A 50-year-old pulmonologist is diagnosed with pulmonary tuberculosis and staed on standard drug therapy. After 1.5 months, the patient has developed fatigue, low grade fever, muscle aches, bone pains and body aches. The patient also complains of pleuritic chest pain. His sputum tests negative for acid fast bacilli. On fuher investigations, the patient tests positive for anti-histone antibodies. Abnormality in which of the following metabolic processes is responsible for patient's current condition?

Patient's symptoms including constitutional symptoms, ahralgia and pleuritic chest pain with positive anti-histone antibodies and recent use of isoniazid point towards the diagnosis of drug induced lupus erythematosus. Drugs undergoing acetylation in liver with the help of N-acetyl transferase are responsible for majority of cases of drug induced SLE. Hepatic expression of N acetyl transferase is genetically determined, and patients with a slow acetylator phenotype are more likely to develop DLE. Drugs undergoing Acetylation and therefore, responsible for DLE: Sulfonamides Hydralazine Isoniazid Procainamide