12 Questions
What is the primary site of action of Isoniazid (INH)?
Mycobacterial cell wall
Which type of bacilli does Rifampin (RIF) primarily work on?
Rapidly growing bacilli
What is the clinical use of Rifampin (RIF) in addition to treating TB?
Treating latent TB in patients with positive tuberculin skin test
Which adverse drug reaction (ADR) is associated with Isoniazid (INH) and requires Pyridoxine supplementation?
Peripheral neuritis
Why is Vitamin B6 prescribed with Isoniazid (INH)?
To counteract antagonism by INH
When is hepatitis caused by Isoniazid (INH) more likely to occur?
In individuals over 40 years old
What is the main mechanism of action of the drug described in the text?
Inhibits bacterial RNA synthesis
Which side effect is NOT associated with the drug?
Neuropathy
What is the consequence of being a fast acetylator of the drug?
Higher levels of toxic metabolites
Which vitamin is affected by the drug's inhibition of pyridoxine?
Vitamin B6
What enzyme isoforms are strongly induced by the drug?
Cytochrome P450 isoforms 2C19, 2C9, 3A4
What type of infection can the drug be used to treat besides TB?
Meningococcal and staphylococcal infections
Study Notes
Isoniazid (INH)
- First-line treatment for tuberculosis
- Bacteriostatic, effective against resting bacilli
- Inhibits the synthesis of mycolic acid, a key component of mycobacterial cell wall
- Penetrates into macrophages
- Clinical uses:
- Treatment of TB
- Treatment of Latent TB in patients with positive tuberculin skin test
- Prophylaxis against active TB in high-risk individuals
- Adverse drug reactions (ADRs):
- Peripheral neuritis (pins and needles sensation in the feet)
- Optic neuritis and atrophy
- Hepatitis (toxic metabolites, age-dependent, and increased with alcohol use)
- Interactions:
- Inhibits cytochrome P450 2C19 isoform, leading to accumulation of drugs metabolized by 2C19
- Slow and fast acetylators: genetic variation affects metabolism and toxicity
Rifampin (Rifampicin)
- Bactericidal, effective against rapidly growing bacilli
- Inhibits RNA synthesis by binding to bacterial DNA-dependent RNA polymerase enzyme
- Clinical uses:
- Treatment of TB
- Prophylaxis against meningococcal and staphylococcal infections
- Adverse drug reactions (ADRs):
- Harmless red-orange discoloration of body secretions (saliva, sweat, urine, tears)
- Hepatitis (less common compared to INH)
- Flu-like syndrome
- Hemolytic anemia
- Interactions:
- Strongly induces most cytochrome P450 isoforms (2C19, 2C9, 3A4)
- Clinically significant drug interactions: warfarin, methadone (faster metabolism, reduced activity)
This quiz provides an overview of Isoniazid (INH) and Rifampin (RIF) in the treatment of tuberculosis, including their mechanisms of action, clinical uses, adverse drug reactions, and drug interactions. Test your knowledge on the first-line treatments for TB!
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
