INBDE Pharmacology Practice Test

Acetaminophen has the potential for liver toxicity when combined with alcohol or taken in excessive daily doses because it can form a reactive metabolite that damages liver cells. Most acetaminophen is safely processed into non-toxic substances, but a small amount is oxidized by liver enzymes to NAPQI, a highly reactive compound. Under normal dosing, NAPQI is quickly detoxified by glutathione and eliminated. When dosing is too high or alcohol is involved, more acetaminophen is shunted toward the NAPQI pathway, and glutathione stores can be depleted. The excess NAPQI then binds to liver cell proteins, causing oxidative stress and hepatocellular injury, which can progress to liver failure. Chronic alcohol use increases the production of NAPQI by inducing enzymes like CYP2E1, raising the risk. If treated early, N-acetylcysteine helps replenish glutathione and neutralize NAPQI. The other drugs listed don’t have this specific, alcohol-triggered liver-toxic pathway linked to their usual therapeutic use.