Trial Outcomes & Findings for Safety and Efficacy of Gabapentin in Postherpetic Neuralgia (NCT NCT00636636)

Last Updated: 2012-02-22

Results Overview

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).

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

452 participants

Primary outcome timeframe

10 weeks

Results posted on

2012-02-22

Participant Flow

Recruitment period was from March 2008 through May 2009.

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.

Participant milestones

Participant milestones
Measure	G-ER Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Study STARTED	221	231
Overall Study Safety & Efficacy of Gabapentin ER	186	194
Overall Study 379	186	194
Overall Study COMPLETED	185	192
Overall Study NOT COMPLETED	36	39

Reasons for withdrawal

Reasons for withdrawal
Measure	G-ER Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Overall Study Other reason	4	6
Overall Study Adverse Event	19	8
Overall Study Lack of Efficacy	7	12
Overall Study Protocol Violation	2	2
Overall Study Lost to Follow-up	0	1
Overall Study Death	0	1
Overall Study Withdrawal by Subject	4	9

Baseline Characteristics

Safety and Efficacy of Gabapentin in Postherpetic Neuralgia

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing	Total n=450 Participants Total of all reporting groups
Age Continuous	65.3 years STANDARD_DEVIATION 13.3 • n=5 Participants	65.9 years STANDARD_DEVIATION 11.1 • n=7 Participants	65.6 years STANDARD_DEVIATION 12.2 • n=5 Participants
Age, Customized <65 years	81 participants n=5 Participants	89 participants n=7 Participants	170 participants n=5 Participants
Age, Customized 65 to 74 years	82 participants n=5 Participants	86 participants n=7 Participants	168 participants n=5 Participants
Age, Customized >=75 years	57 participants n=5 Participants	55 participants n=7 Participants	112 participants n=5 Participants
Sex: Female, Male Female	134 Participants n=5 Participants	147 Participants n=7 Participants	281 Participants n=5 Participants
Sex: Female, Male Male	86 Participants n=5 Participants	83 Participants n=7 Participants	169 Participants n=5 Participants
Race/Ethnicity, Customized Caucasian	196 Participants n=5 Participants	204 Participants n=7 Participants	400 Participants n=5 Participants
Race/Ethnicity, Customized Black	10 Participants n=5 Participants	6 Participants n=7 Participants	16 Participants n=5 Participants
Race/Ethnicity, Customized Asian	1 Participants n=5 Participants	2 Participants n=7 Participants	3 Participants n=5 Participants
Race/Ethnicity, Customized Other	13 Participants n=5 Participants	18 Participants n=7 Participants	31 Participants n=5 Participants

PRIMARY outcome

Timeframe: 10 weeks

Population: ITT, BOCF

Outcome measures

Outcome measures
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Mean Change in Baseline Observation Carried Forward (BOCF) Average Daily Pain Score	-2.12 Scores on a scale 95% Confidence Interval 0.17 • Interval -2.44 to -1.79	-1.63 Scores on a scale 95% Confidence Interval 0.16 • Interval -1.95 to -1.3

SECONDARY outcome

Timeframe: 10 weeks

Population: ITT, BOCF

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).

Outcome measures

Outcome measures
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Patient Global Impression of Change (PGIC)	94 Participants	77 Participants

SECONDARY outcome

Timeframe: 10 weeks

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).

Outcome measures

Outcome measures
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Clinical Global Impression of Change (CGIC)	97 Participants	78 Participants

SECONDARY outcome

Timeframe: 10 weeks

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).

Outcome measures

Outcome measures
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Average Daily Sleep Interference Score	-2.30 Scores on a scale Standard Error 0.16	-1.59 Scores on a scale Standard Error 0.15

OTHER_PRE_SPECIFIED outcome

Timeframe: 10 weeks

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).

