Antimycobacterial Drugs — MCQs
A patient with HIV who is currently on antiretroviral therapy consisting of zidovudine, lamivudine, and nevirapine is diagnosed with tuberculosis. Considering potential drug interactions, which of the following TB drugs should be changed in this patient?
A patient with multidrug-resistant tuberculosis, who is receiving antitubercular drugs, develops an inability to distinguish between red and green colors after a few months. Which antitubercular drug is most likely causing these symptoms?
A 25-year-old female has been diagnosed to be suffering from tuberculosis categorized as category II (sputum +ve) case of relapse. According to the previous RNTCP (Revised National Tuberculosis Control Programme) guidelines, the treatment regimen recommended under DOTS was:
Which of the following drugs can produce dramatic improvement in patients with type 2 lepra reaction?
A patient with TB on DOTS develops orange-red discoloration of urine and tears. Which drug is responsible?
Maximum sterilizing action is shown by which anti-TB drug?
Which of the following antimalarial drugs is a slow-acting erythrocytic schizonticidal drug for malaria?
DEC (diethylcarbamazine) is used for the treatment of:
Paucibacillary leprosy treatment includes
A lady gets pregnant even though she was on contraceptive pills. She is suspected to have consumed
Antimycobacterial Drugs Indian Medical PG Practice Questions and MCQs
Question 1: A patient with HIV who is currently on antiretroviral therapy consisting of zidovudine, lamivudine, and nevirapine is diagnosed with tuberculosis. Considering potential drug interactions, which of the following TB drugs should be changed in this patient?
- A. Isoniazid
- B. Rifampicin (Correct Answer)
- C. Ethambutol
- D. Streptomycin
- E. Pyrazinamide
Explanation: **Rifampicin** - **Rifampicin** is a potent **CYP450 enzyme inducer**, which significantly increases the metabolism of **nevirapine**, a non-nucleoside reverse transcriptase inhibitor (NNRTI), leading to subtherapeutic levels and potential treatment failure. - In patients on **nevirapine-based ART**, **rifampicin** is typically avoided or replaced with other rifamycins (like **rifabutin**), or the antiretroviral regimen is switched to one that is less affected by enzyme induction. *Isoniazid* - **Isoniazid** does not have significant, clinically problematic interactions with the antiretroviral regimen mentioned (zidovudine, lamivudine, nevirapine), and is generally well-tolerated. - It is a cornerstone of TB treatment and is usually continued without dose adjustment or substitution in this scenario. *Pyrazinamide* - **Pyrazinamide** is part of the standard first-line TB treatment regimen and does not have clinically significant drug interactions with zidovudine, lamivudine, or nevirapine. - It can be safely continued without dose adjustment in patients on this ART regimen. *Ethambutol* - **Ethambutol** primarily causes **optic neuritis** as a side effect and does not have significant pharmacokinetic interactions with the antiretroviral drugs listed. - Its use in TB treatment alongside this ART regimen is generally safe and does not require a change. *Streptomycin* - **Streptomycin** is an **aminoglycoside antibiotic** primarily used for multi-drug resistant TB or in specific situations, and its main toxicity is **ototoxicity** and **nephrotoxicity**. - It does not have known significant drug interactions with zidovudine, lamivudine, or nevirapine that would necessitate a change.
Question 2: A patient with multidrug-resistant tuberculosis, who is receiving antitubercular drugs, develops an inability to distinguish between red and green colors after a few months. Which antitubercular drug is most likely causing these symptoms?
- A. Ethambutol (Correct Answer)
- B. Rifampicin
- C. Ethionamide
- D. Cycloserine
Explanation: ***Ethambutol*** - **Ethambutol** is known to cause **optic neuritis**, which can manifest as **red-green color blindness** and decreased visual acuity [1]. - This adverse effect is typically dose-dependent and reversible upon discontinuation of the drug [1].*Rifampicin* - **Rifampicin** is associated with a variety of side effects including **hepatotoxicity**, **orange discoloration of body fluids**, and gastrointestinal upset, but not typically optic neuritis or color blindness. - While it is a potent antitubercular drug, its adverse effect profile does not include ophthalmological issues like those described.*Ethionamide* - **Ethionamide** is known for side effects such as **gastrointestinal disturbance**, **hepatotoxicity**, and **hypothyroidism**. - It can also cause psychiatric side effects and peripheral neuropathy, but not specifically red-green color vision impairment.*Cycloserine* - **Cycloserine** is primarily associated with **neuropsychiatric side effects**, including psychosis, depression, seizures, and peripheral neuropathy [2]. - It does not typically cause optic neuritis or color vision disturbances like those seen with ethambutol.
