To determine the pharmacokinetics of 2 intranasal doses and 1 oral dose of naltrexone compared to an intramuscular dose of naltrexone.

Inclusion Criteria:

• Males and females 18 to 55 years of age, inclusive.
• Provide written informed consent.
• BMI ranging from 18 to 30 kg/m2, inclusive.
• Adequate venous access.
• No clinically significant concurrent medical conditions determined by medical history, physical examination, clinical laboratory examination, vital signs, and 12-lead ECG.
• Male subjects must agree to use an acceptable method of contraception with female partners as well as not to donate sperm throughout the study and for 90 days after the last study drug administration. Female subject of childbearing potential must agree to use an acceptable method of birth control throughout the study and for 30 days after the last study drug administration. Oral contraceptives are prohibited.
• Agree not to ingest alcohol, drinks containing xanthine >500 mg/day (e.g., Coca Cola®, coffee, tea, etc.), or grapefruit/grapefruit juice.
• Participate in strenuous exercise 72 hours prior to admission through the last blood draw of the study.

Exclusion Criteria:

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