FB - Anti-tuberculosis agents Flashcards

1
Q

What are the first line drugs against tuberculosis?

A

(RIPES)

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Streptomycin
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2
Q

What is the mechanism of action of rifampicin?

A

Rifampicin inhibits gene transcription of mycobacteria by blocking the DNA-dependent RNA polymerase, which prevents the bacillus from synthesizing messenger RNA and protein, causing cell death.

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3
Q

State 2 clinical indications for rifampicin

A
  1. Latent / Active tuberculosis

2. Leprosy, against Mycobacterium leprae

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4
Q

Which organism causes tuberculosis?

A

Mycobacterium tuberculosis

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5
Q

Which of the 4 standard first line anti-tuberculosis drugs are safe for use in patients with kidney failure?

A

Rifampicin and Isoniazid

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6
Q

Name 3 adverse effects associated with rifampicin

A
  1. Hepatitis
  2. Cutaneous reactions
  3. Gastrointestinal symptoms
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7
Q

What is the mechanism of action of isoniazid?

A

Isoniazid is activated by the catalase-peroxidase enzyme of M. tuberculosis. The activation of isoniazid produces oxygen-derived free radicals that can inhibit the formation of mycolic acids of the bacterial cell wall, cause DNA damage and, subsequently, the death of the bacillus.

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8
Q

Which enzyme is involved in the metabolism of isoniazid, and presents with wide variation in activity in the community due to genetic polymorphisms?

A

N-acetyl transferase (rapid acetylator vs slow acetylator phenotypes are found in the population due to the genetic polymorphism

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9
Q

State 2 adverse effects related to isoniazid

A

State 2 adverse effects related to isoniazid 1. Peripheral Neuropathy
2. Hepatitis

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10
Q

Patients on isoniazid are often co-administered _________ to help overcome ________ deficiency to avoid peripheral ________ .

A

pyridoxine, vitamin B6, neuropathy

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11
Q

What food – food interactions must patients taking isoniazid be aware for?

A

They should avoid food rich in tyramine and histamine (certain types of fish, cheese and red wine).

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12
Q

What is the mechanism of action of pyrazinamide?

A

Pyrazinamide is converted to its active form, pyrazinoic acid, by the microbial enzymes. The accumulation of pyrazinoic acid decreases the intracellular pH to levels that cause the inactivation of critical pathways necessary for the survival of the bacteria.

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13
Q

Which of the first line anti-tuberculosis drugs is highly effective against the persistent bacilli

A

Pyrazinamide

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14
Q

Which of the 4 standard first line anti-tuberculosis drugs must be avoided or used with caution if the patient suffers from liver disease?

A

(RIP)

Rifampicin
Isoniazid
Pyrazinamide

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15
Q

Which of the 4 standard first line anti-tuberculosis drugs (R.I.P.E) is/are highly associated with causing gout like symptoms?

A
  1. Pyrazinamide (More common with pyrazinamide then ethambutol)
  2. Ethambutol
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16
Q

Which of the 4 standard first line anti-tuberculosis drugs must be avoided or used with caution if the patient suffers from kidney impairment?

A
  1. Pyrazinamide

2. Ethambutol

17
Q

What is the mechanism of action ethambutol?

A

Ethambutol inhibits the arabinosyltransferase enzyme and interferes with the polymerization of arabinose into arabinogalactan, the principal polysaccharide on the mycobacterial cell wall.

18
Q

Which of the 4 standard first line anti-tuberculosis drugs (R.I.P.E) is/are highly associated with causing visual toxicity?

A

Ethambutol

19
Q

Which class of antibiotics does streptomycin belong to?

A

Aminoglycoside

20
Q

How is streptomycin administered?

A

Intramuscular injection

21
Q

In which groups of individuals would physicians have a high index of suspicion for multi drug-resistant tuberculosis?

A

Individuals

  1. who were previously treated for TB,
  2. who have failed TB treatment,
  3. who are known contacts of patients with MDR-TB, or
  4. who come from countries with high prevalence of drug resistant tuberculosis