Question 3: A 25-year-old female has been diagnosed to be suffering from tuberculosis categorized as category II (sputum +ve) case of relapse. According to the previous RNTCP (Revised National Tuberculosis Control Programme) guidelines, the treatment regimen recommended under DOTS was:
- A. 3(HRZE)3 + 2(HRE)3 + 4(HR)3
- B. 2(HRSZE)3 + 1(HRZE)3 + 5(HRE)3 (Correct Answer)
- C. 3(HRSZE)3 + 1(HRZE)3 + 6(HRE)3
- D. 2(HRZE)3 + 5(HR)3
Explanation: ***2(HRSZE)3 + 1(HRZE)3 + 5(HRE)3*** - This regimen reflects the standard **Category II DOTS regimen** under the **previous RNTCP guidelines** for **sputum-positive relapse cases**, which was an 8-month treatment protocol. - The intensive phase consisted of **2 months of daily Streptomycin, Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol (HRSZE)**, followed by **1 month of daily Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol (HRZE)**, and a continuation phase of **5 months of Isoniazid, Rifampicin, and Ethambutol (HRE)** given three times weekly. - **Note:** Under current NTEP (National TB Elimination Programme) guidelines, previously treated cases undergo drug susceptibility testing, and fixed Category II regimens are no longer the standard approach. *3(HRZE)3 + 2(HRE)3 + 4(HR)3* - This is an incorrect combination of drugs and durations that does not match any standard DOTS category under previous RNTCP guidelines. - Category II relapse cases required a five-drug intensive phase including Streptomycin, not a four-drug regimen. *3(HRSZE)3 + 1(HRZE)3 + 6(HRE)3* - While this option includes the correct five-drug intensive phase, the duration is incorrect—the intensive phase with Streptomycin should be **2 months, not 3 months**. - The continuation phase of 6 months (instead of 5 months) also makes the total treatment duration longer than the standard 8-month Category II protocol. *2(HRZE)3 + 5(HR)3* - This regimen represents the **Category I (new cases) regimen** under previous RNTCP guidelines, which used only four drugs in the intensive phase. - It **lacks Streptomycin**, which was essential for Category II (relapse/failure/treatment after default) cases, and the continuation phase lacks Ethambutol, which was included in Category II continuation.
Question 4: Which of the following drugs can produce dramatic improvement in patients with type 2 lepra reaction?
- A. Steroids
- B. Dapsone
- C. Clofazimine
- D. Thalidomide (Correct Answer)
Explanation: **Thalidomide** - **Thalidomide** is highly effective in managing **type 2 lepra reactions (erythema nodosum leprosum)**, leading to rapid resolution of symptoms. - Its anti-inflammatory and immunomodulatory properties directly address the inflammatory cascade characteristic of this reaction. *Steroids* - While **steroids** are effective in treating **type 1 lepra reactions** and severe type 2 reactions, they do not produce the same dramatic, rapid improvement seen with thalidomide in typical type 2 reactions. - Long-term steroid use carries significant side effects, making them less ideal for primary management of type 2 reactions when thalidomide is available. *Dapsone* - **Dapsone** is a crucial component of **multi-drug therapy (MDT)** for leprosy itself, but it does not treat reactions. - It has no significant anti-inflammatory effect on the acute immune-mediated processes of lepra reactions. *Clofazimine* - **Clofazimine** is an anti-inflammatory drug used in lepromatous leprosy treatment and sometimes as an alternative for steroid-resistant type 2 reactions. - However, its effect is generally slower and less dramatic compared to thalidomide in the acute management of typical type 2 lepra reactions.
Question 5: A patient with TB on DOTS develops orange-red discoloration of urine and tears. Which drug is responsible?
