Medicinal Chemistry III- Antitubercular Agents
Questions and Answers
- 1.
A patient is diagnosed with pulmonary tuberculosis and a treatment with isoniazid, rifampin, pyrazinamide and ethambutol was started. Which of the following statements best explains why ethambutol was added to the therapeutic regimen?
- A.
To enhance the antibacterial activity of pyrazinamide
- B.
To provide antibacterial activity against atypical mycobacteria
- C.
To prevent the neurotoxic effects of isoniazide
- D.
To prevent Pneumocystis carinii pneumonia
- E.
To delay the emergence of drug resistance
Correct Answer
E. To delay the emergence of drug resistanceExplanation
Ethambutol was added to the therapeutic regimen to delay the emergence of drug resistance. This is because ethambutol has a different mechanism of action compared to the other drugs in the regimen (isoniazid, rifampin, and pyrazinamide). By using multiple drugs with different mechanisms of action, the chances of the bacteria developing resistance to all of them simultaneously are reduced. This helps to ensure the effectiveness of the treatment and prevent the development of drug-resistant strains of tuberculosis.Rate this question:
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- 2.
A 45-year-old woman complained of blurred vision and inability to distinguish green objects from red objects. The woman, was recently diagnosed with tuberculosis, has been receiving a 4 drug combination regimen for two months. Which of the following drugs has most likely caused these adverse effects?
- A.
Isoniazid
- B.
Pyrazinamide
- C.
Rifampin
- D.
Ethambutol
- E.
Streptomycin
Correct Answer
D. EthambutolExplanation
Ethambutol is the most likely cause of the woman's blurred vision and inability to distinguish green objects from red objects. Ethambutol is known to cause optic neuritis, which can result in visual disturbances such as blurred vision and color blindness. The other drugs listed do not typically cause these specific adverse effects.Rate this question:
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- 3.
The patient was diagnosed with tuberculosis and started on a regimen of 4 antitubercular drugs one month ago. Lab results showed raised serum uric acid of 13 mg /dl. Which of the following drugs has most likely caused the patient’s current symptoms?
- A.
Rifampin
- B.
Pyrazinamide
- C.
Isoniazid
- D.
Streptomycin
Correct Answer
B. PyrazinamideExplanation
Pyrazinamide is the most likely drug that has caused the patient's raised serum uric acid levels. Pyrazinamide is known to cause hyperuricemia, which is an increase in uric acid levels in the blood. This side effect is more common in patients with pre-existing hyperuricemia or gout. Rifampin, isoniazid, and streptomycin are not typically associated with elevated uric acid levels.Rate this question:
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- 4.
The mechanism of action of rifampin includes an inhibition of which of the following enzymes?
- A.
DNA dependent RNA-polymerase
- B.
Arabinosyl transferase
- C.
Transpeptidase
- D.
Topoisomerase II
- E.
RNA-dependent DNA-polymerase
Correct Answer
A. DNA dependent RNA-polymeraseExplanation
Rifampin is a broad-spectrum antibiotic that is primarily used to treat tuberculosis and other bacterial infections. It works by inhibiting the activity of DNA dependent RNA-polymerase, which is an enzyme involved in the transcription of DNA into RNA. By inhibiting this enzyme, rifampin prevents the synthesis of RNA, which is essential for the growth and replication of bacteria. This ultimately leads to the death of the bacteria and the resolution of the infection.Rate this question:
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- 5.
A patient reports tingling sensation in limbs and arms sometimes feel heavy. He was diagnosed with pulmonary tuberculosis and has been receiving isoniazid, rifampin, pyrazinamide and ethambutol for two months. Which of the following drugs would be most appropriate to treat his current symptoms?
- A.
Folic acid
- B.
Pyridoxine
- C.
Cyanocobalamin
- D.
Vitamic C
Correct Answer
B. PyridoxineExplanation
The patient is experiencing symptoms of peripheral neuropathy, which can be a side effect of the anti-tuberculosis medications. Pyridoxine, also known as vitamin B6, is commonly used to prevent and treat peripheral neuropathy caused by isoniazid. It helps to protect and repair the nerves, reducing the tingling sensation and heaviness in the limbs. Folic acid, cyanocobalamin, and vitamin C do not have direct effects on peripheral neuropathy.Rate this question:
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- 6.
- Which of the following antimycobacterial drugs is inactivated by hepatic acetylation, the rate of which depends on genetic background?
- A.
Streptomycin
- B.
Ethambutol
- C.
Rifampin
- D.
Isoniazid
- E.
Pyrazinamide
- F.
Option 6
Correct Answer
D. IsoniazidExplanation
Isoniazid is the correct answer because it is known to be inactivated by hepatic acetylation, and the rate of this inactivation depends on an individual's genetic background. This means that different individuals may metabolize isoniazid at different rates, leading to varying levels of drug activity in the body. This genetic variability can impact the effectiveness and side effects of isoniazid treatment for tuberculosis.Rate this question:
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Mar 21, 2023Quiz Edited by
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Sep 19, 2020Quiz Created by
Suvarna Katti
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