These studies were conducted to investigate changes in haematological parameters of rats fed with prolong graded doses of Anisopus mannii. The limit dose test of Up and Down procedure as revised by Dixon was employed to determine the acute oral toxicity of the plant. The result revealed that the Median lethal dose of the plant is greater than 3000mg/kg body weight. The repeated administration of graded doses of the extract showed a significant (P< 0.05) dose dependent increase in the packed cell volume (PCV) and red blood cells count on 21st and 28th day post extract treatment. However, there were no significant (P> 0.05) difference in the total white blood cells and differential leukocyte count in all the treated groups of rats compared to there respective day zero and control group. These results show that the aqueous stem extract of Anisopus mannii is relatively safe following oral administration and have possible stimulatory effect on red blood cell production.

Industrial relevance: Blood is a good indicator to determine the physiological and pathological status of man and animal. The parameters measured include packed cell volume, haemoglobin, white blood cell count and platelets count. The normal ranges of these parameters can be altered by the ingestion of some toxic plants. The plant Anisopus mannii (Family Asclepiadaceae), is known as ‘Sakayau’or ‘Kashe zaki’(meaning sweet killer) among the Hausas of the northern Nigeria, where a cold decoction of the stem is traditionally used as remedy for hyperglycaemia. Despite the widespread use of this plant in this environment, there is little literature on the scientific evaluation of its haematological effect thus screening of plants for toxicity aiming at ascertaining their safety seems to be promising, as toxicity following overdose or the active principles present in the plant could pose as limitation to their potential usefulness and may even lead to death. This present study therefore investigates the changes in haematological parameters of rats fed with the aqueous extract of the stem of Anisopus mannii with a view of providing base line information on the safety of the plant used in folkloric medicine as oral hypoglycaemic agent.