It is a narcotic and may cause withdrawal symptoms if it is stopped too abruptly. Although Norco withdrawal can be quite unpleasant and uncomfortable, you can be assured that it is not life threatening. Norco withdrawal is possible in people who abuse Norco and in people who take Norco for a legitimate medical use.
Definition of melanin for English Language Learners. : a dark brown or black substance that is a natural part of people's skin, hair, and eyes.
Melanosomes are the granules within melanocytes where melanin is synthesized. In humans, melanin is the primary determinant of skin color and is also found in hair and the iris. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and its reduced forms. Most eumelanins are derived from the amino acid tyrosine.