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The Effect of Sildenafil and Tadalafil on Skeletal Muscle and Perceptual Fatigue

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT01661595
Recruitment Status : Completed
First Posted : August 9, 2012
Results First Posted : July 17, 2018
Last Update Posted : July 17, 2018
Sponsor:
Information provided by (Responsible Party):
The University of Texas Medical Branch, Galveston

Study Type Interventional
Study Design Allocation: Randomized;   Intervention Model: Crossover Assignment;   Masking: Triple (Participant, Care Provider, Investigator);   Primary Purpose: Treatment
Condition Fatigue
Interventions Drug: Sildenafil
Drug: tadalafil
Drug: Placebo
Enrollment 30
Recruitment Details Participants were recruited from the community via flyers and local postings.
Pre-assignment Details 30 subjects enrolled in this study. 6 subjects failed the screening and were withdrawn. 6 subjects chose to withdraw participation before the study began. 18 subjects began the study. 2 subjects were withdrawn during the study. 16 subjects completed the study.
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8. Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8. Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8. Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Period Title: Phase 1: Week 0-4
Started 5 4 5 4
Completed 4 4 5 4
Not Completed 1 0 0 0
Reason Not Completed
Adverse Event             1             0             0             0
Period Title: Phase 2: Week 5-8.
Started 4 4 5 4
Completed 4 4 4 4
Not Completed 0 0 1 0
Reason Not Completed
Protocol Violation             0             0             1             0
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil Total
Hide Arm/Group Description Sildenafil (50mg/day) daily for weeks 0-4, then Placebo daily weeks 5-8. Tadalafil (10mg/day) daily for weeks 0-4, then Placebo daily for weeks 5-8. Placebo daily for weeks 0-4, then Sildenafil (50mg/day) daily for weeks 5-8. Placebo daily for weeks 0-4, then Tadalafil (10mg/day) daily for weeks 5-8. Total of all reporting groups
Overall Number of Baseline Participants 5 4 5 4 18
Hide Baseline Analysis Population Description
30 subjects enrolled in this study. 6 subjects failed the screening and were withdrawn. 6 subjects chose to withdraw participation before the study began. 18 subjects began the study. 2 subjects were withdrawn during the study. 16 subjects completed the study.
Age, Continuous  
Mean (Standard Deviation)
Unit of measure:  Years
Number Analyzed 5 participants 4 participants 5 participants 4 participants 18 participants
53.6  (4.16) 56  (1.41) 52.4  (1.51) 57.25  (2.99) 54.6  (3.22)
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 5 participants 4 participants 5 participants 4 participants 18 participants
Female
4
  80.0%
4
 100.0%
3
  60.0%
2
  50.0%
13
  72.2%
Male
1
  20.0%
0
   0.0%
2
  40.0%
2
  50.0%
5
  27.8%
Region of Enrollment  
Measure Type: Count of Participants
Unit of measure:  Participants
United States Number Analyzed 5 participants 4 participants 5 participants 4 participants 18 participants
5
 100.0%
4
 100.0%
5
 100.0%
4
 100.0%
18
 100.0%
1.Primary Outcome
Title Skeletal Muscle Fatigue as Measured by Biodex 4 Pro After 4 Weeks of Placebo
Hide Description Isokinetic Fatigue Measure (knee extension) is measured on a Biodex System Pro 4 within a 75 degree range of motion. Subjects performed concentric contractions at a fixed speed of 120 degree/sec. 50 contractions were performed at 100% force, one contraction every second. Isokinetic fatigue will be measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug. Data is presented as mean maximum force over all 50 kicks.
Time Frame after 4 weeks of placebo
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalafil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:

