1. Isoniazid (monotherapy for 9 months) 2. Isoniazid + Rifapentine (12 once weekly higher doses)

Antimycobacterial Drugs Flashcards by Musfira Siddiqui

First line of drugs for TB

RIPE
R Rifampin
I  Isoniazid
P Pyrazinamide
E Ethambutol

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What is LTBI?

Latent Tuberculosis Infection. Infected with tuberculosis without sign and symptoms of active TB.

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Treatment for LTBI?

Isoniazid (monotherapy for 9 months)

2. Isoniazid + Rifapentine (12 once weekly higher doses)

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Duration of susceptible TB therapy?

6 months

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Treatment last for 2 years of?

Multidrug resistant TB (MDR-TB)

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Drugs for extensively drug resistant TB (XDR-TB)?

Clofazimine and linezolid

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What is DOT?

Directly Observed Therapy. Patients take drugs under supervision of health care team. Decreases drug resistance and improves cure rates.

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Isoniazid is activated by?

KatG, catalase-peroxidase

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MOA of Isoniazid?

Targets InhA and KasA, inhibits mycolic acid synthesis, disrupting bacterial cell wall

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Isoniazid also called?

INH

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Resistance of Isoniazid develops as?

Mutations/deletion of KatG
Mutation of InhA (acyl carrier protein)
Overexpression of InhA

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Pharmacokinetics of Isoniazid

Oral administration. Food impairs absorption
Undergoes n-acetylation
90 minutes half life
Excreted through kidney

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Adverse effects of Isoniazid?

Hepatitis
Paresthesia of hand n feet (pins and needles sensation)
Convulsions, rashes, fever, nystagmus, ataxia

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Why Isoniazid causes paresthesia?

Due to pyridoxine deficiency. Should take daily pryidoxine (VITAMIN B6)

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Drugs of Rifamycins?

Rifampin
Rifabutin
Rifapentine

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MOA of Rifampin?

Blocks RNA transcription.

By beta subunit of mycobacterium DNA dependent RNA polymerase

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NTM species?

Non Tuberculosis Mycobacterium
M.avium
M.kansasii
M.leprae

Rifampin is used for?

TB
M.kansasii and M.avium
Prophylactically for meningitis
Higly active for M.leprae

Pharmacokinetics of Rifampin?

Oral administration 
Distribution to all body fluids/organs
Undergoes hepatic metabolism 
INDUCE HEPATIC CYTOCHROME P450
Half life 1 to 2 weeks
Excreted in bile and faeces

Orange red colour urine/faeces seen due to?

Rifampin intake

Adverse effects of Rifampin?

Nausea
Vomiting 
Rash
Hepatic dysfunction 
Flu like syndrome (fever chills myalgia)

Drug given for TB + HIV patients?

Rifabutin

Derivative of Rifampin causing hyperpigmentation and neutropenia?

Rifabutin

Drug for LTBI with minimal TB?

Rifapentine (once weekly)

Active form of Pyrazinamide?

Pyrazinoic acid (hydrolyzed by pyrozinamidase)

Drugs that may cause gout?

Pyrazinamide | Ethambutol

MOA of Ethambutol?

Inhibits arabinosyl transferase which is necessary for cell wall synthesis.

Drug causing optic neuritis and diminished visual acuity?

Ethambutol

Ethambutol causes loss of ability to discriminate which two colours?

Red and green

Why second line drugs are used?

1. Patient unable to tolerate 1st line drugs | 2. Resisting TB

2nd line drugs for MDR-TB?

Para-aminosalicyclic acid (PAS) Capreomycin Fluoroquinolones (Moxifloxacin) Bedaquiline

2nd line TB drug given parenterally?

Capreomycin

Drug causing CNS disturbances (confusion, lethargy, anxiety, suicidal thoughts)?

Cycloserine (penetrates CSF)

QT prolongation drugs?

Bedaquiline | Fluoroquinolones (rarely)

Drug for M.avuim complex (MAC)?

Azithromycin

Drugs for Leprosy?

Dapsone Rifampin Clofazimine

MOA of Dapsone?

Inhibits dihydropteroate synthase, blocks folate synthesis pathway

Adverse effects of Dapsone?

Hemolysis (G6PD deficient) Methomoglobinemia Peripheral neuropathy

Dapsone, bactericidal? Clofazimine?

Dapsone is bacteriostatic | Clofazimine is bactericidal

WHO recommended for MDR-TB?

Clofazimine (9 -12 months)

Pinkish brown discoloration of skin?

Clofazimine

Clofazimine decreases risk of?

Erythema nodosum leprosum