Inclusion Criteria:

- Provision of informed consent

- Histological or cytological confirmation of prostate cancer

- Evidence of metastatic disease on CT scan, MRI, or bone scan

- Surgically or continuously medically castrated with LHRH analogue

- Progressive disease after most recent therapy

- Disease progression by CT/MRI

- Bone scan progression: appearance of 1 or more new lesions since last bone scan

- Rising PSA

- World health organization (WHO) performance status 0 to 2

- Life expectancy of 12 weeks or longer

Exclusion Criteria:

- Use of anti-hormonal therapies (including ketoconazole, aminoglutethimide,
finasteride and anti-androgen therapies) within 4 weeks of starting study treatment,
except for bicalutamide and nilutamide which are excluded within 6 weeks of starting
study treatment. Estramustine or estrogens, if taken, have to be stopped at least 4
weeks before starting treatment.

- Definite or suspected personal history or family history of adverse drug reactions,
or hypersensitivity to drugs that are endothelin antagonist; history of severe
hypersensitivity reactions to drugs formulated with polysorbate 80.

- Prior cytotoxic chemotherapy for metastatic prostate cancer

- Radiotherapy within 4 weeks before the start of study therapy

- Systemic radionuclide therapy (ie strontium chloride Sr89, 186Re-labeled HEDP, or
153Sm-EDTMP pentasodium) within 12 weeks before entering study

- Use of potent CYP450 inhibitors (such as itraconazole, ritonavir, indinavir,
erythromycin, troleandomycin, clarithromycin, diltiazem, verapamil) within 2 weeks
before study entry.

- Use of potent CYP450 inducers (such as phenytoin, rifampicin, carbamazepine and
phenobarbitone, St. John's Wort) within 2 weeks before study entry.

NOTE: Dexamethasone is a known inducer of CYP2D6 and CYP3A4 but is not considered
exclusionary for purposes of this study.

- New neurologic symptoms or signs consistent with acute or evolving spinal cord
compression confirmed by magnetic resonance imaging (MRI) (except for those
previously treated and have stable symptoms).

- History of past or current epilepsy, epilepsy syndrome, or other seizure disorder

- History of Migraine or chronic headache

- Symptomatic central nervous system (CNS) metastases

- Absolute Neutrophil Count (ANC) <1.5 x 109/L (1,5000/mm3)

- Platelet count < 100 x 109/L (100,000/mm3)

- Serum bilirubin greater than the upper limit of normal (ULN)

- Alanine amino transferase (ALT) or aspartate amino transferase (AST) greater than 1.5
times the upper limit of normal (ULN)

- Creatinine clearance <50 mL/min

- QT interval corrected for heart rate by the Barrett Formula (QTc) > 470 msec at
screening

- New York Heart Association (NYHA) class II-IV Heart Disease

- Myocardial infarction (heart attack) within past 3 months

- CTCAE grade ≥2 Peripheral Neuropathy

- Treatment with a non-approved or investigational drug within 30 days before study
entry

- Evidence of any other significant clinical symptoms, abnormal laboratory findings or
recent surgery that patients has not recovered from that make it undesirable for the
patient to participate in the study in the opinion of the investigator(s)

- Involvement in the planning and conduct of the study

- Previous treatment in the present study