Chromosomal effects of theophylline measured in mouse marrow cells in vivo.

Doses of 62.5, 125 and 250 mg/kg of theophylline were administered to male B6C3F1 mice by intraperitoneal injection. Chromosome aberrations were scored in first-division metaphases of marrow cells 18 and 36 h post-treatment and sister-chromatid exchanges were quantified in second-division metaphases at 24 h. A modest but statistically significant increase in the number of SCEs occurred, but chromosome aberrations were not significantly different from controls following treatment with any level of the drug at either time period.