From the Faculty of Pharmacy, Department of Pharmacodynamy and Toxicology, Mashhad University of Medical Sciences, P.O. Box 91775-1365, Mashhad, I.R. Iran , hosseinzadeh@mums.ac.ir
Abstract: (3780 Views)
The circadian variation of the toxicity and nociceptive actIvity of
aminophylline as an important methylxanthine was studied in mice. The animals
were housed under controlled light-dark cycles for at least 2 weeks. Acute
toxicity was determined by LD50. Hot-plate test was used for determination of
thermal pain threshold. Doses of 200, 250, 280 and 340 mg/kg of aminophylline
were injected intraperitoneally to four separate groups of six male mice at six
hour intervals (09:00,15:00,21:00,03:00). Mortality was recorded at 1,24, and
48 hours after injection and LD50 value was measured by logit method after 48
hours. The results showed that the lowest nociceptive effect was at the beginning
of the dark phase. The lowest LD50 value was also at the beginning of the dark
phase. This study indicated that the toxicity of aminophylline was maximum at
night and had a different rhythm pattern of nociceptive activity. This indicates
different mechanisms of action for these effects.