Antitubercular drugs are an important topic in pharmacology for B.Pharm, D.Pharm, GPAT, and pharmacist recruitment examinations. Questions frequently cover drug classification, mechanisms of action, therapeutic uses, adverse effects, and the distinguishing features of individual medicines.
This article contains 30 important MCQs on antitubercular drugs, with answers and explanations to help you revise key concepts and prepare for pharmacy examinations.
📝Top 30 Antitubercular Drugs MCQs
1. Which microorganism is primarily responsible for tuberculosis?
A. Staphylococcus aureus
B. Mycobacterium tuberculosis
C. Escherichia coli
D. Streptococcus pyogenes
Correct Answer: B. Mycobacterium tuberculosis
Explanation: Tuberculosis is an infectious disease caused primarily by Mycobacterium tuberculosis. It most commonly affects the lungs but can also affect other organs.
2. Which antitubercular drug inhibits mycolic acid synthesis?
A. Rifampicin
B. Ethambutol
C. Isoniazid
D. Streptomycin
Correct Answer: C. Isoniazid
Explanation: Isoniazid is activated by a mycobacterial enzyme called KatG. Its active form inhibits InhA, interfering with mycolic acid synthesis in the mycobacterial cell wall.
3. Which drug inhibits bacterial DNA-dependent RNA polymerase?
A. Rifampicin
B. Pyrazinamide
C. Ethambutol
D. Isoniazid
Correct Answer: A. Rifampicin
Explanation: Rifampicin inhibits bacterial DNA-dependent RNA polymerase, thereby preventing RNA synthesis. It is a key drug in many treatment regimens for drug-susceptible tuberculosis.
4. Which antitubercular drug can cause optic neuritis?
A. Isoniazid
B. Ethambutol
C. Rifampicin
D. Pyrazinamide
Correct Answer: B. Ethambutol
Explanation: Ethambutol interferes with arabinogalactan synthesis in the mycobacterial cell wall. Its important adverse effect is optic toxicity, which can affect visual acuity and colour vision.
5. Which drug is associated with orange-red discoloration of urine and other body fluids?
A. Ethambutol
B. Isoniazid
C. Rifampicin
D. Pyrazinamide
Correct Answer: C. Rifampicin
Explanation: Rifampicin can cause orange-red discoloration of urine, tears, sweat, and other body fluids. Patients should be informed about this expected effect.
6. Which antitubercular drug is associated with peripheral neuropathy?
A. Isoniazid
B. Rifampicin
C. Ethambutol
D. Bedaquiline
Correct Answer: A. Isoniazid
Explanation: Isoniazid can cause peripheral neuropathy, partly because it interferes with vitamin B6 metabolism. Pyridoxine may be prescribed to prevent or manage this adverse effect in patients who need it.
7. Which vitamin is commonly prescribed with isoniazid for patients at risk of peripheral neuropathy?
A. Vitamin A
B. Vitamin B1
C. Vitamin B6
D. Vitamin K
Correct Answer: C. Vitamin B6
Explanation: Pyridoxine, or vitamin B6, may be given with isoniazid to reduce the risk of peripheral neuropathy, particularly in susceptible patients.
8. Which of the following is one of the four classic first-line antitubercular drugs?
A. Fluconazole
B. Ethambutol
C. Acyclovir
D. Oseltamivir
Correct Answer: B. Ethambutol
Explanation: The four classic first-line drugs commonly taught together are isoniazid, rifampicin, pyrazinamide, and ethambutol. Actual treatment depends on the patient’s condition and current guidelines.
9. What is an important adverse effect of pyrazinamide?
A. Hyperuricemia
B. Permanent hair growth
C. Severe hypoglycemia in every patient
D. Increased visual acuity
Correct Answer: A. Hyperuricemia
Explanation: Pyrazinamide can increase uric acid levels and may cause joint discomfort or precipitate gout in susceptible patients. Hepatotoxicity is another important adverse effect.
10. Which drug is associated with inhibition of arabinosyltransferase?
A. Ethambutol
B. Rifampicin
C. Isoniazid
D. Pyrazinamide
Correct Answer: A. Ethambutol
Explanation: Ethambutol inhibits arabinosyltransferase enzymes involved in the synthesis of arabinogalactan, an important component of the mycobacterial cell wall.
11. Which antitubercular drug is converted into pyrazinoic acid?
A. Rifampicin
B. Pyrazinamide
C. Ethambutol
D. Isoniazid
Correct Answer: B. Pyrazinamide
Explanation: Pyrazinamide is converted by mycobacterial enzymes into pyrazinoic acid. Its precise mechanism is not completely understood, but it disrupts important aspects of mycobacterial physiology.
12. Why are multiple drugs used to treat active tuberculosis?
A. To eliminate the need for adherence
B. To improve treatment effectiveness and reduce the risk of resistance
C. To treat every bacterial infection simultaneously
D. To prevent all adverse effects
Correct Answer: B. To improve treatment effectiveness and reduce the risk of resistance
Explanation: Combination therapy targets susceptible bacteria through multiple medicines and helps reduce the emergence of drug resistance. Patients should follow their prescribed regimen.
