Treatment of filarial lymphoedema and elephantiasis with 5,6-benzo-alpha-pyrone (coumarin).

OBJECTIVE--To study efficacy of treatment of filarial lymphoedema and elephantiasis with 5,6-benzo-alpha-pyrone. DESIGN--Randomised, double blind, placebo controlled study with matching for grade and duration of disease, age, and sex. Treatment was given for 367 days, and subjects were followed up for another year. SETTING--A town in Shandong Province, China. SUBJECTS--104 men and women with chronic unilateral filarial lymphoedema or elephantiasis of the leg: 64 were randomised to benzopyrone and 40 to placebo. By the end of the study 19 patients had dropped out of the treatment group and two out of the placebo group. INTERVENTIONS--Two 200 mg tablets of 5,6-benzo-alpha-pyrone or two placebo tablets given daily. MAIN OUTCOME MEASURES--Volumes of the affected and normal legs estimated every three months, and daily listing of any side effects. RESULTS--Benzopyrone reduced oedema for all grades of lymphoedema during the year of treatment (pW0.001) and the follow up year (p = 0.026). During treatment the mean monthly reductions in leg volume were 0.62% (95% confidence intervals 0.4% to 0.85%), 1.1% (0.71% to 1.6%), and 1.6% (0.89% to 2.3%) of the volume of the normal leg for grades 1, 2, and 3-5 (elephantiasis) of lymphoedema respectively. During follow up the mean monthly reductions were 0.18% (0.01% to 0.35%), 0.54% (0.27% to 0.82%), and 0.87% (0.51% to 1.2%). At the end of the trial the total reduction in oedema was 100%, 95%, and 45% for grades 1, 2, and 3-5. Symptoms and complications were considerably reduced, including attacks of secondary acute inflammation, while side effects were minor and disappeared after one month. In the placebo group there were no changes in the severity of lymphoedema. CONCLUSIONS--5,6-benzo-alpha-pyrone reduces the oedema and many symptoms of filarial lymphoedema and elephantiasis. It has few side effects, and its relatively slow action makes it ideal for use without compression garments.