Outcome measures

Outcome measures
Measure	G-ER n=220 Participants Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=230 Participants Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Mean Change in Last Observation Carried Forward (LOCF) Average Daily Pain Score	-2.40 Scores on a scale Standard Error 0.17	-1.85 Scores on a scale Standard Error 0.17

Adverse Events

G-ER

Serious events: 4 serious events

Other events: 92 other events

Deaths: 0 deaths

Placebo

Serious events: 6 serious events

Other events: 63 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	G-ER n=221 participants at risk Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=231 participants at risk Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Cardiac disorders Cardiac failure congestion	0.00% 0/221 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Skin and subcutaneous tissue disorders Cellulitis	0.00% 0/221 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Renal and urinary disorders Hematuria	0.00% 0/221 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Musculoskeletal and connective tissue disorders Left arm fracture	0.45% 1/221 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Cardiac disorders Myocardial infarction	0.00% 0/221 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Musculoskeletal and connective tissue disorders Osteochondrosis	0.45% 1/221 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).	0.00% 0/231 • 11 weeks (plus 30 days for SAEs) 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).
Respiratory, thoracic and mediastinal disorders Pancoast tumor	0.45% 1/221 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).	0.00% 0/231 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Pancreatitis chronic	0.45% 1/221 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).	0.00% 0/231 • 11 weeks (plus 30 days for SAEs) 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).
Vascular disorders Thrombophlebitis	0.00% 0/221 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).

Other adverse events

Additional Information

Head of R&D

Depomed

Phone: 650-462-5900

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee 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.
Publication restrictions are in place

Restriction type: OTHER

Measure	G-ER n=221 participants at risk Gabapentin Extended Release 1800 mg once daily (qd); 300 mg and 600 mg tablets, oral dosing	Placebo n=231 participants at risk Placebo 1800 mg once daily (qd); 300 mg and 600 mg sugar pills, oral dosing
Musculoskeletal and connective tissue disorders Back pain	0.90% 2/221 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).	1.3% 3/231 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Abdominal pain upper	1.4% 3/221 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).	2.6% 6/231 • Number of events 6 • 11 weeks (plus 30 days for SAEs) 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).
Investigations Blood pressure increased	1.4% 3/221 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).	0.87% 2/231 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Diarrhea	2.7% 6/221 • Number of events 6 • 11 weeks (plus 30 days for SAEs) 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).	2.2% 5/231 • Number of events 5 • 11 weeks (plus 30 days for SAEs) 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).
Nervous system disorders Dizziness	11.3% 25/221 • Number of events 25 • 11 weeks (plus 30 days for SAEs) 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).	1.7% 4/231 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Dry mouth	1.8% 4/221 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).	0.87% 2/231 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Dyspepsia	1.8% 4/221 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
General disorders Fatigue	1.4% 3/221 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).	1.7% 4/231 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).
Nervous system disorders Headache	4.5% 10/221 • Number of events 10 • 11 weeks (plus 30 days for SAEs) 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).	3.9% 9/231 • Number of events 9 • 11 weeks (plus 30 days for SAEs) 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).
Infections and infestations Herpes zoster	1.4% 3/221 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).	0.87% 2/231 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).
Infections and infestations Nasopharyngitis	2.3% 5/221 • Number of events 5 • 11 weeks (plus 30 days for SAEs) 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).	2.6% 6/231 • Number of events 6 • 11 weeks (plus 30 days for SAEs) 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).
Gastrointestinal disorders Nausea	4.5% 10/221 • Number of events 10 • 11 weeks (plus 30 days for SAEs) 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).	3.0% 7/231 • Number of events 7 • 11 weeks (plus 30 days for SAEs) 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).
General disorders Peripheral edema	3.2% 7/221 • Number of events 7 • 11 weeks (plus 30 days for SAEs) 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).	0.43% 1/231 • Number of events 1 • 11 weeks (plus 30 days for SAEs) 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).
Nervous system disorders Post herpetic neuralgia	0.90% 2/221 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).	1.7% 4/231 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).
Nervous system disorders Somnolence	5.4% 12/221 • Number of events 12 • 11 weeks (plus 30 days for SAEs) 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).	3.0% 7/231 • Number of events 7 • 11 weeks (plus 30 days for SAEs) 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).
Ear and labyrinth disorders Vertigo	1.8% 4/221 • Number of events 4 • 11 weeks (plus 30 days for SAEs) 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).	0.87% 2/231 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).
Investigations Weight increased	1.4% 3/221 • Number of events 3 • 11 weeks (plus 30 days for SAEs) 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).	0.87% 2/231 • Number of events 2 • 11 weeks (plus 30 days for SAEs) 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).