Drug repositioning (AKA drug repurposing) involves the investigation of existing drugs for new therapeutic purposes. Drug repositioning (AKA drug repurposing) involves the investigation of existing drugs for new therapeutic purposes. A number of successes have been achieved, the foremost including sildenafil (Viagra) for erectile dysfunction and pulmonary hypertension and thalidomide for leprosy and multiple myeloma. Clinical trials have been performed on posaconazole and ravuconazole for Chagas disease. Other antifungal agents clotrimazole and ketoconazole have been investigated for anti-trypanosome therapy.