- A. Ethambutol
- B. Rifampicin (Correct Answer)
- C. Pyrazinamide
- D. Isoniazid
Explanation: ***Rifampicin*** - **Rifampicin** is well-known for causing **orange-red discoloration** of urine, sweat, tears, and other body fluids due to its intrinsic color. - This side effect is benign and does not indicate liver damage or other serious toxicity, but patients should be informed about it. *Ethambutol* - **Ethambutol** is primarily associated with **optic neuritis**, leading to decreased visual acuity and red-green color blindness. - It does not cause discoloration of body fluids. *Pyrazinamide* - **Pyrazinamide** is commonly associated with **hepatotoxicity** and **hyperuricemia**, which can lead to gout. - It does not cause discoloration of body fluids. *Isoniazid* - **Isoniazid** is known to cause **peripheral neuropathy** (prevented by pyridoxine supplementation) and **hepatotoxicity**. - It does not cause discoloration of body fluids.
Question 6: Maximum sterilizing action is shown by which anti-TB drug?
- A. Pyrazinamide
- B. Streptomycin
- C. INH
- D. Rifampicin (Correct Answer)
Explanation: ***Rifampicin*** - Rifampicin has the **maximum sterilizing activity** among all anti-TB drugs, killing semi-dormant and intermittently metabolizing bacilli in various tissue environments. - Its sterilizing effect is crucial for **shortening treatment duration from 12-18 months to 6 months** and preventing relapses. - Rifampicin acts on persisters that other drugs cannot eliminate, making it the most important sterilizing drug in TB therapy. *Pyrazinamide* - Pyrazinamide has **unique sterilizing activity specifically in acidic environments** (pH < 5.5) within macrophages and caseous necrotic lesions. - While highly effective in acidic conditions where other drugs work poorly, its sterilizing action is environment-specific, not the maximum overall. - Its addition to regimens allows treatment shortening from 9 months to 6 months. *Streptomycin* - Streptomycin is an **aminoglycoside** with bactericidal action against actively dividing extracellular M. tuberculosis. - It does not penetrate cells well and has minimal activity against intracellular or dormant bacilli, thus limited sterilizing action. *INH* - Isoniazid (INH) is the most potent **early bactericidal drug** against rapidly multiplying tubercle bacilli. - While highly effective at reducing bacterial load initially, it has limited activity against dormant persisters and thus less sterilizing action compared to rifampicin.
Question 7: Which of the following antimalarial drugs is a slow-acting erythrocytic schizonticidal drug for malaria?
- A. Lumefantrine
- B. Chloroquine
- C. Pyrimethamine (Correct Answer)
- D. Artemether
Explanation: ***Pyrimethamine*** - **Pyrimethamine** is a **slow-acting** antimalarial drug, primarily effective as an **erythrocytic schizonticide**, meaning it targets the parasite's asexual blood stages. - It works by inhibiting **dihydrofolate reductase**, an enzyme crucial for **folate synthesis** in the malaria parasite, thus disrupting DNA and RNA production. *Lumefantrine* - **Lumefantrine** is a rapidly acting erythrocytic schizonticide, usually co-formulated with **artemether** (as **artemether-lumefantrine**) to provide both fast action and a longer half-life. - It is known for causing rapid clearance of parasites, particularly in uncomplicated **falciparum malaria**. *Chloroquine* - **Chloroquine** is a well-known and historically effective **fast-acting** erythrocytic schizonticide, but its use is now limited due to widespread **parasite resistance**, especially concerning **Plasmodium falciparum**. - It works by preventing the detoxification of **heme** into **hemozoin** within the parasite's food vacuole, leading to parasite death. *Artemether* - **Artemether** is a **rapidly acting** erythrocytic schizonticide derived from artemisinin, known for its quick onset of action and potent antiparasitic effects by producing **free radicals**. - It is typically used in combination therapies, such as **artemether-lumefantrine**, to prevent resistance and enhance efficacy against **malaria**.
