Highly water soluble D. Both A and B E. Both B and C ```
D | C = poorly h20 soluble
56
What is the second line drug that is used for the treatment of drug resistant TB?
Capreomycin
57
All are TRUE regarding its action against mycobacterium except: A. Capreomycin : peptide CHON synthesis inhibitor B. Cycloserine : cell wall synthesis inhibitor C. Aminosalicylic Acid : folate synthesis antagonist D. All of the above E. None of the above
E
58
``` A patient with TB develops streptomycin resistance. Which among the second line agents should you prescribed? A. Amikacin B. Kanamycin C. Capreomycin D. Moxifloxacin ```
B
59
Which among the second line agents may cause crystalluria?
Aminosalicylic acid (8-12g/d in adults; 300mg/kg/d in children)
60
Which antimycobacterial drugs require pyrodoxine intake?
Isoniazid, Cycloserine
61
What are examples of fluoroquinolones which are active agents against atypical mycobacteria?
Ciprofloxacin (750mg 2x a day), Levofloxacin (500-750mg/d) , Moxifloxacin (400mg/d)
62
Which among the following order is true regarding the most active agent against M. tuberculosis A. Levofloxacin > moxifloxacin > ciprofloxacin B. Ciprofloxacin > levofloxacin > moxifloxacin C. Moxifloxacin > ciprofloxacin > levofloxacin D. Moxifloxacin > levofloxacin > ciprofloxacin
D
63
What are the examples of aminoglycoside antibiotics?
Kanamycin and Amikacin
64
TRUE or FALSE: | Kanamycin is for multidrug resistant TB while Amikacin is for streptomycin resistant TB
FALSE BALIKTAD PHOUWZzhHzZZ!!!
65
Resistance to fluoroquinolones is due to a single point mutation in?
Gyrase A subunit
66
Which drug is considered the 'last resort' for multi drug resistant TB?
Linezolid (600mg/d adult dose)
67
What is the gold standard used for the diagnosis of TB?
Culture with Drug Susceptibility testing
68
What are the two classification of TB?
Latent TB and Active TB
69
What are the two types of Active TB?
Pulmonary and extra-pulmo
70
A patient conplains to you of 2weeks of coughy, night sweats, fever, chest pain and weight loss. Your primary diagnosis is TB. What examinations would you order to confirm your diagnosis?
Sputum test (AFB, culture and drug susceptibilty test) Xray Tuberculin Skin testing
71
Your patient was cured of any form of TB after one full course of anti-TB meds. During his follow-up, you examined the sputum smear which turned positive. What is the category of this patient?
Relapse
72
What are the two phases of treatmnt for TB?
Intensive and Continuation Phase
73
Among the 2 phases of treatment for tb, which phase kills slowly dividing bacilli?
Continuation Phase
74
For patients with failure and relapse cases, what class of treatment is to be prescribed?
Class II
75
What are the drugs to be taken and how long are the drugs to be taken in Class I treatment?
2mos isoniazid-rifampin-pyrazinamide-ethambutol combination and 4mos isoniazid-rifampin combi 2HRZE/4HR
76
For patients with new extra pulmonary TB case, what drug and treatment duration is to be given?
2HRZ/4HR
77
In a patient who became positive smear at the 5th month while on treatment will require what drug combination for treatment?
2HRZES/1HREZ/5HRE
78
A chold is presumed to have active TB if 3 or more criteria are present. What are these criteria?
``` Epidemiologic Clinical Immunologic Radiologic Laboratory ```
79
What is the most suggestive of PTB in Radiologic findings?
Hilar/paratracheal adenopathy | Parenchymal changes
80
Which among the first line TB drugs is the most hepatotoxic?
PZA
81
A patient was diagnosed with active TB, smear (-) pulmo TB. What drugs should you give for both intensive and continuation phase?
Intensive: 2HRZ Continuation: 4HR / 6HE
82
In TB meningitis, HRZS combination is given for 2 mos for the intensive phase. What drug combination should you give for the continuation phase?
4HR

Pharmacology (12 decks)

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