50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 0-4. Placebo for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 0-4. Placebo for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
59.69  (33.71) 42.07  (5.19) 67.17  (26.87) 63.24  (8.34)
2.Primary Outcome
Title Skeletal Muscle Fatigue as Measured by Biodex 4 Pro After 4 Weeks of Active Drug
Hide Description Isokinetic Fatigue Measure (knee extension) is measured on a Biodex System Pro 4 within a 75 degree range of motion. Subjects performed concentric contractions at a fixed speed of 120 degree/sec. 50 contractions were performed at 100% force, one contraction every second. Isokinetic fatigue will be measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug. Data is presented as mean maximum force over all 50 kicks.
Time Frame after 4 weeks of active drug
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil / Placebo Tadalafil / Placebo Placebo / Sildenafil Placebo / Tadalafil
Hide Arm/Group Description:

50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 0-4. Placebo for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 0-4. Placebo for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
60.90  (35.60) 42.48  (6.30) 62.68  (24.88) 63.25  (15.12)
3.Primary Outcome
Title Exercised Induced Fatigability as Measured by Fatigue Rating Scale After 4 Weeks of Placebo
Hide Description The fatigue rating scale is a scale from 0 to 10 with 0 being no fatigue at all and 10 being the worst fatigue the subject can imagine. The subject is asked to rate their level of fatigue in their leg. This test was performed before and immedicately after the Biodex leg fatigue test after 4 weeks of placebo. Data is presented as change in scale from pre fatigue test to post fatigue test, with a higher score indicating a greater level of fatigue.
Time Frame after 4 weeks of placebo
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil / Placebo Tadalafil / Placebo Placebo / Sildenafil Placebo / Tadalafil
Hide Arm/Group Description:

50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 0-4. Placebo for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 0-4. Placebo for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: units on a scale
4.33  (1.53) 2.5  (0.58) 7.0  (1.83) 4.75  (0.96)
4.Primary Outcome
Title Exercised Induced Fatigability as Measured by Fatigue Rating Scale After 4 Weeks of Active Drug
Hide Description The fatigue rating scale is a scale from 0 to 10 with 0 being no fatigue at all and 10 being the worst fatigue the subject can imagine. The subject is asked to rate their level of fatigue in their leg. This test was performed before and immedicately after the Biodex leg fatigue test. Data is presented as change in scale from pre fatigue test to post fatigue test, with a higher score indicating a greater level of fatigue.
Time Frame after 4 weeks of active drug
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil / Placebo Tadalafil / Placebo Placebo / Sildenafil Placebo / Tadalafil
Hide Arm/Group Description:

50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 0-4. Placebo for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 0-4. Placebo for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 50 mg/day Sildenafil: (Other Name: Viagra, Revatio) for weeks 5-8.

Sildenafil: 50 mg/day for 4 weeks

Placebo: Placebo 1 capsule per day for four weeks.

Placebo for weeks 0-4. 10 mg/day Tadalafil: (Other Name: Cialis, Adcirca) for weeks 5-8.

tadalafil: 10 mg/day for 4 weeks.

Placebo: Placebo 1 capsule per day for four weeks.

Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: units on a scale
4.5  (2.38) 3.5  (1.73) 5.25  (4.27) 6.0  (1.83)
5.Secondary Outcome
Title Maximum Peak Isometric Leg Strength as Measured by Biodex Pro4 After 4 Weeks of Placebo
Hide Description Peak isometric strength is measured on a Biodex System 4 Pro. This test is isolated to the quadricep muscle of one leg. Isometric test is performed at 90 degrees with 5 seconds of force production for each contraction and 15 seconds of rest. 1 set of 3 contractions at 100% force performed. Isometric strength was measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of placebo
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
145.86  (97.73) 104.17  (23.66) 149.14  (62.67) 148.34  (47.26)
6.Secondary Outcome
Title Maximum Peak Isometric Leg Strength as Measured by Biodex Pro4 After 4 Weeks of Active Drug.
Hide Description Peak isometric strength is measured on a Biodex System 4 Pro. This test is isolated to the quadricep muscle of one leg. Isometric test is performed at 90 degrees with 5 seconds of force production for each contraction and 15 seconds of rest. 1 set of 3 contractions at 100% force performed. Isometric strength was measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of active drug
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
140.09  (82.29) 110.39  (21.26) 133.81  (58.04) 139.96  (50.47)
7.Secondary Outcome
Title Maximum Peak Isokinetic Leg Strength as Measured by Biodex Pro4 After 4 Weeks of Placebo.
Hide Description Isokinetic strength (knee extension) is measured on a Biodex System Pro 4 within a 75 degree range of motion. Subjects performed concentric contractions at a fixed speed of 120 degree/sec. 1 set of 3 contractions were performed at 100% force. Isokinetic strength will be measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of placebo
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
105.15  (49.46) 78.59  (10.25) 117.71  (39.86) 111.67  (23.43)
8.Secondary Outcome
Title Maximum Peak Isokinetic Leg Strength as Measured by Biodex Pro4 After 4 Weeks of Active Drug
Hide Description Isokinetic strength (knee extension) is measured on a Biodex System Pro 4 within a 75 degree range of motion. Subjects performed concentric contractions at a fixed speed of 120 degree/sec. 1 set of 3 contractions were performed at 100% force. Isokinetic strength will be measured at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of active drug
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: Newton-Meters
106.79  (49.69) 79.33  (11.69) 116.48  (37.83) 114.75  (36.49)
9.Secondary Outcome
Title Lean Body Mass as Measured by Dual Energy X-ray Absorptiometry at Week 0.
Hide Description Lean Body Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 0
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 5 4 5 4
Mean (Standard Deviation)
Unit of Measure: kilograms
44.60  (11.62) 41.43  (4.72) 49.93  (10.63) 54.45  (14.28)
10.Secondary Outcome
Title Lean Body Mass as Measured by Dual Energy X-ray Absorptiometry at Week 4.
Hide Description Lean Body Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 4
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 5 4
Mean (Standard Deviation)
Unit of Measure: kilograms
46.29  (14.40) 41.02  (4.05) 50.61  (10.67) 54.85  (14.71)
11.Secondary Outcome
Title Lean Body Mass as Measured by Dual Energy X-ray Absorptiometry at Week 8.
Hide Description Lean Body Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 8
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: kilograms
46.22  (14.68) 40.76  (4.38) 52.09  (10.03) 55.10  (14.42)
12.Secondary Outcome
Title Fat Mass as Measured by Dual Energy X-ray Absorptiometry at Week 0.
Hide Description Fat Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 0
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 5 4 5 4
Mean (Standard Deviation)
Unit of Measure: kilograms
32.35  (11.40) 37.21  (6.81) 32.72  (5.92) 32.10  (6.90)
13.Secondary Outcome
Title Fat Mass as Measured by Dual Energy X-ray Absorptiometry at Week 4.
Hide Description Fat Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 4
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 5 4
Mean (Standard Deviation)
Unit of Measure: kilograms
33.16  (12.42) 37.12  (6.35) 32.30  (5.55) 32.47  (7.08)
14.Secondary Outcome
Title Fat Mass as Measured by Dual Energy X-ray Absorptiometry at Week 8.
Hide Description Fat Mass is calculated from a whole body scan measured on a dual energy x-ray absorptiometry.
Time Frame week 8
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: kilograms
33.60  (12.51) 37.02  (6.21) 32.40  (5.83) 32.79  (7.12)
15.Secondary Outcome
Title Walking Distance at 100% Effort as Measured by Walking Test After 4 Weeks of Placebo
Hide Description Walking performance will be assessed during 2 minutes of walking in long corridor hallways. Subjects will be asked to walk at 100% effort (as quickly as they can safely walk without running) for 2 minutes. Distance traveled for the 2 minutes will be recorded. The walking test will be completed at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of placebo
Hide Outcome Measure Data
Hide Analysis Population Description
1 subject did not complete the walking test
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 3 4 4 4
Mean (Standard Deviation)
Unit of Measure: meters
203.82  (30.51) 189.79  (38.12) 198.41  (14.04) 202.80  (37.84)
16.Secondary Outcome
Title Walking Distance at 100% Effort as Measured by Walking Test After 4 Weeks of Active Drug
Hide Description Walking performance will be assessed during 2 minutes of walking in long corridor hallways. Subjects will be asked to walk at 100% effort (as quickly as they can safely walk without running) for 2 minutes. Distance traveled for the 2 minutes will be recorded. The walking test will be completed at week 4 and week 8. Depending on grouping, the week 4 and week 8 measures may be placebo or active drug. Data will be reported as after 4 weeks of placebo or after 4 weeks of active drug.
