The primary objective of this study is to assess the bioequivalence of two 45-mg hydrocodone bitartrate extended-release tablets and one 90-mg hydrocodone bitartrate extended-release tablet.

Inclusion Criteria:

• Written informed consent is obtained.
• The subject can read, speak, and write in English.
• The subject is a man or woman 18 through 45 years of age, with a body mass index (BMI) of 20.0 to 30.0 kg/m2, inclusive.
• The subject is in good health as determined by medical and psychiatric history, physical examination, ECG, serum chemistry, hematology, urinalysis, and serology.
• Women must be surgically sterile, 2 years postmenopausal, or, if of child-bearing potential, be using an acceptable method of contraception, and agree to continued use of this method for the duration of the study and for 30 days after discontinuation of study drug. Acceptable methods of contraception include abstinence or an intrauterine device (known to have a failure rate of less than 1% per year).
• The subject has a negative alcohol test and urine drug screen.
• The subject must be willing and able to comply with study restrictions and to remain at the study center for the required duration of each study drug period during the study.

Exclusion Criteria:

• The subject has any clinically significant uncontrolled medical conditions (treated or untreated).
• The subject has a clinically significant deviation from normal in ECG or physical examination findings, as determined by the investigator or the medical monitor.
• The subject has habitually consumed, within the past 2 years, more than 21 units of alcohol per week, or has a history of alcohol, narcotic, or any other substance abuse as defined by the Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition, Text Revision (DSM-IV-TR, American Psychiatric Association 2000). NOTE: A unit of alcohol is equal to 1 ounce of hard liquor, 5 ounces of wine, or 8 ounces of beer.
• The subject is a pregnant or lactating woman. (Any women becoming pregnant during the study will be withdrawn from the study.)
• The subject has any disorder that may interfere with drug absorption, distribution, metabolism, or excretion (including GI surgery; a history of appendectomy is allowed).
• The subject has received any investigational drug within 30 days or 5 half-lives (whichever is longer) before the 1st dose of study drug, or in the case of a new chemical entity, 3 months or 5 half-lives (whichever is longer) before the 1st dose of study drug.
• The subject has a known sensitivity or idiosyncratic reaction to hydrocodone or hydromorphone, their related compounds, or to any metabolites, or naltrexone, or any compound listed as being present in a study formulation.
• Other exclusion criteria apply.