STEEP (initial) part of curve -> initial distribution of the drug in the body. Many drugs follow a biphasic elimination curve - first a steep slope then a shallow slope:
For this reason, drugs with a long half-life (e.g., amiodarone, elimination t ½ of about 58 days) are usually started with a loading dose to achieve their desired clinical effect more quickly. So, for example, digoxin has a half-life (or t ½) of 24–36 h this means that a change in the dose will take the best part of a week to take full effect. In clinical practice, this means that it takes 4 to 5 times the half-life for a drug's serum concentration to reach steady state after regular dosing is started, stopped, or the dose changed. Time for a medication to halve its concentration in blood plasmaīiological half-life (also known as elimination half-life, pharmacologic half-life) of a biological substance such as medication is the time it takes from its maximum concentration ( C max) to half of its maximum concentration in the blood plasma, and is denoted by the abbreviation t 1 2
