Safety assessments included AEs, clinical laboratory test results, vital sign measurements, ECG findings, and audiology assessments.

The Core Study safety population (N=922) was defined as the group of subjects who received at least 1 dose of study drug during the study. The Extension Period safety population (N=106) was the group of core study safety population subjects who entered the extension period and received at least 1 dose of study drug in the extension period.

"Average pain over the last 24 hours" score (on an 11-point numerical rating scale where 0 = no pain and 10 = pain as bad as you can imagine).

The Core Study population analyzed (N=727) was the group of subjects who received at least 1 dose of study drug during the maintenance period. The Extension Period population analyzed (N=106) was the group of core study safety population subjects who entered the extension period and received at least 1 dose of study drug in the extension period.

"Pain right now" scores were collected using an 11-point scale where 0 = no pain and 10 = pain as bad as you can imagine. The "pain right now" scores were only collected during the Core Study. "Pain right now" scores were not assessed during the Extension Period.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data. Data were not collected for this outcome measure during the Extension Period.

The MOS Sleep-R is a brief, self-administered 12-item assessment designed to measure key aspects of sleep. It includes a sleep problems index II and 6 subscale scores - sleep disturbance, sleep adequacy, daytime somnolence, snoring, awaken short of breath or with headache, and quantity of sleep. For each individual and time of assessment, quantity of sleep was recorded as the number of hours slept per night. The number of hours it took the subject to fall asleep per night was categorized 1, 2, 3, 4, or 5 corresponding to 0 through 15, 16 through 30, 31 through 45, 46 through 60, or more than 60 minutes, respectively. The other scales were recorded as 1 = all of the time, 2 = most of the time, 3 = some of the time, 4 = a little of the time, or 5 = none of the time. A higher value indicates a better score, therefore a positive change from baseline indicates a better sleep pattern and a negative change from baseline indicates a worsening in sleep pattern.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data. The Extension Period safety population was the group of core study safety population subjects who entered the extension and received at least 1 dose of study drug in the extension period.

The BPI-SF assessed the severity of pain and interference of pain on daily functions. It consists of 9 sections denoted by Q1 to Q8 and Q9A to Q9G according to their order in the questionnaire, that measure pain location, intensity, pain treatment, and functional interference of pain on mood and every day activities. Scores ranged from 0 (none) to 10 (worst as can be). Four of the items (questions 3 to 6) assess severity of pain and 7 items (questions 9A to 9G) assess interference of pain. The pain interference subscale score was determined by calculating the mean of responses to Q9A - Q9G [Q9A (general activity), Q9B (mood),Q9C (walking), Q9D (working), Q9E (relations with others), Q9F (sleep), and Q9G (enjoyment of life)] and the severity of pain subscale score was determined by calculating the mean of responses to Q3 - Q6 [Q3 (worst pain in last 24 hours), Q4 (least pain in last 24 hours), Q5 (average pain), and Q6 ("pain right now")]. A lower score indicates lower pain.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data. The Extension Period safety population was the group of core study safety population subjects who entered the extension and received at least 1 dose of study drug in the extension period.

The SF-36 is a generic health survey with 36 items that measure functional health and well-being from the subject's perspective. The 36 questions are grouped into 11 sections. Some of the sections consist of multiple questions. The survey is summarized into 8 dimensions/scales: physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, and mental health. From the 8 health dimensions, physical component summary, and mental component summary measures are derived. Scores on each scale ranged from 0 to 100; a higher score indicates a better perception of health.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data. The Extension Period safety population was the group of core study safety population subjects who entered the extension period and received at least 1 dose of study drug in the extension period.

The PGIC is an ordinal scale of global evaluation that assesses the change in overall status relative to the start of the study. The scale has only 1 item that measures global change of overall status (improvement or worsening) by the subject on a 7-point scale (Very much improved, Much improved, Minimally improved, No change, Minimally worse, Much worse, Very much worse.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the study. The Extension Period safety population was the group of core study safety population subjects who entered the extension period and received at least 1 dose of study drug in the extension period.

The TSQ is a self-administered questionnaire that consists of 2 parts. Part I has 6 questions (Q1 to Q6) that ask the subject to rate the experience with use of the study drug in comparison to the prestudy pain medication regarding ease of use, convenience, frequency, pain control, and overall satisfaction. Each question was rated on a scale from 1 (extremely satisfied) to 6 (extremely dissatisfied): Q1=Satisfaction with study drug; Q2=Ease of study drug use to treat pain; Q3=Convenience of study drug to treat pain; Q4=Overall drug satisfaction managing pain; Q5=Satisfaction with frequency of use; Q6=Ease of planning study drug use. The number of subjects with each category (1-6) of response for each individual question (Q1-Q6) was summarized for subjects who entered the core study maintenance period and responded to each question. TSQ - Part I was not administered in the extension period.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data.

The TSQ is a self-administered questionnaire that consists of 2 parts. Part II has 2 questions that measure the subject's willingness to continue the use of study drug as pain medication (Q1), and to recommend the study drug to someone else (Q2). Question 1 consists of 6 categories of response rated on a scale from 1 (very willing to continue) to 6 (very unwilling to continue): 1=Very willing to continue; 2=Willing to continue; 3=Somewhat willing to continue; 4=Somewhat unwilling to continue; 5=Unwilling to continue; 6=Very unwilling to continue. Question 2 consists of 3 categories of response: 1=yes; 2=no; 3=undecided. The number of subjects with each category of response for each individual question was summarized for subjects completing the core study maintenance period and for those enrolled in the extension period.

The Core Study population analyzed was the group of subjects who received at least 1 dose of study drug during the maintenance period and provided data. The Extension Period safety population was the group of core study safety population subjects who entered the extension period and received at least 1 dose of study drug in the extension period.