Treatment-resistant immune thrombocytopenic purpura associated with LDN use in a patient with MS

Naltrexone is an opiate m-receptor antagonist approved for treatment of alcohol dependency at a recommended dose of 50 mg/day. The mechanism of action is proposed to be mediated by a normalization of endogenous endorphin levels. Despite few and inconclusive studies (casuistic or open-label), a naltrexone dose of 3–5 mg/day (low-dose naltrexone, LDN) has been suggested to ameliorate a wide range of diseases, especially Crohn disease and multiple sclerosis (MS). Its effect in these conditions is mainly advocated by patients via both formal and informal networks. Reluctance among physicians to prescribe naltrexone has encouraged illegal import. Based on safety data from initial marketing studies conducted in the 1970s, naltrexone has generally been considered safe, with no serious side effects or adverse events. We present a case of therapy-resistant immune thrombocytopenic purpura (ITP) after LDN use in a patient with MS.