Which one of the following drugs is associated with the development of a lupus-like syndrome, especially in patients identified as “slow acetylators”?
**Core Concept**
The question is testing the association between a specific drug and the development of a lupus-like syndrome, particularly in patients with a specific metabolic profile, i.e., "slow acetylators". This is related to the pharmacogenetics of drug metabolism and the potential for drug-induced lupus erythematosus (DILE).
**Why the Correct Answer is Right**
The correct answer is associated with the development of DILE, especially in slow acetylators, due to its mechanism of action and metabolic pathway. The drug in question is a hydralazine-like compound that is metabolized by the liver enzyme N-acetyltransferase 2 (NAT2), which is responsible for acetylation of drugs. Slow acetylators have a variant of the NAT2 gene that leads to reduced enzyme activity, resulting in higher concentrations of the drug and its metabolites, which can trigger an autoimmune response.
**Why Each Wrong Option is Incorrect**
**Option A:** This drug is not commonly associated with DILE and is primarily used for treating hypertension. It is metabolized by the cytochrome P450 enzyme system, not N-acetyltransferase.
**Option B:** This drug is not typically associated with DILE and is used primarily for treating asthma. Its metabolism is not significantly affected by the NAT2 genotype.
**Option C:** This drug is not commonly linked to DILE and is primarily used for treating depression. Its metabolism is not significantly affected by the NAT2 genotype.
**Clinical Pearl / High-Yield Fact**
Slow acetylators are at increased risk of developing DILE with certain drugs, such as hydralazine and procainamide. This is an important consideration in clinical practice, as slow acetylators may require dose adjustments or alternative medications to minimize the risk of DILE.
**Correct Answer:** C. Procainamide is the correct answer.