Det er observeret, at eliminations- halveringstiden øges med dosis fra cirka 3 timer ved 5 mg op til cirka 9 timer ved doser på 400 mg (den højere dosis menes at give et bedre estimat af t½).
The half-life of elimination has been observed to increase with dose, from approximately 3 hours at 5 mg up to approximately 9 hours at doses of 400 mg (the higher dose is believed to provide a better estimate of t½).