Which of the following drugs can cause lupus due to low N-acetyl transferase activity in the blood?
**Core Concept:** N-acetyl-transerase is an enzyme that plays a crucial role in the detoxification of certain drugs and environmental toxins. It functions by conjugating these compounds with acetyl groups, making them more soluble in water and facilitating their excretion via urine or bile. When N-acetyl-transerase activity is low, it leads to increased toxicity and potential side effects of the drugs they modify. Lupus, a systemic autoimmune disorder, can be triggered when the body mistakenly attacks its own tissues and organs due to drug exposure.
**Why the Correct Answer is Right:** The correct answer, D-penicillamine, is an antirheumatic drug commonly used for treating rheumatoid arthritis, Wilson's disease, and other conditions. However, it can lead to the development of a drug-induced lupus-like syndrome, known as DILS (Drug-induced Lupus-like Syndrome). This occurs due to the formation of antinuclear antibodies (ANAs) which are a hallmark of lupus, caused by the unmetabolized drug remaining in the blood. The other options are not associated with low N-acetyl-transerase activity and therefore are not likely to cause lupus as a side effect.
**Why Each Wrong Option is Incorrect:**
A. Penicillin (Option A) is a widely used antibiotic that primarily acts by inhibiting bacterial cell wall synthesis. It does not cause lupus due to low N-acetyl-transerase activity.
B. Prednisolone (Option B) is a potent corticosteroid used to suppress immune system responses in autoimmune diseases. Although prednisolone can cause side effects, low N-acetyl-transerase activity is not a recognized risk factor for drug-induced lupus.
C. Hydroxychloroquine (Option C) is an antimalarial and anti-inflammatory drug. It is generally safe for patients with low N-acetyl-transerase activity, although exact mechanisms of hydroxychloroquine's immunosuppressive effects are not fully understood.
D. D-penicillamine (Option D) is mentioned above as the correct answer. It is associated with low N-acetyl-transerase activity, leading to drug-induced lupus-like syndrome (DILS) including ANA positivity.
**Clinical Pearl:** It is essential for healthcare professionals to monitor patients on D-penicillamine for the development of DILS, as early detection and intervention can prevent severe complications.
**Explanation:** In summary, D-penicillamine is the correct answer because it is an antirheumatic drug that requires N-acetyl-transerase activity for its detoxification, leading to the formation of antinuclear antibodies (ANAs) and drug-induced lupus-like syndrome (DILS). Other options do not cause lupus due to low N-acetyl-transerase activity, making them incorrect choices.