13. Which of the following is a major adverse effect of rifampicin?
A. Drug interactions
B. Improved colour vision
C. Guaranteed prevention of liver injury
D. Increased bone growth in every patient
Correct Answer: A. Drug interactions
Explanation: Rifampicin induces several drug-metabolizing enzymes and transporters. It can reduce the effectiveness of many medicines, so potential interactions must be reviewed.
14. Which antitubercular drug inhibits mycobacterial ATP synthase?
A. Bedaquiline
B. Ethambutol
C. Isoniazid
D. Pyrazinamide
Correct Answer: A. Bedaquiline
Explanation: Bedaquiline inhibits mycobacterial ATP synthase, interfering with energy production. It is used in selected drug-resistant TB regimens.
15. Which important safety concern is associated with bedaquiline?
A. QT interval prolongation
B. Orange-red tears in every patient
C. Optic neuritis in every patient
D. Vitamin C deficiency
Correct Answer: A. QT interval prolongation
Explanation: Bedaquiline can prolong the QT interval, potentially increasing the risk of serious cardiac rhythm disturbances. Appropriate clinical and electrocardiographic monitoring may be required.
16. Which of the following drugs is a fluoroquinolone that may be used in selected TB treatment regimens?
A. Levofloxacin
B. Fluconazole
C. Acyclovir
D. Metformin
Correct Answer: A. Levofloxacin
Explanation: Levofloxacin is a fluoroquinolone antibiotic that may be used in selected drug-resistant TB regimens. Its use depends on susceptibility results and current treatment recommendations.
17. Which antitubercular drug is associated with hearing damage and kidney toxicity?
A. Amikacin
B. Ethambutol
C. Isoniazid
D. Pyrazinamide
Correct Answer: A. Amikacin
Explanation: Amikacin is an aminoglycoside antibiotic that can cause ototoxicity and nephrotoxicity. It is reserved for selected situations because of these risks and the availability of other treatment options.
18. Which drug class does linezolid belong to?
A. Oxazolidinones
B. Rifamycins
C. Fluoroquinolones
D. Macrolides
Correct Answer: A. Oxazolidinones
Explanation: Linezolid is an oxazolidinone antibiotic that inhibits bacterial protein synthesis by acting on the 50S ribosomal subunit. It may be included in selected drug-resistant TB regimens.
19. Which of the following is a potential adverse effect of linezolid?
A. Bone marrow suppression
B. Orange-red discoloration of all body fluids
C. Increased visual acuity
D. Guaranteed prevention of neuropathy
Correct Answer: A. Bone marrow suppression
Explanation: Linezolid can cause thrombocytopenia, anemia, and other blood abnormalities. Peripheral and optic neuropathy may also occur, especially with prolonged treatment.
20. Which antitubercular drug is most strongly associated with optic toxicity?
A. Ethambutol
B. Rifampicin
C. Isoniazid
D. Pyrazinamide
Correct Answer: A. Ethambutol
Explanation: Ethambutol can cause optic neuropathy. Patients should report blurred vision or changes in colour vision promptly.
21. Which statement about latent tuberculosis infection is correct?
A. It always causes symptoms.
B. It can never progress to active disease.
C. Preventive treatment may reduce the risk of developing active TB.
D. It always requires the same regimen as active TB disease.
Correct Answer: C. Preventive treatment may reduce the risk of developing active TB.
Explanation: Latent TB infection does not cause active disease symptoms, but it can progress to active TB. Preventive treatment is selected according to clinical assessment and applicable guidelines.
22. What is a major concern when antitubercular treatment is stopped prematurely or taken incorrectly?
A. Development of drug resistance and treatment failure
B. Guaranteed permanent immunity
C. Elimination of all future infection risk
D. Prevention of all adverse effects
Correct Answer: A. Development of drug resistance and treatment failure
Explanation: Incomplete or inappropriate treatment can contribute to treatment failure and drug resistance. Patients should contact their treatment team if they have difficulty taking their medicines.
23. Which of the following is NOT one of the four classic first-line antitubercular drugs?
A. Isoniazid
B. Rifampicin
C. Pyrazinamide
D. Acyclovir
Correct Answer: D. Acyclovir
Explanation: Acyclovir is an antiviral medicine used for selected herpesvirus infections. The four classic first-line antitubercular drugs are isoniazid, rifampicin, pyrazinamide, and ethambutol.
24. Which of the following best describes the action of rifampicin?
A. Inhibition of DNA-dependent RNA polymerase
B. Inhibition of human insulin production
C. Inhibition of viral neuraminidase
D. Inhibition of histamine receptors
Correct Answer: A. Inhibition of DNA-dependent RNA polymerase
Explanation: Rifampicin blocks bacterial RNA synthesis by inhibiting DNA-dependent RNA polymerase.
