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Safety and Efficacy of Gabapentin in Postherpetic Neuralgia

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: NCT00636636
Recruitment Status : Completed
First Posted : March 14, 2008
Results First Posted : January 13, 2012
Last Update Posted : February 22, 2012
Sponsor:
Information provided by (Responsible Party):
Depomed

Study Type Interventional
Study Design Allocation: Randomized;   Intervention Model: Parallel Assignment;   Masking: Double (Participant, Investigator);   Primary Purpose: Treatment
Condition Neuralgia,Postherpetic
Interventions Drug: Gabapentin Extended Release tablets
Drug: Placebo
Enrollment 452
Recruitment Details Recruitment period was from March 2008 through May 2009.
Pre-assignment Details Study included screening visit, wash-out from all PHN medications as necessary, followed by a week of baseline period. Patients who successfully completed the baseline week, if still continues to meet entry criteria, then get randomized to Active or Placebo groups.
Arm/Group Title G-ER Placebo
Hide Arm/Group Description Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Period Title: Overall Study
Started 221 231
Safety & Efficacy of Gabapentin ER 186 194 [1]
379 186 194 [1]
Completed 185 192
Not Completed 36 39
Reason Not Completed
Other reason             4             6
Adverse Event             19             8
Lack of Efficacy             7             12
Protocol Violation             2             2
Lost to Follow-up             0             1
Death             0             1
Withdrawal by Subject             4             9
[1]
1 patient randomized twice, not included in ITT, but completed medication and counted as completer
Arm/Group Title G-ER Placebo Total
Hide Arm/Group Description Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing Total of all reporting groups
Overall Number of Baseline Participants 220 230 450
Hide Baseline Analysis Population Description
[Not Specified]
Age Continuous  
Mean (Standard Deviation)
Unit of measure:  Years
Number Analyzed 220 participants 230 participants 450 participants
65.3  (13.3) 65.9  (11.1) 65.6  (12.2)
Age, Customized   [1] 
Measure Type: Number
Unit of measure:  Participants
Number Analyzed 220 participants 230 participants 450 participants
<65 years 81 89 170
65 to 74 years 82 86 168
>=75 years 57 55 112
[1]
Measure Description: Of the 452 subjects randomized, 2 subjects were excluded from the intent-to-treat (ITT) population: 1 subject had no baseline data recorded, and 1 subject was randomized twice. Baseline demographics were calculated on the ITT population of 450 participants.
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 220 participants 230 participants 450 participants
Female
134
  60.9%
147
  63.9%
281
  62.4%
Male
86
  39.1%
83
  36.1%
169
  37.6%
Race/Ethnicity, Customized  
Measure Type: Number
Unit of measure:  Participants
Number Analyzed 220 participants 230 participants 450 participants
Caucasian 196 204 400
Black 10 6 16
Asian 1 2 3
Other 13 18 31
1.Primary Outcome
Title Mean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score
Hide Description Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily pain score from baseline to the final week of efficacy treatment period (Week 10).
Time Frame 10 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
ITT, BOCF
Arm/Group Title G-ER Placebo
Hide Arm/Group Description:
Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing
Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Number of Participants Analyzed 220 230
Least Squares Mean (95% Confidence Interval)
Unit of Measure: Scores on a scale
-2.12
(-2.44 to -1.79)
-1.63
(-1.95 to -1.30)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection G-ER, Placebo
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.0125
Comments [Not Specified]
Method ANCOVA
Comments [Not Specified]
Method of Estimation Estimation Parameter Least squares mean difference
Estimated Value -0.49
Confidence Interval (2-Sided) 95%
-0.88 to -0.11
Parameter Dispersion
Type: Standard Error of the mean
Value: 0.20
Estimation Comments [Not Specified]
2.Secondary Outcome
Title Patient Global Impression of Change (PGIC)
Hide Description Patient self-assessment of how much pain had changed at end of treatment period (Week 10) compared to pain at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).
Time Frame 10 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
ITT, BOCF
Arm/Group Title G-ER Placebo
Hide Arm/Group Description:
Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing
Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Number of Participants Analyzed 220 230
Measure Type: Number
Unit of Measure: Participants
94 77
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection G-ER, Placebo
Comments P-value (vs Placebo) for pairwise test of treatment effect between G-ER group and Placebo group is based on Z test for difference between the 2 groups in proportion of participants who were categorized as very much or much improved in PGIC at endpoint. Proportion in each group calculated from number of participants categorized as very much or much improved relative to total number of participants in ITT population.
