Which of the following drug adverse reactions precludes a patient from being * given the same drug in the future?

Correct Answer: C

Rationale: The correct answer is C: Steven-Johnson syndrome from Trimethoprim/Sulfamethoxazole. Steven-Johnson syndrome is a severe and potentially life-threatening adverse reaction characterized by rash, blistering, and mucosal involvement. Once a patient experiences Steven-Johnson syndrome from a specific drug like Trimethoprim/Sulfamethoxazole, they should never be given that drug again due to the high risk of recurrence and the severity of the reaction. This is known as a contraindication, making it unsafe to administer the drug in the future. A, B, and D are incorrect because GI upset from Clarithromycin, skin rash from Ampicillin, and Clostridium difficile superinfection from Ciprofloxacin, while unpleasant, are not typically considered contraindications for future use of the same drug. These adverse reactions can often be managed with dose adjustments, alternative medications, or supportive care without ruling out the drug entirely

Correct Answer: C

Rationale: The correct answer is C: Trimethoprim/Sulfamethoxazole. This combination is the first-line treatment for Pneumocystis carinii pneumonia in patients with HIV-AIDS due to its efficacy against the organism. Trimethoprim inhibits bacterial folic acid synthesis, while sulfamethoxazole inhibits bacterial dihydrofolic acid formation. These drugs work synergistically to target different steps in the folic acid synthesis pathway of Pneumocystis carinii, leading to its effective eradication. Metronidazole (A) is used for anaerobic bacterial infections, Carbenicillin (B) is a penicillin derivative mainly used for Gram-negative bacteria, and Penicillin G (D) is not effective against Pneumocystis carinii.

Correct Answer: A

Rationale: The correct answer is A: Two nucleoside reverse transcriptase inhibitors (NRTIs) + one protease inhibitor (PI). This regimen is typically reserved for advanced cases of AIDS or repeated treatment failures due to its potent antiviral effects. NRTIs inhibit viral replication by interfering with the HIV enzyme reverse transcriptase, while PIs inhibit the enzyme protease, essential for viral maturation. Combining these two classes of drugs provides a strong barrier against HIV resistance. Other choices (B, C, D) are less effective in advanced cases as they do not provide the same level of dual inhibition necessary to combat resistant strains and advanced disease progression.

Correct Answer: A

Rationale: Step-by-step rationale for why A (Lamivudine) is correct: 1. Lamivudine is a nucleoside analog reverse transcriptase inhibitor used to treat chronic hepatitis B. 2. It inhibits the replication of the hepatitis B virus, reducing viral load and liver damage. 3. Clinical studies have shown its efficacy in improving liver function and reducing the risk of cirrhosis. 4. Lamivudine is recommended as a first-line treatment option by major medical guidelines. Summary of why other choices are incorrect: B. Human interferon α: While interferon therapy was previously used, it is no longer recommended as a first-line treatment due to its side effects and lower efficacy compared to newer drugs. C. Amantadine: Amantadine is not recommended for the treatment of chronic hepatitis B as it is not effective against the hepatitis B virus. D. (: This is not a valid drug option for treating chronic hepatitis B.

Correct Answer: B

Rationale: The correct answer is B: Primaquine. Primaquine is a radical curative drug for Plasmodium vivax malaria, as it targets the hypnozoite stage in the liver, preventing relapses. It is also used as prophylaxis in Chloroquine-sensitive regions due to its efficacy against P. vivax and P. ovale. Rationale: 1. Quinine (A) is not a radical curative drug for P. vivax malaria. It is mainly used for treatment of acute malaria. 2. Meoquine (C) is not a radical curative drug for P. vivax malaria and is used more for prophylaxis in certain regions. 3. Chloroquine (D) is not a radical curative drug for P. vivax malaria and is primarily used for treatment and prevention of malaria caused by susceptible strains of Plasmodium species.