25. Which antitubercular drug is associated with hepatotoxicity?
A. Isoniazid
B. Rifampicin
C. Pyrazinamide
D. All of the above
Correct Answer: D. All of the above
Explanation: Isoniazid, rifampicin, and pyrazinamide can all cause liver injury. Monitoring and clinical assessment depend on the treatment regimen and the patient’s risk factors.
26. Which of the following is a major component of the mycobacterial cell wall?
A. Mycolic acids
B. Hemoglobin
C. Insulin
D. Keratin
Correct Answer: A. Mycolic acids
Explanation: Mycolic acids are important components of the mycobacterial cell envelope. Isoniazid inhibits their synthesis, making this a high-yield pharmacology concept.
27. Which of the following is an important feature of drug-resistant tuberculosis treatment?
A. All patients receive exactly the same regimen.
B. Treatment is selected according to drug resistance and clinical factors.
C. Antibiotics are never required.
D. Treatment can always be stopped when symptoms improve.
Correct Answer: B. Treatment is selected according to drug resistance and clinical factors.
Explanation: Drug-resistant TB requires an appropriately selected regimen based on resistance testing, prior treatment, patient factors, and current treatment guidance.
28. Which antitubercular drug is associated with hyperuricemia and possible gout?
A. Pyrazinamide
B. Acyclovir
C. Oseltamivir
D. Fluconazole
Correct Answer: A. Pyrazinamide
Explanation: Pyrazinamide may increase serum uric acid levels. This can be clinically important in patients with a history of gout.
29. Which of the following is a correct drug-mechanism match?
A. Isoniazid — inhibition of mycolic acid synthesis
B. Rifampicin — inhibition of viral neuraminidase
C. Ethambutol — inhibition of HIV protease
D. Bedaquiline — inhibition of human cyclooxygenase
Correct Answer: A. Isoniazid — inhibition of mycolic acid synthesis
Explanation: Isoniazid inhibits mycolic acid synthesis in susceptible mycobacteria. The other options describe incorrect mechanisms.
30. Which statement about antitubercular drugs is most accurate?
A. Every TB patient can use the same treatment without assessment.
B. Adverse effects never occur.
C. Treatment depends on the type of TB, drug susceptibility, and patient-specific factors.
D. A single medicine is always sufficient for active TB.
Correct Answer: C. Treatment depends on the type of TB, drug susceptibility, and patient-specific factors.
Explanation: TB treatment must be selected according to clinical circumstances and current guidelines. Drug susceptibility, adverse effects, interactions, and patient characteristics can all influence the regimen.
📑Quick Revision: Important Antitubercular Drugs
- Isoniazid: Inhibits mycolic acid synthesis; can cause peripheral neuropathy.
- Rifampicin: Inhibits DNA-dependent RNA polymerase; can cause orange-red discoloration of body fluids.
- Pyrazinamide: Converted to pyrazinoic acid; can cause hyperuricemia and hepatotoxicity.
- Ethambutol: Inhibits arabinogalactan synthesis; can cause optic toxicity.
- Bedaquiline: Inhibits ATP synthase; can prolong the QT interval.
- Linezolid: Inhibits bacterial protein synthesis; can cause bone marrow suppression.
- Levofloxacin: Inhibits DNA gyrase and topoisomerase IV.
- Amikacin: Inhibits the 30S ribosomal subunit; can cause ototoxicity and nephrotoxicity.
📋Frequently Asked Questions
1. What are the four classic first-line antitubercular drugs?
The four classic drugs are isoniazid, rifampicin, pyrazinamide, and ethambutol. Their use and combination depend on the prescribed treatment regimen.
2. Which antitubercular drug causes orange-red discoloration of body fluids?
Rifampicin can cause orange-red discoloration of urine, tears, sweat, and other body fluids.
3. Which antitubercular drug can cause peripheral neuropathy?
Isoniazid can cause peripheral neuropathy. Pyridoxine (vitamin B6) may be prescribed to prevent or manage this adverse effect in susceptible patients.
4. Which antitubercular drug can cause optic neuritis?
Ethambutol can cause optic toxicity, including optic neuritis and changes in colour vision.
5. Why are multiple drugs used in TB treatment?
Combination therapy improves treatment effectiveness and helps reduce the risk of drug resistance.
6. Which antitubercular drug inhibits ATP synthase?
Bedaquiline inhibits mycobacterial ATP synthase and is used in selected drug-resistant TB regimens.
🎯 Conclusion
Antitubercular drugs are important for pharmacology examinations and clinical pharmacy studies. Focus on their mechanisms of action, major adverse effects, and distinguishing features to prepare effectively for MCQs.
Related reading: Study our detailed guide to Antitubercular Drugs: Classification, Mechanism, Uses and Side Effects.
Disclaimer: This article is intended for educational and examination-preparation purposes. It does not replace professional medical advice or an individualized TB treatment plan.
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