Health Science: Drug Half-life Andros Gel 1.62% is a drug used to treat adult males who have low or no testosterone. It is marketed by Abbott Laboratory and has the half-life an advertised estimated half-life of between 10 and 100 hours. The half-life of a drug is the amount of time it takes the drug to be reduced to one-half its original amount. Drugs decay in the bloodstream according to the exponential decay model A Aoe ^-kt, where A0 is the amount of the drug initial treed, and k is the decay constant. The exponential decay models for the 10- hour and 100-hour half-life estimates are, respectively, A = Aoe-o ^-0.06931t. Just by observing the models, how do you tell which one corresponds to the 10-hour half-life estimate? y present, A is the amount present t hours after being admonish- Source: www.drugs.com