Drug Therapy of Tuberculosis
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Questions and Answers

What specific component of the mycobacterial cell wall does Isoniazid inhibit the synthesis of?

Mycolic acid.

What is the full name of the drug commonly referred to as INH?

Isonicotinylhydrazide.

What specific bacterial infections is Rifampin primarily indicated for?

Rifampin is primarily indicated for infections caused by M.tuberculosis and M.leprae.

Why is the inhibition of mycolic acid synthesis significant in the treatment of tuberculosis?

<p>It disrupts the cell wall of mycobacteria, leading to their death.</p> Signup and view all the answers

In the context of Staphylococcal infections, what conditions can Rifampin be used to treat?

<p>Rifampin can be used to treat Staphylococcal endocarditis and osteomyelitis.</p> Signup and view all the answers

In the context of tuberculosis treatment, what class of drug does Isoniazid belong to?

<p>Anti-tuberculosis drug.</p> Signup and view all the answers

What is the mechanism through which Isoniazid exerts its action against tuberculosis-causing bacteria?

<p>By inhibiting the synthesis of mycolic acids.</p> Signup and view all the answers

How does Rifampin contribute to meningococcal disease management?

<p>Rifampin is used for meningococcal prophylaxis to prevent the spread of meningitis.</p> Signup and view all the answers

What is the role of Rifampin in the chemoprophylaxis for children with H. influenzae?

<p>Rifampin is utilized in chemoprophylaxis for contacts of children with H. influenzae to prevent infections.</p> Signup and view all the answers

Explain the significance of Rifampin's antibacterial activity on public health.

<p>Rifampin's antibacterial activity is significant in controlling diseases like tuberculosis and leprosy, impacting public health positively.</p> Signup and view all the answers

What is the primary mechanism of action of Isoniazid in the treatment of tuberculosis?

<p>Isoniazid primarily acts by inhibiting the synthesis of mycolic acid, an essential component of the bacterial cell wall.</p> Signup and view all the answers

How does Pyrazinamide contribute to the effectiveness of tuberculosis treatment?

<p>Pyrazinamide works by disrupting mycobacterial membrane transport and energy production, particularly in acidic environments.</p> Signup and view all the answers

What is the role of Streptomycin in the treatment regimen for tuberculosis?

<p>Streptomycin is an aminoglycoside antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.</p> Signup and view all the answers

Why is Rifampin considered a cornerstone drug in the treatment of tuberculosis?

<p>Rifampin is crucial because it inhibits bacterial RNA synthesis by binding to RNA polymerase, which helps prevent the replication of Mycobacterium tuberculosis.</p> Signup and view all the answers

Discuss why multidrug therapy is essential in treating tuberculosis caused by M.tuberculosis.

<p>Multidrug therapy is essential to prevent the development of drug resistance and to ensure a more effective and comprehensive eradication of the bacteria.</p> Signup and view all the answers

What are the primary adverse effects associated with the treatment regimen for TB?

<p>Adverse effects include tinnitus, vertigo, ataxia, and nephrotoxicity.</p> Signup and view all the answers

Why is the use of this TB treatment regimen contraindicated in pregnancy?

<p>It is contraindicated in pregnancy due to the potential teratogenic effects on the developing fetus.</p> Signup and view all the answers

List the drugs included in the standard TB therapeutic regimen and their supplementation timeline.

<p>The regimen includes isoniazid (INH), rifampin, supplemented with pyrazinamide and ethambutol during the first 2 months.</p> Signup and view all the answers

What role does pyridoxine (vitamin B6) play in the TB treatment regimen?

<p>Pyridoxine is used to prevent isoniazid-induced neuropathy.</p> Signup and view all the answers

What is the duration of the TB treatment regimen mentioned, and why is adherence crucial?

<p>The treatment lasts for six months, and adherence is crucial to prevent drug resistance.</p> Signup and view all the answers

Why is a single drug regimen inappropriate for treating active TB?

<p>A single drug regimen is inappropriate because active TB requires a combination of at least two anti-TB drugs to effectively eliminate the bacteria and prevent resistance.</p> Signup and view all the answers

What is a crucial component in the treatment of active tuberculosis?

<p>A crucial component is the use of two or more anti-TB drugs as part of a regimen to combat the infection effectively.</p> Signup and view all the answers

What can happen if only one anti-TB drug is used for active TB treatment?

<p>Using only one anti-TB drug can lead to treatment failure and the development of drug-resistant strains of TB.</p> Signup and view all the answers

What is the primary objective of combining anti-TB drugs in treatment?

