This will be a randomized, open-label, 3-treatment, 3-period, crossover, single-dose study in healthy subjects. Eighteen (18) subjects will complete the study; dropouts may be replaced at the discretion of the sponsor. Three treatments are:

Treatment A: Revatio 20 mg intact tablet. Treatment B: Revatio 20 mg crushed tablet mixed with apple sauce. Treatment C: Revatio 20 mg extemporaneously prepared suspension (EP). Blood samples for the analysis of sildenafil in plasma will be obtained pre-dose and up to 14 hours post dose in each period. Tolerability and safety will be assessed by reported adverse events during each study period.

Inclusion Criteria:

• Healthy male/female subjects between the ages of 18 and 55 years, inclusive. Healthy is defined as no clinically relevant abnormalities identified by a detailed medical history, full physical examination, including blood pressure and pulse rate measurement, 12-lead ECG and clinical laboratory tests.
• Body Mass Index (BMI) of 17.5 to 30.5 kg/m2; and a total body weight >50 kg (110 lbs).
• An informed consent document signed and dated by the subject or a legally acceptable representative.
• Subjects who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, ocular or allergic (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing) disease or clinical findings at Screening.
• History of febrile illness within 5 days prior to the first dose.
• Any condition possibly affecting drug absorption (eg, gastrectomy).
• A positive urine drug screen.