Vicodin is the brand name for a combination drug consisting of hydrocodone bitartrate and acetaminophen, whereas Tylenol 3 is the brand name for a combination drug consisting of codeine phosphate and acetaminophen, according to Drugs.com. Both consist of a narcotic pain reliever along with acetaminophen for the treatment of moderate-to-severe pain and are prescribed for similar reasons. Hydrocodone is chemically related to codeine and is classified as a semisynthetic opioid. Codeine occurs naturally.
Vicodin tablets containing three different dosages of hydrocodone are available: 5 milligrams, 7.5 milligrams and 10 milligrams, explains AbbVie, the manufacturer of Vicodin. The dosage of acetaminophen is 300 milligrams for each variety. In contrast, Tylenol 3 consists of 30 milligrams of codeine combined with 300 milligrams of acetaminophen.
A dosage of 30 milligrams of orally administered codeine is equivalent to approximately 2 to 5 milligrams of hydrocodone, according to CliniCalc.com. Codeine has an average half-life of approximately 2.9 hours, whereas hydrocodone has an average half-life of 3.8 hours. Codeine is a prodrug, meaning that it must be metabolized to an active compound in the body, whereas hydrocodone is not. Orally administered codeine is metabolized to morphine in the liver, reports PharmGKB. The effectiveness of codeine in treating pain can be highly variable among patients due to differences in hepatic metabolism.