A purpose of this protocol is to is to compare the metabolites of the toxic bioactivating pathway after acetaminophen alone or acetaminophen followed by Propylene Glycol (PG) and to determine if it prevents the formation of the toxic metabolites of acetaminophen.

The purpose of this protocol is to contribute to our overarching purpose, which is to determine if inhibiting the bioactivation of acetaminophen (APAP) can prevent liver injury, and to further describe the initiating mechanisms of APAP induced liver injury. APAP induced liver injury is caused by metabolism and/or the resulting metabolites when APAP undergoes reductive metabolism via the cytochrome P450 (CYP) system, principally via CYP 2E1. Inhibition of CYP 2E1 activity protects against toxicity in rodents and tissue culture. Our prior research indicates that inhibition of CYP 2E1 by administering a pediatric preparation of APAP containing Propylene Glycol (PG), a known CYP 2E1 inhibitor, results in reduced production of CYP 2E1 derived metabolites via competitive inhibition.

In this proposed protocol the investigators will provide therapeutic doses of APAP and a separately administered non toxic dose of PG over a two-week period to healthy subjects. 20-75% of healthy people who take therapeutic doses of APAP for 7-28 days will have an asymptomatic and subclinical rise in transaminase levels that will return to baseline without adverse effect or therapy. 3 The return to baseline occurs despite continued dosing of APAP.

A primary purpose is to determine if PG is, in fact, the substance in the liquid preparation responsible for the effect the investigators observed in the investigators initial study. A secondary purpose is to obtain plasma samples for secondary metabolomic analysis to elucidate the effect of CYP 2E1 inhibition.

Specific Aims

• 1 To demonstrate that co-administration of PG with APAP prevents the rise in AST/ALT expected in approximately one third of subjects following therapeutic dosing of APAP over days.
• 2 To show that PG administered with APAP reduces toxic P450-derived metabolite production following therapeutic APAP administration.
• 3 To obtain plasma samples to undergo metabolomic and other analyses to determine the effects of CYP 2E1 inhibition in the setting of APAP administration.
• 4 To undergo metabolomic analyses on the day LFT's peak to determine differences in metabolomics parameters between subjects receiving propylene glycol plus acetaminophen versus just acetaminophen alone.

Inclusion Criteria:

• Healthy volunteers ages 20-40
• Patients not taking any chronic medications

Exclusion Criteria:

• Any history of liver disease
• Frequent alcohol use (2 or more drinks more than 4 times per week)
• Pregnant women
• Chronic medical condition requiring daily pharmacotherapy or the use of any daily prescription medications.
• Unable to provide informed consent

We plan to publish the data in near future but there is no plan on sharing the individual participant data

During Participation in the study (6 weeks)

Adverse events were be monitored at every by trained investigators at the Harvard-Thorndike Clinical Research Center at Beth Israel Deaconess Medical Center. Additionally, study participants were instructed to contact the study team for any symptoms out of the ordinary.