Abstract
The experiment was started with a daily oral dose of 10 milligram per kilogram and gradually increased up to 30 milligram or 40 milligram per kilogram once daily. No appreciable toxic effect was observed at least for a period of 20 weeks of continued administration. The maximal blood level of lsoniazid indicated 30 microgram per millilitre after the oral dose of 30 microgram per kilogram which corresponds to the blood level analogically expected from the clinical use of Isoniazid on human. The percentage of leucocyte especially that of eosinophilic leucocyte indicated somewhat higher percentage of 9 to 20 in Monkey I (M1) and 8 percent in Monkey III (M3) both of which were 2 percent before administration. Other findings of blood examination were normal. After termination of the administration, it was observed on Monkey I (M1) that the hair of a palm-size area of the skin on the back fell out and its reproduction did not occur which might indicate some toxicity of this drug. Pathohistologic findings are not available since these animals were not autopsied.
