Murdoch University Research Repository

Welcome to the Murdoch University Research Repository

The Murdoch University Research Repository is an open access digital collection of research
created by Murdoch University staff, researchers and postgraduate students.

Learn more

Efficacy of oryzalin and associated histological changes in Cryptosporidium-infected neonatal rats

Armson, A., Menon, K., O'Hara, A., MacDonald, L.M., Read, C.M., Sargent, K., Thompson, R.C.A. and Reynoldson, J.A. (2002) Efficacy of oryzalin and associated histological changes in Cryptosporidium-infected neonatal rats. Parasitology, 125 (02). pp. 113-117.

PDF - Published Version
Download (220kB)
Link to Published Version:
*Subscription may be required


This paper reports the anti-cryptosporidial effects of, and concomitant amelioration of the histological changes in the gut of neonatal rats with intestinal cryptosporidiosis treated with the dinitroaniline, oryzalin. The ED50 was determined to be 7 mg/kg using twice daily doses administered for 3 consecutive days. A maximum inhibition of 85.5% was achieved at 25 mg/kg and this inhibition remained constant despite increasing the oryzalin dose to 200 mg/kg. Cryptosporidiosis significantly decreased the intestinal villus/crypt (VC) ratio by approximately 50% (duodenum = 2.3, jejunum = 2.5 and ileum = 1.7) when compared to uninfected untreated controls (duodenum = 4.3, jejunum = 5.9 and ileum = 4.5). Treatment with oryzalin doubled the VC ratio in the duodenum, jejunum and ileum following doses of 5 mg, 50 mg and 200 mg/kg respectively. Oryzalin concentrations in the small intestine contents and plasma were determined, using HPLC, at 0.5, 1 and 2 h after dosing. The much greater dose required to return VC ratios to normal in the ileum (200 mg/kg) compared to the duodenum (6.25 mg/kg) appeared to reflect the decreased concentration of the drug in the distal small intestine. Concentrations of oryzalin equivalent to the in vitro IC50 were maintained for 2 h in the first half of the small intestine following a single dose of 100 mg/kg.

Item Type: Journal Article
Murdoch Affiliation(s): School of Veterinary and Biomedical Sciences
Publisher: Cambridge University Press
Item Control Page Item Control Page


Downloads per month over past year