Melphalan, busulfan and P32These drugs may help where other medications do not. Melphalan, or radioactive phosphorous (also called P32) were common therapies used in the past to treat myeloproliferative neoplasms (MPNS). Why are these drugs no longer commonly used? Melphalan, or radioactive phosphorous can cause infertility and can damage the bone marrow. These drugs are also known to increase the risk of developing acute leukaemia. Why take these drugs? Haematologists still use both drugs to treat MPNs when other drugs are not working, when other drugs cause side effects, or when it is difficult for patients to take hydroxycarbamide tablets. Taking radioactive phosphorus Phosphorous 32 is given as an injection. It is a radioactive drug and is usually given via nuclear medicine departments. Injections are needed only very infrequently. The nuclear medicine department will give you written information about the radioactivity associated with radioactive phosphorous. More information If you’d like more information you can download our leaflets about MPN medications.