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.0434
Comments [Not Specified]
Method Z test
Comments [Not Specified]
Method of Estimation Estimation Parameter Difference in proportion
Estimated Value 0.092
Confidence Interval (2-Sided) 95%
-0.00 to 0.18
Estimation Comments [Not Specified]
3.Secondary Outcome
Title Clinical Global Impression of Change (CGIC)
Hide Description Investigator assessment of patient's overall PHN symptoms at end of treatment period (Week 10) compared to overall PHN symptoms at baseline; scored on 7-point numerical rating scale (where 1 = very much improved, 7 = very much worse). Results presented as number of participants categorized at end of treatment (Week 10) as "very much improved" (score = 1) or "much improved" (score = 2).
Time Frame 10 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title G-ER Placebo
Hide Arm/Group Description:
Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing
Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Number of Participants Analyzed 220 230
Measure Type: Number
Unit of Measure: Participants
97 78
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection G-ER, Placebo
Comments P-value (vs Placebo) for pairwise test of treatment effect between G-ER group and Placebo group is based on Z test for difference between the 2 groups in proportion of participants who were categorized as very much or much improved in CGIC at endpoint. Proportion in each group calculated from number of participants categorized as very much or much improved relative to total number of participants in ITT population.
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.0268
Comments [Not Specified]
Method Z test
Comments [Not Specified]
Method of Estimation Estimation Parameter Difference in proportion
Estimated Value 0.102
Confidence Interval (2-Sided) 95%
0.01 to 0.19
Estimation Comments [Not Specified]
4.Secondary Outcome
Title Average Daily Sleep Interference Score
Hide Description Assessed on 11-point numeric rating scale (where 0 = pain does not interfere with sleep, 10 = pain completely interferes with sleep); evaluated from daily sleep entry in electronic diary. Results presented as least squares (LS) mean change in baseline observation carried forward (BOCF) average daily sleep interference score from baseline to final week of treatment period (Week 10).
Time Frame 10 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title G-ER Placebo
Hide Arm/Group Description:
Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing
Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Number of Participants Analyzed 220 230
Least Squares Mean (Standard Error)
Unit of Measure: Scores on a scale
-2.30  (0.16) -1.59  (0.15)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection G-ER, Placebo
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.0001
Comments [Not Specified]
Method ANCOVA
Comments [Not Specified]
Method of Estimation Estimation Parameter Least square mean difference
Estimated Value -0.71
Confidence Interval (2-Sided) 95%
-1.07 to -0.35
Parameter Dispersion
Type: Standard Error of the mean
Value: 0.18
Estimation Comments P-value versus Placebo for pairwise test of difference of LS mean change from baseline between G-ER and Placebo groups is based on t-test of Type III analysis.
5.Other Pre-specified Outcome
Title Mean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score
Hide Description Average daily pain scored on 11-point numerical rating scale (where 0 = no pain, 10 = worst possible pain). Results presented as least squares (LS) mean change in last observation carried forward (LOCF) average daily pain score from baseline to final week of efficacy treatment period (Week 10).
Time Frame 10 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title G-ER Placebo
Hide Arm/Group Description:
Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing
Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Number of Participants Analyzed 220 230
Least Squares Mean (Standard Error)
Unit of Measure: Scores on a scale
-2.40  (0.17) -1.85  (0.17)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection G-ER, Placebo
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.007
Comments [Not Specified]
Method ANCOVA
Comments [Not Specified]
Method of Estimation Estimation Parameter Least square mean difference
Estimated Value -0.55
Confidence Interval (2-Sided) 95%
-0.96 to -0.15
Parameter Dispersion
Type: Standard Error of the mean
Value: 0.20
Estimation Comments [Not Specified]
Time Frame 11 weeks (plus 30 days for SAEs)
Adverse Event Reporting Description AEs and SAEs collected from signing of consent form through completion of Tapering Week Visit (Week 11); SAEs collected for 30 days after completion of Tapering Week (Week 11).
