Tolerability of Biphasic-Release Hydrocodone Bitartrate/Acetaminophen Tablets (MNK-155): A Phase III, Multicenter, Open-Label Study in Patients With Osteoarthritis or Chronic Low Back Pain.

Purpose: This study aimed to assess the tolerability of the extended use (≤35 days) of MNK-155, a biphasic (immediate-release/extended-release) hydrocodone bitartrate/N-acetyl-p-aminophenol (acetaminophen) (IR/ER HB/APAP) 7.5/325-mg fixed-dose combination analgesic agent, in patients with chronic noncancer pain (CNCP) caused by osteoarthritis or chronic low back pain. IR/ER HB/APAP tablets deliver 25% of the HB dose and 50% of the APAP dose by IR and the remainder by ER over a 12-hour dosing interval. Although IR/ER HB/APAP is being developed for the management of moderate to severe acute pain, this model of CNCP was used for assessing tolerability over a term longer than would be possible in a model of acute pain.

Methods: This Phase III, multicenter, open-label study enrolled patients with moderate to severe OA (knee or hip) pain despite the use of nonopioid or opioid analgesic agents, or with moderate to severe CLBP present for several hours per day for ≥3 months. Patients received a 3-tablet initial dose of IR/ER HB/APAP (total dose, 22.5/975 mg) on day 1, followed by 2 tablets of IR/ER HB/APAP (total dose, 15/650 mg) q12h for up to 35 days. Tolerability, the primary end point, was assessed using time to treatment discontinuation, the prevalence of treatment-emergent adverse events (TEAEs), vital sign measurements, pulse oximetry, clinical laboratory tests, and compliance. Secondary outcomes included the modified Brief Pain Inventory-Short Form, the Western Ontario and McMaster Universities Arthritis Index, and The Roland-Morris Low Back Pain and Disability Questionnaire.

Findings: Of the 153 patients enrolled (95 women [62.1%]; mean age, 53.9 [14.5] years; OA, n = 73; CLBP, n = 80), 37 (24.2%) discontinued the study early (mean time to discontinuation, 21.3 days). Thirteen patients (8.5%) discontinued because of TEAEs. A total of 88 patients (57.5%) reported ≥1 TEAE, 65 (42.5%) of whom experienced AEs considered by the investigator as treatment related. The most frequent TEAEs were nausea (16.3%), somnolence (14.4%), and constipation (11.1%). Eight severe TEAEs were experienced by 6 (3.9%) patients and included single occurrences of nausea, fatigue, nasopharyngitis, elevated liver enzymes, headache, nightmare, and ejaculation delay. No serious treatment-related AEs were reported. Clinically significant changes in laboratory values were reported in 13 patients, 6 of whom had abnormal liver function test results that did not meet Hy's law criteria for acute liver failure. Most laboratory abnormalities were mild and transient. Measures of pain intensity, function, and quality of life improved from baseline but in an open-label study these changes cannot be attributed to treatment.

Implications: The safety profile of IR/ER HB/APAP during extended use was consistent with those of other low-dose opioid/APAP combination products. IR/ER HB/APAP is intended for acute pain; its efficacy for relief of CNCP would require further evaluation in an active- or placebo-controlled study. ClinicalTrials.gov Identifier: NCT01722864.