Time Frame after 4 weeks of active drug
Hide Outcome Measure Data
Hide Analysis Population Description
1 subject did not complete the walking test.
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 3 4 4 4
Mean (Standard Deviation)
Unit of Measure: meter
197.01  (32.72) 178.56  (17.84) 200.19  (13.99) 203.46  (31.11)
17.Secondary Outcome
Title Perceptual Fatigue as Measured by Multidimensional Fatigue Symptom Inventory - Short Form Total Score at Week 0
Hide Description Fatigue symptoms will be measured using the 30-item Multidimensional Fatigue Symptom Inventory - Short Form, a validated measure that yields one overall score of total fatigue calculated using five sub scales (general, physical, emotional, mental, vigor). With the exception of the vigor sub scale, higher scores indicate greater fatigue. Total fatigue score is calculated by summing the sub categories (general, physical, emotional and mental) and subtracting vigor. Total scores range from -24 to 96, with a higher score indicating more fatigue.
Time Frame Week 0
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: scores on a scale
9.66  (19.55) -7.5  (5.45) -8  (3.61) -3.75  (9.54)
18.Secondary Outcome
Title Perceptual Fatigue as Measured by Multidimensional Fatigue Symptom Inventory - Short Form Total Score at Week 4
Hide Description Fatigue symptoms will be measured using the 30-item Multidimensional Fatigue Symptom Inventory - Short Form, a validated measure that yields one overall score of total fatigue calculated using five sub scales (general, physical, emotional, mental, vigor). With the exception of the vigor sub scale, higher scores indicate greater fatigue. Total fatigue score is calculated by summing the sub categories (general, physical, emotional and mental) and subtracting vigor. Total scores range from -24 to 96, with a higher score indicating more fatigue.
Time Frame week 4
Hide Outcome Measure Data
Hide Analysis Population Description
1 subject did not complete the week 4 MFSI questionnaire
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 3 4 4
Mean (Standard Deviation)
Unit of Measure: scores on a scale
6.33  (26.08) -3.33  (10.97) -6.33  (2.31) -3.5  (12.66)
19.Secondary Outcome
Title Perceptual Fatigue as Measured by Multidimensional Fatigue Symptom Inventory - Short Form Total Score at Week 8
Hide Description Fatigue symptoms will be measured using the 30-item Multidimensional Fatigue Symptom Inventory - Short Form, a validated measure that yields one overall score of total fatigue calculated using five sub scales (general, physical, emotional, mental, vigor). With the exception of the vigor sub scale, higher scores indicate greater fatigue. Total fatigue score is calculated by summing the sub categories (general, physical, emotional and mental) and subtracting vigor. Total scores range from -24 to 96, with a higher score indicating more fatigue.
Time Frame week 8
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: scores on a scale
9.67  (19.09) 3.25  (27.54) -9.67  (6.81) -9.25  (1.26)
20.Other Pre-specified Outcome
Title Hemoglobin Level at Week 0
Hide Description Hemoglobin was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 11.6 - 15.0 g/dL.
Time Frame week 0
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: g/dL
13.42  (0.97) 12.78  (0.71) 12.4  (0.53) 13.05  (0.90)
21.Other Pre-specified Outcome
Title Hemoglobin Level Measured at Week 4
Hide Description Hemoglobin was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 11.6 - 15.0 g/dL.
Time Frame week 4
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: g/dL
13.05  (0.49) 12.03  (0.43) 12.6  (0.37) 13.2  (0.47)
22.Other Pre-specified Outcome
Title Hemoglobin Level Measured at Week 8
Hide Description Hemoglobin was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 11.6 - 15.0 g/dL.
Time Frame week 8
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: g/dL
13.55  (0.35) 11.97  (0.76) 12.5  (0.08) 12.95  (1.17)
23.Other Pre-specified Outcome
Title Hematocrit Level Measured at Week 0
Hide Description Hematocrit was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 35.7 - 45.2%.
Time Frame week 0
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: percent of red blood cells
39.53  (2.16) 38.55  (1.42) 37.25  (2.07) 31.88  (13.09)
24.Other Pre-specified Outcome
Title Hematocrit Level Was Measured at 4 Weeks
Hide Description Hematocrit was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 35.7 - 45.2%.
Time Frame 4 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: percent of red blood cells
39.08  (0.84) 37.38  (0.82) 38.13  (0.77) 39.1  (1.81)
25.Other Pre-specified Outcome
Title Hematocrit Level Measured at Week 8
Hide Description Hematocrit was measured by University of Texas Medical Branch Clinical Laboratory. Normal ranges are 35.7 - 45.2%.
Time Frame week 8
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Sildenafil, Then Placebo Tadalfil, Then Placebo Placebo, Then Sildenafil Placebo, Then Tadalafil
Hide Arm/Group Description:
Sildenafil daily (50mg/day) for weeks 0-4. Then Placebo daily for weeks 5-8.
Tadalafil (10mg/day) for week 0-4. Then Placebo daily for week 5-8.
Placebo daily for weeks 0-4. Then Sildenafil daily (50mg/day) for weeks 5-8.
Placebo for week 0-4, then Tadalafil (10mg/day) for week 5-8.
Overall Number of Participants Analyzed 4 4 4 4
Mean (Standard Deviation)
Unit of Measure: percent of red blood cells
40.38  (0.44) 36.6  (1.94) 38.1  (1.19) 38.4  (3.24)
Time Frame [Not Specified]
Adverse Event Reporting Description [Not Specified]
 