 
Arm/Group Title G-ER Placebo
Hide Arm/Group Description Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
All-Cause Mortality
G-ER Placebo
Affected / at Risk (%) Affected / at Risk (%)
Total   --/--      --/--    
Hide Serious Adverse Events
G-ER Placebo
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   4/221 (1.81%)      6/231 (2.60%)    
Cardiac disorders     
Cardiac failure congestion  1  0/221 (0.00%)  0 1/231 (0.43%)  1
Myocardial infarction  1  0/221 (0.00%)  0 1/231 (0.43%)  1
Gastrointestinal disorders     
Pancreatitis chronic  1  1/221 (0.45%)  1 0/231 (0.00%)  0
Musculoskeletal and connective tissue disorders     
Left arm fracture  1  1/221 (0.45%)  1 1/231 (0.43%)  1
Osteochondrosis  1  1/221 (0.45%)  1 0/231 (0.00%)  0
Renal and urinary disorders     
Hematuria  1  0/221 (0.00%)  0 1/231 (0.43%)  1
Respiratory, thoracic and mediastinal disorders     
Pancoast tumor  1  1/221 (0.45%)  1 0/231 (0.00%)  0
Skin and subcutaneous tissue disorders     
Cellulitis  1  0/221 (0.00%)  0 1/231 (0.43%)  1
Vascular disorders     
Thrombophlebitis  1  0/221 (0.00%)  0 1/231 (0.43%)  1
Indicates events were collected by systematic assessment
1
Term from vocabulary, MedDRA (9.0)
Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 1%
G-ER Placebo
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   92/221 (41.63%)      63/231 (27.27%)    
Ear and labyrinth disorders     
Vertigo  1  4/221 (1.81%)  4 2/231 (0.87%)  2
Gastrointestinal disorders     
Abdominal pain upper  1  3/221 (1.36%)  3 6/231 (2.60%)  6
Diarrhea  1  6/221 (2.71%)  6 5/231 (2.16%)  5
Dry mouth  1  4/221 (1.81%)  4 2/231 (0.87%)  2
Dyspepsia  1  4/221 (1.81%)  4 1/231 (0.43%)  1
Nausea  1  10/221 (4.52%)  10 7/231 (3.03%)  7
General disorders     
Fatigue  1  3/221 (1.36%)  3 4/231 (1.73%)  4
Peripheral edema  1  7/221 (3.17%)  7 1/231 (0.43%)  1
Infections and infestations     
Herpes zoster  1  3/221 (1.36%)  3 2/231 (0.87%)  2
Nasopharyngitis  1  5/221 (2.26%)  5 6/231 (2.60%)  6
Investigations     
Blood pressure increased  1  3/221 (1.36%)  3 2/231 (0.87%)  2
Weight increased  1  3/221 (1.36%)  3 2/231 (0.87%)  2
Musculoskeletal and connective tissue disorders     
Back pain  1  2/221 (0.90%)  2 3/231 (1.30%)  3
Nervous system disorders     
Dizziness  1  25/221 (11.31%)  25 4/231 (1.73%)  4
Headache  1  10/221 (4.52%)  10 9/231 (3.90%)  9
Post herpetic neuralgia  1  2/221 (0.90%)  2 4/231 (1.73%)  4
Somnolence  1  12/221 (5.43%)  12 7/231 (3.03%)  7
Indicates events were collected by systematic assessment
1
Term from vocabulary, MedDRA (9.0)
Certain Agreements
Principal Investigators are NOT employed by the organization sponsoring the study.
There IS 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.
The PI agree that the sponsor shall have the right to the first publication of the results of the study which is intended to be joint, multi-center publication. Following the first publication, the PI may publish data or results from the study, provided however PI submits the proposed publication to sponsor for review at least 60 days prior to the data of the proposed publication.Sponsor may remove any information that is considered confidential and or proprietary other than study data.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Head of R&D
Organization: Depomed
Phone: 650-462-5900 ext 108
EMail: msweeney@depomed.com
Layout table for additonal information
Responsible Party: Depomed
ClinicalTrials.gov Identifier: NCT00636636    
Obsolete Identifiers: NCT01465321
Other Study ID Numbers: 81-0062
First Submitted: February 21, 2008
First Posted: March 14, 2008
Results First Submitted: October 13, 2011
Results First Posted: January 13, 2012
Last Update Posted: February 22, 2012