Question 8: DEC (diethylcarbamazine) is used for the treatment of:
- A. Dracunculiasis (Dracunculus medinensis)
- B. Schistosomiasis (Schistosoma species)
- C. Taeniasis (Taenia species)
- D. Filariasis (Wuchereria bancrofti and Brugia malayi) (Correct Answer)
Explanation: ***Filariasis (Wuchereria bancrofti and Brugia malayi)*** - **Diethylcarbamazine (DEC)** is the drug of choice for treating **lymphatic filariasis** caused by *Wuchereria bancrofti* and *Brugia malayi*. - DEC works by killing the **microfilariae** and adult worms in the lymphatic system. *Dracunculiasis (Dracunculus medinensis)* - Treatment for **dracunculiasis** primarily involves mechanical removal of the worm by winding it around a stick, with supportive care like analgesics and antibiotics for secondary infections. - DEC is **ineffective** against *Dracunculus medinensis*. *Schistosomiasis (Schistosoma species)* - The standard treatment for all forms of **schistosomiasis** is **praziquantel**. - DEC has **no significant efficacy** against *Schistosoma* species. *Taeniasis (Taenia species)* - **Taeniasis**, caused by tapeworms like *Taenia saginata* and *Taenia solium*, is effectively treated with **praziquantel** or **niclosamide**. - DEC is **not indicated** for the treatment of tapeworm infections.
Question 9: Paucibacillary leprosy treatment includes
- A. Rifampicin 600 mg once a month for 6 months + Dapsone 100 mg daily for 6 months (Correct Answer)
- B. Rifampicin 600 mg daily + Dapsone 100 mg daily for 6 months
- C. Rifampicin 600 mg + Dapsone 100 mg + Clofazimine for 12 months
- D. Dapsone 100 mg daily + Clofazimine 300 mg daily for 6 months
Explanation: ***Rifampicin 600 mg once a month for 6 months + Dapsone 100 mg daily for 6 months*** - The World Health Organization (WHO) recommends **multi-drug therapy (MDT)** for paucibacillary leprosy, which comprises **Rifampicin 600 mg once monthly** and **Dapsone 100 mg daily** for a total of **6 months**. - This regimen is crucial for effective bacterial eradication and preventing drug resistance in paucibacillary forms of the disease, which have **five or fewer skin lesions**. - The once-monthly Rifampicin dosing is due to its **potent bactericidal activity** and **prolonged post-antibiotic effect**. *Rifampicin 600 mg daily + Dapsone 100 mg daily for 6 months* - While both drugs are part of the paucibacillary regimen, **Rifampicin** is administered **monthly**, not **daily**. - Daily Rifampicin administration is not the WHO standard and could potentially increase the risk of **side effects** and **drug toxicity** without additional therapeutic benefit in paucibacillary leprosy. *Rifampicin 600 mg + Dapsone 100 mg + Clofazimine for 12 months* - The addition of **Clofazimine** is characteristic of the **multibacillary leprosy** regimen, not paucibacillary. - **Multibacillary leprosy** involves extensive disease (more than 5 skin lesions) with higher bacterial load and requires a **12-month treatment** duration with three drugs including Clofazimine. *Dapsone 100 mg daily + Clofazimine 300 mg daily for 6 months* - This regimen excludes **Rifampicin**, which is a critical component of treatment for both paucibacillary and multibacillary leprosy due to its **strong bactericidal action**. - Furthermore, **Clofazimine** is typically included in **multibacillary regimens** and is not part of the standard paucibacillary protocol.
Question 10: A lady gets pregnant even though she was on contraceptive pills. She is suspected to have consumed
- A. Ciprofloxacin
- B. Rifampicin (Correct Answer)
- C. Streptomycin
- D. None of these
Explanation: ***Rifampicin*** - **Rifampicin** is a potent inducer of **hepatic microsomal enzymes** (cytochrome P450 enzymes), particularly CYP3A4. - This enzyme induction leads to increased metabolism and thus decreased effectiveness of **oral contraceptive pills**, raising the risk of unintended pregnancy. *Ciprofloxacin* - **Ciprofloxacin** is a **quinolone antibiotic** that primarily works by inhibiting bacterial DNA gyrase and topoisomerase IV. - It does not significantly induce hepatic enzymes or interfere with the efficacy of **oral contraceptive pills**. *Streptomycin* - **Streptomycin** is an **aminoglycoside antibiotic** that inhibits bacterial protein synthesis. - It is not known to have a significant drug interaction with **oral contraceptive pills** that would lead to contraceptive failure. *None of these* - This option is incorrect because **Rifampicin** is well-documented to reduce the effectiveness of **oral contraceptive pills**.
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