FURTHER EXPERIENCE OF THE SPECIFIC CURATIVE ACTION IN AMOEBIC DISEASE OF HYPODERMIC INJECTIONS OF SOLUBLE SALTS OF EMETINE

Involvement of the area postrema and the nucleus tractus solitarius in the emetogenic action of emetine in rats

OBJECTIVES

The aim of the present study was to demonstrate the effective dose of emetine for inducing nausea and/or emesis, and the effects of emetine on the excitability of central neurons in the area postrema (AP) and the nucleus tractus solitarius (NTS).

METHODS

Rats were used as experimental animals. We measured the conditioned taste aversion (CTA) induced by the intraperitoneal administration of emetine solution (0.03, 0.1, 0.3, 0.5, and 1.0 mM in saline) and that of only saline. We also performed immunohistochemical analyses of c-Fos expression in the area postrema and the NTS, to examine changes in the excitability of brainstem neurons that may be responsible for emetine-induced nausea and/or emesis.

RESULTS

The emetine-induced CTA occurred in a dose-dependent manner. The half maximal inhibitory concentration (IC₅₀) of emetine on the saccharin preference was calculated to be 0.348 mM using the Hill equation. In the animals injected with emetine (0.5 and 1.0 mM), many c-Fos-like immunoreactive (Fos-ir) cells were observed in the area postrema and the NTS, while few Fos-ir cells were identified in the animals injected with saline. The average number of Fos-ir cells in the area postrema and the NTS was significantly larger in animals injected with emetine than in animals injected with saline.

CONCLUSIONS

The present study demonstrated a dose-responsive manner of emetine effects and emetine-induced upregulation of neuronal excitability in the area postrema and the NTS that form a part of the induction mechanisms of emetine-induced nausea and/or emesis.

Schistosomiasis chemotherapy

After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200,000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies.

Toxicology of ipecac: a review

The general effectiveness and safety of Ipecac syrup, per se, has not been questioned, but rather an attempt has been made to consolidate pertinent literature dealing with the toxic manifestations of Ipecac fluid extract. Ipecac contains both emetine and cephaeline and the toxicity of Ipecac fluid extract is consistent with reports on the toxicity of both compounds. The majority of the work has involved emetine since it is in higher concentration in Ipecac fluid extract than is cephaeline. Comparison of the clinical picture presented in syrup or fluid extract of Ipecac overdose and emetine toxicity in amebiasis treatment permits us to summarize the general characteristics of Ipecac alkaloid toxicity as involving primarily gastrointestinal, cardiovascular, and neuromuscular foci.