Ivermectin: Placebo-controlled studies
Emesis, ataxia, and mydriasis are cardinal signs of ivermectin toxicity. The safety, tolerability, and pharma-cokinetics of escalating high-dose ivermectin have been studied in 68 healthy subjects in a randomized, double-blind, placebo-controlled study in the following doses:
- 30 mg fasted
- 60 mg fasted . 90 mg fasted
- 120 mg fasted . 30 mg fed
Ivermectin was generally well tolerated. Quantitative pupillometry ruled out any mydriatic effect of ivermectin. There was no nervous system toxicity associated with oral ivermectin at any of the doses. There were no serious clinical or laboratory adverse events. Three of the fifty-one subjects who took ivermectin fasted reported minor adverse gastrointestinal events: fecal abnormality, nausea, and vomiting; six reported minor neurological adverse events: headache, anxiety, and dizziness. There were no adverse events in the subjects who took ivermectin 120 mg. The absorption of ivermectin was about 2.5 times higher when it was given after a high-fat meal.
Sarcoptes scabiei
In a randomized, double-blind comparison of the efficacy of oral ivermectin and topical gamma-benzene hexachlor-ide 53 patients were randomly allocated to either a single oral dose of ivermectin 150-200 micrograms/kg and a placebo topical solution, or a single dose of gamma-benzene hexachloride topical solution 1% and placebo tablets. Patients who did not fulfil the criteria for clinical cure within 15 days, defined as the absence of both pruritus and clinical lesions or a reduction in signs and symptoms to a mild degree, repeated the initial treatment.
Of the 53 patients 43 completed the study (19 of those treated with ivermectin and 24 of those treated with gamma-benzene hexachloride). After 15 days 74% of the patients treated with ivermectin and 54% of the patients treated with gamma-benzene hexachloride were considered to be cured. At 29 days both treatments were equally effective, with cure rates of 95% and 96% respectively. Adverse effects were mild and transient in both groups. One of the patients treated with ivermectin had hypotension, one had abdominal pain, one had vomiting, and one complained of headache. There were no abnormalities on routine laboratory testing.
Wuchereria bancrofti
In a double-blind, placebo-controlled study in Ghana single doses of ivermectin 150-200 micrograms/kg and albendazole 400 mg, either separately or in combination, were given to 1425 individuals for Wuchereria bancrofti infection. Of these, 340 were microfilariae-positive before treatment. Ivermectin and ivermectin plus albendazole both produced statistically significant reductions in mean microfilaria counts at follow-up; the effect of ivermectin was longer lasting. Albendazole produced a non-significant reduction. Adverse reactions were few and mostly mild, and there were no severe reactions.