<p>The primary objective is to increase the effectiveness of treatment and minimize the risk of drug resistance.</p> Signup and view all the answers

How does the understanding of drug resistance impact the management of active TB cases?

<p>Understanding drug resistance impacts management by necessitating a treatment plan that involves multiple drugs to ensure successful eradication of the pathogen.</p> Signup and view all the answers

What are two significant adverse effects associated with Ethambutol?

<p>Hyperuricemia and hepatotoxicity.</p> Signup and view all the answers

Explain how Ethambutol affects the mycobacterial cell wall.

<p>It decreases carbohydrate polymerization by blocking arabinosyltransferase.</p> Signup and view all the answers

In what way does the mechanism of action of Ethambutol contribute to its therapeutic effect?

<p>By inhibiting arabinosyltransferase, Ethambutol disrupts the formation of the mycobacterial cell wall.</p> Signup and view all the answers

Why is it important to monitor for hyperuricemia in patients taking Ethambutol?

<p>Because hyperuricemia can lead to gout and other complications.</p> Signup and view all the answers

What role does arabinosyltransferase play in the context of Ethambutol's action?

<p>Arabinosyltransferase is essential for synthesizing the mycobacterial cell wall.</p> Signup and view all the answers

Study Notes

Drug Therapy of Tuberculosis

  • Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis bacteria.
  • More than a quarter of the global population has been infected with M. tuberculosis.
  • TB primarily affects the lungs but can also impact other organs.
  • First-line TB drugs consist of Isoniazid, Rifampin, Pyrazinamide, and Ethambutol.

Classification of Anti-Tuberculosis Drugs

  • First-line drugs: Rifampin, Isoniazid (INH), Pyrazinamide, Ethambutol
  • Second-Line drugs: Streptomycin, Aminoglycosides (amikacin, kanamycin), Ethionamide, p-aminosalicylic acid (PAS), Imipenem-cilastatin, Fluoroquinolones

Mechanism of Action of Antituberculous Drugs

  • Isoniazid (INH): Inhibits mycolic acid synthesis, a component of the mycobacterial cell wall. It's converted to an active metabolite by the bacterial enzyme catalase-peroxidase (KatG)
  • Rifampin: Binds to the β-subunit of DNA-dependent RNA polymerase (rpoB), forming a stable complex which inhibits RNA synthesis
  • Pyrazinamide: A prodrug that converts to pyrazinoic acid, inhibiting mycobacterial cell membranes. Works best in an acidic environment.
  • Ethambutol: Decreases carbohydrate polymerization in the mycobacterial cell wall by blocking arabinosyltransferase, affecting cell wall synthesis.
  • Streptomycin: A aminoglycoside which interferes with the 30S component of ribosomes, leading to irreversible inhibition of bacterial protein synthesis.

Adverse Effects and Contraindications

  • Isoniazid: Hepatotoxicity, drug interactions (inhibits cytochrome P-450), systemic lupus erythematosus, metabolic acidosis, vitamin B6 deficiency (peripheral neuropathy, anemia), seizures (high doses, refractory to benzodiazepines)
  • Rifampin: Hepatotoxicity, orange-tan discoloration of body fluids, drug interactions (induces cytochrome P-450)
  • Pyrazinamide: Hyperuricemia, hepatotoxicity
  • Ethambutol: Optic neuropathy (red-green color blindness), reversible, hyperuricemia
  • Streptomycin: Tinnitus, vertigo, ataxia, nephrotoxicity. Contraindicated in pregnancy and renal failure.

Therapeutic Regimen for Tuberculosis

  • Six months of treatment with Isoniazid, pyridoxine (Vitamin B6), and Rifampin.
  • First two months can include Pyrazinamide and Ethambutol
  • Multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB are significant challenges requiring tailored treatment, which depends heavily on culture sensitivities.

Latent Tuberculosis Infection (LTBI) Treatment

  • 9 months of INH and pyridoxine (Vitamin B6) are recommended for individuals with positive PPD tests but no active TB.

Resistance to Medications

  • Resistances are driven by mutations, mainly in KatG (INH) and rpoB (Rifampin) genes reducing drug binding to the target enzyme. Avoiding monotherapy is critical.

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Lecture (24) Drug Therapy of Tuberculosis PDF

Description

Explore the various drug therapies for treating tuberculosis, including an in-depth look at first-line and second-line medications. Understand the mechanisms of action for each drug and their roles in combating TB. Test your knowledge on this crucial topic in infectious disease management.

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