It is an alkaloid from Cephaelis ipecacuanha. Emetine is a potent and directly acting amoebicide—kills trophozoites but has no effect on cysts.
EMETINE
It is an alkaloid from
Cephaelis ipecacuanha. Emetine is a potent
and directly acting amoebicide—kills trophozoites but has no effect on cysts.
It acts by inhibiting protein synthesis in amoebae by arresting intra-ribosomal
translocation of tRNA-amino acid complex.
The stool in acute dysentery is rapidly cleared of the trophozoites
and symptomatic relief occurs in 1–3 days (even faster than metronidazole), but
it is not curative in the sense that the patient continues to pass cysts in the
stool. It is highly efficacious in amoebic liver abscess also.
Emetine cannot be given orally because it will be vomited out.
It is administered by s.c. or i.m. injection: 60 mg OD. It should be given only
till acute symptoms subside; not more than 10 days in any case. It is concentrated
in liver, kidney, spleen and lungs. Emetine is very slowly excreted in urine
taking 1–2 months. Thus, a second course should not be repeated within 6 weeks,
otherwise cumulative toxicity can occur.
Toxicity of emetine is high.
Local: It is an irritant; pain, stiffness and eczematous lesions
occur at the site of injection.
Nausea and vomiting are frequent. After parenteral
administration this is central in origin due to stimulation of CTZ. Vomiting
due to oral dose of emetine is primarily because of gastric irritation.
Abdominal cramps and diarrhoea due to emetine toxicity may be
confused with that due to intestinal amoebiasis itself.
Weakness and stiffness of muscles; a myositis like picture may
be present.
Hypotension, tachycardia, ECG changes and myocarditis are the
most serious complications. To avoid these, strict bed rest must be imposed
during emetine therapy and exercise should be prohibited for another 1–2
months.
Emetine is contraindicated in presence of cardiac or renal
disease and during pregnancy.
Use
Because of the above
drawbacks, emetine is now seldom used as a reserve drug in severe intestinal or
extraintestinal amoebiasis, or for patients not responding to or not tolerating
metronidazole. A luminal amoebicide must always follow emetine to eradicate the
cyst forming trophozoites.
It is also effective
in liver fluke infestation.
EMETINE HCl: 60 mg /2
ml inj.
Dehydroemetine
It is a semisynthetic derivative of emetine; equally
effective but less cumulative and less toxic to the heart. Thus, it is
preferred over emetine by most physicians.
Dose: 60–100 mg s.c./i.m.OD
for not more than 10 days.
DEHYDROEMETINE HCl: 30 mg/ml inj, 1 and 2 ml amps.
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