Effect of coadministration of procainamide and isoniazid on each other's acetylation pathway

Acetylator polymorphism in Parkinson's disease

Acetylator phenotype has been determined using sulphamethazine in 100 patients with Parkinson's disease and in 93 age-matched normal control subjects. Sixty-nine patients and 54 control subjects were classified as slow acetylators (NS). No relation was found among acetylator polymorphism and age at onset or clinical stage of disease. Amongst slow acetylators, the percentage of acetylated sulphamethazine in plasma was significantly lower in patients than in controls. Despite this finding, the results do not support any relationship between acetylator polymorphism and the risk of developing Parkinson's disease.

Potential influence of body weight on the clearance of polymorphically acetylated drugs

The acetylation clearance of sulfamethazine was found to be significantly dependent upon body weight in both intermediate and rapid acetylators. The correlation between acetylation clearance and body weight was stronger in the rapid acetylator. It is recommended that weight-corrected acetylation clearance values be used when constructing distribution histograms for phenotyping purposes. Within a phenotypic mode, body weight may be useful in providing initial estimates of dosing needs.

Acetylator phenotype and lupus erythematosus

There are several known therapeutic implications of acetylator phenotype; among them, the association of a higher incidence of procainamide- and hydralazine-induced lupus in slow acetylators. Presumably, this is because acetylation of the aromatic amine or hydrazine functional group leads to a non-toxic product. Several other drugs which have been implicated in drug-induced lupus also contain an aromatic amine or hydrazine group. The clinical and laboratory characteristics of drug-induced and idiopathic lupus are similar but the degree to which the pathophysiological mechanisms are related, if at all, is unknown. There is also evidence reported for an association between the slow acetylator phenotype and idiopathic lupus. If true, this relationship should provoke some new experimental approaches to investigation into the mechanism of idiopathic lupus.