Unable to obtain FDA approval

This study is being done to determine the systemic absorption of nasally inhaled acetaminophen (Tylenol®) versus orally ingested acetaminophen by comparing the serum drug concentrations of the two groups obtained at various times after study drug administration.

This study is aimed at addressing a significant void in the current literature regarding nasally administered acetaminophen pharmacokinetics. The pharmacokinetics of acetaminophen following oral and rectal administration have been well studied but to date there are no published studies determining the pharmacokinetics of acetaminophen following intranasal administration. This route is currently popular among heroin users. Understanding the pharmacokinetics of nasally administered acetaminophen will help physicians address the important clinical implications of acetaminophen toxicity in this population.

Ten healthy adult volunteers age 18 to 45 years will be recruited for this pilot project. Study participants will be randomized in permuted blocks to receive either oral or intranasal administration of a standardized 500 mg dose of acetaminophen. Blood samples will be drawn from a peripheral intravenous catheter at 0, 5, 15, 30, 45, 60, 90, 120, 150, 240, 360, and 480 minutes after study drug administration and sent to the laboratory for determination of serum acetaminophen concentration. After a one week washout period, each participant will cross over to receive 500 mg of acetaminophen via the remaining route of administration in the second arm of the study. The serial acetaminophen concentrations will be utilized to perform pharmacokinetic calculations.

Inclusion Criteria:

• Healthy volunteers 18 to 45 years of age

Exclusion Criteria:

• Known hypersensitivity to acetaminophen
• Prior dosing of acetaminophen or product containing acetaminophen in the preceding 7 days
• Hepatic insufficiency and/or failure, or any known liver disease
• History of nasal polyps
• History of nasal trauma in past 14 days
• History of nasal bleeding in past 14 days
• History of asthma, emphysema or any serious respiratory diseases
• Pregnancy or breastfeeding