Arm/Group Title Sildenafil Tadalfil Placebo
Hide Arm/Group Description Sildenafil (50mg/day) daily for 4 weeks. Tadalafil (10mg/day) daily for 4 weeks. Placebo daily for week 4 weeks.
All-Cause Mortality
Sildenafil Tadalfil Placebo
Affected / at Risk (%) Affected / at Risk (%) Affected / at Risk (%)
Total   0/10 (0.00%)      0/8 (0.00%)      0/18 (0.00%)    
Hide Serious Adverse Events
Sildenafil Tadalfil Placebo
Affected / at Risk (%) # Events Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   0/10 (0.00%)      0/8 (0.00%)      0/18 (0.00%)    
Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 0%
Sildenafil Tadalfil Placebo
Affected / at Risk (%) # Events Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   2/10 (20.00%)      0/8 (0.00%)      0/18 (0.00%)    
General disorders       
Syncope [1]  1/10 (10.00%)  1 0/8 (0.00%)  0 0/18 (0.00%)  0
Skin and subcutaneous tissue disorders       
Redness at site of muscle biopsy  1/10 (10.00%)  1 0/8 (0.00%)  0 0/18 (0.00%)  0
[1]
Syncope following administration of Sildenafil 50mg.
Certain Agreements
Principal Investigators are NOT employed by the organization sponsoring the study.
There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Melinda Sheffield-Moore
Organization: University of Texas Medical Branch
Phone: 409-772-8707
EMail: melmoore@utmb.edu
Layout table for additonal information
Responsible Party: The University of Texas Medical Branch, Galveston
ClinicalTrials.gov Identifier: NCT01661595    
Other Study ID Numbers: 12-153
First Submitted: August 7, 2012
First Posted: August 9, 2012
Results First Submitted: April 24, 2018
Results First Posted: July 17, 2018
Last Update Posted: July 17, 2018