Spontaneous systemic lupus erythematosus and acelylator phenotype.

Fifteen patients with spontaneous systemic lupus erythematosus (SLE) have been phenotyped by determination of plasma isoniazid (INH) half-life. Seven patients had signs of renal insufficiency. Of the 15 patients, 13 were slow and only 2 rapid acetylators. No correlation was found between the plasma INH half-lives and the renal function. Thus, there is the same marked predominance of slow acetylators in patients with spontaneous SLE as in patients with the drug-induced SLE-like syndrome.