BUILD 3: Bosentan Use in Interstitial Lung Disease

Inclusion Criteria:

- Signed informed consent

- Male or female aged 18 years or older (females of child-bearing potential must have
been surgically sterilized or use a reliable method of contraception.)

- Proven diagnosis of IPF according to American Thoracic Society / European Respiratory
Society (ATS-ERS) statement, of <3 years, with surgical lung biopsy (SLB)

Exclusion Criteria:

- Interstitial lung disease due to conditions other than IPF.

- Presence of extensive honeycombing (HC) on baseline high-resolution computed
tomography (HRCT) scan.

- Severe concomitant illness limiting life expectancy (<1 year).

- Severe restrictive lung disease.

- Obstructive lung disease.

- Diffusing capacity of the lung for carbon monoxide <30% predicted.

- Residual volume > or = 120% predicted.

- Documented sustained improvement of patient's IPF condition up to 12 months prior to
randomization with or without IPF-specific therapy.

- Recent pulmonary or upper respiratory tract infection (up to 4 weeks prior to
randomization).

- Acute or chronic impairment (other than dyspnea) limiting the ability to comply with
study requirements.

- Chronic heart failure with New York Heart Association (NYHA) class III/IV or known
left ventricular ejection fraction <25%.

- Alanine aminotransferase (ALT/SGPT) and/or aspartate aminotransferase (AST/SGOT) >
1.5 times the upper limit of the normal ranges.

- Moderate to severe hepatic impairment.

- Serum creatinine > or = 2.5 mg/dl or chronic dialysis.

- Hemoglobin concentration <75% the lower limit of the normal ranges.

- Systolic blood pressure <85 mmHg.

- Pregnancy or breast-feeding.

- Current drug or alcohol dependence.

- Chronic treatment with the following drugs prescribed for IPF (within 4 weeks of
randomization):oral corticosteroids (>20 mg/day of prednisone or equivalent),
immunosuppressive or cytotoxic drugs, antifibrotic drugs, chronic use of
N-acetylcysteine (prescribed for IPF).

- Oral anticoagulants other than those indicated for a venous or arterial thrombotic
disease.

- Treatment with glibenclamide (glyburide) and calcineurin inhibitors (cyclosporine A,
tacrolimus) up to 1 week prior to randomization.

- Treatment with an endothelin receptor antagonist up to 3 months prior to
randomization.

- Participation in the BUILD 1 trial.

- Treatment with another investigational drug up to 3 months prior to randomization or
planned treatment.

- Known hypersensitivity to bosentan or any of the excipients.