Calotropis procera is an evergreen perennial shrub, which is found mainly in the arid regions and produces copious latex when cut. It has been reported to possess medicinal properties but equally pose deleterious effect in animals. In a bid to exploit its pharmacological properties, it was necessary to ascertain its level of safety. A toxicological evaluation of the aqueous extract of fresh leaves of the plant was therefore conducted in the more sensitive female rabbits of the same weight range. Low levels of phytochemicals (alkaloids, saponins, tannins, cardiac glycosides and flavonoids) were found, while elemental analyses showed traces of iron, lead, sodium, and potassium in concentrations of 0.23, 0.03, 0.82 and 9.5 mg/g, respectively. Acute toxicity study was conducted with oral administration of 200, 400, 800 and 1600 mg/kg of the extract once to groups I, II, III and IV, respectively with a 24 h observation period. Clinical signs such as mouth chewing, photophobia, bradycardia, coughing, vomiting and convulsion amongst others were noticed. Four rabbits died within 24 h and LD 50 was estimated (940 mg/kg). 80, 40 and 20 mg/kg of the extract were administered daily to groups I, II, and III, respectively, during sub-acute toxicity study for 14 days. Grossly, catarrhal enteritis and mesenteric congestion of the small intestines, congestion of the lungs, hepatization and paleness of the liver, congestion and pallor of the kidney cortex, and congestion of the meninges were noticed. Histopathological examination of the tissues revealed mild pulmonary oedema and peribronchial lymphocytic infiltration of the lungs, hepatization of the liver, disruption of cardiac architecture, generalised cell necrosis and erosion of the villi of the small intestine. All the rabbits that survived gained weight, which is indicative of some nutrient value in the extract. It was concluded that the extract had dose-dependent deleterious effects on the tissues as higher dose groups were more affected. Hence, it is evident that sub-chronic toxicity studies would reveal greater lesions to better ascertain extent of damage.
