The following pharmacology definition has been taken from the Pharmacology and Experimental Therapeutics Department Glossary at Boston University School of Medicine.
The “absorption rate constant” for a drug administered by a route other than the intravenous. The rate of absorption of a drug absorbed from its site of application according to first-order kinetics. ka is determined directly, or indirectly, as the slope of the linear relationship between the logarithm of the amount un absorbed and t, when natural logarithms, i.e. logarithms to the base e, are used. The half-time for absorption is computed as 0.693/ka, i.e. ln 2/ka.
The copyright of the text is hold by Trustees of Boston University. Permission has been granted for its use in this blog.