Chronic filaritic lymphoedema and elephantiasis, in India, were treated orally with 5,6 benzo-α-pyrone (56BaP; 1,2 benzo-α-pyrone; coumarin) in a double-blind, randomized, matched-group trial. Each group finally contained 40-55 patients. Patients were observed for about 2 years (ranging from 6 to 45 months, with 75% completing the 2 years). The 56BaP slowly, but very significantly (P<0.0001), reduced all grades of lymphoedema and elephantiasis. Two thirds of the oedema was lost by grade 2 over 2 years. Grades 3 to 5 were reduced by a fifth over that time. The greater the initial oedema, the greater was its rate of resolution. A slowly worsening condition thus became a slowly improving one. Slowness has its advantages: compression stockings, that are impractical in hot, wet or dirty conditions, are not necessary. The slowly remodelling fibrous tissue, while lessening in amount, is still able to hold the tissues together. The 56BaP considerably improved many symptoms and complications, particularly bursting-pains, inflammation and ulcers. It is cheap and of very low toxicity. Diethylcarbamazine (DEC) was studied with and without 56 BaP. DEC alone gave some reduction of the oedema, but this was much smaller than that with 56 BaP. It considerably worsened the reductions by 56 BaP, while 56 BaP slightly improved those by DEC and reduced the fever caused by DEC. Together, they reduced feelings of swelling and bursting-pain, fungal infections, lymphangitis and lymphadenitis more than when used alone.
