Drug Induced Lupus

Drug-induced lupus erythematosus (DILE) is a lupus-like syndrome triggered by medications, resolving after stopping the drug.

• High risk drugs: procainamide, hydralazine, isoniazid, quinidine, minocycline, methyldopa, TNF inhibitors, interferon, terbinafine, penicillamine, anti-epileptics (phenytoin, carbamazepine).

• Antihistone antibodies in 95% (not in minocycline, TNF inhibitor cases which show anti-dsDNA); slow acetylators (hydralazine, procainamide) and HLA-DR4 predispose.

• Older patients, men and women equally affected (unlike SLE).

• Typically after months to years of therapy; renal and central nervous system disease rare.

• Arthralgia and myalgia (most), pleuritis/pericarditis (serositis), fever, malaise, weight loss.

• Rash (photosensitive) less than in SLE; discoid lesions rare; subacute cutaneous lupus with terbinafine, thiazides, calcium channel blockers (anti-Ro positive).

• Hepatosplenomegaly, mild cytopenias.

• Glomerulonephritis and neuropsychiatric features unusual (more with TNF inhibitors, hydralazine).

• Temporal relationship to drug exposure for at least 3 to 6 months, symptoms resolving after discontinuation.

• ANA positive; antihistone antibodies (IgG), normal complement, anti-dsDNA and anti-Sm usually negative.

• Count, creatinine, urinalysis, ESR/CRP, chest radiograph if serositis, ECG/echocardiogram for pericardial involvement.

• Hydralazine-associated: ANCA-positive vasculitis may occur (MPO, perinuclear).

• Exclude idiopathic SLE (anti-dsDNA, low complement, renal disease).

• Stop the offending drug (cornerstone); symptoms resolve over weeks to months; serology may remain positive for a year or more.

• Mild: NSAIDs (naproxen 500 mg twice daily).

• Moderate to severe (serositis, severe arthritis): prednisolone 20 to 40 mg daily tapered over weeks; hydroxychloroquine 200 mg twice daily.

• Hydralazine-induced vasculitis or renal disease: prednisolone 1 mg/kg, immunosuppression (cyclophosphamide, rituximab) as for ANCA vasculitis.

• TNF inhibitor lupus: stop the drug, switch to another class.

• Alternative therapy chosen for the underlying indication, avoiding drug rechallenge.

• Follow antibodies and clinical status until resolution.